<div><h4>Complete resolution of focal-on-diffuse myocardial activity pattern on FDG PET-CT by prolonging the dietary preparation protocol in cardiac sarcoidosis.</h4><i>Kherajani P, Farag AA, Morgan WS, Hage FG, Bhambhvani P</i><br /><AbstractText>Patient preparation is crucial for reliable interpretation of cardiac inflammation FDG PET. We share our experience of improved reporting confidence and propose a simple approach of prolonging preparation (from 24 to 48 hours) with the high-fat, no-carbohydrate, and protein-permitted diet followed by fasting in cardiac sarcoidosis in cases with diffuse or focal-on-diffuse myocardial FDG uptake.</AbstractText><br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 31 Jul 2023; epub ahead of print</small></div>

<div><h4>Coronary vascular dysfunction is associated with increased risk of death in patients with peripheral artery disease.</h4><i>Peri-Okonny PA, Patel KK, Garcia RA, Thomas M, ... Thompson RC, Bateman TM</i><br /><b>Background</b><br />Peripheral artery disease (PAD) and coronary vascular dysfunction are common in patients with cardiometabolic disease. Neither the prevalence of coronary vascular dysfunction among patients with PAD nor the prognostic impact with these two conditions present together has been well studied.<br /><b>Methods</b><br />Consecutive patients who underwent PET MPI were analyzed for presence of coronary vascular dysfunction [myocardial blood flow reserve (MBFR) < 2]. Cox regression was used to examine the association of reduced MBFR with mortality in patients with PAD, as well as the association of comorbid MBFR < 2 and PAD with all-cause death.<br /><b>Results</b><br />Among 13,940 patients, 1936 (14%) had PAD, 7782 (56%) had MBFR < 2 and 1346 (10%) had both PAD and MBFR < 2. Reduced MBFR was very common (69.5%) and was associated with increased risk of all-cause death (HR 1.69, 95%CI 1.32, 2.16, p < 0.01) in patients with PAD. Patients with both PAD and MBFR < 2, and those with either PAD or reduced MBFR had increased risk of death compared to those with neither condition: PAD + MBFR < 2 [(HR 95%CI), 2.30; 1.97-2.68], PAD + MBFR ≥ 2 (1.37; (1.08-1.72), PAD - MBFR < 2 (1.98; 1.75-2.25), p < 0.001 for all).<br /><b>Conclusion</b><br />Coronary vascular dysfunction was common in patients with PAD and was associated with increased risk of death.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 31 Jul 2023; epub ahead of print</small></div>

<div><h4>Automated cardiovascular risk categorization through AI-driven coronary calcium quantification in cardiac PET acquired attenuation correction CT.</h4><i>van Velzen SGM, Dobrolinska MM, Knaapen P, van Herten RLM, ... Greuter MJW, Išgum I</i><br /><b>Background</b><br />We present an automatic method for coronary artery calcium (CAC) quantification and cardiovascular risk categorization in CT attenuation correction (CTAC) scans acquired at rest and stress during cardiac PET/CT. The method segments CAC according to visual assessment rather than the commonly used CT-number threshold.<br /><b>Methods</b><br />The method decomposes an image containing CAC into a synthetic image without CAC and an image showing only CAC. Extensive evaluation was performed in a set of 98 patients, each having rest and stress CTAC scans and a dedicated calcium scoring CT (CSCT). Standard manual calcium scoring in CSCT provided the reference standard.<br /><b>Results</b><br />The interscan reproducibility of CAC quantification computed as average absolute relative differences between CTAC and CSCT scan pairs was 75% and 85% at rest and stress using the automatic method compared to 121% and 114% using clinical calcium scoring. Agreement between automatic risk assessment in CTAC and clinical risk categorization in CSCT resulted in linearly weighted kappa of 0.65 compared to 0.40 between CTAC and CSCT using clinically used calcium scoring.<br /><b>Conclusion</b><br />The increased interscan reproducibility achieved by our method may allow routine cardiovascular risk assessment in CTAC, potentially relieving the need for dedicated CSCT.<br /><br />© 2022. The Author(s).<br /><br /><small>J Nucl Cardiol: 01 Jul 2023; 30:955-969</small></div>

<div><h4>PET/CT-identified atrial hypermetabolism is an index of atrial inflammation in patients with atrial fibrillation.</h4><i>Kupusovic J, Weber M, Bruns F, Kessler L, ... Rischpler C, Siebermair J</i><br /><b>Background</b><br />Although atrial inflammation has been implicated in the pathophysiology of atrial fibrillation (AF), the identification of atrial inflammation remains challenging. We aimed to establish a positron emission tomography/computed tomography (PET/CT) protocol with <sup>18</sup>Fluor-labeled fluorodeoxyglucose (<sup>18</sup>F-FDG) for the detection of atrial hypermetabolism as surrogate for inflammation in AF.<br /><b>Methods</b><br />We included n = 75 AF and n = 75 non-AF patients undergoing three common PET/CT protocols (n = 25 per group) optimized for the detection of (a) inflammation and (b) malignancy in predefined fasting protocols, and (c) cardiac viability allowing for maximized glucose uptake. <sup>18</sup>F-FDG-uptake was analyzed in predefined loci.<br /><b>Results</b><br />Differences of visual atrial uptake in AF vs non-AF patients were observed in fasting (inflammation [13/25 vs 0/25] and malignancy [10/25 vs 0/25]) protocols while viability protocols showed non-specific uptake in both the groups. In the inflammation protocol, AF patients showed higher uptake in the right atrium [(SUVmax: 2.5 ± .7 vs 2.0 ± .7, P = .01), atrial appendage (SUVmax: 2.4 ± .7 vs 2.0 ± .6, P = .03), and epicardial adipose tissue (SUVmax: 1.4 ± .5 vs 1.1 ± .4, P = .04)]. Malignancy and viability protocols failed to differentiate between AF and non-AF.<br /><b>Conclusion</b><br />Glucose uptake suppression protocols appear suitable in detecting differential atrial <sup>18</sup>F-FDG uptake between AF and non-AF patients. Imaging-based assessment of inflammation might help to stratify AF patients offering individualized therapeutic approaches.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 17 Aug 2023; epub ahead of print</small></div>

