| 1. |
- Harms, Hendrik J., et al.
(författare)
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Association of right ventricular myocardial blood flow with pulmonary pressures and outcome in cardiac amyloidosis
- 2023
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Ingår i: JACC Cardiovascular Imaging. - : Elsevier. - 1936-878X .- 1876-7591.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Cardiac amyloidosis (CA) is a restrictive and infiltrative cardiomyopathy, characterized by increased biventricular filling pressures and low output. Symptoms are predominantly of right heart origin. The role of right ventricular (RV) myocardial blood flow (MBF) in CA has not been studied.Objectives: This study aimed to first associate RV MBF measured by using positron emission tomography (PET) with reference standards of RV pressures and then to explore its prognostic value in CA.Methods: Cardiac PET was performed at rest in 52 patients with CA and 9 healthy control subjects. MBF was quantified from the right and left ventricles by using 11C-acetate, 15O-water, or both (n = 25). RV pressure was measured invasively or by echocardiography. Associations between biventricular MBF toward symptoms, RV function, and outcome (death or acute heart failure) were studied in patients with CA.Results: MBF of the right ventricle (MBFRV) and the ratio of MBFRV and MBF of the left ventricle (MBFRV/LV) for the 2 tracers were significantly correlated (r > 0.92). MBFRV was directly correlated with RV systolic pressures with both tracers (P ≤ 0.005). MBFLV was inversely correlated with wall thickness (P < 0.0001). MBFRV/LV was significantly associated with N-terminal pro–B-type natriuretic peptide levels, New York Heart Association functional class, RV pressures, and RV systolic function (all; P < 0.001). Twenty-six cardiac events (25 deaths) occurred during follow-up (median 44 months). MBFRV/LV higher than 56% was associated with a diagnosis of pulmonary hypertension (AUC: 0.96 [95% CI: 0.91-1.00]; P < 0.0001); and predicted outcome with hazard ratio 9.0 (95% CI: 4.2-14.5), P < 0.0001).Conclusions: Measurements of MBFRV using PET are feasible, as confirmed with 2 different tracers. Imbalance between RV and LV myocardial perfusion is associated with increased RV load and adverse events in cardiac amyloidosis.
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| 2. |
- Harms, Hendrik J, et al.
(författare)
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Automatic calculation of myocardial external efficiency using a single 11C-acetate PET scan.
- 2018
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Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1071-3581 .- 1532-6551. ; 25:6, s. 1937-1944
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Myocardial external efficiency (MEE) is defined as the ratio of kinetic energy associated with cardiac work [forward cardiac output (FCO)*mean systemic pressure] and the chemical energy from oxygen consumed (MVO2) by the left ventricular mass (LVM). We developed a fully automated method for estimating MEE based on a single 11C-acetate PET scan without ECG-gating.METHODS AND RESULTS: Ten healthy controls, 34 patients with aortic valve stenosis (AVS), and 20 patients with mitral valve regurgitation (MVR) were recruited in a dual-center study. MVO2 was calculated using washout of 11C -acetate activity. FCO and LVM were calculated automatically using dynamic PET and parametric image formation. FCO and LVM were also obtained using cardiac magnetic resonance (CMR) in all subjects. The correlation between MEEPET-CMR and MEEPET was high (r = 0.85, P < 0.001) without significant bias. MEEPET was 23.6 ± 4.2% for controls and was lowered in AVS (17.2 ± 4.3%, P < 0.001) and in MVR (18.0 ± 5.2%, P = 0.004). MEEPET was strongly associated with both NYHA class (P < 0.001) and the magnitude of valvular dysfunction (mean aortic gradient: P < 0.001, regurgitant fraction: P = 0.009).CONCLUSION: A single 11C-acetate PET yields accurate and automated MEE results on different scanners. MEE might provide an unbiased measurement of the phenotypic response to valvular disease.
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| 3. |
- Harms, Hendrik J, et al.
