Journal of Nuclear Cardiology最新文献

Introduction: Serial PET imaging is routinely employed to monitor treatment response in patients with suspected cardiac sarcoidosis (CS). Corticosteroids remain the mainstay of therapy in CS. However, there are no data available on the cardiovascular outcomes and optimal timing interval to obtain repeat PET while factoring in the influence of corticosteroid taper in relation to surveillance imaging.

Methods: We identified 81 patients with suspected CS (Age: 56.3 ± 1.9, 67% male, LVEF 46.5 ± 3) who were treatment naïve and demonstrated inflammation on baseline PET, subsequently started on moderate-dose prednisone monotherapy (i.e., 30-40 mg/day), and had a diagnostic follow-up PET. Treatment response was graded as complete (CTR) or partial (PTR), and no-response (NTR). Patients were divided into tertiles based on follow-up time between PET scans; tertile-1 (<3.2 months; median 3.1 months), tertile-2 (3.2 - 6.8 months; median 5.9 months), and tertile-3 (>6.8 months; median 9.8 months). Corticosteroid taper was captured by measuring weekly changes in prednisone from start of treatment to up to one-year follow-up. Major adverse cardiovascular events (MACE), defined as sustained ventricular arrhythmias were documented during the first year post-baseline PET.

Results: Treatment response CTR/PTR/NTR rates were similar across tertiles: (tertile-1 (92%) vs tertile-2 (86.2%) vs tertile-3 (85.2%); p=0.76). Taper rates and one-year cumulative prednisone dose were similar between the three groups (P=0.9). No significant difference was found in short-term MACE between the tertile groups (p=0.89). Similarly, MACE did not differ significantly according to treatment response status (p=0.39).

Conclusion: Surveillance time and taper rates do not seem to influence treatment response on PET scans among patients initiated on moderate-dose prednisone only. Similar MACE rates were observed despite variations in follow-up time and treatment response status.

Rationale: Transient ischemic dilation (TID) of the left ventricular (LV) cavity is considered a high-risk marker in patients with abnormal single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Stress image acquisition in Rubidium-82 (⁸²Rb) PET occurs at peak stress compared to 30-60 minutes post stress with SPECT. We aimed to evaluate the prognostic value of TID among patients undergoing ⁸²Rb PET MPI.

Methods: A total of 9878 consecutive patients with LVEF ≥40% undergoing rest/pharmacologic stress ⁸²Rb PET MPI from 2010-2016 were followed for a median of 3.2 years. The primary clinical outcome of cardiac death was assessed after adjusting for pre-test risk, known coronary artery disease (CAD), rest left ventricular ejection fraction (LVEF), summed stress score (SSS), LVEF reserve (LVEF-R), myocardial blood flow reserve (MBFR) and early (90-day) revascularization. Pre-specified interactions between TID ratio and SSSwere included to assess potential differences in the prognostic value of TID in patients based on perfusion.

Results: Mean age of the cohort was 69.0 (11.7) years, 56.1% female, 49.8% with known CAD, 27.9% with abnormal perfusion (SSS>0).There were 451 cardiac deaths. Higher TID ratio was associated with a significantly higher risk of cardiac death, even after accounting for LVEF-R and MBFR (HR per 0.1 unit increase =1.25 (1.11, 1.41), p<0.001). This was seen both among patients with normal (HR for TID per 0.1 unit increase= 1.24 (95% CI: 1.01, 1.52), p=0.04) and abnormal (HR for TID per 0.1 unit increase= 1.14 (95% CI: 1.02, 1.28), p=0.03) perfusion.

Conclusion: TID on rest/stress ⁸²RbPET MPI offers independent prognostic value in patients with both normal and abnormal perfusion beyond other risk markers, among patients with LVEF >40%.