<div><h4>Coronary artery calcium score and pre-test probabilities as gatekeepers to predict and rule out perfusion defects in positron emission tomography.</h4><i>Clerc OF, Frey SM, Honegger U, Amrein MLF, ... Haaf P, Zellweger MJ</i><br /><b>Background</b><br />Little is known about the gatekeeper performance of coronary artery calcium score (CACS) before myocardial perfusion positron emission tomography (PET), compared with updated pre-test probabilities from American and European guidelines (pre-test-AHA/ACC, pre-test-ESC).<br /><b>Methods</b><br />We enrolled participants without known coronary artery disease undergoing CACS and Rubidium-82 PET. Abnormal perfusion was defined as summed stress score ≥ 4. Using Bayes\' formula, pre-test probabilities and CACS were combined into post-test probabilities.<br /><b>Results</b><br />We included 2050 participants (54% male, mean age 64.6 years) with median CACS 62 (IQR 0-380), pre-test-ESC 17% (11-26), pre-test-AHA/ACC 27% (16-44), and abnormal perfusion in 437 participants (21%). To predict abnormal perfusion, area under the curve of CACS was 0.81, pre-test-AHA/ACC 0.68, pre-test-ESC 0.69, post-test-AHA/ACC 0.80, and post-test-ESC 0.81 (P < 0.001 for CACS vs. each pre-test, and each post-test vs. pre-test). CACS = 0 had 97% negative predictive value (NPV), pre-test-AHA/ACC ≤ 5% 100%, pre-test-ESC ≤ 5% 98%, post-test-AHA/ACC ≤ 5% 98%, and post-test-ESC ≤ 5% 96%. Among participants, 26% had CACS = 0, 2% pre-test-AHA/ACC ≤ 5%, 7% pre-test-ESC ≤ 5%, 23% post-test-AHA/ACC ≤ 5%, and 33% post-test-ESC ≤ 5% (all P < 0.001).<br /><b>Conclusions</b><br />CACS and post-test probabilities are excellent predictors of abnormal perfusion and can rule it out with very high NPV in a substantial proportion of participants. CACS and post-test probabilities may be used as gatekeepers before advanced imaging. Coronary artery calcium score (CACS) predicted abnormal perfusion (SSS ≥ 4) in myocardial positron emission tomography (PET) better than pre-test probabilities of coronary artery disease (CAD), while pre-test-AHA/ACC and pre-test-ESC performed similarly (left). Using Bayes\' formula, pre-test-AHA/ACC or pre-test-ESC were combined with CACS into post-test probabilities (middle). This calculation reclassified a substantial proportion of participants to low probability of CAD (0-5%), not needing further imaging, as shown for AHA/ACC probabilities (2% with pre-test-AHA/ACC to 23% with post-test-AHA/ACC, P < 0.001, right). Very few participants with abnormal perfusion were classified under pre-test or post-test probabilities 0-5%, or under CACS 0. AUC: area under the curve. Pre-test-AHA/ACC: Pre-test probability of the American Heart Association/American College of Cardiology. Post-test-AHA/ACC: Post-test probability combining pre-test-AHA/ACC and CACS. Pre-test-ESC: Pre-test probability of the European Society of Cardiology. SSS: Summed stress score.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 06 Jul 2023; epub ahead of print</small></div>

<div><h4>Amyloid myopathy: expanding the clinical spectrum of transthyretin amyloidosis-case report and literature review.</h4><i>Ungericht M, Wanschitz J, Kroiss AS, Röcken C, ... Loescher WN, Poelzl G</i><br /><AbstractText>We identified two patients with transthyretin (ATTR) amyloid myopathy (one ATTR variant amyloidosis, ATTRv; one wild-type ATTR amyloidosis, ATTRwt). Myopathy was the initial manifestation in ATTRwt, whereas it followed neuropathy and cardiomyopathy in ATTRv. The ATTRwt patient showed muscular tracer uptake on <sup>99m</sup>Tc-DPD planar scintigraphy at the time of initial diagnosis, consistent with ATTR amyloid myopathy. The ATTRv patient underwent heart transplantation because of progressive heart failure. Within the next two years, progressive myopathic symptoms and extracardiac tracer uptake on <sup>99m</sup>Tc-DPD planar scintigraphy were documented, attributable to ATTR amyloid myopathy. Interstitial amyloid deposits were confirmed by muscle biopsy in both patients, with a particularly high amyloid burden in the adipose tissue. This case report highlights the frequent concomitant presence of cardiac ATTR amyloidosis and ATTR amyloid myopathy. ATTR amyloid myopathy may precede cardiac manifestation in ATTRwt or occur after heart transplantation in ATTRv. Due to the high diagnostic accuracy of <sup>99m</sup>Tc-DPD scintigraphy for detecting ATTR amyloid myopathy and the emergence of novel therapeutics, it is important to increase the awareness of its presence.</AbstractText><br /><br />© 2022. The Author(s).<br /><br /><small>J Nucl Cardiol: 01 Aug 2023; 30:1420-1426</small></div>

