| 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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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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| 3. |
- Johnson, Geoffrey B., et al.
(författare)
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PET Imaging of Tumor Perfusion : A Potential Cancer Biomarker?
- 2020
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Ingår i: Seminars in nuclear medicine. - : Elsevier BV. - 0001-2998 .- 1558-4623. ; 50:6, s. 549-561
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Forskningsöversikt (refereegranskat)abstract
- Perfusion, as measured by imaging, is considered a standard of care biomarker for the evaluation of many tumors. Measurements of tumor perfusion may be used in a number of ways, including improving the visual detection of lesions, differentiating malignant from benign findings, assessing aggressiveness of tumors, identifying ischemia and by extension hypoxia within tumors, and assessing treatment response. While most clinical perfusion imaging is currently performed with CT or MR, a number of methods for PET imaging of tumor perfusion have been described. The inert PET radiotracer 15O-water PET represents the recognized gold standard for absolute quantification of tissue perfusion in both normal tissue and a variety of pathological conditions including cancer. Other cancer PET perfusion imaging strategies include the use of radiotracers with high first-pass uptake, analogous to those used in cardiac perfusion PET. This strategy produces more visually pleasing high-contrast images that provide relative rather than absolute perfusion quantification. Lastly, multiple timepoint imaging of PET tracers such as 18F-FDG, are not specifically optimized for perfusion, but have advantages related to availability, convenience, and reimbursement. Multiple obstacles have thus far blocked the routine use of PET imaging for tumor perfusion, including tracer production and distribution, image processing, patient body coverage, clinical validation, regulatory approval and reimbursement, and finally feasible clinical workflows. Fortunately, these obstacles are being overcome, especially within larger imaging centers, opening the door for PET imaging of tumor perfusion to become standard clinical practice. In the foreseeable future, it is possible that whole-body PET perfusion imaging with 15O-water will be able to be performed in a single imaging session concurrent with standard PET imaging techniques such as 18F-FDG-PET. This approach could establish an efficient clinical workflow. The resultant ability to measure absolute tumor blood flow in combination with glycolysis will provide important complementary information to inform prognosis and clinical decisions.
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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- Rosengren, Sara, et al.
(författare)
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Outcome prediction by myocardial external efficiency from 11C-acetate positron emission tomography in cardiac amyloidosis
- 2024
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Ingår i: ESC Heart Failure. - : John Wiley & Sons. - 2055-5822. ; 11:1, s. 44-53
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Tidskriftsartikel (refereegranskat)abstract
- AimsThis study aimed to study the prognostic value of myocardial oxygen consumption (MVO2) and myocardial external efficiency (MEE) from 11C-acetate positron emission tomography (PET) in cardiac amyloidosis (CA) patients.Methods and resultsForty-eight CA patients, both transthyretin (ATTR) and immunoglobulin light chain (AL) amyloidosis, and 20 controls were included. All subjects were examined with 11C-acetate PET and echocardiography. MVO2, forward stroke volume (FSV), and left ventricular mass (LVM) were derived from 11C-acetate PET and used to calculate MEE. CA patients were followed for survival and the prognostic impact of clinical, echocardiographic, and 11C-acetate PET parameters was analysed. MVO2 and MEE were reduced in CA compared with controls, but without significant difference between deceased and surviving CA patients. The ratio of 11C-acetate PET-derived FSV and LVM was also reduced in CA and significantly lowered in deceased patients compared with survivors. In univariate analysis, New York Heart Association class, N-terminal pro-brain natriuretic peptide, and the 11C-acetate PET parameters FSV/LVM and MEE were the strongest prognostic factors. Of the 11C-acetate PET parameters, FSV/LVM was the strongest survival predictor with hazard ratio of 0.56 per 0.1 mL/g (95% confidence interval 0.39–0.81, P = 0.002) and independently prognostic in a multivariate model. MEE significantly separated deceased from surviving CA patients with the cut-off of 15.7% (P = 0.032). Survival was significantly shorter with FSV/LVM below 0.27 mL/g (P < 0.001), also when separating AL- and ATTR-CA.ConclusionsReduced MEE was associated with shorter survival in CA patients, but FSV/LVM was the strongest survival predictor and the only independently prognostic 11C-acetate PET parameter in multivariate analysis.
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