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1.	Allencherril, Joseph, et al. (författare) Appropriateness of anteroseptal myocardial infarction nomenclature evaluated by late gadolinium enhancement cardiovascular magnetic resonance imaging 2018 Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 0022-0736. ; 51:2, s. 218-223 Tidskriftsartikel (refereegranskat)abstract Background: In traditional literature, it appears that "anteroseptal" MIs with Q waves in V1-V3 involve basal anteroseptal segments although studies have questioned this belief. Methods: We studied patients with first acute anterior Q-wave (>. 30. ms) MI. All underwent late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (MRI). Results: Those with Q waves in V1-V2 (n = 7) evidenced LGE >. 50% in 0%, 43%, 43%, 57%, and 29% of the basal anteroseptal, mid anteroseptal, apical anterior, apical septal segments, and apex, respectively. Patients with Q waves in V1-V3 (n = 14), evidenced involvement was 14%, 43%, 43%, 50%, and 7% of the same respective segments. In those with extensive anterior Q waves (n = 7), involvement was 0%, 71%, 57%, 86%, and 86%. Conclusions: Q-wave MI in V1-V2/V3 primarily involves mid- and apical anterior and anteroseptal segments rather than basal segments. Data do not support existence of isolated basal anteroseptal or septal infarction. "Anteroapical infarction" is a more appropriate term than "anteroseptal infarction.".
2.	Allencherril, Joseph, et al. (författare) Correlation of anteroseptal ST elevation with myocardial infarction territories through cardiovascular magnetic resonance imaging 2018 Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 0022-0736. ; 51:4, s. 563-568 Tidskriftsartikel (refereegranskat)abstract Background: Anteroseptal ST elevation myocardial infarction (STEMI) is traditionally defined on the electrocardiogram (ECG) by ST elevation (STE) in leads V1-V3, with or without involvement of lead V4. It is commonly taught that such infarcts affect the basal anteroseptal myocardial segment. While there are suggestions in the literature that Q waves limited to V1-V4 represent predominantly apical infarction, none have evaluated anteroseptal ST elevation territories. We compared the distribution of the myocardium at risk (MaR) in STEMI patients presenting with STE limited to V1-V4 and those with more extensive STE (V1-V6). Methods: We identified patients in the MITOCARE study presenting with a first acute STEMI and new STE in at least two contiguous anterior leads from V1 to V6. Patients underwent cardiac magnetic resonance (CMR) imaging three to five days after acute infarction. Results: Thirty-two patients met inclusion criteria. In patients with STE in V1-V4 (n = 20), myocardium at risk (MaR) > 50% was seen in 0%, 85%, 75%, 100%, and 90% in the basal anteroseptal, mid anteroseptal, apical anterior, apical septal segments, and apex, respectively. The group with STE in V1-V6 (n = 12), MaR > 50% was seen in 8%, 83%, 83%, 92%, and 83% of the same segments. Conclusions: Patients with acute STEMI and STE in leads V1-V4, exhibit MaR in predominantly apical territories and rarely in the basal anteroseptum. We found no evidence to support existence of isolated basal anteroseptal or septal STEMI. “Anteroapical” infarction is a more precise description than “anteroseptal” infarction for acute STEMI patients exhibiting STE in V1-V4.
3.	Arvidsson, Per M., et al. (författare) Hemodynamic forces using four-dimensional flow MRI : An independent biomarker of cardiac function in heart failure with left ventricular dyssynchrony? 2018 Ingår i: American Journal of Physiology - Heart and Circulatory Physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 315:6, s. 1627-1639 Tidskriftsartikel (refereegranskat)abstract Patients with heart failure with left ventricular (LV) dyssynchrony often do not respond to cardiac resynchronization therapy (CRT), indicating that the pathophysiology is insufficiently understood. Intracardiac hemodynamic forces computed from four-dimensional (4-D) flow MRI have been proposed as a new measure of cardiac function. We therefore aimed to investigate how hemodynamic forces are altered in LV dyssynchrony. Thirty-one patients with heart failure and LV dyssynchrony and 39 control subjects underwent cardiac MRI with the acquisition of 4-D flow. Hemodynamic forces were computed using Navier-Stokes equations and integrated over the manually delineated LV volume. The ratio between transverse (lateral-septal and inferior-anterior) and longitudinal (apical-basal) forces was calculated for systole and diastole separately and compared with QRS duration, aortic valve opening delay, global longitudinal strain, and ejection fraction (EF). Patients exhibited hemodynamic force patterns that were significantly altered compared with control subjects, including loss of longitudinal forces in diastole (force ratio, control subjects vs. patients: 0.32 vs. 0.90, P < 0.0001) and increased transverse force magnitudes. The systolic force ratio was correlated with global longitudinal strain and EF (P < 0.01). The diastolic force ratio separated patients from control subjects (area under the curve: 0.98, P < 0.0001) but was not correlated to other dyssynchrony measures (P > 0.05 for all). Hemodynamic forces by 4-D flow represent a new approach to the quantification of LV dyssynchrony. Diastolic force patterns separate healthy from diseased ventricles. Different force patterns in patients indicate the possible use of force analysis for risk stratification and CRT implantation guidance. NEW & NOTEWORTHY In this report, we demonstrate that patients with heart failure with left ventricular dyssynchrony exhibit significantly altered hemodynamic forces compared with normal. Force patterns in patients mechanistically reflect left ventricular dysfunction on the organ level, largely independent of traditional dyssynchrony measures. Force analysis may help clinical decision making and could potentially be used to improve therapy outcomes.
4.	Arvidsson, Per Martin, et al. (författare) Kinetic energy of left ventricular blood flow across heart failure phenotypes and in subclinical diastolic dysfunction 2022 Ingår i: Journal of Applied Physiology. - : American Physiological Society. - 1522-1601 .- 8750-7587. ; 133:3, s. 697-709 Tidskriftsartikel (refereegranskat)abstract BACKGROUND: Kinetic energy (KE) of intracardiac blood flow reflects myocardial work spent on accelerating blood and provides a mechanistic window into diastolic filling dynamics. Diastolic dysfunction may represent an early stage in the development of heart failure (HF). Here we evaluated the hemodynamic effects of impaired diastolic function in subjects with and without HF, testing the hypothesis that left ventricular KE differs between controls, subjects with subclinical diastolic dysfunction (SDD), and HF patients.METHODS: We studied 77 subjects (16 controls, 20 subjects with SDD, 16 HFpEF, 9 HFmrEF, and 16 HFrEF patients, age- and sex-matched at the group level). Cardiac magnetic resonance at 1.5T included intracardiac 4D flow and cine imaging. Left ventricular KE was calculated as 0.5mv 2. RESULTS: Systolic KE was similar between groups (p>0.4), also after indexing to stroke volume (p=0.25), and was primarily driven by ventricular emptying rate (p<0.0001, R 2=0.52). Diastolic KE was higher in heart failure patients than controls (p<0.05) but similar between SDD and HFpEF (p>0.18), correlating with inflow conditions (E-wave velocity, p<0.0001, R 2=0.24) and end-diastolic volume (p=0.0003, R 2=0.17) but not with average e' (p=0.07). CONCLUSIONS: Diastolic KE differs between controls and heart failure, suggesting more work is spent filling the failing ventricle, while systolic KE does not differentiate between well-matched groups with normal ejection fraction even in the presence of relaxation abnormalities and heart failure. Mechanistically, KE reflects the acceleration imparted on the blood and is driven by variations in ventricular emptying and filling rates, volumes, and heart rate, regardless of underlying pathology.
5.	Arvidsson, Per Martin, et al. (författare) Kinetic energy of left ventricular blood flow across heart failure phenotypes and in subclinical diastolic dysfunction. 2022 Ingår i: Journal of applied physiology (Bethesda, Md. : 1985). - : American Physiological Society. - 1522-1601. Tidskriftsartikel (refereegranskat)abstract Kinetic energy (KE) of intracardiac blood flow reflects myocardial work spent on accelerating blood and provides a mechanistic window into diastolic filling dynamics. Diastolic dysfunction may represent an early stage in the development of heart failure (HF). Here we evaluated the hemodynamic effects of impaired diastolic function in subjects with and without HF, testing the hypothesis that left ventricular KE differs between controls, subjects with subclinical diastolic dysfunction (SDD), and HF patients.We studied 77 subjects (16 controls, 20 subjects with SDD, 16 HFpEF, 9 HFmrEF, and 16 HFrEF patients, age- and sex-matched at the group level). Cardiac magnetic resonance at 1.5T included intracardiac 4D flow and cine imaging. Left ventricular KE was calculated as 0.5mv2.Systolic KE was similar between groups (p>0.4), also after indexing to stroke volume (p=0.25), and was primarily driven by ventricular emptying rate (p<0.0001, R2=0.52). Diastolic KE was higher in heart failure patients than controls (p<0.05) but similar between SDD and HFpEF (p>0.18), correlating with inflow conditions (E-wave velocity, p<0.0001, R2=0.24) and end-diastolic volume (p=0.0003, R2=0.17) but not with average e' (p=0.07).Diastolic KE differs between controls and heart failure, suggesting more work is spent filling the failing ventricle, while systolic KE does not differentiate between well-matched groups with normal ejection fraction even in the presence of relaxation abnormalities and heart failure. Mechanistically, KE reflects the acceleration imparted on the blood and is driven by variations in ventricular emptying and filling rates, volumes, and heart rate, regardless of underlying pathology.