<div><h4>Decline in typical angina among patients referred for cardiac stress testing.</h4><i>Rozanski A, Han D, Miller RJH, Gransar H, ... Thomson LEJ, Berman DS</i><br /><b>Objective</b><br />To evaluate temporal trends in the prevalence of typical angina and its clinical correlates among patients referred for stress/rest SPECT myocardial perfusion imaging (MPI).<br /><b>Patients and methods</b><br />We evaluated the prevalence of chest pain symptoms and their relationship to inducible myocardial ischemia among 61,717 patients undergoing stress/rest SPECT-MPI between January 2, 1991 and December 31, 2017. We also assessed the relationship between chest pain symptom and angiographic findings among 6,579 patients undergoing coronary CT angiography between 2011 and 2017.<br /><b>Results</b><br />The prevalence of typical angina among SPECT-MPI patients declined from 16.2% between 1991 and 1997 to 3.1% between 2011 and 2017, while the prevalence of dyspnea without any chest pain increased from 5.9 to 14.5% over the same period. The frequency of inducible myocardial ischemia declined over time within all symptom groups, but its frequency among current patients (2011-2017) with typical angina was approximately three-fold higher versus other symptom groups (28.4% versus 8.6%, p < 0.001). Overall, patients with typical angina had a higher prevalence of obstructive CAD on CCTA than those with other clinical symptoms, but 33.3% of typical angina patients had no coronary stenoses, 31.1% had 1-49% stenoses, and 35.4% had ≥ 50% stenoses.<br /><b>Conclusions</b><br />The prevalence of typical angina has declined to a very low level among contemporary patients referred for noninvasive cardiac tests. The angiographic findings among current typical angina patients are now quite heterogeneous, with one-third of such patients having normal coronary angiograms. However, typical angina remains associated with a substantially higher frequency of inducible myocardial ischemia compared to patients with other cardiac symptoms.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 06 Jul 2023; epub ahead of print</small></div>

<div><h4>Fibroblast activation protein imaging in atrial fibrillation: a proof-of-concept study.</h4><i>Li L, Gao J, Chen BX, Liu X, ... Yang MF, Xie B</i><br /><b>Background</b><br />To evaluate the feasibility of using radiolabeled fibroblast activation protein inhibitor (FAPI) PET/CT imaging to assess activated fibroblasts in the atria of individuals with AF and to identify factors contributing to enhanced atrial activity.<br /><b>Methods</b><br />We constructed left atrial appendage (LAA) pacing beagle dog AF models (n = 5) and conducted <sup>18</sup>F-FAPI PET/CT imaging at baseline and eight weeks after pacing. Right atrial (RA) specimens were collected from these models. Additionally, 28 AF patients and ten age- and sex-matched healthy volunteers underwent <sup>18</sup>F-FAPI PET/CT imaging.<br /><b>Results</b><br />RA of AF beagles showed increased <sup>18</sup>F-FAPI uptake. Among AF patients, 18 out of 28 (64.3%) exhibited enhanced atrial FAPI activity. No atrial <sup>18</sup>F-FAPI uptake was observed in the sham beagle and healthy volunteers. In animal RA specimens, <sup>18</sup>F-FAPI activity correlated positively with FAP mRNA (r = .98, P = .002) and protein (r = .82, P = .03) levels, as well as collagen I mRNA expression (r = .85, P = .02). B-type natriuretic peptide levels were associated with atrial <sup>18</sup>F-FAPI activity (OR = 3.01, P = .046).<br /><b>Conclusion</b><br />This proof-of-concept study suggests that <sup>18</sup>F-FAPI PET/CT imaging may be a feasible method for evaluating activated fibroblasts in the atria of AF patients.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 25 Aug 2023; epub ahead of print</small></div>

<div><h4>Machine learning to predict hemodynamically significant CAD based on traditional risk factors, coronary artery calcium and epicardial fat volume.</h4><i>Yu W, Yang L, Zhang F, Liu B, ... Yang X, Wang Y</i><br /><AbstractText>We sought to establish an explainable machine learning (ML) model to screen for hemodynamically significant coronary artery disease (CAD) based on traditional risk factors, coronary artery calcium (CAC) and epicardial fat volume (EFV) measured from non-contrast CT scans. 184 symptomatic inpatients who underwent Single Photon Emission Computed Tomography/Myocardial Perfusion Imaging (SPECT/MPI) and Invasive Coronary Angiography (ICA) were enrolled. Clinical and imaging features (CAC and EFV) were collected. Hemodynamically significant CAD was defined when coronary stenosis severity ≥ 50% with a matched reversible perfusion defect in SPECT/MPI. Data was randomly split into a training cohort (70%) on which five-fold cross-validation was done and a test cohort (30%). The normalized training phase was preceded by the selection of features using recursive feature elimination (RFE). Three ML classifiers (LR, SVM, and XGBoost) were used to construct and choose the best predictive model for hemodynamically significant CAD. An explainable approach based on ML and the SHapley Additive exPlanations (SHAP) method was deployed to generate individual explanation of the model\'s decision. In the training cohort, hemodynamically significant CAD patients had significantly higher age, BMI and EFV, higher proportions of hypertension and CAC comparing with controls (P all < .05). In the test cohorts, hemodynamically significant CAD had significantly higher EFV and higher proportion of CAC. EFV, CAC, diabetes mellitus (DM), hypertension, and hyperlipidemia were the highest ranking features by RFE. XGBoost produced better performance (AUC of 0.88) compared with traditional LR model (AUC of 0.82) and SVM (AUC of 0.82) in the training cohort. Decision Curve Analysis (DCA) demonstrated that XGBoost model had the highest Net Benefit index. Validation of the model also yielded a favorable discriminatory ability with the AUC, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 0.89, 68.0%, 96.8%, 94.4%, 79.0% and 83.9% in the XGBoost model. A XGBoost model based on EFV, CAC, hypertension, DM and hyperlipidemia to assess hemodynamically significant CAD was constructed and validated, which showed favorable predictive value. ML combined with SHAP can offer a transparent explanation of personalized risk prediction, enabling physicians to gain an intuitive understanding of the impact of key features in the model.</AbstractText><br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 11 Jul 2023; epub ahead of print</small></div>

