<div><h4>F-FDG PET/CT-derived total lesion glycolysis predicts abscess formation in patients with surgically confirmed infective endocarditis: Results of a retrospective study at a tertiary center.</h4><i>Sag SJM, Menhart K, Hitzenbichler F, Schmid C, ... Grosse J, Sag CM</i><br /><b>Background</b><br />Abnormal activity of <sup>18</sup>F-FDG PET/CT is a major Duke criterion in the diagnostic work-up of infective prosthetic valve endocarditis (IE). We hypothesized that quantitative lesion assessment by <sup>18</sup>F-FDG PET/CT-derived standard maximum uptake ratio (SURmax), metabolic volume (MV), and total lesion glycolysis (TLG) might be useful in distinct subgroups of IE patients (e.g. IE-related abscess formation).<br /><b>Methods</b><br />All patients (n = 27) hospitalized in our tertiary IE referral medical center from January 2014 to October 2018 with preoperatively performed <sup>18</sup>F-FDG PET/CT and surgically confirmed IE were included into this retrospective analysis.<br /><b>Results</b><br />Patients with surgically confirmed abscess formation (n = 10) had significantly increased MV (by ~ fivefold) and TLG (by ~ sevenfold) as compared to patients without abscess (n = 17). Receiver operation characteristics (ROC) analyses demonstrated that TLG (calculated as MV × SURmean, i.e. TLG (SUR)) had the most favorable area under the ROC curve (0.841 [CI 0.659 to 1.000]) in predicting IE-related abscess formation. This resulted in a sensitivity of 80% and a specificity of 88% at a cut-off value of 14.14 mL for TLG (SUR).<br /><b>Conclusion</b><br />We suggest that <sup>18</sup>F-FDG PET/CT-derived quantitative assessment of TLG (SUR) may provide a novel diagnostic tool in predicting endocarditis-associated abscess formation.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 01 Jun 2023; epub ahead of print</small></div>

<div><h4>FDG-PET/CT and rest myocardial perfusion imaging to predict high-degree atrioventricular block recovery in cardiac sarcoidosis.</h4><i>Lucinian YA, Martineau P, Poenaru R, Tremblay-Gravel M, ... Harel F, Pelletier-Galarneau M</i><br /><b>Backgrounds</b><br />High-degree atrioventricular block (AVB) recovery in CS has been shown to be highly variable despite immunosuppressive treatment, with no reliable tool available to predict odds of reversibility. This study sought to evaluate the potential of combined fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and resting myocardial perfusion imaging (rMPI) to predict reversibility of newly diagnosed high-grade AVB in cardiac sarcoidosis (CS).<br /><b>Methods</b><br />We performed a single-center, retrospective analysis of patients with CS presenting with high-grade AVB who underwent combined FDG-PET/CT and rMPI. The 2016 JCS and the 2014 HRS diagnostic criteria were used for the diagnosis of CS. Patients with a history of coronary artery disease or prior immunosuppressive treatment were excluded. Patients were divided into AVB recovery and non-recovery subgroups. CS disease staging was based on FDG-PET and rMPI findings: (Stage 0) normal FDG-PET and rMPI (Stage 1) positive FDG-PET and normal rMPI (Stage 2) positive FDG-PET with perfusion deficits on rMPI (Stage 3) normal FDG-PET with perfusion deficits on rMPI.<br /><b>Results</b><br />Twenty-seven patients, including 13 demonstrating AVB recovery, were identified. Eleven out of fourteen (78.6%) patients presenting with stage 1 CS demonstrated AVB recovery. Stage 1 CS was significantly more present in the recovery group compared to the non-recovery group (84.6% vs 21.4%, P = .002). Eleven presented with stage 2 CS, with only 2 (18.2%) recovering AV nodal conduction. Stage 2 CS presented more frequently in the non-recovery group (64.3% vs 15.4%, P = .020).<br /><b>Conclusions</b><br />Combined FDG-PET and rMPI employed to stage CS disease presenting with high-degree AVB appears to have good performance for predicting likelihood of recovery.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 31 May 2023; epub ahead of print</small></div>

<div><h4>A rare case of extensive biventricular cardiac sarcoidosis with reversible torrential tricuspid regurgitation.</h4><i>Okafor J, Azzu A, Ahmed R, Cassimon B, ... Guha K, Khattar R</i><br /><AbstractText>Reversal of torrential tricuspid regurgitation is rarely seen. We describe a case in which effective immunosuppression alongside conventional heart failure therapies lead to reversibility of torrential tricuspid regurgitation in a patient with cardiac sarcoidosis. We also discuss the diagnostic challenge in distinguishing cardiac sarcoidosis from other myocardial diseases in a patient presenting with biventricular failure.</AbstractText><br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 31 May 2023; epub ahead of print</small></div>