(författare)
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First-Pass Techniques Applied to Standard Dynamic Cardiac PET : A reappraisal of Old Invasive Techniques to Assess Cardiac Function
- 2020
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Ingår i: Seminars in nuclear medicine. - : Elsevier BV. - 0001-2998 .- 1558-4623. ; 50:4, s. 349-356
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Forskningsöversikt (refereegranskat)abstract
- Cardiac PET is increasingly performed with dynamic imaging to measure tracer pharmacokinetics in the myocardium. If the early time frames of the PET protocol are sufficiently short and the total amount of injected radioactivity is correctly measured the indicator dilution principle can be applied to PET with most tracers in clinical use, similar to invasive and other noninvasive techniques. The first-pass of the tracer through the heart and lungs can be used to quantify some highly important aspects of cardiovascular function, such as forward cardiac output, transit times, and partial volumes in the central compartments. Additionally, ECG-gated first pass images provide direct access to cardiac volumes and ejection fractions, even for tracers with poor trapping in the myocardial wall, for instance 15O-water. This review summarizes the basic approaches of the indicator dilution principle in clinical use with invasive techniques, and how these techniques can be integrated into a cardiac PET scan.
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| 4. |
- Kero, Tanja, et al.
(författare)
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Quantitative myocardial blood flow imaging with integrated time-of-flight PET-MR
- 2017
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Ingår i: EJNMMI Physics. - : Springer Science and Business Media LLC. - 2197-7364. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The use of integrated PET-MR offers new opportunities for comprehensive assessment of cardiac morphology and function. However, little is known on the quantitative accuracy of cardiac PET imaging with integrated time-of-flight PET-MR. The aim of the present work was to validate the GE Signa PET-MR scanner for quantitative cardiac PET perfusion imaging. Eleven patients (nine male; mean age 59 years; range 46-74 years) with known or suspected coronary artery disease underwent (15)O-water PET scans at rest and during adenosine-induced hyperaemia on a GE Discovery ST PET-CT and a GE Signa PET-MR scanner. PET-MR images were reconstructed using settings recommended by the manufacturer, including time-of-flight (TOF). Data were analysed semi-automatically using Cardiac VUer software, resulting in both parametric myocardial blood flow (MBF) images and segment-based MBF values. Correlation and agreement between PET-CT-based and PET-MR-based MBF values for all three coronary artery territories were assessed using regression analysis and intra-class correlation coefficients (ICC). In addition to the cardiac PET-MR reconstruction protocol as recommended by the manufacturer, comparisons were made using a PET-CT resolution-matched reconstruction protocol both without and with TOF to assess the effect of time-of-flight and reconstruction parameters on quantitative MBF values.RESULTS: Stress MBF data from one patient was excluded due to movement during the PET-CT scanning. Mean MBF values at rest and stress were (0.92 ± 0.12) and (2.74 ± 1.37) mL/g/min for PET-CT and (0.90 ± 0.23) and (2.65 ± 1.15) mL/g/min for PET-MR (p = 0.33 and p = 0.74). ICC between PET-CT-based and PET-MR-based regional MBF was 0.98. Image quality was improved with PET-MR as compared to PET-CT. ICC between PET-MR-based regional MBF with and without TOF and using different filter and reconstruction settings was 1.00.CONCLUSIONS: PET-MR-based MBF values correlated well with PET-CT-based MBF values and the parametric PET-MR images were excellent. TOF and reconstruction settings had little impact on MBF values.
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| 5. |
- Magnusson, Peter, et al.