6.	Arvidsson, Per M., et al. (författare) Left and right ventricular hemodynamic forces in healthy volunteers and elite athletes assessed with 4D flow magnetic resonance imaging 2017 Ingår i: American Journal of Physiology - Heart and Circulatory Physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 312:2, s. 314-328 Tidskriftsartikel (refereegranskat)abstract Intracardiac blood flow is driven by hemodynamic forces that are exchanged between the blood and myocardium. Previous studies have been limited to 2D measurements or investigated only left ventricular (LV) forces. Right ventricular (RV) forces and their mechanistic contribution to asymmetric redirection of flow in the RV have not been measured. We therefore aimed to quantify 3D hemodynamic forces in both ventricles in a cohort of healthy subjects, using magnetic resonance imaging 4D flow measurements. Twenty five controls, 14 elite endurance athletes, and 2 patients with LV dyssynchrony were included. 4D flow data were used as input for the Navier-Stokes equations to compute hemodynamic forces over the entire cardiac cycle. Hemodynamic forces were found in a qualitatively consistent pattern in all healthy subjects, with variations in amplitude. LV forces were mainly aligned along the apical-basal longitudinal axis, with an additional component aimed toward the aortic valve during systole. Conversely, RV forces were found in both longitudinal and short-axis planes, with a systolic force component driving a slingshot-like acceleration that explains the mechanism behind the redirection of blood flow toward the pulmonary valve. No differences were found between controls and athletes when indexing forces to ventricular volumes, indicating that cardiac force expenditures are tuned to accelerate blood similarly in small and large hearts. Patients’ forces differed from controls in both timing and amplitude. Normal cardiac pumping is associated with specific force patterns for both ventricles, and deviation from these forces may be a sensitive marker of ventricular dysfunction. Reference values are provided for future studies. New & Noteworthy Biventricular hemodynamic forces were quantified for the first time in healthy controls and elite athletes (n = 39). Hemodynamic forces constitute a slingshot-like mechanism in the right ventricle, redirecting blood flow toward the pulmonary circulation. Force patterns were similar between healthy subjects and athletes, indicating potential utility as a cardiac function biomarker.
7.	Arvidsson, Per Martin, et al. (författare) Quantification of left and right atrial kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements. 2013 Ingår i: Journal of Applied Physiology. - : American Physiological Society. - 1522-1601 .- 8750-7587. ; 114:10, s. 1472-1481 Tidskriftsartikel (refereegranskat)abstract Kinetic energy (KE) of atrial blood has been postulated as a possible contributor to ventricular filling. Therefore, we aimed to quantify the left and right atrial blood KE using cardiac magnetic resonance (CMR). Fifteen healthy volunteers underwent CMR at 3T, including a four-dimensional phase contrast flow sequence. Mean left atrial (LA) KE was lower than right atrial (RA) KE (1.1±0.1 mJ vs 1.7±0.1 mJ, P<0.01). Three KE peaks were seen in both atria; one in ventricular systole, one during early ventricular diastole, and one during atrial contraction. The systolic LA peak was significantly smaller than the RA peak (P<0.001), and the early diastolic LA peak was larger than the RA peak (P<0.05). Rotational flow contained 46 ± 7% of total KE, and conserved energy better than non-rotational flow did. The KE increase in early diastole was higher in the LA (P<0.001). Systolic KE correlated with the combination of atrial volume and systolic velocity of the atrioventricular plane displacement (R2=0.57 for LA and R2=0.64 for RA). Early diastolic KE of the LA correlated with LV mass (R2=0.28), however no such correlation was found in the right heart. This suggests that LA KE increases during early ventricular diastole due to LV elastic recoil, indicating that LV filling is dependent on diastolic suction. RV relaxation does not seem to contribute to atrial KE. Instead, atrial KE generated during ventricular systole may be conserved in a hydraulic "flywheel" and transferred to the RV through helical flow, which may contribute to RV filling.
8.	Arvidsson, Per M., et al. (författare) The shape of the healthy heart is optimized for vortex ring formation 2016 Ingår i: Journal of Cardiovascular Magnetic Resonance. - 1097-6647. ; 18, s. 1-2 Tidskriftsartikel (refereegranskat)
9.	Arvidsson, Per, et al. (författare) Vortex ring behavior provides the epigenetic blueprint for the human heart. 2016 Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6 Tidskriftsartikel (refereegranskat)abstract The laws of fluid dynamics govern vortex ring formation and precede cardiac development by billions of years, suggesting that diastolic vortex ring formation is instrumental in defining the shape of the heart. Using novel and validated magnetic resonance imaging measurements, we show that the healthy left ventricle moves in tandem with the expanding vortex ring, indicating that cardiac form and function is epigenetically optimized to accommodate vortex ring formation for volume pumping. Healthy hearts demonstrate a strong coupling between vortex and cardiac volumes (R(2) = 0.83), but this optimized phenotype is lost in heart failure, suggesting restoration of normal vortex ring dynamics as a new, and possibly important consideration for individualized heart failure treatment. Vortex ring volume was unrelated to early rapid filling (E-wave) velocity in patients and controls. Characteristics of vortex-wall interaction provide unique physiologic and mechanistic information about cardiac diastolic function that may be applied to guide the design and implantation of prosthetic valves, and have potential clinical utility as therapeutic targets for tailored medicine or measures of cardiac health.
10.	Atar, Dan, et al. (författare) Effect of intravenous TRO40303 as an adjunct to primary percutaneous coronary intervention for acute ST-elevation myocardial infarction: MITOCARE study results. 2015 Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 1522-9645 .- 0195-668X. ; 36:2, s. 112-119 Tidskriftsartikel (refereegranskat)abstract The MITOCARE study evaluated the efficacy and safety of TRO40303 for the reduction of reperfusion injury in patients undergoing revascularization for ST-elevation myocardial infarction (STEMI).
11.	Atar, Dan, et al. (författare) Rationale and Design of the 'MITOCARE' Study: A Phase II, Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Assess the Safety and Efficacy of TRO40303 for the Reduction of Reperfusion Injury in Patients Undergoing Percutaneous Coronary Intervention for Acute Myocardial Infarction 2012 Ingår i: Cardiology. - : S. Karger AG. - 1421-9751 .- 0008-6312. ; 123:4, s. 201-207 Tidskriftsartikel (refereegranskat)abstract Treatment of acute ST-elevation myocardial infarction (STEMI) by reperfusion using percutaneous coronary intervention (PCI) or thrombolysis has provided clinical benefits; however, it also induces considerable cell death. This process is called reperfusion injury. The continuing high rates of mortality and heart failure after acute myocardial infarction (AMI) emphasize the need for improved strategies to limit reperfusion injury and improve clinical outcomes. The objective of this study is to assess safety and efficacy of TRO40303 in limiting reperfusion injury in patients treated for STEMI. TRO40303 targets the mitochondrial permeability transition pore, a promising target for the prevention of reperfusion injury. This multicenter, double-blind study will randomize patients with STEMI to TRO40303 or placebo administered just before balloon inflation or thromboaspiration during PCI. The primary outcome measure will be reduction in infarct size (assessed as plasma creatine kinase and troponin I area under the curve over 3 days). The main secondary endpoint will be infarct size normalized to the myocardium at risk (expressed by the myocardial salvage index assessed by cardiac magnetic resonance). The study is being financed under an EU-FP7 grant and conducted under the auspices of the MITOCARE research consortium, which includes experts from clinical and basic research centers, as well as commercial enterprises, throughout Europe. Results from this study will contribute to a better understanding of the complex pathophysiology underlying myocardial injury after STEMI. The present paper describes the rationale, design and the methods of the trial. Copyright (c) 2012 S. Karger AG, Basel
12.	Berg, Jonathan, et al. (författare) Mild hypothermia attenuates ischemia/reperfusion injury - insights from serial non-invasive pressure-volume loops 2023 Ingår i: Cardiovascular Research. - : Oxford University Press (OUP). - 1755-3245 .- 0008-6363. ; 119:12, s. 2230-2243 Tidskriftsartikel (refereegranskat)abstract BACKGROUND: Mild hypothermia, 32-35°C, reduces infarct size in experimental studies, potentially mediating reperfusion injuries, but human trials have been ambiguous. To elucidate the cardioprotective mechanisms of mild hypothermia, we analyzed cardiac performance in a porcine model of ischemia/reperfusion, with serial cardiovascular magnetic resonance (CMR) imaging throughout one week using non-invasive pressure-volume loops.METHODS AND RESULTS: Normothermia and Hypothermia groups sessions (n=7+7 pigs, nonrandom allocation) were imaged with CMR at baseline and subjected to 40 minutes of normothermic ischemia by catheter intervention. Thereafter, the Hypothermia group was rapidly cooled (mean 34.5°C) for 5 minutes before reperfusion. Additional CMR sessions at two hours, 24 hours, and seven days acquired ventricular volumes and ischemic injuries (unblinded analysis).Stroke volume (-24%; p=0.029; Friedmans test) and ejection fraction (-20%; p=0.068) were notably reduced at 24h in the Normothermia group compared to baseline. In contrast, the decreases were ameliorated in the Hypothermia group (stroke volume: -6%; p=0.77; ejection fraction: -6%; p=0.13). Mean arterial pressure remained stable in Normothermic animals (-3%, p=0.77) but dropped two hours post-reperfusion in hypothermic animals (-18%, p=0.007). Both groups experienced a decrease and partial recovery pattern for PV loop-derived variables over one week, but the adverse effects tended attenuated in the Hypothermia group. Infarct sizes were 10±8% in Hypothermic and 15±8% in Normothermic animals (p=0.32). Analysis of covariance at 24 hours indicated that hypothermia has cardioprotective properties incremental to reducing infarct size, such as higher external power (p=0.061) and lower arterial elastance (p=0.015).CONCLUSION: Using non-invasive pressure-volume loops by CMR, we observed that mild hypothermia at reperfusion alleviates the heart's work after ischemia/reperfusion injuries during the first week and preserves short-term cardiac performance. This hypothesis-generating study suggests hypothermia to have cardioprotective properties, incremental to reducing infarct size. The primary cardioprotective mechanism was likely an afterload reduction acutely unloading the left ventricle.
