Journal of Nuclear Cardiology最新文献

Background: Transthyretin cardiac amyloidosis (ATTR-CM) is an increasingly recognized cause of heart failure (HF) in older adults. Several therapies for ATTR-CM are now available, with more currently in development. As such, there is an increasing need for methods to assess response to therapy. We evaluated the associations between serial 99m-technetium pyrophosphate (^99mTc-PYP) deep learning measurements with changes in other imaging parameters and clinical outcomes.

Methods: We included patients with a diagnosis of ATTR-CM and at least two ^99mTc-PYP studies followed through the Amyloidosis Program of Calgary. Patients underwent laboratory testing, echocardiography, and cardiovascular magnetic resonance unless contraindications were present. ^99mTc-PYP images were quantified using our previously developed deep learning methodology including assessment of cardiac pyrophosphate activity (CPA) and volume of involvement (VOI).

Results: In total, 85 patients were included, with a median population age of 79 years (interquartile range [IQR]: 72 - 84) and 76 (89%) male patients. In patients on therapy, there was a reduction in VOI (median: 100 to 51, P < 0.001), CPA (median: 165 to 81, P < 0.001), native T1 (median: 1400 to 1387, P = 0.005), and extracellular volume (median: 50 to 49, P = 0.035) during a median time of 369 days (IQR: 365-516) between scans. There was a modest correlation between change in CPA and change in native T1 (ρ = 0.376, P = 0.009). After adjusting for age, treatment, and CPA at follow-up, an increase in CPA during follow-up was also associated with an increased risk (adjusted hazard ratio: 2.31 per standard deviation increase, 95% confidence interval: 1.28-4.17, P = 0.005).

Conclusions: Serial ^99mTc-PYP quantitation has modest correlations with other measures of disease burden including native T1. Changes in these measures were associated with risk of cardiovascular death or HF hospitalization, suggesting that the serial measurements may be clinically meaningful surrogate endpoints.

Background: Assessment of myocardial sympathetic innervation with iodine-123-metaiodobenzylguanidine ([¹²³I]mIBG) scintigraphy is conventionally performed by determining the heart-to-mediastinum ratio (HMR) on planar images. This study aimed to investigate the feasibility of determining HMR from reprojected [¹²³I]mIBG planar images derived from tomographic data by a ring-configured cadmium-zinc-telluride (CZT) gamma camera and its agreement with HMR determined from [¹²³I]mIBG planar images by an Anger gamma camera, in the assessment of myocardial sympathetic innervation.

Methods: A total of 105 study participants (suspected idiopathic rapid-eye-movement sleep behavior disorder n = 55, early-stage Parkinson's Disease n = 36, and healthy controls n = 14) who were referred for [¹²³I]mIBG myocardial scintigraphy were included, in addition to eight phantom experiments simulating a range of HMR. HMR was determined from planar and reprojected planar images acquired with an Anger gamma camera and a ring-configured CZT gamma camera, respectively, for all study participants and phantom experiments. Agreement in HMR between the two imaging methods was analyzed in Bland-Altman plots. Intra- and interobserver variability was evaluated for both imaging methods in a subset of images.

Results: The agreement between planar and reprojected planar images was good, with a mean difference in HMR of 0.11 (95% limits of agreement -0.16 to 0.38) for the study participants. Intra- and interobserver variability was low and comparable for both imaging methods. Results from the phantom experiments were consistent with those from the study participants.

Conclusions: Determining HMR from reprojected [¹²³I]mIBG myocardial scintigraphy planar images acquired with a ring-configured CZT gamma camera is feasible and shows good agreement with HMR determined from planar images by a conventional Anger gamma camera.

Background: The novel perfusion single photon emission computed tomography (SPECT) tracer ^99mTc-4BOH shows potential for accurate myocardial blood flow (MBF) quantification. This study aimed to determine the optimal pharmacokinetic model and dynamic acquisition protocol for ^99mTc-4BOH in coronary artery disease patients.