<div><h4>Meta-analysis of the effectiveness of heparin in suppressing physiological myocardial FDG uptake in PET/CT.</h4><i>Chan SH, Huang CK, Luzhbin D, Hou PN, Chang YT, Wu J</i><br /><b>Background</b><br />The present meta-analysis aims to investigate the effectiveness of heparin administration in suppressing physiological myocardial <sup>18</sup>F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET)/computed tomography (CT), as its role in this regard has not been well investigated.<br /><b>Methods</b><br />PRISMA guidelines were used to interrogate the PubMed, Embase, Cochrane library, Web of Knowledge, and www.clinicaltrail.gov databases from the earliest records to March 2023. The final analysis included five randomized controlled trials (RCTs). Meta-analysis was conducted to compare the effectiveness of unfractionated heparin (UFH) administration versus non-UFH administration, and subgroup analysis based on fixed and variable fasting durations was conducted. Effect sizes were pooled using a random-effects model, and the pooled odds ratios (ORs) were calculated.<br /><b>Results</b><br />Five eligible RCTs with a total of 910 patients (550 with heparin, 360 without heparin) were included. The forest plot analysis initially indicated no significant difference in the suppression of myocardial FDG uptake between the UFH and non-UFH groups (OR 2.279, 95% CI 0.593 to  8.755, p = 0.23), with a high degree of statistical heterogeneity (I<sup>2</sup> = 91.16%). Further subgroup analysis showed that the fixed fasting duration group with UFH administration had statistically significant suppression of myocardial FDG uptake (OR 4.452, 95% CI 1.221 to 16.233, p = 0.024), while the varying fasting duration group did not show a significant effect.<br /><b>Conclusions</b><br />According to the findings of our meta-analysis, we suggest that intravenous administration of UFH can be considered as a supplementary approach to suppress myocardial FDG uptake.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 31 May 2023; epub ahead of print</small></div>

<div><h4>Exponential dosing to standardize myocardial perfusion image quality with rubidium-82 PET.</h4><i>Tavoosi A, Khetarpal R, Wells RG, Beanlands RSB, deKemp RA</i><br /><b>Background</b><br /><sup>82</sup>Rb PET is commonly performed using the same injected activity in all patients, resulting in lower image quality in larger patients. This study compared <sup>82</sup>Rb dosing with exponential vs proportional functions of body weight on the standardization of myocardial perfusion image (MPI) quality.<br /><b>Methods</b><br />Two sequential cohorts of N = 60 patients were matched by patient weight. Rest and dipyridamole stress <sup>82</sup>Rb PET was performed using 0.1 MBq·kg<sup>-2</sup> exponential and 9 MBq·kg<sup>-1</sup> proportional dosing. MPI scans were compared qualitatively with visual image quality scoring (IQS) and quantitatively using the myocardium-to-blood contrast-to-noise ratio (CNR) and blood background signal-to-noise ratio (SNR) as a function of body weight.<br /><b>Results</b><br />Average (min-max) patient body weight was 81 ± 18 kg (46-137 kg). Proportional dosing resulted in decreasing CNR, SNR, and visual IQS with increasing body weight (P < 0.05). Exponential dosing eliminated the weight-dependent decreases in these image quality metrics that were observed in the proportional dosing group.<br /><b>Conclusion</b><br /><sup>82</sup>Rb PET dosing as an exponential (squared) function of body weight produced consistent stress perfusion image quality over a wide range of patient weights. Dramatically lower doses can be used in lighter patients, with the equivalent population dose shifted toward the heavier patients to standardize diagnostic image quality.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 31 May 2023; epub ahead of print</small></div>

<div><h4>Autonomic denervation, myocardial hypoperfusion and fibrosis may predict ventricular arrhythmia in the early stages of Chagas cardiomyopathy.</h4><i>de Brito ASX, Moll-Bernardes RJ, Pinheiro MVT, Camargo GC, ... Rosado-de-Castro PH, de Sousa AS</i><br /><b>Background</b><br />Sudden cardiac death (SCD) can be the first clinical event of Chagas heart disease (CHD). However, current guidelines contain no clear recommendation for early cardioverter-defibrillator implantation. Using imaging modalities, we evaluated associations among autonomic denervation, myocardial hypoperfusion, fibrosis and ventricular arrhythmia in CHD.<br /><b>Methods and results</b><br />Twenty-nine patients with CHD and preserved left ventricular function underwent 123I-metaiodobenzylguanidine (MIBG) scintigraphy, 99mTc-methoxyisobutylisonitrile (MIBI) myocardial perfusion and cardiac magnetic resonance imaging (MRI). They were divided into arrhythmic (≥ 6 ventricular premature complexes/h and/or non-sustained ventricular tachycardia on 24-hour Holter, n = 15) and non-arrhythmic (< 6 ventricular premature complexes/h and no ventricular tachycardia; n = 14) groups. The arrhythmic group had higher denervation scores from MIBG imaging (23.2 ± 18.7 vs 5.6 ± 4.9; P < .01), hypoperfusion scores from MIBI SPECT (4.7 ± 6.8 vs 0.29 ± 0.6: P = .02), innervation/perfusion mismatch scores (18.5 ± 17.5 vs 5.4 ± 4.8; P = .01) and fibrosis by late gadolinium enhancement on MRI (14.3% ± 13.5% vs 4.0% ± 2.9%; P = .04) than the non-arrhythmic group.<br /><b>Conclusion</b><br />These imaging parameters were associated with ventricular arrhythmia in early CHD and may enable risk stratification and the implementation of primary preventive strategies for SCD.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 24 May 2023; epub ahead of print</small></div>