13.	Berg, Jonathan, et al. (författare) Ventricular longitudinal function by cardiovascular magnetic resonance predicts cardiovascular morbidity in HFrEF patients 2022 Ingår i: ESC Heart Failure. - : Wiley. - 2055-5822. ; 9:4, s. 2313-2324 Tidskriftsartikel (refereegranskat)abstract Aims: Ventricular longitudinal function measured as basal-apical atrioventricular plane displacement (AVPD) or global longitudinal strain (GLS) is a potent predictor of mortality and could potentially be a predictor of heart failure-associated morbidity. We hypothesized that low AVPD and GLS are associated with the combined endpoint of cardiovascular mortality and heart failure-associated morbidity. Methods and results: Two hundred eighty-seven patients (age 62 ± 12 years, 78% male) with heart failure with reduced (≤40%) ejection fraction (HFrEF) referred to a cardiovascular magnetic resonance exam were included. Ventricular longitudinal function, ventricular volume, and myocardial fibrosis or infarction were analysed from cine and late gadolinium enhancement images. National registries provided data on causes of cardiovascular hospitalizations and cardiovascular mortality for the combined endpoint. Time-to-event analysis capable of including reoccurring events was employed with a 5-year follow-up. HFrEF patients had EF 26.5 ± 8.0%, AVPD 7.8 ± 2.4 mm, and GLS −7.5 ± 3.0%. In contrast, ventricular longitudinal function was approximately twice as large in an age-matched control group (AVPD 15.3 ± 1.6 mm; GLS −20.6 ± 2.0%; P < 0.001 for both). There were 578 events in total, and the majority were HF hospitalizations (n = 418). Other major events were revascularizations (n = 64), cardiovascular deaths (n = 40), and myocardial infarctions (n = 21). One hundred fifty-five (54%) patients experienced at least one event (mean 2.0, range 0–64). Of these patients, 119 (71%) had three events or fewer, and the first three events comprised 51% of all events (295 events). Patients in the bottom AVPD or GLS tertile (<6.8 mm or >−6.1%) overall experienced more than 3 times as many events as the top tertile (>8.8 mm or <−8.4%; P < 0.001). Patients in this tertile also faced more cardiovascular deaths (P < 0.05), HF hospitalizations (P = 0.001), myocardial infarctions (only GLS: P = 0.032), and accumulated longer in-hospital length-of-stay overall (AVPD 20.9 vs. 9.1 days; GLS 22.4 vs. 6.5 days; P = 0.001 for both), and from HF hospitalizations (AVPD 19.3 vs. 8.3 days; GLS 19.3 vs. 5.4 days; P = 0.001 for both). In multivariate analysis adjusted for significant covariates, AVPD and GLS remained independent predictors of events (hazard ratio 1.12 per-mm-decrease and 1.13 per-%-increase) alongside hyponatremia (<135 mmol/L), aetiology of HF, and LV end-diastolic volume index. Conclusions: Low ventricular longitudinal function is associated with an increase in number of events as well as longer in-hospital stay from cardiovascular causes. In addition, AVPD and GLS have independent prognostic value for cardiovascular mortality and morbidity in HFrEF patients.
14.	Berggren, Klas, et al. (författare) Super-Resolution Cine Image Enhancement for Fetal Cardiac Magnetic Resonance Imaging 2022 Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 56:1, s. 223-231 Tidskriftsartikel (refereegranskat)abstract BackgroundFetal cardiac magnetic resonance imaging (MRI) improves the diagnosis of congenital heart defects, but is sensitive to fetal motion due to long image acquisition time. This may be overcome with faster image acquisition with low resolution, followed by image enhancement to provide clinically useful images.PurposeTo combine phase-encoding undersampling with super-resolution neural networks to achieve high-resolution fetal cine cardiac MR images with short acquisition time.Study TypeProspective.SubjectsTwenty-eight fetuses (gestational week 36 [interquartile range 33–38 weeks]).Field Strength/Sequence1.5 T, balanced steady-state free precession (bSSFP) cine sequence.AssessmentImages were acquired using fully sampled Doppler ultrasound-gated clinical bSSFP cine as reference, with equivalent cine sequences with decreased phase-encoding resolution (25%, 33%, and 50% of clinical standard). Two super-resolution methods based on convolutional neural networks were proposed and evaluated (phasrGAN and phasrresnet). Data were partitioned into training (36 cine slices), validation (3 cine slices), and test sets (67 cine slices) without overlap. Conventional reconstruction methods using bicubic interpolation and k-space zeropadding were used for comparison. Three blinded observers scored image quality between 1 and 10.Statistical TestsImage scores are reported as median [interquartile range] and were compared using Mann–Whitney's nonparametric test with P < 0.05 showing statistically significant differences.ResultsBoth proposed methods showed no significant difference in image quality compared to clinical images (8 [7–8.5]) down to 33% (phasrGAN 8 [6.5–8]; phasrresnet 8 [7–8], all P ≥ 0.19) phase-encoding resolution, i.e., up to three times faster image acquisition, whereas bicubic interpolation and k-space zeropadding showed significantly lower quality for 33% phase-encoding resolution (both 7 [6–8]).Data ConclusionSuper-resolution enhancement can be used for fetal cine cardiac MRI to reduce image acquisition time while maintaining image quality. This may lead to an improved success rate for fetal cine MR imaging, as the impact of fetal motion is lessened by shortened acquisitions.Level of Evidence1Technical EfficacyStage 2
15.	Bidhult, Sebastian, et al. (författare) A new vessel segmentation algorithm for robust blood flow quantification from two-dimensional phase-contrast magnetic resonance images 2019 Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 39:5, s. 327-338 Tidskriftsartikel (refereegranskat)abstract Blood flow measurements in the ascending aorta and pulmonary artery from phase-contrast magnetic resonance images require accurate time-resolved vessel segmentation over the cardiac cycle. Current semi-automatic segmentation methods often involve time consuming manual correction, relying on user experience for accurate results. The purpose of this study was to develop a semi-automatic vessel segmentation algorithm with shape constraints based on manual vessel delineations for robust segmentation of the ascending aorta and pulmonary artery, to evaluate the proposed method in healthy volunteers and patients with heart failure and congenital heart disease, to validate the method in a pulsatile flow phantom experiment, and to make the method freely available for research purposes. Algorithm shape constraints were extracted from manual reference delineations of the ascending aorta (n=20) and pulmonary artery (n=20) and were included into a semi-automatic segmentation method only requiring manual delineation in one image. Bias and variability (bias±SD) for flow volume of the proposed algorithm versus manual reference delineations were 0·0±1·9ml in the ascending aorta (n=151; 7 healthy volunteers; 144 heart failure patients) and -1·7±2·9 ml in the pulmonary artery (n=40; 25 healthy volunteers; 15 patients with atrial septal defect). Inter-observer bias and variability were lower (p=0·008) for the proposed semi-automatic method (-0·1±0·9ml) compared to manual reference delineations (1·5±5·1ml). Phantom validation showed good agreement between the proposed method and timer-and-beaker flow volumes (0·4±2·7ml). In conclusion, the proposed semi-automatic vessel segmentation algorithm can be used for efficient analysis of flow and shunt volumes in the aorta and pulmonary artery. This article is protected by copyright. All rights reserved.
16.	Bidhult, Sebastian, et al. (författare) Independent validation of metric optimized gating for fetal cardiovascular phase-contrast flow imaging 2019 Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 81:1, s. 495-503 Tidskriftsartikel (refereegranskat)abstract PURPOSE: To validate metric optimized gating phase-contrast MR (MOG PC-MR) flow measurements for a range of fetal flow velocities in phantom experiments. 2) To investigate intra- and interobserver variability for fetal flow measurements at an imaging center other than the original site.METHODS: MOG PC-MR was compared to timer/beaker measurements in a pulsatile flow phantom using a heart rate (∼145 bpm), nozzle diameter (∼6 mm), and flow range (∼130-700 mL/min) similar to fetal imaging. Fifteen healthy fetuses were included for intra- and interobserver variability in the fetal descending aorta and umbilical vein.RESULTS: Phantom MOG PC-MR flow bias and variability was 2% ± 23%. Accuracy of MOG PC-MR was degraded for flow profiles with low velocity-to-noise ratio. Intra- and interobserver coefficients of variation were 6% and 19%, respectively, for fetal descending aorta; and 10% and 17%, respectively, for the umbilical vein.CONCLUSION: Phantom validation showed good agreement between MOG and conventionally gated PC-MR, except for cases with low velocity-to-noise ratio, which resulted in MOG misgating and underestimated peak velocities and warranted optimization of sequence parameters to individual fetal vessels. Inter- and intraobserver variability for fetal MOG PC-MR imaging were comparable to previously reported values.
17.	Bidhult, Sebastian L, et al. (författare) A new validated T2* analysis method with certainty estimates for cardiac and liver iron load determination 2015 Ingår i: Journal of Cardiovascular Magnetic Resonance. - 1097-6647. ; 17:Suppl 1, s. 52-52 Tidskriftsartikel (refereegranskat)abstract Journal of Cardiovascular Magnetic Resonance 2015, 17:P52. doi:10.1186/1532-429X-17-S1-P52
18.	Bidhult, Sebastian, et al. (författare) Validation of a new T2* algorithm and its uncertainty value for cardiac and liver iron load determination from MRI magnitude images. 2015 Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 75:4, s. 1717-1729 Tidskriftsartikel (refereegranskat)abstract To validate an automatic algorithm for offline T2* measurements, providing robust, vendor-independent T2*, and uncertainty estimates for iron load quantification in the heart and liver using clinically available imaging sequences.