(författare)
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Positron emission tomography (O-15-water, C-11-acetate, C-11-HED) risk markers and nonsustained ventricular tachycardia in hypertrophic cardiomyopathy
- 2020
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Ingår i: IJC Heart & Vasculature. - : Elsevier BV. - 2352-9067. ; 26:26
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Tidskriftsartikel (refereegranskat)abstract
- Background: The objectives of the study were to describe positron emission tomography (PET) parameters, using the tracers O-15-water at rest/stress, C-11-acetate, and C-11-HED, with regard to nonsustained ventricular tachycardia (NSVT) in hypertrophic cardiomyopathy (HCM). PET offers quantitative assessment of pathophysiology throughout the left ventricular segments, including the endocardium/epicardium. The potential use PET in risk stratification remains to be elucidated. NSVT provides a marker for sudden cardiac death.Methods: Patients with a validated diagnosis of HCM who had an implantable cardioverter-defibrillator were interrogated at 12 months and independently of PET-examinations.Results: In total, 25 patients (mean age 56.8 +/- 12.9 years, 76% males) were included and 10 reported NSVT. Mean myocardial blood flow (MBF) at rest was 0.91 ml/g/min and decreased at stress, 1.59 ml/ g/min. The mean gradient (endocardium/epicardium quotient) at rest was 1.14 +/- 0.09, while inverse at stress (mean 0.92 +/- 0.16). Notably, MBF gradient at stress was significantly lower in patients with NSVT (p = 0.022) and borderline at rest (p = 0.059) while global MBF at rest and stress were not. Mean myocardial oxygen consumption (MVO2) was 0.088 ml/g/min (higher in NSVT, p = 0.023) and myocardial external efficiency 18.5%. Using C-11-HED, the mean retention index was 0.11 min (1) and a higher volume of distribution (p = 0.089) or transmural gradient of clearance rate (p = 0.061) or lower clearance rate (p = 0.052) showed a tendency of association of NSVT.Conclusions: The endocardium/epicardium MBF gradient at stress is significantly lower in HCM patients with NSVT. This provides a novel approach to further refine risk stratification of sudden cardiac death.
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| 6. |
- Nordström, Jonny, et al.
(författare)
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Effect of PET-CT misalignment on the quantitative accuracy of cardiac 15O-water PET
- 2022
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Ingår i: Journal of Nuclear Cardiology. - : Springer Science and Business Media LLC. - 1071-3581 .- 1532-6551. ; 29:3, s. 1119-1128
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Quantification of myocardial blood flow (MBF) with PET requires accurate attenuation correction, which is performed using a separate CT. Misalignment between PET and CT scans has been reported to be a common problem. The purpose of the present study was to assess the effect of PET CT misalignment on the quantitative accuracy of cardiac 15O-water PET.METHODS: Ten clinical patients referred for evaluation of ischemia and assessment of MBF with 15O-water were included in the study. Eleven different misalignments between PET and CT were induced in 6 different directions with 10 and 20 mm amplitudes: caudal (+Z), cranial (- Z), lateral (±X), anterior (+Y), and anterior combined with cranial (+ Y and - Z). Blood flow was quantified from rates of washout (MBF) and uptake (transmural MBF, MBFt) for the whole left ventricle and the three coronary territories. The results from all misalignments were compared to the original scan without misalignment.RESULTS: MBF was only minorly affected by misalignments, but larger effects were seen in MBFt. On the global level, average absolute deviation across all misalignments for MBF was 1.7% ± 1.4% and for MBFt 5.4% ± 3.2 Largest deviation for MBF was - 4.8% ± 5.8% (LCX, X + 20) and for MBFt - 19.3% ± 9.6% (LCX, X + 20). In general, larger effects were seen in LAD and LCX compared to in RCA.CONCLUSION: The quantitative accuracy of MBF from 15O-water PET, based on the washout of the tracer, is only to a minor extent affected by misalignment between PET and CT.
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| 7. |
- Nordström, Jonny, et al.
(författare)
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Influence of patient motion on quantitative accuracy in cardiac 15O-water positron emission tomography.