<div><h4>Real world experience of therapeutic monitoring of medically treated prosthetic valve infective endocarditis by F-FDG-PET/CT.</h4><i>Bucy L, Erpelding ML, Boursier C, Lefevre B, ... Goehringer F, AEPEI study group (Association pour l’Étude et la Prévention de l’Endocardite Infectieuse)</i><br /><b>Introduction</b><br /><sup>18</sup>F-FDG-PET/CT is recommended to improve the diagnosis of prosthetic valve infective endocarditis (PVIE) and is a major criterion in the ESC-2015 classification. However, there is little evidence for its usefulness in the follow-up of medically treated PVIE patients.<br /><b>Methods</b><br />A monocentric retrospective analysis of patients hospitalized for PVIE between January 2013 and December 2019 who were not treated with surgery and who had at least two <sup>18</sup>F-FDG-PET/CT examinations during their medical management.<br /><b>Results</b><br />Among 170 patients with PVIE, 117 were treated with antibiotic therapy but no surgery. Of these, 36 (31%) had at least two <sup>18</sup>F-FDG-PET/CT examinations. At initial imaging, 28 patients had heterogeneous FDG uptake on their prosthetic valve and eight on their associated aortic graft. Hypermetabolism of spleen and bone marrow (HSBM) was observed in 18 and 19 patients, respectively. At the first follow-up <sup>18</sup>F-FDG-PET/CT, 21 (58%) patients still had heterogeneous uptake, indicating persistent active endocarditis. HSBM was still present at the last follow-up imaging in four of the six patients with recurrent PVIE.<br /><b>Conclusion</b><br /><sup>18</sup>F-FDG-PET/CT monitoring of medically treated patients with PVIE provides valuable additional information and prospective multicentric study should be conducted to assess its usefulness.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 31 Jul 2023; epub ahead of print</small></div>

<div><h4>A new perspective on an old method: gated SPECT imaging for left ventricular contractile function assessment.</h4><i>San Miguel L, Goldschmidt E, Brisbin AK, Redruello M, Masoli OH</i><br /><AbstractText>The ejection fraction (LVEF) is a commonly used marker of left ventricular function. However, because it is strongly influenced by loading conditions, it can be inaccurate in representing cardiac contractility. We therefore evaluated a gated SPECT based tool to simultaneously assess preload, afterload, and contractility. Using gated SPECT-determined ventricular volumes and arterial tension measurements, we calculated ventricular and arterial elastance (Ev and Ea), as well as end-diastolic volumes, which are surrogates for contractility, afterload, and preload, respectively. We applied this protocol to 1462 consecutive patients and assessed the ventricular function in patients with and without myocardial infarction. The median LVEF was 68% (IQR 62-74%). Patients with infarction exhibited decreased contractility (ventricular elastance of 3 mmHg/ml vs. 6 mmHg/ml), compensated by an increase of preload (end-diastolic volume of 100 ml vs. 78 ml) and a decrease in afterload (arterial elastance of 1.8 mmHg/ml vs. 2.2 ml/mmHg). These interactions yielded a preserved ejection fraction in both groups. Gated SPECT-measured volumes were consistent with values reported in the literature. In addition, the combination of nuclear imaging and arterial tension measurement accounted for not only the ejection fraction but also the loading context, providing a more accurate representation of cardiac contractility.</AbstractText><br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 25 Jul 2023; epub ahead of print</small></div>

<div><h4>Cardiac amyloidosis in Latin America: Gaps and opportunities to increase awareness of the disease. Findings from the AMILO-LATAM research group.</h4><i>Mut F, Carvajal I, Camilletti J, Erriest J, Alexanderson E, Grossman GB</i><br /><b>Background</b><br />Cardiac amyloidosis (CA) is an under-diagnosed disease presenting as a restrictive cardiomyopathy with high morbidity and mortality. Wild-type transthyretin amyloid cardiomyopathy (ATTR-CM) is mostly seen in elderly patients, with increasing prevalence as life expectancy is growing. New diagnostic imaging techniques and treatments allow for a better prognosis, but lack of clinical awareness delays timely diagnosis and appropriate management. Our purpose was to investigate the knowledge of clinicians regarding ATTR-CM and to assess the availability of imaging resources in the Latin-American region.<br /><b>Methods and results</b><br />Two online surveys were distributed among clinicians and nuclear medicine professionals, respectively: one asking about awareness of CA in different clinical scenarios, and the other about the availability of diagnostic resources and studies performed. 406 responses were received for the first survey and 82 for the second, representing 17 and 14 countries, respectively. A significant lack of awareness was identified among clinicians, although appropriate diagnostic resources are generally available. Survey data showed that very few patients are evaluated for ATTR-CM in most Latin-American countries.<br /><b>Conclusions</b><br />The surveys demonstrated the need for educational programs and other measures to increase clinical awareness and early detection of CA, so patients receive timely treatment and management of the disease.<br /><br />© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 01 Aug 2023; 30:1592-1601</small></div>

<div><h4>Role of nuclear cardiology in diagnosis and risk stratification of coronary microvascular disease.</h4><i>Ruddy TD, Tavoosi A, Taqueti VR</i><br /><AbstractText>Coronary flow reserve (CFR) with positron emission tomography/computed tomography (PET/CT) has an important role in the diagnosis of coronary microvascular disease (CMD), aids risk stratification and may be useful in monitoring therapy. CMD contributes to symptoms and a worse prognosis in patients with coronary artery disease (CAD), nonischemic cardiomyopathies, and heart failure. CFR measurements may improve our understanding of the role of CMD in symptoms and prognosis in CAD and other cardiovascular diseases. The clinical presentation of CAD has changed. The prevalence of nonobstructive CAD has increased to about 50% of patients with angina undergoing angiography. Ischemia with nonobstructive arteries (INOCA) is recognized as an important cause of symptoms and has an adverse prognosis. Patients with INOCA may have ischemia due to CMD, epicardial vasospasm or diffuse nonobstructive CAD. Reduced CFR in patients with INOCA identifies a high-risk group that may benefit from management strategies specific for CMD. Although measurement of CFR by PET/CT has excellent accuracy and repeatability, use is limited by cost and availability. CFR measurement with single-photon emission tomography (SPECT) is feasible, validated, and would increase availability and use of CFR. Patients with CMD can be identified by reduced CFR and selected for specific therapies.</AbstractText><br /><br />© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 01 Aug 2023; 30:1327-1340</small></div>