19.	Bidhult, Sebastian, et al. (författare) Validation of a T1 and T2 mapping software for quantitative MRI 2016 Ingår i: Journal of Cardiovascular Magnetic Resonance. - 1097-6647. ; 18 Tidskriftsartikel (refereegranskat)
20.	Bidhult, Sebastian, et al. (författare) Validation of T1 and T2 algorithms for quantitative MRI : Performance by a vendor-independent software 2016 Ingår i: BMC Medical Imaging. - : Springer Science and Business Media LLC. - 1471-2342. ; 16:1 Tidskriftsartikel (refereegranskat)abstract Background: Determination of the relaxation time constants T1 and T2 with quantitative magnetic resonance imaging is increasingly used for both research and clinical practice. Recently, groups have been formed within the Society of Cardiovascular Magnetic Resonance to address issues with relaxometry. However, so far they have avoided specific recommendations on methodology due to lack of consensus and current evolving research. Standardised widely available software may simplify this process. The purpose of the current study was to develop and validate vendor-independent T1 and T2 mapping modules and implement those in the versatile and widespread software Segment, freely available for research and FDA approved for clinical applications. Results: The T1 and T2 mapping modules were developed and validated in phantoms at 1.5T and 3T with reference standard values calculated from reference pulse sequences using the Nelder-Mead Simplex optimisation method. The proposed modules support current commonly available MRI pulse sequences and both 2- and 3-parameter curve fitting. Images acquired in patients using three major vendors showed vendor-independence. Bias and variability showed high agreement with T1 and T2 reference standards for T1 (range 214-1752ms) and T2 (range 45-338ms), respectively. Conclusions: The developed and validated T1 and T2 mapping and quantification modules generated relaxation maps from current commonly used MRI sequences and multiple signal models. Patient applications showed usability for three major vendors.
21.	Bock, Jelena, et al. (författare) Validation and reproducibility of cardiovascular 4D-flow MRI from two vendors using 2 × 2 parallel imaging acceleration in pulsatile flow phantom and in vivo with and without respiratory gating 2018 Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. Tidskriftsartikel (refereegranskat)abstract Background: 4D-flow magnetic resonance imaging (MRI) is increasingly used. Purpose: To validate 4D-flow sequences in phantom and in vivo, comparing volume flow and kinetic energy (KE) head-to-head, with and without respiratory gating. Material and Methods: Achieva dStream (Philips Healthcare) and MAGNETOM Aera (Siemens Healthcare) 1.5-T scanners were used. Phantom validation measured pulsatile, three-dimensional flow with 4D-flow MRI and laser particle imaging velocimetry (PIV) as reference standard. Ten healthy participants underwent three cardiac MRI examinations each, consisting of cine-imaging, 2D-flow (aorta, pulmonary artery), and 2 × 2 accelerated 4D-flow with (Resp+) and without (Resp−) respiratory gating. Examinations were acquired consecutively on both scanners and one examination repeated within two weeks. Volume flow in the great vessels was compared between 2D- and 4D-flow. KE were calculated for all time phases and voxels in the left ventricle. Results: Phantom results showed high accuracy and precision for both scanners. In vivo, higher accuracy and precision (P < 0.001) was found for volume flow for the Aera prototype with Resp+ (–3.7 ± 10.4 mL, r = 0.89) compared to the Achieva product sequence (–17.8 ± 18.6 mL, r = 0.56). 4D-flow Resp− on Aera had somewhat larger bias (–9.3 ± 9.6 mL, r = 0.90) compared to Resp+ (P = 0.005). KE measurements showed larger differences between scanners on the same day compared to the same scanner at different days. Conclusion: Sequence-specific in vivo validation of 4D-flow is needed before clinical use. 4D-flow with the Aera prototype sequence with a clinically acceptable acquisition time (<10 min) showed acceptable bias in healthy controls to be considered for clinical use. Intra-individual KE comparisons should use the same sequence.
22.	Bolger, Ann F, 1957-, et al. (författare) Transit of blood flow through thehuman left ventricle mapped by cardiovascular magnetic resonance 2007 Ingår i: Journal of Cardiovascular Magnetic Resonance. - : Informa UK Limited. - 1097-6647 .- 1532-429X. ; 9:5, s. 741-747 Tidskriftsartikel (refereegranskat)abstract BACKGROUND:The transit of blood through the beating heart is a basic aspect of cardiovascular physiology which remains incompletely studied. Quantification of the components of multidirectional flow in the normal left ventricle (LV) is lacking, making it difficult to put the changes observed with LV dysfunction and cardiac surgery into context.METHODS:Three dimensional, three directional, time resolved magnetic resonance phase-contrast velocity mapping was performed at 1.5 Tesla in 17 normal subjects, 6 female, aged 44+/-14 years (mean+/-SD). We visualized and measured the relative volumes of LV flow components and the diastolic changes in inflowing kinetic energy (KE). Of total diastolic inflow volume, 44+/-11% followed a direct, albeit curved route to systolic ejection (videos 1 and 2), in contrast to 11% in a subject with mildly dilated cardiomyopathy (DCM), who was included for preliminary comparison (video 3). In normals, 16+/-8% of the KE of inflow was conserved to the end of diastole, compared with 5% in the DCM patient. Blood following the direct route lost or transferred less of its KE during diastole than blood that was retained until the next beat (1.6+/-1.0 millijoules vs 8.2+/-1.9 millijoules, p<0.05); whereas, in the DCM patient, the reduction in KE of retained inflow was 18-fold greater than that of the blood tracing the direct route.CONCLUSION:Multidimensional flow mapping can measure the paths, compartmentalization and kinetic energy changes of blood flowing into the LV, demonstrating differences of KE loss between compartments, and potentially between the flows in normal and dilated left ventricles.
23.	Bolger, Ann F, 1957-, et al. (författare) Tredimensionellt MR-blodflöde och diastolisk kinetisk energi kvantiferat med magnetisk resonanstomografi efter kirurgisk vänsterkammarrekonstruktion. Ny teknik för utvärdering av kammarfunktion. 2007 Ingår i: Riksstämman,2007. Konferensbidrag (övrigt vetenskapligt/konstnärligt)
24.	Brandt Heiberg, Einar, 1973- (författare) Efficient representations in matlab made easy - a tensor array toolbox 2001 Ingår i: Proceedings of Nordic Matlab Conference, 2001. ; , s. 213-216 Konferensbidrag (refereegranskat)abstract Tensors can be used to create efficient and intuitive representations for a wide variety of applications, including signal and image processing, mechanics and fluid dynamics. In order to achieve this in Matlab, a toolbox was developed designed to enhance Matlab's ability to store and manipulate arrays, such that each element in the array can be vectors or general tensors. This paper describes the implementation of the tool box and gives several examples on the usage of tensor representations for signal and image processing. Furthermore, the representation and processing of uncertain data using tensor representations is described as well.
25.	Cain, Peter, et al. (författare) Quantitative polar representation of left ventricular myocardial perfusion, function and viability using SPECT and cardiac magnetic resonance: initial results. 2005 Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 25:4, s. 215-222 Tidskriftsartikel (refereegranskat)abstract Background: The clinical management of patients with coronary artery disease (CAD) often involves a complex assessment of the extent and severity of changes in left ventricular (LV) myocardial perfusion, function and viability. We aimed to explore the feasibility of integrative quantitative representation of LV perfusion, function and viability in adjacent polar plots. In order to assess the clinical usefulness of the quantitative methods, we also explored the relationship and determined the agreement between visual scoring and quantitative measurement of regional perfusion and function. Methods: Ten patients with CAD underwent rest and stress 99mTc-tetrofosmin single photon emission computed tomography (SPECT) and cardiac magnetic resonance (CMR) imaging. Software was developed in-house for generating polar plots from semi-automatic quantification of rest and stress perfusion from SPECT, function from cine CMR and viability from delayed contrast enhancement (DE) CMR. The agreement between visual assessment and quantification of both perfusion and function was tested by Kendall's coefficient of concordance (W). Results: Polar plots were created using quantitative data from the semi-automatic analysis of perfusion, function and viability. Kendall's W for agreement between quantitative measurement and visual scoring was 1·0 (P<0·001) for perfusion and 0·85 (P<0·001) for function. Conclusions: Side-by-side quantitative polar representation of LV perfusion, function and viability is feasible and may aid in the complex assessment of these parameters. The agreement between quantitative measurement and visual scoring was very good for both perfusion and function.
26.	Carlhall, C., et al. (författare) Reply [2] 2006 Ingår i: American Journal of Physiology. Heart and Circulatory Physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 291:5 Annan publikation (övrigt vetenskapligt/konstnärligt)
27.	Carlhäll, Carljohan, 1973-, et al. (författare) Contribution of mitral annular excursion and shape dynamics to total left ventricular volume change 2004 Ingår i: American Journal of Physiology. Heart and Circulatory Physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 287:4, s. H1836-H1841 Tidskriftsartikel (refereegranskat)abstract The mitral annulus (MA) has a complex shape and motion, and its excursion has been correlated to left ventricular (LV) function. During the cardiac cycle the annulus’ excursion encompasses a volume that is part of the total LV volume change during both filling and emptying. Our objective was to evaluate the contribution of MA excursion and shape variation to total LV volume change. Nine healthy subjects aged 56 ± 11 (means ± SD) years underwent transesophageal echocardiography (TEE). The MA was outlined in all time frames, and a four-dimensional (4-D) Fourier series was fitted to the MA coordinates (3-D+time) and divided into segments. The annular excursion volume (AEV) was calculated based on the temporally integrated product of the segments’ area and their incremental excursion. The 3-D LV volumes were calculated by tracing the endocardial border in six coaxial planes. The AEV (10 ± 2 ml) represented 19 ± 3% of the total LV stroke volume (52 ± 12 ml). The AEV correlated strongly with LV stroke volume (r = 0.73; P < 0.05). Peak MA area occurred during middiastole, and 91 ± 7% of reduction in area from peak to minimum occurred before the onset of LV systole. The excursion of the MA accounts for an important portion of the total LV filling and emptying in humans. These data suggest an atriogenic influence on MA physiology and also a sphincter-like action of the MA that may facilitate ventricular filling and aid competent valve closure. This 4-D TEE method is the first to allow noninvasive measurement of AEV and may be used to investigate the impact of physiological and pathological conditions on this important aspect of LV performance.