- 2022
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Ingår i: Journal of Nuclear Cardiology. - : Springer Nature. - 1071-3581 .- 1532-6551. ; 29:4, s. 1742-1752
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Patient motion is a common problem during cardiac PET. The purpose of the present study was to investigate to what extent motions influence the quantitative accuracy of cardiac 15O-water PET/CT and to develop a method for automated motion detection.METHOD: Frequency and magnitude of motion was assessed visually using data from 50 clinical 15O-water PET/CT scans. Simulations of 4 types of motions with amplitude of 5 to 20 mm were performed based on data from 10 scans. An automated motion detection algorithm was evaluated on clinical and simulated motion data. MBF and PTF of all simulated scans were compared to the original scan used as reference.RESULTS: Patient motion was detected in 68% of clinical cases by visual inspection. All observed motions were small with amplitudes less than half the LV wall thickness. A clear pattern of motion influence was seen in the simulations with a decrease of myocardial blood flow (MBF) in the region of myocardium to where the motion was directed. The perfusable tissue fraction (PTF) trended in the opposite direction. Global absolute average deviation of MBF was 3.1% ± 1.8% and 7.3% ± 6.3% for motions with maximum amplitudes of 5 and 20 mm, respectively. Automated motion detection showed a sensitivity of 90% for simulated motions ≥ 10 mm but struggled with the smaller (≤ 5 mm) simulated (sensitivity 45%) and clinical motions (accuracy 48%).CONCLUSION: Patient motion can impair the quantitative accuracy of MBF. However, at typically occurring levels of patient motion, effects are similar to or only slightly larger than inter-observer variability, and downstream clinical effects are likely negligible.
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| 8. |
- Nordström, Jonny, et al.
(författare)
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Left ventricular volumes and ejection fraction from cardiac ECG-gated 15O-water positron emission tomography compared to cardiac magnetic resonance imaging using simultaneous hybrid PET/MR
- 2023
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Ingår i: Journal of Nuclear Cardiology. - : Springer Nature. - 1071-3581 .- 1532-6551. ; 30:4, s. 1352-1362
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Tidskriftsartikel (refereegranskat)abstract
- Background15O-water PET is the gold standard for noninvasive quantification of myocardial blood flow. In addition to evaluation of ischemia, the assessment of cardiac function and remodeling is important in all cardiac diseases. However, since 15O-water is freely diffusible and standard uptake images show little contrast between the myocardium and blood pool, the assessment of left-ventricular (LV) volumes and ejection fraction (EF) is challenging. Therefore, the aim of the present study was to investigate the feasibility of calculating LV volumes and EF from first-pass analysis of 15O-water PET, by comparison with cardiac magnetic resonance imaging (CMR) using a hybrid PET/MR scanner.MethodsTwenty-four patients with known or suspected CAD underwent a simultaneous ECG-gated cardiac PET/MR scan. The 15O-water first-pass images (0-50 seconds) were analyzed using the CarPET software and the CMR images were analyzed using the software Segment, for LV volumes and EF calculations. The LV volumes and EF were compared using correlation and Bland–Altman analysis. In addition, inter- and intra-observer variability of LV volumes and EF were assessed for both modalities.ResultsThe correlation between PET and CMR was strong for volumes (r > 0.84) and moderate for EF (r = 0.52), where the moderate correlation for EF was partly due to the small range of EF values. Agreement was high for all parameters, with a slight overestimation of PET values for end-diastolic volume but with no significant mean bias for other parameters. Inter- and intra-observer agreement of volumes was high and comparable between PET and CMR. For EF, inter-observer agreement was higher for PET and intra-observer agreement was higher for CMR.ConclusionLV volumes and EF can be calculated by first-pass analysis of a 15O-water PET scan with high accuracy and comparable precision as with CMR.