<div><h4>Diagnostic accuracy of bone scintigraphy imaging for transthyretin cardiac amyloidosis: systematic review and meta-analysis.</h4><i>Ahluwalia N, Roshankar G, Draycott L, Jimenez-Zepeda V, ... Han D, Miller RJH</i><br /><b>Background</b><br />Bone scintigraphy imaging is frequently used to investigate patients with suspected transthyretin cardiac amyloidosis (ATTR-CM). However, the reported accuracy for interpretation approaches has changed over time. We performed a systematic review and meta-analysis to determine the diagnostic accuracy of visual planar grading, heart-to-contralateral (HCL) ratio, and quantitative analysis of SPECT imaging and evaluate reasons for shifts in reported accuracy.<br /><b>Methods</b><br />We performed a systematic review to identify studies of the diagnostic accuracy of bone scintigraphy for ATTR-CM from 1990 until February 2023 using PUBMED and EMBASE. Studies were reviewed separately by two authors for inclusion and for risk of bias assessment. Summary receiver operating characteristic curves and operating points were determined with hierarchical modeling.<br /><b>Results</b><br />Out of a total of 428 identified studies, 119 were reviewed in detail and 23 were included in the final analysis. The studies included a total of 3954 patients, with ATTR-CM diagnosed in 1337 (39.6%) patients and prevalence ranging from 21 to 73%. Visual planar grading and quantitative analysis had higher diagnostic accuracy (.99) than HCL ratio (.96). Quantitative analysis of SPECT imaging had the highest specificity (97%) followed by planar visual grade (96%) and HCL ratio (93%). ATTR-CM prevalence accounted for some of the observed between study heterogeneity.<br /><b>Conclusions</b><br />Bone scintigraphy imaging is highly accurate for identifying patients with ATTR-CM, with between study heterogeneity in part explained by differences in disease prevalence. We identified small differences in specificity, which may have important clinical implications when applied to low-risk screening populations.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 24 May 2023; epub ahead of print</small></div>

<div><h4>Observer studies of image quality of denoising reduced-count cardiac single photon emission computed tomography myocardial perfusion imaging by three-dimensional Gaussian post-reconstruction filtering and deep learning.</h4><i>Pretorius PH, Liu J, Kalluri KS, Jiang Y, ... Wernick MN, King MA</i><br /><b>Background</b><br />The aim of this research was to asses perfusion-defect detection-accuracy by human observers as a function of reduced-counts for 3D Gaussian post-reconstruction filtering vs deep learning (DL) denoising to determine if there was improved performance with DL.<br /><b>Methods</b><br />SPECT projection data of 156 normally interpreted patients were used for these studies. Half were altered to include hybrid perfusion defects with defect presence and location known. Ordered-subset expectation-maximization (OSEM) reconstruction was employed with the optional correction of attenuation (AC) and scatter (SC) in addition to distance-dependent resolution (RC). Count levels varied from full-counts (100%) to 6.25% of full-counts. The denoising strategies were previously optimized for defect detection using total perfusion deficit (TPD). Four medical physicist (PhD) and six physician (MD) observers rated the slices using a graphical user interface. Observer ratings were analyzed using the LABMRMC multi-reader, multi-case receiver-operating-characteristic (ROC) software to calculate and compare statistically the area-under-the-ROC-curves (AUCs).<br /><b>Results</b><br />For the same count-level no statistically significant increase in AUCs for DL over Gaussian denoising was determined when counts were reduced to either the 25% or 12.5% of full-counts. The average AUC for full-count OSEM with solely RC and Gaussian filtering was lower than for the strategies with AC and SC, except for a reduction to 6.25% of full-counts, thus verifying the utility of employing AC and SC with RC.<br /><b>Conclusion</b><br />We did not find any indication that at the dose levels investigated and with the DL network employed, that DL denoising was superior in AUC to optimized 3D post-reconstruction Gaussian filtering.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 23 May 2023; epub ahead of print</small></div>

<div><h4>Review of cardiovascular imaging in the Journal of Nuclear Cardiology 2022: positron emission tomography, computed tomography, and magnetic resonance.</h4><i>Murphy J, AlJaroudi WA, Hage FG</i><br /><AbstractText>In 2022, the Journal of Nuclear Cardiology® published many excellent original research articles and editorials focusing on imaging in patients with cardiovascular disease. In this review of 2022, we summarize a selection of articles to provide a concise recap of major advancements in the field. In the first part of this 2-part series, we addressed publications pertaining to single-photon emission computed tomography. In this second part, we focus on positron emission tomography, cardiac computed tomography, and cardiac magnetic resonance. We specifically review advances in imaging of non-ischemic cardiomyopathy, cardio-oncology, infectious disease cardiac manifestations, atrial fibrillation, detection and prognostication of atherosclerosis, and technical improvements in the field. We hope that this review will be useful to readers as a reminder to articles they have seen during the year as well as ones they have missed.</AbstractText><br /><br />© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.<br /><br /><small>J Nucl Cardiol: 19 May 2023; epub ahead of print</small></div>