28.	Carlhäll, Carljohan, 1973-, et al. (författare) Reply to article: Misinterpretation About the Contribution of the Left Ventricular Long-Axis Shortening to the Stroke Volume 2006 Ingår i: American Journal of Physiology. Heart and Circulatory Physiology. - : American Physiological Society. - 0363-6135 .- 1522-1539. ; 291:5, s. 2551-2552 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
29.	Carlsson, Marcus, et al. (författare) Functional Contribution of Circumferential Versus Longitudinal Strain : Different Concepts Suggest Conflicting Results. 2018 Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 71:2, s. 254-255 Tidskriftsartikel (refereegranskat)
30.	Carlsson, Marcus, et al. (författare) Myocardium at risk after acute infarction in humans on cardiac magnetic resonance: quantitative assessment during follow-up and validation with single-photon emission computed tomography. 2009 Ingår i: JACC: Cardiovascular Imaging. - : Elsevier BV. - 1876-7591 .- 1936-878X. ; 2:5, s. 569-576 Tidskriftsartikel (refereegranskat)abstract OBJECTIVES: Our goal was to validate myocardium at risk on T2-weighted short tau inversion recovery (T2-STIR) cardiac magnetic resonance (CMR) over time, compared with that seen with perfusion single-photon emission computed tomography (SPECT) in patients with ST-segment elevation myocardial infarction, and to assess the amount of salvaged myocardium after 1 week. BACKGROUND: To assess reperfusion therapy, it is necessary to determine how much myocardium is salvaged by measuring the final infarct size in relation to the initial myocardium at risk of the left ventricle (LV). METHODS: Sixteen patients with first-time ST-segment elevation myocardial infarction received (99m)Tc tetrofosmin before primary percutaneous coronary intervention. SPECT was performed within 4 h and T2-STIR CMR within 1 day, 1 week, 6 weeks, and 6 months. At 1 week, patients were injected with a gadolinium-based contrast agent for quantification of infarct size. RESULTS: Myocardium at risk at occlusion on SPECT was 33 +/- 10% of the LV. Myocardium at risk on T2-STIR did not differ from SPECT, at day 1 (29 +/- 7%, p = 0.49) or week 1 (31 +/- 6%, p = 0.16) but declined at week 6 (10 +/- 12%, p = 0.0096 vs. 1 week) and month 6 (4 +/- 11%, p = 0.0013 vs. 1 week). There was a correlation between myocardium at risk demonstrated by T2-STIR at week 1 and myocardium at risk by SPECT (r(2) = 0.70, p < 0.001), and the difference between the methods on Bland-Altman analysis was not significant (-2.3 +/- 5.7%, p = 0.16). Both modalities identified myocardium at risk in the same perfusion territory and in concordance with angiography. Final infarct size was 8 +/- 7%, and salvage was 75 +/- 19% of myocardium at risk. CONCLUSIONS: This study demonstrates that T2-STIR performed up to 1 week after reperfusion can accurately determine myocardium at risk as it was before opening of the occluded artery. CMR can also quantify salvaged myocardium as myocardium at risk minus final infarct size.
31.	Carlsson, Marcus, et al. (författare) Quantification and visualization of cardiovascular 4D velocity mapping accelerated with parallel imaging or k-t BLAST: head to head comparison and validation at 1.5 T and 3 T 2011 Ingår i: Journal of Cardiovascular Magnetic Resonance. - 1097-6647. ; 13:55 Tidskriftsartikel (refereegranskat)abstract Background: Three-dimensional time-resolved (4D) phase-contrast (PC) CMR can visualize and quantify cardiovascular flow but is hampered by long acquisition times. Acceleration with SENSE or k-t BLAST are two possibilities but results on validation are lacking, especially at 3 T. The aim of this study was therefore to validate quantitative in vivo cardiac 4D-acquisitions accelerated with parallel imaging and k-t BLAST at 1.5 T and 3 T with 2D-flow as the reference and to investigate if field strengths and type of acceleration have major effects on intracardiac flow visualization. Methods: The local ethical committee approved the study. 13 healthy volunteers were scanned at both 1.5 T and 3 T in random order with 2D-flow of the aorta and main pulmonary artery and two 4D-flow sequences of the heart accelerated with SENSE and k-t BLAST respectively. 2D-image planes were reconstructed at the aortic and pulmonary outflow. Flow curves were calculated and peak flows and stroke volumes (SV) compared to the results from 2D-flow acquisitions. Intra-cardiac flow was visualized using particle tracing and image quality based on the flow patterns of the particles was graded using a four-point scale. Results: Good accuracy of SV quantification was found using 3 T 4D-SENSE (r(2) = 0.86, -0.7 +/- 7.6%) and although a larger bias was found on 1.5 T (r(2) = 0.71, -3.6 +/- 14.8%), the difference was not significant (p = 0.46). Accuracy of 4D k-t BLAST for SV was lower (p < 0.01) on 1.5 T (r(2) = 0.65, -15.6 +/- 13.7%) compared to 3 T (r(2) = 0.64, -4.6 +/- 10.0%). Peak flow was lower with 4D-SENSE at both 3 T and 1.5 T compared to 2D-flow (p < 0.01) and even lower with 4D k-t BLAST at both scanners (p < 0.01). Intracardiac flow visualization did not differ between 1.5 T and 3 T (p = 0.09) or between 4D-SENSE or 4D k-t BLAST (p = 0.85). Conclusions: The present study showed that quantitative 4D flow accelerated with SENSE has good accuracy at 3 T and compares favourably to 1.5 T. 4D flow accelerated with k-t BLAST underestimate flow velocities and thereby yield too high bias for intra-cardiac quantitative in vivo use at the present time. For intra-cardiac 4D-flow visualization, however, 1.5 T and 3 T as well as SENSE or k-t BLAST can be used with similar quality.
32.	Carlsson, Marcus, et al. (författare) Quantification of left and right ventricular kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements 2012 Ingår i: American Journal of Physiology: Heart and Circulatory Physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 302:4, s. 893-900 Tidskriftsartikel (refereegranskat)abstract Carlsson M, Heiberg E, Toger J, Arheden H. Quantification of left and right ventricular kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements. Am J Physiol Heart Circ Physiol 302: H893-H900, 2012. First published December 16, 2011; doi: 10.1152/ajpheart. 00942.2011.-We aimed to quantify kinetic energy (KE) during the entire cardiac cycle of the left ventricle (LV) and right ventricle (RV) using four-dimensional phasecontrast magnetic resonance imaging (MRI). KE was quantified in healthy volunteers (n = 9) using an in-house developed software. Mean KE through the cardiac cycle of the LV and the RV were highly correlated (r(2) = 0.96). Mean KE was related to end-diastolic volume (r(2) = 0.66 for LV and r(2) = 0.74 for RV), end-systolic volume (r(2) = 0.59 and 0.68), and stroke volume (r(2) = 0.55 and 0.60), but not to ejection fraction (r(2) = 0.01, P = not significant for both). Three KE peaks were found in both ventricles, in systole, early diastole, and late diastole. In systole, peak KE in the LV was lower (4.9 +/- 0.4 mJ, P = 0.004) compared with the RV (7.5 +/- 0.8 mJ). In contrast, KE during early diastole was higher in the LV (6.0 +/- 0.6 mJ, P = 0.004) compared with the RV (3.6 +/- 0.4 mJ). The late diastolic peaks were smaller than the systolic and early diastolic peaks (1.3 +/- 0.2 and 1.2 +/- 0.2 mJ). Modeling estimated the proportion of KE to total external work, which comprised similar to 0.3% of LV external work and 3% of RV energy at rest and 3 vs. 24% during peak exercise. The higher early diastolic KE in the LV indicates that LV filling is more dependent on ventricular suction compared with the RV. RV early diastolic filling, on the other hand, may be caused to a higher degree of the return of the atrioventricular plane toward the base of the heart. The difference in ventricular geometry with a longer outflow tract in the RV compared with the LV explains the higher systolic KE in the RV.
33.	Carlsson, Marcus, et al. (författare) The Quantitative Relationship between Longitudinal and Radial Function in Left, Right and Total Heart Pumping in Humans. 2007 Ingår i: American Journal of Physiology: Heart and Circulatory Physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 293:1, s. 636-644 Tidskriftsartikel (refereegranskat)abstract The total heart volume variation (THVV) during systole has been proposed to be caused by radial function of the ventricles, but definitive data for both ventricles have not been presented. Furthermore, the right ventricle (RV) has been suggested to have a greater longitudinal pumping component than the left ventricle (LV). Therefore, we aimed to compare the stroke volume (SV) generated by radial function to the volume variation of the left, right, and total heart. To do this, we also needed to develop a new method for measuring the contribution of the longitudinal atrioventricular plane displacement (AVPD) to the RVSV (RVSVAVPD). For our study, 11 volunteers underwent cine MRI in the short- and long-axis planes and MRI flow measurement in all vessels leading to and from the heart. The left, right, and total heart showed correlations between volume variation from flow measurements and radial function calculated as SV minus the longitudinal function (r = 0.81, P < 0.01; r = 0.80, P < 0.01; and r = 0.92, P < 0.001, respectively). Compared with the LV, the RV had a greater AVPD (23.4 +/- 0.8 vs. 16.4 +/- 0.5 mm), center of volume movement (13.0 +/- 0.7 vs. 7.8 +/- 0.4 mm), and, RVSVAVPD (82 +/- 2% vs. 60 +/- 2%) (P < 0.001 for all). We found that THVV is predominantly caused by radial function of the ventricles. Longitudinal AVPD accounts for similar to 80% of the RVSV, compared with similar to 60% for the LVSV. This difference explains the larger portion of THVV found on the left side of the heart.
