BACKGROUND: Cardiac positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are widely used for the assessment of coronary artery disease. While SPECT remains more available, workforce s...BACKGROUND: Cardiac positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are widely used for the assessment of coronary artery disease. While SPECT remains more available, workforce shortages and training demands contribute to geographic disparities in PET availability, impacting patient access to advanced imaging. Therefore, we assessed trends in the U.S. cardiac nuclear imaging workforce. METHODS: Data from Medicare Part B (2013-2022), provided by the Centers for Medicare & Medicaid Services, were analyzed to assess trends in cardiac nuclear imaging services billed by physicians. The analysis focused on the number of readers, their gender, specialty, geographic distribution, and workload. RESULTS: From 2013 to 2022, the proportion of SPECT procedures declined from 95.8% (2,303,194 scans; 4393 per 100,000 Medicare beneficiaries) to 86.3% (1,386,358 scans; 2130 per 100,000 Medicare beneficiaries) of total nuclear cardiology procedures, while the proportion of PET procedures increased from 4.2% (99,861 scans; 190 per 100,000 Medicare beneficiaries) to 13.7% (220,366 scans; 339 per 100,000 Medicare beneficiaries). The majority of studies were interpreted by readers performing 50 or more studies annually. From 2013 to 2022, the number of SPECT-only readers declined from 17,013 to 13,491, while PET-only readers increased from 66 to 386. Readers interpreting both SPECT and PET doubled from 822 to 1643. Only 1 in 10 nuclear imaging readers were women and the majority were cardiologists. The median (interquartile range) number of studies per reader was higher for cardiologists compared to those of other specialties. Geographic disparities were evident, with most nuclear imaging readers practicing in Texas, Florida, and California, while the fewest were in Wyoming, Alaska, Vermont, and Washington, D.C. CONCLUSIONS: While SPECT remained the most commonly used modality in 2022, its use has declined, whereas PET use has increased, accompanied by similar trends in the number of readers. Gender and geographic disparities persist in the distribution of nuclear cardiology imaging specialists. Addressing these gaps is essential to ensuring equitable access to nuclear imaging expertise.
Martin EB, Kassira A, Stuckey A
… +4 more, Whittle B, Guthrie S, Kennel SJ, Wall JS
J Nucl Cardiol
· 2026 Feb · PMID 40914639
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Systemic amyloidosis is a complex disorder, making early and accurate diagnosis challenging. The most common types are associated with misfolded transthyretin or immunoglobulin light chains, where cardiac and renal amylo...Systemic amyloidosis is a complex disorder, making early and accurate diagnosis challenging. The most common types are associated with misfolded transthyretin or immunoglobulin light chains, where cardiac and renal amyloidosis portend the worst prognosis. Peptide p5+14 can bind all types of amyloid via multivalent electrostatic interactions. When radiolabeled with either iodine-124 or technetium-99m, it can be used to detect cardiac and extracardiac amyloid deposits using positron emission tomography/computed tomography (PET/CT) or single-photon emission computed tomography/CT (SPECT/CT) imaging, respectively. I-p5+14 (I-evuzamitide) has been evaluated in eight investigator-initiated studies and is now in a pivotal Phase 3 study (REVEAL) for the detection of cardiac amyloidosis. Both radiotracers image cardiac transthyretin (ATTR) and immunoglobulin light chain (AL) amyloidosis; however, due to the characteristics of the radionuclides, the images and image data are similar but uniquely different and complementary. Using data collected from the University of Tennessee Medical Center experiences, herein, we summarize and contrast characteristics of I-evuzamitide and Tc-p5+14 as radiotracers for amyloid detection.
Myocardial viability assessment can be valuable in the management of selected patients with moderate-to-severe ischemic cardiomyopathy. Among the viability imaging modalities, 18F-fluorodeoxyglucose positron emission tom...Myocardial viability assessment can be valuable in the management of selected patients with moderate-to-severe ischemic cardiomyopathy. Among the viability imaging modalities, 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) is a key tool for evaluating myocardial metabolic activity, helping to distinguish viable myocardium from scar tissue. Optimal metabolic preparation is crucial to enhance myocardial glucose uptake and ensure accurate imaging, particularly in diabetic patients with variable insulin resistance. This review presents a clinical case illustrating the role of 18F-FDG PET in myocardial viability assessment, explores different metabolic preparation protocols, and examines their clinical implications. The hyperinsulinemic euglycemic clamp (HEC) remains the most effective technique; however,alternative protocols, such as intravenous glucose loading with insulin, are increasingly utilized for their efficiency and practicality. A comparative analysis of these methods provides insight into their suitability for different patient populations. This review also emphasizes the importance of a standardized yet adaptable approach to metabolic preparation,considering individual patient factors and institutional resources. Emerging literature supporting optimized PET imaging protocols is highlighted to help guide clinical decision-making for revascularization in patients with moderate-to-severe ischemic cardiomyopathy.