Methods: Sixty patients underwent 10-minute rest and stress dynamic ^99mTc-4BOH SPECT scans. One-tissue (1T), reversible two-tissue (2T), and irreversible two-tissue (2Ti) compartment models applied to myocardial time-activity curves using image-derived input functions. Model selection relied on the K₁ agreement with ¹³N-NH₃ MBF in 8 patients and on the reliability of K₁ across all 60 patients. The optimal acquisition time was further investigated by K₁ reliability and its correlation with 10-minute results. Regional analyses were performed on 3 coronary territories and 17 American Heart Association (AHA) segments.

Results: The 1T model provided stable and reliable K₁ estimates for 10-, 8-, 6-, and 4-minute scans, with consistent bias and standard deviation relative to ¹³N-NH₃ MBF. Across all 60 patients, 1T outperformed 2T and 2Ti, showing the lowest relative standard error and fewest unreliable estimates, resulting in a rest K₁ of 0.72 ± 0.18 mL/g/min and a stress K₁ of 1.62 ± 0.35 mL/g/min using the 10-minute scan. Strong correlations (r > 0.9, P < 0.001) were observed between K₁ from shortened (8, 6, 4 minutes) and 10-minute scans but decreased at 2 minutes. Regional analyses confirmed that 4-minute scans with 1T yielded reliable K₁ quantification (r > 0.9, P < 0.001).

Conclusion: The 1T model is optimal for dynamic ^99mTc-4BOH SPECT and a 4-min scan is sufficient for reliable global and regional MBF quantification.

Background: This study aimed to investigate the relationship between pressure overload-induced right ventricular (RV) fibrotic remodeling detected by ^99mTc-fibroblast activation protein inhibitor (FAPI) single photon emission computed tomography/computed tomography (SPECT/CT) and echocardiographic biomechanical adaptation/maladaptation in chronic thromboembolic pulmonary hypertension (CTEPH).

Methods: Thirty-seven CTEPH patients scheduled for balloon pulmonary angiography (BPA) underwent baseline ^99mTc-FAPI SPECT/CT, speckle-tracking echocardiography (measuring RV global strain [GS] and free-wall strain [FWS]), and right heart catheterization. Baseline RV FAPI uptake (peak myocardial-to-blood ratio, TBR_peak) was compared with RV strain and RV-pulmonary artery coupling parameters. Twenty patients received repeated BPA sessions, and a subgroup of 10 underwent repeat FAPI SPECT and strain analysis after a single BPA.

Results: Baseline global RV FAPI TBR_peak varied among CTEPH patients (mean ± SD: 2.92 ± 0.96; range: 1.44-4.76). Patients without RV uptake exhibited significantly higher strain values and preserved RV-pulmonary artery coupling compared to those with uptake. TBR_peak of free wall correlated positively with RVGS (r = 0.450, P = 0.005), RVGS/sPAP (global right ventricular longitudinal strain/systolic pulmonary artery pressure) (r = 0.370, P = 0.024), right ventricular free-wall longitudinal strain (RVFWS, r = 0.386, P = 0.018), and RVFWS/sPAP (r = 0.347, P = 0.035). Following a single BPA, RV FAPI uptake decreased in 6 of 10 patients and increased modestly in 4. Changes in FAPI uptake (global ΔTBR_peak) significantly correlated with ΔRVGS (r = 0.697, P = 0.025), ΔRVFWS (r = 0.710, P = 0.022), ΔRVGS/sPAP (r = 0.694, P = 0.026), ΔRVFWS/sPAP (r = 0.700, P = 0.024).

Conclusion: In CTEPH, RV fibrotic remodeling quantified by FAPI SPECT/CT correlated with echocardiographic RV strain and ventricular-pulmonary artery coupling. Following BPA, changes in RV FAPI uptake appeared dynamic, with fluctuations potentially corresponding to alterations in both RV strain and ventricular-pulmonary coupling parameters.