34.	Cheimariotis, Grigorios Aris, et al. (författare) Automatic lung segmentation in functional SPECT images using active shape models trained on reference lung shapes from CT 2018 Ingår i: Annals of Nuclear Medicine. - : Springer Science and Business Media LLC. - 0914-7187 .- 1864-6433. ; 32:2, s. 94-104 Tidskriftsartikel (refereegranskat)abstract Objective: Image segmentation is an essential step in quantifying the extent of reduced or absent lung function. The aim of this study is to develop and validate a new tool for automatic segmentation of lungs in ventilation and perfusion SPECT images and compare automatic and manual SPECT lung segmentations with reference computed tomography (CT) volumes. Methods: A total of 77 subjects (69 patients with obstructive lung disease, and 8 subjects without apparent perfusion of ventilation loss) performed low-dose CT followed by ventilation/perfusion (V/P) SPECT examination in a hybrid gamma camera system. In the training phase, lung shapes from the 57 anatomical low-dose CT images were used to construct two active shape models (right lung and left lung) which were then used for image segmentation. The algorithm was validated in 20 patients, comparing its results to reference delineation of corresponding CT images, and by comparing automatic segmentation to manual delineations in SPECT images. Results: The Dice coefficient between automatic SPECT delineations and manual SPECT delineations were 0.83 ± 0.04% for the right and 0.82 ± 0.05% for the left lung. There was statistically significant difference between reference volumes from CT and automatic delineations for the right (R = 0.53, p = 0.02) and left lung (R = 0.69, p < 0.001) in SPECT. There were similar observations when comparing reference volumes from CT and manual delineations in SPECT images, left lung (bias was − 10 ± 491, R = 0.60, p = 0.005) right lung (bias 36 ± 524 ml, R = 0.62, p = 0.004). Conclusion: Automated segmentation on SPECT images are on par with manual segmentation on SPECT images. Relative large volumetric differences between manual delineations of functional SPECT images and anatomical CT images confirms that lung segmentation of functional SPECT images is a challenging task. The current algorithm is a first step towards automatic quantification of wide range of measurements.
35.	Dicks, Demetrius L., et al. (författare) Persistent Decline in Longitudinal and Radial Strain After Coronary Microembolization Detected on Velocity Encoded Phase Contrast Magnetic Resonance Imaging 2009 Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 30:1, s. 69-76 Tidskriftsartikel (refereegranskat)abstract Purpose: To use velocity-encoded phase contrast (PC) MRI in assessing the effect of coronary microembolization on longitudinal and radial myocardial strain. Materials and Methods: A combined X-ray and MR system (XMR) was used for selective left anterior descending artery catheterization and microinfarct assessment in swine (n = 6). The embolized area at risk was defined on perfusion MRI followed by administration of a 7500 count (size = 100-300 mu m) of the embolic agent. Quantification of strain and microinfarction was performed at 1 h and 1 week using PC-MRI and delayed enhancement (DE) MRI, respectively. At postmortem, sliced hearts were stained to define microinfarction. Results: Baseline longitudinal and radial strain did not differ between area-at-risk and remote myocardium. The embolized territory (area at risk) showed significant decline in longitudinal strain from -11.5 +/- 3.2% to 1.8 +/- 2.5% at 1 h (P < 0.05) and -3.9 +/- 1.1% at 1 week (P < 0.05). Similarly, regional radial strain progressively declined from 23.6 +/- 2.5% at baseline to 12.5 +/- 3.7% at 1 h (P < 0.05) and 4.8 +/- 5.0% at 1 week (P < 0.01). The size of microinfarction was not significantly different between DE-MRI and histochemical staining. Conclusion: PC-MRI is sensitive in assessing changes in regional longitudinal and radial strain after coronary embolization. Longitudinal and radial strain of the hyperenhanced patchy microinfarction demonstrates persistent decline over the course of 1 week.
36.	Dorniak, Karolina, et al. (författare) Required temporal resolution for accurate thoracic aortic pulse wave velocity measurements by phase-contrast magnetic resonance imaging and comparison with clinical standard applanation tonometry : Cardiovascular Spring Meeting 2016 Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 16:1, s. 1-9 Tidskriftsartikel (refereegranskat)abstract Background: Pulse wave velocity (PWV) is a biomarker for arterial stiffness, clinically assessed by applanation tonometry (AT). Increased use of phase-contrast cardiac magnetic resonance (CMR) imaging allows for PWV assessment with minor routine protocol additions. The aims were to investigate the acquired temporal resolution needed for accurate and precise measurements of CMR-PWV, and develop a tool for CMR-PWV measurements. Methods: Computer phantoms were generated for PWV = 2–20 m/s based on human CMR-PWV data. The PWV measurements were performed in 13 healthy young subjects and 13 patients at risk for cardiovascular disease. The CMR-PWV was measured by through-plane phase-contrast CMR in the ascending aorta and at the diaphragm level. Centre-line aortic distance was determined between flow planes. The AT-PWV was assessed within 2 h after CMR. Three observers (CMR experience: 15, 4, and <1 year) determined CMR-PWV. The developed tool was based on the flow-curve foot transit time for PWV quantification. Results: Computer phantoms showed bias 0.27 ± 0.32 m/s for a temporal resolution of at least 30 ms. Intraobserver variability for CMR-PWV were: 0 ± 0.03 m/s (15 years), -0.04 ± 0.33 m/s (4 years), and -0.02 ± 0.30 m/s (<1 year). Interobserver variability for CMR-PWV was below 0.02 ± 0.38 m/s. The AT-PWV overestimated CMR-PWV by 1.1 ± 0. 7 m/s in healthy young subjects and 1.6 ± 2.7 m/s in patients. Conclusions: An acquired temporal resolution of at least 30 ms should be used to obtain accurate and precise thoracic aortic phase-contrast CMR-PWV. A new freely available research tool was used to measure PWV in healthy young subjects and in patients, showing low intra- and interobserver variability also for less experienced CMR observers. Keywords: Aorta, Pulse wave velocity, Temporal resolution, Magnetic resonance imaging, Phase contrast, Applanation tonometry
37.	Dunås, Tora, 1988- (författare) Blood flow assessment in cerebral arteries with 4D flow magnetic resonance imaging : an automatic atlas-based approach 2018 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Background: Disturbed blood flow to the brain has been associated with several neurological diseases, from stroke and vascular diseases to Alzheimer’s and cognitive decline. To determine the cerebral arterial blood flow distribution, measurements are needed in both distal and proximal arteries.4D flow MRI makes it possible to obtain blood flow velocities from a volume covering the entire brain in one single scan. This facilitates more extensive flow investigations, since flow rate assessment in specific arteries can be done during post-processing. The flow rate assessment is still rather laborious and time consuming, especially if the number of arteries of interest is high. In addition, the quality of the measurements relies heavily on the expertise of the investigator.The aim of this thesis was to develop and evaluate an automatic post-processing tool for 4D flow MRI that identifies the main cerebral arteries and calculates their blood flow rate with minimal manual input. Atlas-based labeling of brain tissue is common in toolboxes for analysis of neuroimaging-data, and we hypothesized that a similar approach would be suitable for arterial labeling. We also wanted to investigate how to best separate the arterial lumen from background for calculation of blood flow.Methods: An automatic atlas-based arterial identification method (AAIM) for flow assessment was developed. With atlas-based labeling, voxels are labeled based on their spatial location in MNI-space, a stereotactic coordinate system commonly used for neuroimaging analysis. To evaluate the feasibility of this approach, a probabilistic atlas was created from a set of angiographic images derived from 4D flow MRI. Included arteries were the anterior (ACA), middle (MCA) and posterior (PCA) cerebral arteries, as well as the internal carotid (ICA), vertebral (VA), basilar (BA) and posterior communicating (PCoA) arteries. To identify the arteries in an angiographic image, a vascular skeleton where each branch represented an arterial segment was extracted and labeled according to the atlas. Labeling accuracy of the AAIM was evaluated by visual inspection.Next, the labeling method was adapted for flow measurements by pre-defining desired regions within the atlas. Automatic flow measurements were then compared to measurements at manually identified locations. During the development process, arterial identification was evaluated on four patient cohorts, with and without vascular disease. Finally, three methods for flow quantification using 4D flow MRI: k-means clustering; global thresholding; and local thresholding, were evaluated against a standard reference method.Results: The labeling accuracy on group level was between 96% and 87% for all studies, and close to 100% for ICA and BA. Short arteries (PCoA) and arteries with large individual anatomical variation (VA) were the most challenging. Blood flow measurements at automatically identified locations were highly correlated (r=0.99) with manually positioned measurements, and difference in mean flow was negligible.Both global and local thresholding out-performed k-means clustering, since the threshold value could be optimized to produce a mean difference of zero compared to reference. The local thresholding had the best concordance with the reference method (p=0.009, F-test) and was the only method that did not have a significant correlation between flow difference and flow rate. In summary, with a local threshold of 20%, ICC was 0.97 and the flow rate difference was -0.04 ± 15.1 ml/min, n=308.Conclusion: This thesis work demonstrated that atlas-based labeling was suitable for identification of cerebral arteries, enabling automated processing and flow assessment in 4D flow MRI. Furthermore, the proposed flow rate quantification algorithm reduced some of the most important shortcomings associated with previous methods. This new platform for automatic 4D flow MRI data analysis fills a gap needed for efficient in vivo investigations of arterial blood flow distribution to the entire vascular tree of the brain, and should have important applications to practical use in neurological diseases.