BACKGROUND: It is unclear whether coronary artery stenosis, plaque burden, and composition differ between major epicardial arteries supplying ischemic myocardial territories. METHODS: We studied 837 symptomatic patients...BACKGROUND: It is unclear whether coronary artery stenosis, plaque burden, and composition differ between major epicardial arteries supplying ischemic myocardial territories. METHODS: We studied 837 symptomatic patients undergoing coronary computed tomography angiography (CTA) and O-water positron emission tomography (PET) myocardial perfusion imaging for suspected obstructive coronary artery disease. Coronary CTA was analyzed using artificial intelligence-guided quantitative computed tomography (AI-QCT) to assess stenosis and atherosclerotic plaque characteristics. Myocardial ischemia was defined by regional PET perfusion in the left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territories. RESULTS: Among arteries supplying ischemic territories, the LAD exhibited significantly higher stenosis and both absolute and normalized plaque volumes compared to LCX and RCA (P < .001 for all). Multivariable logistic regression showed diameter stenosis (P = .001-.015), percent atheroma volume (PAV; P < .001), and percent noncalcified plaque volume (NCPV) (P = .001-.017) were associated with ischemia across all three arteries. Percent calcified plaque volume (CPV) was associated with ischemia only in the RCA (P = .001). CONCLUSIONS: The degree of stenosis and atherosclerotic burden are significantly higher in the LAD as compared to LCX and RCA, both in epicardial coronary arteries supplying nonischemic or ischemic myocardial territories. In all the three main coronary arteries, both luminal narrowing and plaque burden are independent predictors of ischemia, where the plaque burden is mainly driven by noncalcified plaque. However, many vessels supplying ischemic territories have a relatively low degree of stenosis and plaque burden, especially in the LCX and RCA, limiting the ability of diameter stenosis and PAV to predict myocardial ischemia.
Ramirez G, Lemley M, Shanbhag A
… +26 more, Kwiecinski J, Miller RJH, Kavanagh PB, Liang JX, Dey D, Slipczuk L, Travin MI, Alexanderson E, Carvajal-Juarez I, Packard RRS, Al-Mallah M, Einstein AJ, Feher A, Acampa W, Knight S, Le VT, Mason S, Sanghani R, Wopperer S, Chareonthaitawee P, Buechel RR, Rosamond TL, deKemp RA, Berman DS, Di Carli MF, Slomka PJ
J Nucl Cardiol
· 2025 Oct · PMID 40774620
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BACKGROUND: The REgistry of Flow and Perfusion Imaging for Artificial Intelligence with positron emission tomography (REFINE PET) was established to collect multicenter PET and associated computed tomography (CT) images,...BACKGROUND: The REgistry of Flow and Perfusion Imaging for Artificial Intelligence with positron emission tomography (REFINE PET) was established to collect multicenter PET and associated computed tomography (CT) images, together with clinical data and outcomes, into a comprehensive research resource. REFINE-PET will enable validation and development of both standard and novel cardiac PET/CT processing methods. METHODS: REFINE-PET is a multicenter, international registry that contains both clinical and imaging data. The PET scans were processed using QPET software (Cedars-Sinai Medical Center, Los Angeles, CA), while the CT scans were processed using deep learning (DL) to detect coronary artery calcium (CAC). Patients were followed up for the occurrence of major adverse cardiovascular events (MACE), which include death, myocardial infarction, unstable angina, and late revascularization (>90 days from PET). RESULTS: The REFINE-PET registry currently contains data for 35595 patients from 14 sites, with additional patient data and sites anticipated. Comprehensive clinical data (including demographics, medical history, and stress test results) were integrated with more than 2100 imaging variables across 34 categories. The registry is poised to address a broad range of clinical questions, supported by correlating invasive angiography (within 6 months of PET myocardial perfusion imaging [MPI]) in 5955 patients and a total of 9278 major adverse cardiovascular events during a median follow-up of 4.2 years. CONCLUSIONS: The REFINE-PET registry leverages the integration of clinical, multimodality imaging, and novel quantitative and AI tools to advance the role of PET/CT MPI in diagnosis and risk stratification.