<div><h4>Improving evaluation for TTR amyloidosis by interactive filtering of Tc-99 m PYP SPECT images. The role for \"clean blood pool\" imaging.</h4><i>Hansen CL</i><br /><b>Background</b><br />Myocardial imaging with bone agents such as Tc-99 m PYP and HMDP has assumed a central role in the evaluation of patients with suspected transthyretin (TTR) amyloidosis. Visual scoring (VS) (0-3 +) and the heart to contralateral lung ratio (HCL) classify many patients as equivocal when mediastinal uptake is apparent but cannot be further differentiated into myocardial uptake versus blood pool. SPECT imaging has been recommended but current reconstruction protocols frequently produce amorphous mediastinal activity that also fails to discriminate between myocardial activity and blood pool. We hypothesized that interactive filtering interactively using a deconvolving filter would improve this.<br /><b>Methods</b><br />We identified 176 sequential patients referred for TTR amyloid imaging. All patients had planar imaging, 101 had planar imaging with a large field of view camera that allowed HCL measurements. SPECT imaging was performed on a 3-headed digital camera with lead fluorescence attenuation correction. One study was excluded for technical reasons. We created software to allow interactive filtering while reconstructing the images then overlay them on attenuation mu maps to assist localization of myocardial/mediastinal uptake. Conventional Butterworth and an interactive inverse Gaussian filters were employed to differentiate myocardial uptake from residual blood pool. We defined \"clean blood pool\" (CBP) as recognizable blood pool with no activity in the surrounding myocardium. A scan was determined diagnostic if it showed CBP, positive uptake or no identifiable mediastinal uptake.<br /><b>Results</b><br />76/175 (43%) were equivocal (1 +) by visual uptake. Of these 22 (29%) were diagnostic by Butterworth but 71 (93%) were by inverse gaussian (p < .0001). 71/101 (70%) were equivocal by HCL (1-1.5). Of these, 25 (35%) were diagnostic by Butterworth but 68 (96%) were diagnostic by inverse gaussian (p < .0001). This was driven by a greater than threefold increase in the identification of CBP by inverse gaussian filtering.<br /><b>Conclusion</b><br />CBP can be identified in the vast majority of patients with equivocal PYP scans using optimized reconstruction and can greatly reduce the number of equivocal scans.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 12 May 2023; epub ahead of print</small></div>

<div><h4>Impact of change of ischemic burden on the outcomes of ESRD patients awaiting kidney transplantation.</h4><i>Tottleben J, Torres A, Doukky R</i><br /><b>Background</b><br />In asymptomatic patients with end-stage renal disease (ESRD) wait-listed for kidney transplantation (KT), it is unclear whether a change in ischemic burden on serial surveillance SPECT myocardial perfusion imaging (MPI) impacts outcome.<br /><b>Methods and results</b><br />In a retrospective cohort of 700 asymptomatic KT candidates with ≥ 2 sequential SPECT-MPI studies, we defined a significant change in ischemic burden between MPIs as ΔSDS of ≥ 2 points. Patients were followed for mean 19 ± 12 months after MPI<sub>2</sub> for cardiac death or myocardial infarction. Between MPIs, 29 (4%) subjects received coronary revascularization which was associated with a greater incidence of reduction in ischemic burden on MPI<sub>2</sub> (31% vs. 17%, P = 0.049). Among 514 patients with no ischemia on MPI<sub>1</sub> (SDS ≤ 1), 15% had new ischemia on MPI<sub>2</sub> which was associated with increased MACE (adjusted HR 1.75; CI 1.02-3.01; P = 0.041). Among 186 patients with ischemia on MPI<sub>1</sub> (SDS ≥ 2), 66% had improvement of ischemic burden on MPI<sub>2</sub> which was associated with significantly lower MACE (adjusted HR 0.46; CI 0.25-0.82; P = 0.009). There was no significant interaction between coronary revascularization and improvement in ischemic burden impacting outcome (interaction P = 0.845).<br /><b>Conclusion</b><br />Among KT candidates who underwent serial MPI for CAD surveillance, new ischemia was associated with increased MACE risk. Improvement in ischemic burden was associated with lower MACE risk irrespective of coronary revascularization status.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 11 May 2023; epub ahead of print</small></div>

<div><h4>Pentoxifylline reduces inflammation and prevents myocardial perfusion derangements in experimental chronic Chagas\' cardiomyopathy.</h4><i>Tanaka DM, Fabricio CG, Marin-Neto JA, de Barros Filho ACL, ... Romano MMD, Simões MV</i><br /><b>Background</b><br />Myocardial perfusion defect (MPD) is common in chronic Chagas cardiomyopathy (CCC) and is associated with inflammation and development of left ventricular systolic dysfunction. We tested the hypothesis that pentoxifylline (PTX) could reduce inflammation and prevent the development of MPD in a model of CCC in hamsters.<br /><b>Methods and results</b><br />We investigated with echocardiogram and rest myocardial perfusion scintigraphy at baseline (6-months after T. cruzi infection/saline) and post-treatment (after additional 2-months of PTX/saline administration), female Syrian hamsters assigned to 3 groups: T. cruzi-infected animals treated with PTX (CH + PTX) or saline (CH + SLN); and uninfected control animals (CO). At the baseline, all groups showed similar left ventricular ejection fraction (LVEF) and MPD areas. At post-treatment evaluation, there was a significant increase of MPD in CH + SLN group (0.8 ± 1.6 to 9.4 ± 9.7%), but not in CH + PTX (1.9 ± 3.0% to 2.7 ± 2.7%) that exhibited MPD area similar to CO (0.0 ± 0.0% to 0.0 ± 0.0%). The LVEF decreased in both infected groups. Histological analysis showed a reduced inflammatory infiltrate in CH + PTX group (395.7 ± 88.3 cell/mm<sup>2</sup>), as compared to CH + SLN (515.1 ± 133.0 cell/mm<sup>2</sup>), but larger than CO (193.0 ± 25.7 cell/mm<sup>2</sup>). The fibrosis and TNF-α expression was higher in both infected groups.<br /><b>Conclusions</b><br />The prolonged use of PTX is associated with positive effects, including prevention of MPD development and reduction of inflammation in the chronic hamster model of CCC.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 10 May 2023; epub ahead of print</small></div>