38.	Edlund, Jonathan, et al. (författare) Noninvasive Assessment of Left Ventricular Pressure-Volume Relations : Inter- and Intraobserver Variability and Assessment Across Heart Failure Subtypes 2022 Ingår i: American Journal of Cardiology. - : Elsevier BV. - 1879-1913 .- 0002-9149. ; 184, s. 48-55 Tidskriftsartikel (refereegranskat)abstract A novel method to derive pressure-volume (PV) loops noninvasively from cardiac magnetic resonance images has recently been developed. The aim of this study was to evaluate inter- and intraobserver variability of hemodynamic parameters obtained from noninvasive PV loops in healthy controls, subclinical diastolic dysfunction (SDD), and patients with heart failure with preserved ejection fraction, mildly reduced ejection fraction, and reduced ejection fraction. We included 75 subjects, of whom 15 were healthy controls, 15 subjects with SDD (defined as fulfilling 1 to 2 echocardiographic criteria for diastolic dysfunction), and 15 patients with preserved ejection fraction, 15 with mildly reduced ejection fraction, and 15 with reduced ejection fraction. PV loops were computed using time-resolved left ventricular volumes from cardiac magnetic resonance images and a brachial blood pressure. Inter- and intraobserver variability and intergroup differences of PV loop-derived hemodynamic parameters were assessed. Bias was low and limits of agreement were narrow for all hemodynamic parameters in the inter- and intraobserver comparisons. Interobserver difference for stroke work was 2 ± 9%, potential energy was 4 ± 11%, and maximal ventricular elastance was -4 ± 7%. Intraobserver for stroke work was -1 ± 7%, potential energy was 3 ± 4%, and maximal ventricular elastance was 1 ± 5%. In conclusion, this study presents a fully noninvasive left ventricular PV loop analysis across healthy controls, subjects with SDD, and patients with heart failure with preserved or impaired systolic function. In conclusion, the method for PV loop computation from clinical-standard manual left ventricular segmentation was rapid and robust, bridging the gap between clinical and research settings.
39.	Edlund, Jonathan, et al. (författare) Noninvasive Assessment of Left Ventricular Pressure-Volume Relations: Inter- and Intraobserver Variability and Assessment Across Heart Failure Subtypes. 2022 Ingår i: The American journal of cardiology. - : Elsevier BV. - 1879-1913 .- 0002-9149. Tidskriftsartikel (refereegranskat)abstract A novel method to derive pressure-volume (PV) loops noninvasively from cardiac magnetic resonance images has recently been developed. The aim of this study was to evaluate inter- and intraobserver variability of hemodynamic parameters obtained from noninvasive PV loops in healthy controls, subclinical diastolic dysfunction (SDD), and patients with heart failure with preserved ejection fraction, mildly reduced ejection fraction, and reduced ejection fraction. We included 75 subjects, of whom 15 were healthy controls, 15 subjects with SDD (defined as fulfilling 1 to 2 echocardiographic criteria for diastolic dysfunction), and 15 patients with preserved ejection fraction, 15 with mildly reduced ejection fraction, and 15 with reduced ejection fraction. PV loops were computed using time-resolved left ventricular volumes from cardiac magnetic resonance images and a brachial blood pressure. Inter- and intraobserver variability and intergroup differences of PV loop-derived hemodynamic parameters were assessed. Bias was low and limits of agreement were narrow for all hemodynamic parameters in the inter- and intraobserver comparisons. Interobserver difference for stroke work was 2 ± 9%, potential energy was 4 ± 11%, and maximal ventricular elastance was -4 ± 7%. Intraobserver for stroke work was -1 ± 7%, potential energy was 3 ± 4%, and maximal ventricular elastance was 1 ± 5%. In conclusion, this study presents a fully noninvasive left ventricular PV loop analysis across healthy controls, subjects with SDD, and patients with heart failure with preserved or impaired systolic function. In conclusion, the method for PV loop computation from clinical-standard manual left ventricular segmentation was rapid and robust, bridging the gap between clinical and research settings.
40.	Edlund, Jonathan, et al. (författare) Validation and quantification of left ventricular function during exercise and free breathing from real-time cardiac magnetic resonance images 2022 Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1 Tidskriftsartikel (refereegranskat)abstract Exercise cardiovascular magnetic resonance (CMR) can unmask cardiac pathology not evident at rest. Real-time CMR in free breathing can be used, but respiratory motion may compromise quantification of left ventricular (LV) function. We aimed to develop and validate a post-processing algorithm that semi-automatically sorts real-time CMR images according to breathing to facilitate quantification of LV function in free breathing exercise. A semi-automatic algorithm utilizing manifold learning (Laplacian Eigenmaps) was developed for respiratory sorting. Feasibility was tested in eight healthy volunteers and eight patients who underwent ECG-gated and real-time CMR at rest. Additionally, volunteers performed exercise CMR at 60% of maximum heart rate. The algorithm was validated for exercise by comparing LV mass during exercise to rest. Respiratory sorting to end expiration and end inspiration (processing time 20 to 40 min) succeeded in all research participants. Bias ± SD for LV mass was 0 ± 5 g when comparing real-time CMR at rest, and 0 ± 7 g when comparing real-time CMR during exercise to ECG-gated at rest. This study presents a semi-automatic algorithm to retrospectively perform respiratory sorting in free breathing real-time CMR. This can facilitate implementation of exercise CMR with non-ECG-gated free breathing real-time imaging, without any additional physiological input.
41.	Engblom, Henrik, et al. (författare) A new automatic algorithm for quantification of myocardial infarction imaged by late gadolinium enhancement cardiovascular magnetic resonance : Experimental validation and comparison to expert delineations in multi-center, multi-vendor patient data 2016 Ingår i: Journal of Cardiovascular Magnetic Resonance. - : Springer Science and Business Media LLC. - 1097-6647 .- 1532-429X. ; 18:1 Tidskriftsartikel (refereegranskat)abstract Background: Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) using magnitude inversion recovery (IR) or phase sensitive inversion recovery (PSIR) has become clinical standard for assessment of myocardial infarction (MI). However, there is no clinical standard for quantification of MI even though multiple methods have been proposed. Simple thresholds have yielded varying results and advanced algorithms have only been validated in single center studies. Therefore, the aim of this study was to develop an automatic algorithm for MI quantification in IR and PSIR LGE images and to validate the new algorithm experimentally and compare it to expert delineations in multi-center, multi-vendor patient data. Methods: The new automatic algorithm, EWA (Expectation Maximization, weighted intensity, a priori information), was implemented using an intensity threshold by Expectation Maximization (EM) and a weighted summation to account for partial volume effects. The EWA algorithm was validated in-vivo against triphenyltetrazolium-chloride (TTC) staining (n = 7 pigs with paired IR and PSIR images) and against ex-vivo high resolution T1-weighted images (n = 23 IR and n = 13 PSIR images). The EWA algorithm was also compared to expert delineation in 124 patients from multi-center, multi-vendor clinical trials 2-6 days following first time ST-elevation myocardial infarction (STEMI) treated with percutaneous coronary intervention (PCI) (n = 124 IR and n = 49 PSIR images). Results: Infarct size by the EWA algorithm in vivo in pigs showed a bias to ex-vivo TTC of -1 ± 4%LVM (R = 0.84) in IR and -2 ± 3%LVM (R = 0.92) in PSIR images and a bias to ex-vivo T1-weighted images of 0 ± 4%LVM (R = 0.94) in IR and 0 ± 5%LVM (R = 0.79) in PSIR images. In multi-center patient studies, infarct size by the EWA algorithm showed a bias to expert delineation of -2 ± 6 %LVM (R = 0.81) in IR images (n = 124) and 0 ± 5%LVM (R = 0.89) in PSIR images (n = 49). Conclusions: The EWA algorithm was validated experimentally and in patient data with a low bias in both IR and PSIR LGE images. Thus, the use of EM and a weighted intensity as in the EWA algorithm, may serve as a clinical standard for the quantification of myocardial infarction in LGE CMR images. Clinical trial registration: CHILL-MI: NCT01379261. MITOCARE: NCT01374321.
42.	Engblom, Henrik, et al. (författare) Design of clinical cardioprotection trials using CMR : Impact of myocardial salvage index and a narrow inclusion window on sample size 2015 Ingår i: Journal of Cardiovascular Magnetic Resonance. - 1097-6647. ; 17:suppl 1 Konferensbidrag (refereegranskat)
43.	Engblom, Henrik, et al. (författare) Importance of standardizing timing of hematocrit measurement when using cardiovascular magnetic resonance to calculate myocardial extracellular volume (ECV) based on pre- and post-contrast T1 mapping 2018 Ingår i: Journal of Cardiovascular Magnetic Resonance. - : Springer Science and Business Media LLC. - 1097-6647 .- 1532-429X. ; 20:1 Tidskriftsartikel (refereegranskat)abstract Background: Cardiovascular magnetic resonance (CMR) can be used to calculate myocardial extracellular volume fraction (ECV) by relating the longitudinal relaxation rate in blood and myocardium before and after contrast-injection to hematocrit (Hct) in blood. Hematocrit is known to vary with body posture, which could affect the calculations of ECV. The aim of this study was to test the hypothesis that there is a significant increase in calculated ECV values if the Hct is sampled after the CMR examination in supine position compared to when the patient arrives at the MR department. Methods: Forty-three consecutive patients including various pathologies as well as normal findings were included in the study. Venous blood samples were drawn upon arrival to the MR department and directly after the examination with the patient remaining in supine position. A Modified Look-Locker Inversion recovery (MOLLI) protocol was used to acquire mid-ventricular short-axis images before and after contrast injection from which motion-corrected T1 maps were derived and ECV was calculated. Results: Hematocrit decreased from 44.0 ± 3.7% before to 40.6 ± 4.0% after the CMR examination (p < 0.001). This resulted in a change in calculated ECV from 24.7 ± 3.8% before to 26.2 ± 4.2% after the CMR examination (p < 0.001). All patients decreased in Hct after the CMR examination compared to before except for two patients whose Hct remained the same. Conclusion: Variability in CMR-derived myocardial ECV can be reduced by standardizing the timing of Hct measurement relative to the CMR examination. Thus, a standardized acquisition of blood sample for Hct after the CMR examination, when the patient is still in supine position, would increase the precision of ECV measurements.