BACKGROUND: The optimal method for evaluating coronary artery disease in liver transplant candidates (LTCs) remains controversial. To date no studies have compared the hemodynamic and symptomatic response to vasodilator...BACKGROUND: The optimal method for evaluating coronary artery disease in liver transplant candidates (LTCs) remains controversial. To date no studies have compared the hemodynamic and symptomatic response to vasodilator stress between LTCs and patients without chronic liver disease. METHODS: We conducted a retrospective study of LTCs who underwent regadenoson nuclear stress testing with either Tc-tetrofosmin single-photon emission computed tomography (SPECT; N = 224) or Rubidium positron emission tomography (N = 36). These patients were compared to controls matched for age, sex, body mass index, cardiovascular comorbidities, and imaging modality who underwent clinically indicated regadenoson stress test. RESULTS: LTCs were less likely to experience symptoms in response to regadenoson than controls (65% vs 86 %, P < .001). Additionally, the increase in heart rate was blunted in LTCs (ΔHR: 13 beats per minute [bpm], interquartile range [IQR]: 11-15 vs 29 bpm, IQR: 27-31, P < .001). During the median follow-up period of 2.0 ± 1.5 years, 78 deaths occurred in LTCs. In the multivariable analysis, ΔHR (hazard ratio [HZR]: .975, 95% confidence interval [CI]: .951-.999, P = .042) and changes in diastolic blood pressure (ΔDBP, HZR: 1.037, 95% CI: 1.003-1.071, P = .031) were significantly associated with mortality regardless of Model for End-stage Liver Disease (MELD) score, age, cardiovascular comorbidities, and stress test results. In addition, LTCs with both high MELD score (≥15) and low ΔHR (≤10 bpm) had worse overall survival than patients with a low MELD score (<15) and high ΔHR (>10 bpm, HZR: 5.54, 95% CI: 3.21-9.53, P < .001), low MELD score and low ΔHR (HZR: 6.62, 95% CI: 3.25-13.49, P < .001), and high MELD score and low ΔHR (HZR: 2.91, 95% CI: 1.50-5.64, P = .002). CONCLUSIONS: In this retrospective cohort analysis, LTCs exhibited a reduced hemodynamic response detected as lower ΔHR as well as fewer symptoms in response to regadenoson during stress testing. Reduced hemodynamic response was significantly associated with mortality and provided incremental prognostic value in addition to MELD score. Further prospective studies are required to validate these findings.
BACKGROUND: This study aimed to evaluate the prognostic value of myocardial Tc-pyrophosphate (PYP) uptake in patients undergoing PYP imaging for suspected transthyretin cardiac amyloidosis (ATTR-CA). METHODS: A retrospec...BACKGROUND: This study aimed to evaluate the prognostic value of myocardial Tc-pyrophosphate (PYP) uptake in patients undergoing PYP imaging for suspected transthyretin cardiac amyloidosis (ATTR-CA). METHODS: A retrospective analysis of 301 consecutive patients who underwent PYP imaging for suspected ATTR-CA was performed. Myocardial PYP uptake was graded visually using the Perugini classification (grade 0-3) and quantified by the heart-to-contralateral lung uptake (H/CL) ratio. The primary outcome was combined cardiac death and documented fatal ventricular arrhythmias (ventricular fibrillation [VF] and sustained ventricular tachycardia [VT] lasting >30 seconds). RESULTS: Among the 301 patients, 90 had positive myocardial PYP uptake on SPECT. During a median follow-up of 668 days (interquartile range, 186-868 days), 36 patients died, including 13 cardiac deaths. Fatal ventricular arrhythmias were documented in 6 patients (2 aborted VF and 4 sustained VT). The primary outcome occurred in 8 of 211 (4%) patients with negative PYP SPECT and in 10 of 90 (11%) patients with positive PYP SPECT. Kaplan-Meier analyses showed a significantly higher incidence of the primary outcome in patients with positive PYP SPECT than in those without (P=.018). In contrast, all-cause mortality did not differ significantly between the two groups (P=.36). Multivariable Cox proportional hazards regression analyses showed that PYP SPECT positivity was an independent predictor of the primary outcome in patients with suspected ATTR-CA (adjusted hazard ratio: 2.86 [95% confidence interval: 1.10-7.41]; P =.031). CONCLUSIONS: Significant myocardial PYP uptake was associated with an increased risk of adverse cardiac events in patients with suspected ATTR-CA.