<div><h4>Combined evaluation of CAC score and myocardial perfusion imaging in patients at risk of cardiovascular disease: where are we and what do the data say.</h4><i>Mannarino T, D\'Antonio A, Assante R, Zampella E, ... Cuocolo A, Acampa W</i><br /><AbstractText>Advances in the prevention and treatment of cardiovascular disease (CVD) over the last decades have led to a marked reduction in mortality for CVD. Nevertheless, atherosclerosis leading to coronary artery disease and stroke remains one of the most common causes of death in the world. The usefulness of imaging tests in the early identification of disease led to identify subjects at major risk of poor outcomes, suggesting risk factor modification. The aim of this article is to analyze the state of art of combined imaging in patients at risk of CVD referred to MPI evaluation, to highlight the present and potential features able to provide incremental prognostic information to help clinicians in patient management and to reduce adverse events.</AbstractText><br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 10 May 2023; epub ahead of print</small></div>

<div><h4>Adjustment of acquisition arc in cardiac malposition during myocardial perfusion SPECT imaging: computer simulation based on deterministic modeling.</h4><i>Qutbi M</i><br /><b>Objectives</b><br />To simulate cardiac malpositions, leftward and rightward shift and dextrocardia, and also to compare distribution of activity of septal and lateral walls of left ventricle acquired in standard acquisition arc and after relevant adjustment.<br /><b>Methods</b><br />In this study, digital phantoms with cardiac malpositions are designed and procedure of acquisition of scan in standard arc (from right anterior oblique to left posterior oblique) and adjusted acquisition arc is simulated. The three situations of malposition including leftward and rightward shift and dextrocardia are considered. For all types, acquisition is conducted in standard and then adjusted arcs (from anterior to posterior and also from right to left for leftward and rightward shifts, respectively, and for dextrocardia, from left anterior oblique to right posterior oblique). All obtained projections are reconstructed using the algorithm of filtered back projection. During forward projection to obtain sinograms, radiation attenuation is also modeled by incorporation of a simplified transmission map to emission map. The resulting tomographic slices of the LV (septum, apex, and lateral wall) are presented visually and are compared by plotting intensity profiles of the walls. Finally, normalized error images are also computed. All the computations are performed in MATLAB software package.<br /><b>Results</b><br />In transverse slice, septum and lateral wall are attenuated progressively from apex, which is closer to the camera, to the base in similar fashion. In tomographic slices of standard acquisition arc, the septum shows remarkably higher activity compared to lateral wall. However, after adjustment, both seems equally intense and progressively being attenuated from apex to base, similar to that found in phantom with normally positioned heart. Likewise, for the phantom with rightward shift, when the scanning was done in standard arc, the septum is more intense than the lateral wall. And similarly, adjustment of the arc renders both walls equally intense. In dextrocardia, level of attenuation of basal parts of septum and lateral wall is higher in 360° arc compared to adjusted 180° arc.<br /><b>Conclusion</b><br />Adjustment of acquisition arc exerts perceptible changes in distribution of activity over LV walls which are more compatible with normally positioned heart.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 04 May 2023; epub ahead of print</small></div>