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| 9. |
- Nordström, Jonny
(författare)
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Quantitative cardiac 15O-water PET : Assessment of left-ventricular function, remodeling, and impact of patient motion
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- International guidelines advocate the use of noninvasive cardiac imaging as the initial diagnostic test for coronary artery disease, the global leading cause of death according to the world health organization. Within the wide spectrum of cardiac imaging, 15O-water PET is the gold standard for noninvasive quantification of myocardial blood flow (MBF). However, because 15O-water is a metabolically inert and freely diffusible tracer, the net retention of 15O-water in the myocardium is zero and there is no contrast between the myocardial wall and the cavity in a standard uptake image of 15O-water. The lack of contrast poses difficulties for the measurement of cardiac function and remodeling, paramount assessments for coronary artery disease evaluation along with MBF. Part one of the aim of this thesis is the development and evaluation of methods for assessment of cardiac function and remodeling in terms of left-ventricular (LV) volumes and ejection fraction (EF), LV mass (LVM), and LV wall thickness (WT). Part two is focused on patient motion, which occurs frequently in all cardiac PET studies and represents a possible source for induced error in the quantification of MBF. The feasibility of LV volumes and EF calculations was shown in paper I, where cardiac-gated parametric blood-pool images and first-pass images were imported into a commercially available software for SPECT. The method was, however, too laborious for clinical practice but served as an important proof-of-concept. In paper II, LV volumes and EF calculations were performed using first-pass images in the same software used for standard analysis of 15O-water PET and MBF assessment. The results were improved compared to paper I and the method was feasible for clinical implementation. In paper III, LVM and WT calculations were performed using segmentation of perfusable tissue fraction (PTF) images. The results showed high accuracy compared to cardiac magnetic resonance (MR) imaging, and the method was highly automated, allowing for ready clinical implementation. In papers IV-V, the impact of patient motion on the quantitative accuracy of 15O-water PET was investigated. Simulations showed a minimal impact of PET-CT misalignment on MBF, but did show that impact of dynamic motion during PET acquisition was more pronounced. Visual inspection of clinical scans showed frequent motion, but at a small amplitude with generally limited impact according to the simulations. An automated motion detection algorithm was developed which was highly accurate in detecting larger types of motion. A clear pattern of motion-induced artifacts were discovered, which may help improve their visual detection.
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| 10. |
- Rosengren, Sara, et al.
(författare)
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Diagnostic Accuracy of [11C]PIB Positron Emission Tomography for Detection of Cardiac Amyloidosis
- 2020
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Ingår i: JACC Cardiovascular Imaging. - : Elsevier BV. - 1936-878X .- 1876-7591. ; 13:6, s. 1337-1347
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: This dual-site study evaluated the diagnostic accuracy of the method.BACKGROUND: Pittsburgh compound ([11C]PIB) positron emission tomography (PIB-PET) has shown promise as a specific and noninvasive method for the diagnosis of cardiac amyloidosis (CA).METHODS: The study had 2 parts. In the initial study, 51 subjects were included, 36 patients with known CA and increased wall thickness (15 immunoglobulin light chain [AL] and 21 transthyretin [ATTR] amyloidosis) and 15 control patients (7 were nonamyloid hypertrophic and 8 healthy volunteers). Subjects underwent PIB-PET and echocardiography. Sensitivity and specificity of PIB-PET were established for 2 simple semiquantitative approaches, standardized uptake value ratio (SUVR) and retention index (RI). The second part of the study included 11 amyloidosis patients (5 AL and 6 hereditary ATTR) without increased wall thickness to which the optimal cutoff values of SUVR (>1.09) and RI (>0.037 min-1) were applied prospectively.RESULTS: The diagnostic accuracy of visual inspection of [11C]PIB uptake was 100% in discriminating CA patients with increased wall thickness from controls. Semiquantitative [11C]PIB uptake discriminated CA from controls with a 94% (95% confidence interval [CI]: 80% to 99%) sensitivity for both SUVR and RI and specificity of 93% (95% CI: 66% to 100%) for SUVR and 100% (95% CI: 75% to 100%) for RI. [11C]PIB uptake was significantly higher in AL-CA than in ATTR-CA patients (p < 0.001) and discriminated AL-CA from controls with 100% (95% CI: 88% to 100%) accuracy for both the semiquantitative measures. In the prospective group without increased wall thickness, RI was elevated compared to controls (p = 0.001) and 5 of 11 subjects were evaluated as [11C]PIB PET positive.CONCLUSIONS: In a dual-center setting, [11C]PIB PET was highly accurate in detecting cardiac involvement in the main amyloid subtypes, with 100% accuracy in AL amyloidosis. A proportion of amyloidosis patients without known cardiac involvement were [11C]PIB PET positive, indicating that the method may detect early stages of CA.
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