Cardiac amyloidosis radionuclide imaging (CARI) has transformed the diagnostic approach to suspected transthyretin cardiomyopathy (ATTR-CM), enabling non-invasive diagnosis and reducing the need for biopsy. This review p...Cardiac amyloidosis radionuclide imaging (CARI) has transformed the diagnostic approach to suspected transthyretin cardiomyopathy (ATTR-CM), enabling non-invasive diagnosis and reducing the need for biopsy. This review provides practical guidance for performing and interpreting CARI, illustrated by a clinical case. Exclusion of monoclonal gammopathy is essential to preserve specificity. When absent, Perugini grade 2-3 uptake on single-photon emission computed tomography (SPECT) is diagnostic; planar imaging or heart-to-contralateral ratios alone are insufficient. Optimal practice includes validated tracers (99mTc-DPD, -PYP, -HMDP), correct timing to avoid blood pool activity, and SPECT - preferably with CT - for accurate localization. Interpretation should account for pitfalls such as non-diffuse uptake, artifacts, and alternative causes (e.g., AL amyloidosis, infarction, drug toxicity). Emerging applications include quantitative SPECT/CT for staging, prognosis, and therapy monitoring, though standardization is needed. Adherence to expert consensus and technical standards maximizes diagnostic accuracy and safe integration of CARI into the management of cardiac amyloidosis.
BACKGROUND: This study aimed to develop a dedicated tracer with high first-pass extraction fraction and stable heart retention for single-photon emission computed tomography (SPECT) myocardial perfusion imaging and flow...BACKGROUND: This study aimed to develop a dedicated tracer with high first-pass extraction fraction and stable heart retention for single-photon emission computed tomography (SPECT) myocardial perfusion imaging and flow measurement. METHODS: Three Tc-labeled compounds (Tc-4BOH, Tc-3BOH, and Tc-2BOH) were evaluated by mouse ex vivo distribution and swine planar imaging studies. Tc-4BOH was identified as a candidate and compared with Tc-Teboroxime and Tc-Sestamibi in swine on cadmium zinc telluride SPECT to study organ uptake and kinetic properties. Head-to-head comparisons of Tc-4BOH with Tc-Sestamibi and N-NH were performed on two separate pilot cohorts each comprising 10 patients. RESULTS: The myocardial uptake of Tc-4BOH demonstrated significantly higher levels than Tc-Sestamibi in swine and human, evidenced by higher K values (swine rest: .81 ± .03 mL/g/min vs .43 ± .09 mL/g/min, P < .001; stress: 1.19 ± .26 mL/g/min vs .50 ± .10 mL/g/min, P < .001; human rest: .74 ± .09 mL/g/min vs .38 ± .04 mL/g/min, P < .001; stress 1.42 ± .17 mL/g/min vs .59 ± .07 mL/g/min, P < .001). k values of Tc-4BOH were lower than those of Tc-Teboroxime (rest: .18 ± .03/min vs .26 ± .01/min, P < .001; stress: .26 ± .04/min vs .38 ± .08/min, P < .01), suggesting greater stability than Tc-Teboroxime in the swine. Three- to 8-min data after injection are sufficient to produce high-quality perfusion images that offer clear visualization of the myocardium and minimal interference artifacts due to favorable heart-to-liver ratios of Tc-4BOH. Furthermore, K values from Tc-4BOH SPECT significantly correlated with N-NH positron emission tomography myocardial blood flow (MBF) (ρ = .83 on per-patient level, P < .001; ρ = .81 on per-vessel level, P < .001). CONCLUSIONS: Tc-4BOH exhibited an encouraging pharmacokinetic profile with high and relatively stable cardiac uptake. It constitutes a promising candidate as myocardial perfusion radiotracer for SPECT MBF quantification.
Hijazi W, Feng Y, Southern DA
… +11 more, Chew D, Filipchuk N, Mylonas I, Kazmi M, Banijamali H, Har B, James M, Wilton S, Slomka PJ, Berman D, Miller RJ