<div><h4>4D display of CT LV endocardial and epicardial models morphed from PET Rb-82 perfusion studies accurately quantifies segmental myocardial thickening.</h4><i>Piccinelli M, Cooke CD, Folks R, Garcia EV</i><br /><b>Background</b><br />MPI-derived LV wall thickening assessments for diagnostic purposes has been part of clinical guidelines for two decades. It relies on visual evaluation of tomographic slices or regional quantification displayed in 2D polar maps. 4D displays have not entered clinical usage nor have they been validated on their potential to provide equivalent information. The purpose of this work was to validate a 4D realistic display recently designed to quantitatively represent the thickening information from gated MPI into CT-morphed endocardial and epicardial moving surfaces.<br /><b>Methods</b><br />Forty patients who underwent <sup>82</sup>Rb PET were selected based on LV perfusion quantification. CTA templates of heart anatomy were selected to represent the LV anatomy. Generic CT-derived LV endocardial and epicardial surfaces were modified to represent the end diastolic (ED) phase according to PET-derived ED LV dimensions and wall thickness. These CT myocardial surfaces were then morphed by means of thin plate spline (TPS) techniques, according to the gated PET slices count changes (WTh<sub>PET</sub>) and LV wall motion (WMo<sub>PET</sub>). A geometric thickening (GeoTh) equivalent to LV WTh<sub>PET</sub> was defined on epicardial and endocardial CT surfaces over the cardiac cycle and the two measures compared. WTh<sub>PET</sub> and GeoTh correlations were performed on a case-by-case basis, by segment and by pooling all 17 segments. Pearson\'s correlation coefficients (PCC) were calculated to assess the equivalence of the two measures.<br /><b>Results</b><br />Two cohorts of patients (normal and abnormal) were identified based on SSS. R coefficients were as follows: for all pooled segments PCC<sub>stress</sub> and PCC<sub>rest</sub> were respectively 0.91 and 0.89 (normal), and 0.9 and 0.91 (abnormal); when individual 17 segments were considered mean PCC<sub>stress</sub> = 0.92 [0.81-0.98] and mean PCC<sub>rest</sub> = 0.93 [0.83-0.98] for the abnormal perfusion group; mean PCC<sub>stress</sub> = 0.89 [0.78-0.97] and mean PCC<sub>rest</sub> = 0.89 [0.77-0.97] for the normal. When individual studies were considered, R was always > .70 with the exception of five abnormal studies. Inter-user analysis was also conducted.<br /><b>Conclusions</b><br />Our novel technique for the visualization of LV wall thickening by means of 4D CT endocardial and epicardial surface models accurately replicated <sup>82</sup>Rb slice thickening results showing promise for its usage for diagnostic purposes.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 02 May 2023; epub ahead of print</small></div>

<div><h4>[Ga]Ga-NODAGA-E[(cRGDyK)] angiogenesis PET following myocardial infarction in an experimental rat model predicts cardiac functional parameters and development of heart failure.</h4><i>Bentsen S, Jensen JK, Christensen E, Petersen LR, ... Ripa RS, Kjaer A</i><br /><b>Background</b><br />Angiogenesis has increasingly been a target for imaging and treatment over the last decade. The integrin α<sub>v</sub>β<sub>3</sub> is highly expressed in cells during angiogenesis and are therefore a promising target for imaging. In this study, we aimed to investigate the PET tracer [<sup>68</sup>Ga]Ga-RGD as a marker of angiogenesis following MI and its ability to predict cardiac functional parameters.<br /><b>Methods</b><br />First, the real-time interaction between [<sup>68</sup>Ga]Ga-RGD and integrin α<sub>v</sub>β<sub>3</sub> was investigated using surface plasmon resonance (SPR). Second, an animal study was performed to investigate the [<sup>68</sup>Ga]Ga-RGD uptake in the infarcted area after one and four weeks following MI in a rat model (MI = 68, sham surgery = 36). Finally, the specificity of the [<sup>68</sup>Ga]Ga-RGD tracer was evaluated ex vivo using histology, autoradiography, gamma counting and flow cytometry.<br /><b>Results</b><br />SPR showed that [<sup>68</sup>Ga]Ga-RGD has a high affinity for integrin α<sub>v</sub>β<sub>3</sub>, forming a strong and stable binding. PET/CT showed a significantly higher uptake of [<sup>68</sup>Ga]Ga-RGD in the infarcted area compared to sham one week (p < 0.001) and four weeks (p < 0.001) after MI. The uptake of [<sup>68</sup>Ga]Ga-RGD after one week correlated to end diastolic volume (r = 0.74, p < 0.001) and ejection fraction (r = - 0.71, p < 0.001) after four weeks.<br /><b>Conclusion</b><br />This study demonstrates that [<sup>68</sup>Ga]Ga-RGD has a high affinity for integrin α<sub>v</sub>β<sub>3</sub>, which enables the evaluation of angiogenesis and remodeling. The [<sup>68</sup>Ga]Ga-RGD uptake after one week indicates that [<sup>68</sup>Ga]Ga-RGD may be used as an early predictor of cardiac functional parameters and possible development of heart failure after MI. These encouraging data supports the clinical translation and future use in MI patients.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 01 May 2023; epub ahead of print</small></div>