Lower extremity peripheral artery disease (PAD) is characterized by impairment of blood flow associated with arterial stenosis and frequently coexisting microvascular disease and is associated with high rates of morbidity and mortality. Current diagnostic modalities have limited accuracy in early diagnosis, risk stratification, preprocedural assessment, and evaluation of therapy and are focused on the detection of obstructive atherosclerotic disease. Early diagnosis and assessment of both large vessels and microcirculation may improve risk stratification and guide therapeutic interventions. SPECT and PET imaging have been shown to be accurate to detect changes in perfusion in preclinical models and clinical disease, and have the potential to overcome limitations of existing diagnostic modalities, while offering novel information about perfusion, metabolic, and molecular processes. This review provides a comprehensive reassessment of radiotracer-based imaging of PAD in preclinical and clinical studies, emphasizing the challenges that arise due to the complex physiology in the peripheral vasculature. We will also highlight the latest advancements, underscoring emerging artificial intelligence and big data analysis, as well as clinically relevant areas where the field could advance in the next decade.

Background: Motion correction (MC) is critical for accurate quantification of myocardial blood flow (MBF) and flow reserve (MFR) from ¹⁸F-flurpiridaz PET myocardial perfusion imaging (MPI). However, manual correction is time consuming and introduces inter-observer variability. We aimed to validate an automatic MC algorithm for ¹⁸F-flurpiridaz PET-MPI in terms of diagnostic performance for predicting coronary artery disease (CAD).

Methods: In total, 231 patients who underwent invasive coronary angiography and rest/pharmacologic stress ¹⁸F-flurpiridaz PET-MPI from phase III Flurpiridaz trial (NCT01347710) were enrolled. For manual MC, two operators (Reader 1 and Reader 2) shifted each frame's images in three directions. The automatic MC algorithm, initially developed for ⁸²Rb-chloride PET-MPI, was optimized for ¹⁸F-flurpiridaz. Diagnostic performance was compared using minimal segmental MBF/MFR with and without MC to predict CAD ≥70% stenosis by angiography.

Results: Manual MC took 10 minutes per case (both stress and rest) on average, while automatic MC required <17 seconds. The area under the receiver operating characteristic curves (AUCs) for significant CAD using minimal segmental MBF were comparable between automatic and manual MC (AUC=0.877 automatic, AUC=0.888 Reader 1 and AUC=0.892 Reader 2; all p>0.05). AUCs of minimal segmental MBF with manual and automatic MC were significantly higher than without MC (p<0.05 for both). Similar findings were observed with minimal segmental MFR.

Conclusions: Automatic MC can be performed rapidly, with diagnostic performance for predicting obstructive CAD comparable to manual MC. This method could be utilized for analysis of MBF/MFR in patients undergoing ¹⁸F-flurpiridaz PET-MPI.

Background: In myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT), ungated studies are used for evaluation of perfusion defects despite motion blur. We investigate the potential benefit of motion correction using a deep-learning (DL) network for evaluating perfusion defects.

Methods: We employed a DL network for cardiac motion correction in ECG-gated SPECT-MPI images, wherein the image data from different cardiac phases are combined with respect to a reference gate to reduce motion blur. For training the DL network, 197 cases were used. Given the variability of gated images during the cardiac cycle, we investigated the detectability of perfusion defects in two distinct reference gates. To assess perfusion defect detection, we performed receiver-operating characteristic (ROC) analyses on the motion-corrected images using a separate test dataset of clinical 194 subjects, in which studies were created from actual patient data with inserted simulated-lesions as ground truth. The reconstructed images were assessed by the quantitative-perfusion SPECT (QPS) software. We also evaluated the performance on reduced-count studies (by two and four folds).

Results: The quantitative results, measured by area-under-the-ROC curve (AUC), demonstrated that DL motion correction improves the detectability of perfusion defects significantly on both standard- and reduced-count studies, and that the detectability can vary with reference cardiac phases. A joint assessment from two reference phases achieved AUC = 0.841 on the quarter-count data, higher than with ungated full-count data (AUC = 0.795, P-value = 0.0054).

Conclusions: DL motion correction can benefit assessment of perfusion defects in standard- and reduced-count SPECT-MPI studies. It can also be beneficial to evaluate perfusion images over multiple cardiac phases.