<div><h4>Cardiac metastases from neuroendocrine neoplasms: complementary role of SSTR PET/CT and cardiac MRI.</h4><i>Arnfield EG, Tam L, Pattison DA, Younger J, ... Ladwa R, Ramsay S</i><br /><b>Background</b><br />Cardiac metastases from neuroendocrine neoplasms (NENs) are being detected with increasing frequency, although the optimal imaging strategy remains unclear. We performed a single-center retrospective study to explore the role of somatostatin receptor positron emission tomography/computed tomography (SSTR PET/CT) and cardiac magnetic resonance imaging (CMR) in NEN cardiac metastases, determine the degree of concordance between the findings of these imaging modalities, and examine the advantages and disadvantages of each imaging technique. A secondary aim was to determine if cardiac metastases were associated with adverse cardiac events during peptide receptor radionuclide therapy (PRRT).<br /><b>Methods and results</b><br />19 patients with NEN cardiac metastases were identified. A retrospective review of electronic medical records was performed, and if available SSTR PET/CT and CMR were blindly re-reviewed by imaging specialists, documenting the number and location of cardiac metastases. All 19 patients had SSTR PET/CT, and 10/19 patients had CMR. SSTR PET/CT identified more metastases than CMR. When identified on CMR, metastases were more accurately localized. 12/19 patients received PRRT, with no cardiac adverse effects.<br /><b>Conclusion</b><br />SSTR PET/CT and CMR are complementary investigations in the imaging of NEN cardiac metastases. SSTR PET/CT appears more sensitive for lesion detection, and CMR offers better lesion characterization. Both investigations present useful information for the planning of treatment including PRRT, which was administered safely.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 16 Aug 2023; epub ahead of print</small></div>

<div><h4>Prognosis and follow-up of patients with prosthetic valve endocarditis treated conservatively in relation to WBC-SPECT imaging.</h4><i>Grambow-Velilla J, Mahida B, Benali K, Deconinck L, ... Rouzet F, Hyafil F</i><br /><b>Background</b><br />Our objective was to evaluate in patients with prosthetic valve endocarditis (PVE) treated conservatively, the prognostic value of white blood cell (WBC) signal intensity on SPECT and to describe the evolution of the WBC signal under antibiotics.<br /><b>Methods</b><br />Patients with PVE treated conservatively and positive WBC-SPECT imaging were identified retrospectively. Signal intensity was classified as intense if equal to or higher, or mild if lower, than the liver signal. Clinical, biological, imaging and follow-up information were collected from medical files.<br /><b>Results</b><br />Among 47 patients, WBC signal was classified as intense in 10 patients and as mild, in 37. The incidence of the primary composite endpoint (death, late cardiac surgery, or relapse) was significantly higher in patients with intense vs. mild signal (90% vs. 11%). Twenty-five patients underwent a second WBC-SPECT imaging during follow-up. The prevalence of WBC signal decreased progressively from 89% between 3 and 6 weeks to 42% between 6 and 9 weeks and 8% more than 9 weeks after initiation of antibiotics.<br /><b>Conclusions</b><br />In patients with PVE treated conservatively, intense WBC signal was associated with poor outcome. WBC-SPECT imaging appears as an interesting tool for risk stratification and to monitor locally the efficacy of antibiotic treatment.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 10 Jul 2023; epub ahead of print</small></div>

<div><h4>Pharmacological and metabolic parameters of [F]flubrobenguane in clinical imaging populations.</h4><i>Mair BA, Zelt JGE, Nekesa K, Saint-Georges Z, ... deKemp RA, Rotstein BH</i><br /><b>Background</b><br />Cardiac sympathetic nervous system molecular imaging has demonstrated prognostic value. Compared with meta-[<sup>11</sup>C]hydroxyephedrine, [<sup>18</sup>F]flubrobenguane (FBBG) facilitates reliable estimation of SNS innervation using similar analytical methods and possesses a more convenient physical half-life. The aim of this study was to evaluate pharmacokinetic and metabolic properties of FBBG in target clinical cohorts.<br /><b>Methods</b><br />Blood sampling was performed on 20 participants concurrent to FBBG PET imaging (healthy = NORM, non-ischemic cardiomyopathy = NICM, ischemic cardiomyopathy = ICM, post-traumatic stress disorder = PTSD). Image-derived blood time-activity curves were transformed to plasma input functions using cohort-specific corrections for plasma protein binding, plasma-to-whole blood distribution, and metabolism.<br /><b>Results</b><br />The plasma-to-whole blood ratio was 0.78 ± 0.06 for NORM, 0.64 ± 0.06 for PTSD and 0.60 ± 0.14 for (N)ICM after 20 minutes. 22 ± 4% of FBBG was bound to plasma proteins. Metabolism of FBBG in (N)ICM was delayed, with a parent fraction of 0.71 ± 0.05 at 10 minutes post-injection compared to 0.53 ± 0.03 for PTSD/NORM. While there were variations in metabolic rate, metabolite-corrected plasma input functions were similar across all cohorts.<br /><b>Conclusions</b><br />Rapid plasma clearance of FBBG limits the impact of disease-specific corrections of the blood input function for tracer kinetic modeling.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 26 Jul 2023; epub ahead of print</small></div>