<div><h4>F-sodium fluoride positron emission tomography following coronary computed tomography angiography in predicting long-term coronary events: a 5-year follow-up study.</h4><i>Kitagawa T, Sasaki K, Fujii Y, Ikegami Y, ... Hirokawa Y, Nakano Y</i><br /><b>Purpose</b><br />The predictive value of <sup>18</sup>F-sodium fluoride (<sup>18</sup>F-NaF) positron emission tomography (PET) in combination with coronary computed tomography (CT) angiography (CCTA) for future coronary events has attracted interest. We evaluated the potential of <sup>18</sup>F-NaF PET/CT following CCTA to predict major coronary events (MACE) during a 5-year follow-up period.<br /><b>Methods</b><br />Forty patients with coronary atherosclerotic lesions detected on CCTA underwent <sup>18</sup>F-NaF PET/CT examination. Each lesion was evaluated for luminal stenosis and high-risk plaque (HRP) with < 30 Hounsfield units and a > 1.1 remodeling index on CCTA. Focal <sup>18</sup>F-NaF uptake in each lesion was quantified using the maximum tissue-to-background ratio (TBR<sub>max</sub>), and the maximum TBR<sub>max</sub> per patient (M-TBR<sub>max</sub>) was determined. We followed MACE (cardiac death, acute coronary syndrome, and/or coronary revascularization > 6 months after <sup>18</sup>F-NaF PET/CT) for 5 years.<br /><b>Results</b><br />In total, 142 coronary lesions were analyzed. Eleven patients experienced any MACE. Patients with MACE showed a higher M-TBR<sub>max</sub> than those without (1.40 ± .19 vs. 1.18 ± .18, P = .0011), and the optimal M-TBR<sub>max</sub> cutoff to predict MACE was 1.29. Patients with M-TBR<sub>max</sub> of ≥ 1.29 had a higher risk of MACE than those with lower values (P = .012, log-rank test), whereas patients with obstructive stenosis and those with HRP did not. Multivariate Cox proportional analysis adjusted for age, sex, coronary risk factors, and CCTA findings showed that M-TBR<sub>max</sub> of ≥ 1.29 remained an independent predictor of 5-year MACE (hazard ratio, 5.4; 95% confidence interval, 1.1-25.4; P = .034).<br /><b>Conclusion</b><br /><sup>18</sup>F-NaF PET/CT following CCTA provides useful strategies to predict 5-year MACE.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 01 May 2023; epub ahead of print</small></div>

<div><h4>Echocardiographic indices of left ventricular function and filling pressure are not related to blood pool activity on pyrophosphate scintigraphy.</h4><i>Asif T, Gupta A, Murthi M, Soman P, Singh V, Malhotra S</i><br /><b>Background</b><br />Pyrophosphate (PYP) imaging has a high diagnostic accuracy for transthyretin cardiac amyloidosis (ATTR-CA). Indeterminate findings are often reported due to persistent blood pool activity, presumed to be from low cardiac output. We evaluated the relationship between blood pool activity on PYP imaging and echocardiographic indices of cardiac function.<br /><b>Methods</b><br />Clinical and imaging data of 189 patients referred for PYP scintigraphy were evaluated. All patients underwent planar imaging and SPECT (diagnostic standard). Among those with a negative PYP SPECT, persistent left ventricular blood pool activity on planar images was inferred by a visual score ≥2 or a heart-to-contralateral (HCL) ratio ≥ 1.5. Absence of blood pool activity was inferred when both visual score was < 2 and HCL was < 1.5. Left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), stroke volume index (SVi), and left atrial pressure (LAP) were calculated from standard transthoracic echocardiograms.<br /><b>Results</b><br />ATTR-CA was present in 43 (23%) patients. Among those with a negative PYP SPECT, 11 patients had significant blood pool activity. Patients with ATTR-CA had a lower LVEF, SVi, and GLS, with a higher LAP, compared to those without ATTR-CA. Among those without ATTR-CA, there were no significant differences in these parameters.<br /><b>Conclusion</b><br />Approximately 8% of patients with a negative PYP SPECT have significant blood pool activity. Measures of cardiac function are not different among those with and without blood pool activity. PYP SPECT should be routinely performed in all patients to avoid false image interpretation.<br /><br />© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 01 May 2023; 30:708-715</small></div>

<div><h4>Left ventricular assist device infection on F-flourodeoxyglucose positron emission tomography.</h4><i>Kaur S, Bartley P, Gordon S, Higgins A, Bhat P, Jaber W</i><br /><AbstractText>The rising prevalence of heart failure with limited transplant availability has resulted in increased use of continuous left ventricular assist device (LVAD) support. LVAD driveline remains exposed to environment which predisposes it to high rates of infection. We describe a case of a persistent driveline infection in a patient for which <sup>18</sup>F-FDG PET/CT was utilized to diagnose deep-seated infection.</AbstractText><br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 25 Apr 2023; epub ahead of print</small></div>

<div><h4>Dynamic perfusion SPECT for functional evaluation in symptomatic patients with myocardial bridging.</h4><i>Xu R, Yang H, Zhang J, Chen S, ... Li C, Ge J</i><br /><b>Background</b><br />The aim of this study was to investigate the feasibility and diagnostic value of myocardial flow reserve (MFR) assessed by rest/stress myocardial perfusion imaging with dynamic single-photon emission computed tomography (SPECT) in the functional evaluation of myocardial bridge (MB).<br /><b>Methods</b><br />From May 2017 to July 2021, patients with angiographically confirmed isolated MB on the left anterior descending artery (LAD) who underwent dynamic SPECT myocardial perfusion imaging were retrospectively included. The assessment of semiquantitative indices of myocardial perfusion (summed stress scores, SSS) and quantitative parameters (MFR) was performed.<br /><b>Results</b><br />A total of 49 patients were enrolled. The mean age of the subjects was 61.0 ± 9.0 years. All of the patients were symptomatic, and 16 cases (32.7%) presented with typical angina. SPECT-derived MFR showed a borderline significantly negative correlation with SSS (r = 0.261, P = .070). There was a trend of higher prevalence of impaired myocardial perfusion defined as MFR < 2 than as SSS ≥ 4 (42.9% vs 26.5%; P = .090).<br /><b>Conclusion</b><br />Our data support that SPECT MFR may be a useful parameter for the functional assessment of MB. In patients with MB, the use of dynamic SPECT could be a potential method for hemodynamic assessment.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 24 Apr 2023; epub ahead of print</small></div>