44.	Engblom, Henrik, et al. (författare) Quantification of myocardial salvage by myocardial perfusion SPECT and cardiac magnetic resonance - reference standards for ECG development. 2014 Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 1532-8430 .- 0022-0736. ; 47:4, s. 525-534 Forskningsöversikt (refereegranskat)abstract In order to determine the cardioprotective efficacy of acute reperfusion therapy, assessed as myocardial salvage, in patients with acute coronary occlusion, the final myocardial infarct (MI) size needs to be related to the amount of ischemic myocardium during coronary occlusion, referred to as the myocardium at risk (MaR). There are currently several imaging approaches available for quantification of both MI size and MaR in vivo of which some have been validated both in pre-clinical and clinical settings. These methods often involve the use of either myocardial perfusion SPECT or cardiac magnetic resonance (CMR). These imaging methods could potentially be used to further develop and validate ECG methods for determination of MI size and MaR. Therefore, the aim of the present review is to give an overview of myocardial perfusion SPECT and CMR methods available for assessment of myocardial salvage by determination of MI size and MaR.
45.	Engblom, Henrik, et al. (författare) Rapid Initial Reduction of Hyperenhanced Myocardium After Reperfused First Myocardial Infarction Suggests Recovery of the Peri-Infarction Zone One-Year Follow-Up by MRI 2009 Ingår i: Circulation Cardiovascular Imaging. - 1942-0080. ; 2:1, s. 47-55 Tidskriftsartikel (refereegranskat)abstract Background-The time course and magnitude of infarct involution, functional recovery, and normalization of infarct-related electrocardiographic (ECG) changes after acute myocardial infarction (MI) are not completely known in humans. We sought to explore these processes early after MI and during infarct-healing using cardiac MRI. Methods and Results-Twenty-two patients with reperfused first-time MI were examined by MRI and ECG at 1, 7, 42. 182, and 365 days after infarction. Global left ventricular function and regional wall thickening were assessed by cine MRI, and injured myocardium was depicted by delayed contrast-enhanced MRI. Infarct size by ECG was estimated by QRS scoring. The reduction of hyperenhanced myocardium occurred predominantly during the first week after infarction (64% of the 1-year reduction). Furthermore, during the first week the amount of nonhyperenhanced myocardium increased significantly (P<0.001,), although the left ventricular mass remained unchanged. Left ventricular ejection fraction increased gradually, whereas the greater the regional transmural extent of hyperenhancement at day 1, the later the recovery of regional wall thickening. Regional wall thickening decreased progressively with increasing initial transmural extent of hyperenhancement (P-trend<0.0001). The time course and magnitude of decrease in QRS score corresponded with the reduction of hyperenhanced myocardium. Conclusions-The early reduction of hyperenhanced myocardium May reflect recovery of hyperenhanced, reversibly injured myocardium), which must be considered when predicting functional recovery from delayed contrast-enhanced MRI findings early after infarction. Also, the time course and magnitude for reduction of hyperenhanced myocardium were associated with normalization of infarct-related ECG changes. (Circ Cardiovasc Imaging. 2009;2:47-55.)
46.	Engblom, Henrik, et al. (författare) Sample Size in Clinical Cardioprotection Trials Using Myocardial Salvage Index, Infarct Size, or Biochemical Markers as Endpoint. 2016 Ingår i: Journal of the American Heart Association. - 2047-9980. ; 5:3, s. 002708-002708 Tidskriftsartikel (refereegranskat)abstract Cardiac magnetic resonance (CMR) can quantify myocardial infarct (MI) size and myocardium at risk (MaR), enabling assessment of myocardial salvage index (MSI). We assessed how MSI impacts the number of patients needed to reach statistical power in relation to MI size alone and levels of biochemical markers in clinical cardioprotection trials and how scan day affect sample size.
47.	Engblom, Henrik, et al. (författare) Size and transmural extent of first-time reperfused myocardial infarction assessed by cardiac magnetic resonance can be estimated by 12-lead electrocardiogram. 2005 Ingår i: American Heart Journal. - : Elsevier BV. - 1097-6744 .- 0002-8703. ; 150:5, s. 920-920 Tidskriftsartikel (refereegranskat)
48.	Engblom, Henrik, et al. (författare) The endocardial extent of reperfused first-time myocardial infarction is more predictive of pathologic Q waves than is infarct transmurality: a magnetic resonance imaging study. 2007 Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 27:2, s. 101-108 Tidskriftsartikel (refereegranskat)abstract Historically, Q-wave myocardial infarction (MI) has been equated with transmural MI. This association have, however, recently been rejected. The endocardial extent of MI is another potential determinant of pathological Q waves, since the first part of the QRS complex where the Q wave appears reflects depolarization of subendocardial myocardium. Therefore, the aim of the present study was to test the hypothesis that endocardial extent of MI is more predictive of pathological Q waves than is MI transmurality and to investigate the relationship between QRS scoring of the ECG and MI characteristics. Twenty-nine patients with reperfused first-time MI were prospectively enrolled. One week after admission, delayed contrast-enhanced magnetic resonance imaging (DE-MRI) was performed and 12-lead ECG was recorded. Size, transmurality and endocardial extent of MI were assessed by DE-MRI. Q waves were identified with Minnesota coding and electrocardiographic MI size was estimated by QRS scoring of the ECG. There was a significant difference between patients with and without Q waves with regard to MI size (P = 0.03) and endocardial extent of MI (P = 0.01), but not to mean and maximum MI transmurality (P = 0.09 and P = 0.14). Endocardial extent was the only independent predictor of pathological Q waves. Endocardial extent of MI was most strongly correlated to QRS score (r = 0.86, P < 0.001) of the MI variables tested. The endocardial extent of reperfused first-time acute MI is more predictive of pathological Q waves than is MI transmurality.
49.	Fransson, Helen, et al. (författare) An automatic method for quantification of myocardium at risk from myocardial perfusion SPECT in patients with acute coronary occlusion. 2010 Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1532-6551 .- 1071-3581. ; 17, s. 831-840 Tidskriftsartikel (refereegranskat)abstract BACKGROUND: In order to determine myocardial salvage, accurate quantification of myocardium at risk (MaR) is necessary. We present a validated novel automatic segmentation algorithm for quantification of MaR by myocardial perfusion SPECT (MPS) in patients with acute coronary occlusion. METHODS AND RESULTS: Twenty-nine patients with coronary occlusion were injected with a perfusion tracer before reperfusion, and underwent rest MPS within 4 hours. The MaR was quantified using the proposed algorithm (Segment software), the software Quantitative Perfusion SPECT (QPS) and by manual segmentation. The Segment MaR algorithm used a threshold of 55% of maximal counts and an a priori model based on normal coronary artery perfusion territories. The MaR was 30 +/- 10% left ventricular mass (%LVM) by manual segmentation, 31 +/- 12%LVM by Segment, and 36 +/- 14%LVM by QPS. There was a good agreement between automatic and manual segmentation for both of the algorithms with a lower bias for Segment (.8 +/- 4.0%LVM) than for QPS (5.8 +/- 5.8%LVM) when compared to manual segmentation. CONCLUSIONS: The Segment MaR algorithm can be used to correctly assess MaR from MPS images in patients with acute coronary occlusion without access to tracer-specific normal database. The MaR in relation to final infarct size enables determination of myocardial salvage.
50.	Fransson, Helen, et al. (författare) An Improved Method for Automatic Segmentation of the Left Ventricle in Myocardial Perfusion SPECT. 2009 Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 50:2, s. 205-213 Tidskriftsartikel (refereegranskat)abstract This study describes and validates a new method for automatic segmentation of left ventricular mass (LVM) in myocardial perfusion SPECT (MPS) images. This is important for estimating the size of a perfusion defect as percentage of the left ventricle. METHODS: A total of 101 patients with known or suspected coronary artery disease underwent both rest and stress MPS and MRI. A new automated algorithm was trained in 20 patients (40 MPS studies) and tested in 81 patients (162 MPS studies). The algorithm, which segmented the left ventricle in the MPS images, is based on Dijkstra's algorithm and finds an optimal mid-mural line through the left ventricular wall. From this line, the endocardium and epicardium are identified on the basis of an individually estimated wall thickness and signal intensity. The algorithm was validated by comparing LVM in both stress and rest MPS, with LVM of the manually segmented left ventricle from MRI as the reference standard. For comparison, LVM was quantified using the software quantitative perfusion SPECT (QPS). RESULTS: The mean difference +/- SD in LVM between MPS and MRI was lower for the new method (6% +/- 15% LVM) than for QPS (18% +/- 19% LVM) for both mean difference (P < 0.001) and SD (P = 0.015). Linear regression analysis of LVM, comparing MPS and MRI, yielded R(2) = 0.83 using the new method and R(2) = 0.80 using QPS. Interstudy variability, measured as the coefficient of variance between rest MPS and stress MPS, was 6% for both the new method and QPS. Both the new algorithm and QPS systematically overestimated LVM in hearts with thin myocardium and underestimated LVM in hearts with thick myocardium. CONCLUSION: The new segmentation algorithm quantifies LVM with a significantly lower bias and variability than does the commercially available QPS software, when compared to manually segmented LVM by MRI. This makes the new algorithm an attractive method to use for estimating the size of the perfusion defect when expressing it as percentage of the left ventricle. This study shows that inaccurate estimation of wall thickness is the main source of error in automatic segmentation.

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