<div><h4>Prognostic value of myocardial flow reserve measured with CZT cardiac-dedicated SPECT low-dose dynamic myocardial perfusion imaging in patients with INOCA.</h4><i>Li L, Pang Z, Wang J, Chen Y, ... He Z, Li J</i><br /><b>Background</b><br />Clinical use of dynamic myocardial perfusion imaging (D-MPI) of cadmium-zinc-telluride (CZT) cardiac-dedicated SPECT is growing, showing a higher application value than conventional SPECT. The prognostic value of ischemia in patients with non-obstructive coronary arteries (INOCA) remains an important challenge for investigation. The primary objective of this study was to investigate the prognostic value of myocardial flow reserve (MFR) measured with low-dose D-MPI of CZT cardiac-dedicated SPECT in the assessment of patients with INOCA.<br /><b>Methods</b><br />Consecutive screening of patients with INOCA and obstructive coronary artery disease (OCAD) who had coronary angiography (CAG) data was performed within three months before or after D-MPI imaging. The patients who met the inclusion criteria were retrospectively analyzed and follow-up by telephone was performed. The enrolled patients were then divided into the INOCA and OCAD groups. INOCA was defined as signs and/or symptoms of myocardial ischemia but with < 50% epicardial stenosis. OCAD was defined as obstructive stenosis (≥ 50% stenosis) of epicardial coronary arteries or their major branches on the CAG. Medical treatments, Seattle Angina Questionnaire (SAQ) scores, and major adverse cardiac events (MACEs) were studied. The Kaplan-Meier survival curve, Log-rank test, and univariable COX regression analysis were used to evaluate the prognosis of patients and associated predictors, with P < 0.05 being considered statistically significant.<br /><b>Results</b><br />A total of 303 patients (159 males and 144 females) were enrolled for the final analysis after excluding 24 patients who were lost to follow-up. The mean age of the included cases was 61.94 ± 8.59 years, of which 203 (67.0%) cases were OCAD and 100 (33.0%) cases were INOCA, respectively. The median follow-up was 16 months (14-21 months). Kaplan-Meier survival curves showed that the incidence of MACE was similar in the INOCA and OCAD groups (log-rank P = 0.2645), while those with reduced MFR showed a higher incidence of MACE than those with normal MFR (log-rank P = 0.0019). The subgroup analysis in the OCAD group revealed that 105 patients with reduced MFR had a higher incidence of MACE than those with normal MFR (log-rank P = 0.0226). The subgroup analysis in the INOCA group showed that 37 patients with reduced MFR had a higher incidence of MACE than those with normal MFR in the INOCA group (log-rank P = 0.0186). Univariable Cox regression analysis showed for every 1 unit increase in MFR, the risk of MACE for INOCA was reduced by 66.1% and that for OCAD by 64.2%. For each 1 mL·g<sup>-1</sup>·min<sup>-1</sup> increase in LV-sMBF, the risk of MACE was reduced by 72.4% in INOCA patients and 63.6% in OCAD patients.<br /><b>Conclusions</b><br />MFR measured with low-dose D-MPI CZT SPECT provides incremental prognostic value in patients with INOCA. Patients with reduced MFR show an increased risk of MACE, increased symptom burdens, and impaired quality of life. INOCA patients with reduced MFR experienced higher rate of MACE than OCAD patients with normal MFR.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 11 Jul 2023; epub ahead of print</small></div>

<div><h4>SPECT myocardial blood flow quantitation for the detection of angiographic stenoses with cardiac-dedicated CZT SPECT.</h4><i>Zhang J, Xie J, Li M, Fang W, Hsu B</i><br /><b>Purpose</b><br />CZT SPECT with the enhanced imaging characteristic facilitates SPECT myocardial blood flow (MBF) quantitation moving toward a clinical utility to uncover myocardial ischemia. The purpose of this study was to investigate the diagnostic performance of stress MBF, myocardial flow reserve (MFR) and myocardial flow capacity (MFC) derived from CZT SPECT in the detection of coronary artery disease (CAD).<br /><b>Methods</b><br />One-hundred and eighty patients underwent two-day rest/adenosine-stress scans for SPECT MBF quantitation. All dynamic SPECT images were reconstructed and corrected with necessary corrections. The one-tissue two-compartment kinetic model was utilized to fit kinetic parameters (K1, k2 and FBV) by numeric optimization and converted to MBF from K1. Rest MBF, stress MBF and MFR in left ventricle and coronary territories were calculated from flow polar maps. MFC was assessed by extents of moderately and severely abnormal flow statuses using an integrated flow diagram. Per-patient and per-vessel analyses were performed to determine cutoff values for the detection of angiographically obstructive and flow-limited CAD.<br /><b>Results</b><br />Using the threshold of ≥ 50% stenosis, 149 patients (82.78%) were classified to have obstructive lesions in 355 vessels (65.74%). Using the threshold of ≥ 70% stenosis, 113 patients (62.78%) were classified to have flow-limited lesions in 282 vessels (52.22%). On per-patient analysis, the optimal cutoff values of stress MBF and MFR to detect ≥ 50% stenosis were (1.44 ml/min/g, 1.96) and (1.34 ml/min/g and 1.75) to detect ≥ 70% stenosis. The optimal cutoff values for severely and combined moderately severely abnormal MFC extents were (2.3-2.5%, 23.1%) and (7.5%, 29.4%), respectively. The overall sensitivity of MFC (0.84-0.86, 0.86-0.90) to detect ≥ 50% and ≥ 70% lesions surpassed those of stress MBF (0.78. 0.78) and MFR (0.80, 0.75) (all p < 0.05) with similar specificity (MFC = 0.84-0.90, 0.87-0.91; stress MBF = 0.87, 0.91; MFR = 0.84, 0.89) (all p≥ 0.05).<br /><b>Conclusion</b><br />The non-invasive SPECT MBF quantitation using CZT SPECT is a reliable method to detect angiographically obstructive and flow-limited CAD. Myocardial flow capacity can outperform with higher diagnostic sensitivity than stress MBF or MFR alone.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 25 Jul 2023; epub ahead of print</small></div>

<div><h4>Accurate and efficient rapid acquisition early post-injection stress-first CZT SPECT myocardial perfusion imaging with tetrofosmin and attenuation correction.</h4><i>Case JA, Courter SA, McGhie A, Patel KK, ... Burgett EV, Bateman TM</i><br /><b>Introduction</b><br />Myocardial perfusion imaging (MPI) protocols have not changed significantly despite advances in instrumentation and software. We compared an early post-injection, stress-first SPECT protocol to standard delayed imaging.<br /><b>Methods</b><br />95 patients referred for SPECT MPI were imaged upright and supine on a Spectrum Dynamics D-SPECT CZT system with CT attenuation correction. Patients received injection of <sup>99m</sup>Tc tetrofosmin at peak of regadenoson stress and were imaged. Early post-stress (mean 17 ± 2 minutes) and Standard 1-h delay (mean 61 ± 13 min). Three blinded readers evaluated images for overall interpretation, perceived need for rest imaging, image quality, and reader confidence. Laboratory efficiency was also evaluated.<br /><b>Results</b><br />Blinded readers had the same response for the need for rest in 77.9% of studies. Studies also had the same interpretation in 89.5% of studies. Reader confidence was high (86.0% (Early) and 90.3% (Standard p = 0.52. Image quality was good or excellent in 87.4% Early vs 96.8% Standard (p = 0.09). Time between patient check-in and end of stress imaging was 104 ± (Standard) to 60 ± 18 minutes (Early) (p < 0.001).<br /><b>Conclusion</b><br />Early post-injection stress-only imaging using CZT SPECT/CT appears promising with Tc-99m tetrofosmin with similar image quality, reader confidence, diagnosis, and need for a rest scan.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 18 Jul 2023; epub ahead of print</small></div>

<div><h4>The incremental value of coronary artery calcium score in predicting long-term prognosis and defining the warranty period of normal adenosine stress-only myocardial perfusion imaging using CZT SPECT.</h4><i>Kamerman M, van Dijk JD, Timmer JR, Ottervanger JP, ... Jager PL, Mouden M</i><br /><b>Background</b><br />Normal stress-only (SO) myocardial perfusion imaging (MPI) using SPECT reduces imaging time and radiation dose with a good prognosis. However, the long-term prognostic value of combining coronary artery calcium score (CACS) with SO MPI to determine the warranty period remains unknown. Hence, we assessed the incremental prognostic value of CACS and its impact on the warranty period of normal SO MPI using SPECT.<br /><b>Methods</b><br />We retrospectively included 1375 symptomatic patients without a history of coronary artery disease (CAD) and a normal SO MPI using adenosine who underwent simultaneous CAC scoring. Annual major adverse cardiac events (MACE) rates were calculated for CACS categories: 0, 1-399, 400-999, and ≥1000.<br /><b>Results</b><br />The mean age was 60.0 ± 11.8 years (66.9% female) with a median follow-up of 10.3 [IQR 9.6-10.9] years. The warranty period for annual MACE rate for normal SO SPECT extended the total follow-up time in years. MACE rate categorized by CAC categories demonstrated an increase in MACE rates with increasing CACS; CACS 0 and CACS 1-399 were associated with a 10-year warranty period, CACS 400-999 had a warranty period of 4 years and no warranty period could be given for CACS≥1000 (5.9 % at 1 year).<br /><b>Conclusions</b><br />CACS as an adjunct to normal pharmacological SO MPI provides additional prognostic information and aids in determining a warranty period.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 17 Aug 2023; epub ahead of print</small></div>

<div><h4>Detection and correction of patient motion in dynamic O-water PET MPI.</h4><i>Christensen NL, Nordström J, Madsen S, Madsen MA, ... Lubberink M, Tolbod LP</i><br /><b>Background</b><br />Patient motion constitutes a limitation to <sup>15</sup>O-water cardiac PET imaging. We examined the ability of image readers to detect and correct patient motion using simulated motion data and clinical patient scans.<br /><b>Methods</b><br />Simulated data consisting of 16 motions applied to 10 motion-free scans were motion corrected using two approaches, pre-analysis and post-analysis for motion identification. Both approaches employed a manual frame-by-frame correction method. In addition, a clinical cohort was analyzed for assessment of prevalence and effect of motion and motion correction.<br /><b>Results</b><br />Motion correction was performed on 94% (pre-analysis) and 64% (post-analysis) of the scans. Large motion artifacts were corrected in 91% (pre-analysis) and 74% (post-analysis) of scans. Artifacts in MBF were reduced in 56% (pre-analysis) and 58% (post-analysis) of the scans. The prevalence of motion in the clinical patient cohort (n = 762) was 10%. Motion correction altered exam interpretation in only 10 (1.3%) clinical patient exams.<br /><b>Conclusion</b><br />Frame-by-frame motion correction after visual inspection is useful in reducing motion artifacts in cardiac <sup>15</sup>O-water PET. Reviewing the initial results (parametric images and polar maps) as part of the motion correction process, reduced erroneous corrections in motion-free scans. In a large clinical cohort, the impact of motion correction was limited to few patients.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 28 Aug 2023; epub ahead of print</small></div>

<div><h4>Transthyretin amyloid cardiomyopathy disease burden quantified using Tc-pyrophosphate SPECT/CT: volumetric parameters versus SUVmax ratio at 1 and 3 hours.</h4><i>Watanabe S, Nakajima K, Toshima F, Wakabayashi H, ... Konishi T, Kinuya S</i><br /><b>Background</b><br />Various parameters derived from technetium-99m pyrophosphate (<sup>99m</sup>Tc-PYP) single-photon emission computed tomography (SPECT) correlate with the severity of transthyretin amyloid cardiomyopathy (ATTR-CM). However, the optimal metrics and image acquisition timing required to quantify the disease burden remain uncertain.<br /><b>Methods and results</b><br />We retrospectively evaluated <sup>99m</sup>Tc-PYP SPECT/CT images of 23 patients diagnosed with ATTR-CM using endomyocardial biopsies and/or gene tests. All patients were assessed by SPECT/CT 1 hour after <sup>99m</sup>Tc-PYP injection, and 13 of them were also assessed at 3 hours. We quantified <sup>99m</sup>Tc-PYP uptake using the volumetric parameters, cardiac PYP volume (CPV) and cardiac PYP activity (CPA). We also calculated the SUVmax ratios of myocardial SUVmax/blood pool SUVmax, myocardial SUVmax/bone SUVmax, and the SUVmax retention index. We assessed the correlations between uptake parameters and the four functional parameters associated with prognosis, namely left ventricular ejection fraction, global longitudinal strain, myocardial extracellular volume, and troponin T. CPV and CPA correlated more closely than the SUVmax ratios with the four prognostic factors. Significant correlations between volumetric parameters and prognostic factors were equivalent between 1 and 3 hours.<br /><b>Conclusions</b><br />The disease burden of ATTR-CM was quantified more accurately by volumetric evaluation of <sup>99m</sup>Tc-PYP SPECT/CT than SUVmax ratios and the performance was equivalent between 1 and 3 hours.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 21 Aug 2023; epub ahead of print</small></div>

<div><h4>Use of PET/CT to detect myocardial inflammation and the risk of malignant arrhythmia in chronic Chagas disease.</h4><i>de Oliveira RS, Moll-Bernardes R, de Brito AX, Pinheiro MVT, ... Rosado-de-Castro PH, de Sousa AS</i><br /><b>Background</b><br />Chagas heart disease (CHD) is characterized by progressive myocardial inflammation associated with myocardial fibrosis and segmental abnormalities that may lead to malignant ventricular arrhythmia and sudden cardiac death. This arrhythmia might be related to the persistence of parasitemia or inflammation in the myocardium in late-stage CHD. Positron emission tomography/computed tomography (PET/CT) has been used to detect myocardial inflammation in non-ischemic cardiomyopathies, such as sarcoidosis, and might be useful for risk prediction in patients with CHD.<br /><b>Methods and results</b><br />Twenty-four outpatients with chronic CHD were enrolled in this prospective cross-sectional study between May 2019 and March 2022. The patients were divided into two groups: those with sustained ventricular tachycardia and/or aborted sudden cardiac death who required implantable cardioverter-defibrillators, and those with the same stages of CHD and no complex ventricular arrhythmia. Patients underwent <sup>18</sup>F-fluorodeoxyglucose (<sup>18</sup>F-FDG) and <sup>68</sup>Ga-DOTATOC PET/CT, and blood samples were collected for qualitative parasite assessment by polymerase chain reaction. Although similar proportions of patients with and without complex ventricular arrhythmia showed <sup>18</sup>F-FDG and <sup>68</sup>Ga-DOTATOC uptake, <sup>68</sup>Ga-DOTATOC corrected SUV<sub>max</sub> was higher in patients with complex arrhythmia (3.4 vs 1.7; P = .046), suggesting that inflammation could be associated with the presence of malignant arrhythmia in the late stages of CHD. We also detected Trypanosoma cruzi in both groups, with a nonsignificant trend of increased parasitemia in the group with malignant arrhythmia (66.7% vs 33.3%).<br /><b>Conclusion</b><br /><sup>18</sup>F-FDG and <sup>68</sup>Ga-DOTATOC uptake on PET/CT may be useful for the detection of myocardial inflammation in patients with Chagas cardiomyopathy, and <sup>68</sup>Ga-DOTATOC uptake may be associated with the presence of malignant arrhythmia, with potential therapeutic implications.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 21 Aug 2023; epub ahead of print</small></div>

<div><h4>Myocardial creep and cardiorespiratory motion correction improves diagnostic accuracy of Rubidium-82 cardiac positron emission tomography.</h4><i>Lassen ML, Rasmussen T, Byrne C, Holmvang L, Kjaer A, Hasbak P</i><br /><b>Aim</b><br />To evaluate the feasibility of retrospectively detecting and correcting periodical (cardiac and respiratory motion) and non-periodical shifts of the myocardial position (myocardial creep) using only the acquired Rubidium-82 positron emission tomography raw (listmode) data.<br /><b>Methods</b><br />This study comprised 25 healthy participants (median age = 23 years) who underwent repeat rest/adenosine stress Rubidium-82 myocardial perfusion imaging (MPI) and 53 patients (median age = 64 years) considered for revascularization who underwent a single MPI session. All subjects were evaluated for myocardial creep during MPI by assessing the myocardial position every 200 ms. A proposed motion correction protocol, including corrections for cardiorespiratory and creep motion (3xMC), was compared to a guideline-recommended protocol (Standard<sub>Recon</sub>). For the volunteers, we report test-retest repeatability using standard error of measurements (SEM). For the patient cohort, we evaluated the area under the receiver operating curve (AUC) for both stress and ischemic total perfusion deficits (sTPD and iTPD, respectively) using myocardial ischemia defined as fractional flow reserve values < 0.8 in the relevant coronary segment as the gold standard.<br /><b>Results</b><br />Test-retest repeatability was significantly improved following corrections for myocardial creep (SEM; sTPD: Standard<sub>Recon</sub> = 2.2, 3xMC = 1.8; iTPD: Standard<sub>Recon</sub> = 1.6, 3xMC = 1.2). AUC analysis of the ROC curves revealed significant improvements for iTPD measurements following 3xMC [sTPD: Standard<sub>Recon</sub> = 0.88, 3xMC = 0.92 (P = .21); iTPD: Standard<sub>Recon</sub> = 0.88, 3xMC = 0.95 (P = .039)].<br /><b>Conclusion</b><br />3xMC has the potential to improve the diagnostic accuracy of myocardial MPI obtained from positron emission tomography. Therefore, its use should be considered both in clinical routine and large-scale multicenter studies.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 25 Aug 2023; epub ahead of print</small></div>

<div><h4>Hybridizing machine learning in survival analysis of cardiac PET/CT imaging.</h4><i>Juarez-Orozco LE, Niemi M, Yeung MW, Benjamins JW, ... van der Harst P, Klén R</i><br /><b>Background</b><br />Machine Learning (ML) allows integration of the numerous variables delivered by cardiac PET/CT, while traditional survival analysis can provide explainable prognostic estimates from a restricted number of input variables. We implemented a hybrid ML-and-survival analysis of multimodal PET/CT data to identify patients who developed myocardial infarction (MI) or death in long-term follow up.<br /><b>Methods</b><br />Data from 739 intermediate risk patients who underwent coronary CT and selectively stress <sup>15</sup>O-water-PET perfusion were analyzed for the occurrence of MI and all-cause mortality. Images were evaluated segmentally for atherosclerosis and absolute myocardial perfusion through 75 variables that were integrated through ML into an ML-CCTA and an ML-PET score. These scores were then modeled along with clinical variables through Cox regression. This hybridized model was compared against an expert interpretation-based and a calcium score-based model.<br /><b>Results</b><br />Compared with expert- and calcium score-based models, the hybridized ML-survival model showed the highest performance (CI .81 vs .71 and .64). The strongest predictor for outcomes was the ML-CCTA score.<br /><b>Conclusion</b><br />Prognostic modeling of PET/CT data for the long-term occurrence of adverse events may be improved through ML imaging score integration and subsequent traditional survival analysis with clinical variables. This hybridization of methods offers an alternative to traditional survival modeling of conventional expert image scoring and interpretation.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 01 Sep 2023; epub ahead of print</small></div>