<div><h4>Patient-tailored risk assessment of obstructive coronary artery disease using Rubidium-82 PET-based myocardial flow quantification with visual interpretation.</h4><i>Koenders SS, van Dalen JA, Jager PL, Mouden M, Slump CH, van Dijk JD</i><br /><b>Introduction</b><br />Our aim was to estimate the probability of obstructive CAD (oCAD) for an individual patient as a function of the myocardial flow reserve (MFR) measured with Rubidium-82 (Rb-82) PET in patients with a visually normal or abnormal scan.<br /><b>Materials and methods</b><br />We included 1519 consecutive patients without a prior history of CAD referred for rest-stress Rb-82 PET/CT. All images were visually assessed by two experts and classified as normal or abnormal. We estimated the probability of oCAD for visually normal scans and scans with small (5%-10%) or larger defects (> 10%) as function of MFR. The primary endpoint was oCAD on invasive coronary angiography, when available.<br /><b>Results</b><br />1259 scans were classified as normal, 136 with a small defect and 136 with a larger defect. For the normal scans, the probability of oCAD increased exponentially from 1% to 10% when segmental MFR decreased from 2.1 to 1.3. For scans with small defects, the probability increased from 13% to 40% and for larger defects from 45% to > 70% when segmental MFR decreased from 2.1 to 0.7.<br /><b>Conclusion</b><br />Patients with > 10% risk of oCAD can be distinguished from patients with < 10% risk based on visual PET interpretation only. However, there is a strong dependence of MFR on patient\'s individual risk of oCAD. Hence, combining both visual interpretation and MFR results in a better individual risk assessment which may impact treatment strategy.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 19 Apr 2023; epub ahead of print</small></div>

<div><h4>Interaction of impaired myocardial flow reserve and extent of myocardial ischemia assessed using N-ammonia positron emission tomography imaging on adverse cardiovascular outcomes.</h4><i>Miura S, Okizaki A, Kumamaru H, Manabe O, ... Miyazaki C, Yamashita T</i><br /><b>Background</b><br />Myocardial flow reserve (MFR) and the extent of myocardial ischemia identify patients at high risk of major adverse cardiovascular events (MACEs). Associations between positron emission tomography (PET)-assessed extent of ischemia, MFR, and MACEs is unclear.<br /><b>Method</b><br />Overall, 640 consecutive patients with suspected or known coronary artery disease undergoing <sup>13</sup>N-ammonia myocardial perfusion PET were followed-up for MACEs. Patients were categorized into three groups based on myocardial ischemia severity: Group I (n = 335), minimal (myocardial ischemia < 5%); Group II (n = 150), mild (5-10%); and Group III (n = 155), moderate-to-severe (> 10%).<br /><b>Results</b><br />Cardiovascular death and MACEs occurred in 17 (3%) and 93 (15%) patients, respectively. Following statistical adjustment for confounding factors, impaired MFR (global MFR < 2.0) was revealed as an independent predictor of MACEs in Groups I (hazard ratio [HR], 2.89; 95% confidence interval [CI], 1.48-5.64; P = 0.002) and II (HR, 3.40; 95% CI 1.37-8.41; P = 0.008) but was not significant in Group III (HR, 1.15; 95% CI 0.59-2.26; P = 0.67), with a significant interaction (P < 0.0001) between the extent of myocardial ischemia and MFR.<br /><b>Conclusion</b><br />Impaired MFR was significantly associated with increased risk of MACEs in patients with ≤ 10% myocardial ischemia but not with those having > 10% ischemia, allowing a clinically effective risk stratification.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 03 Apr 2023; epub ahead of print</small></div>

<div><h4>Comparison of cardio-focal and chest reconstruction of technetium-99m pyrophosphate scintigraphy for diagnosis of transthyretin cardiac amyloidosis: a quality assurance study.</h4><i>Akincioglu C, Murthi M, Romsa J, Warrington J, Malhotra S</i><br /><b>Background</b><br />SPECT improves diagnostic specificity of Technetium-99m pyrophosphate (PYP) scintigraphy. Diagnostic performance of PYP data, reconstructed as either chest or cardio-focal SPECT is not known.<br /><b>Methods</b><br />In this quality assurance study, blinded evaluation of PYP SPECT/CT data from 102 Caucasian patients (mean age 76 ± 11 years, 67% men) was performed by two readers. Reader 1 reviewed planar and PYP chest SPECT, while reader 2 reviewed planar and cardio-focal PYP SPECT. Demographic, clinical, and other testing data were obtained from the electronic medical records.<br /><b>Results</b><br />A total of 41 patients (40%) were considered positive based on myocardial uptake on chest PYP SPECT. Of these, 98% of the patients had a Perugini score ≥ 2 on planar imaging. There was good agreement between the two readers for visual score ≥ 2 (k = .88, P < .001) and excellent agreement for myocardial uptake on tomographic imaging (98%, P < .001). Only one study was categorized as false negative by cardio-focal SPECT reconstruction. Non-diffuse myocardial uptake was identified in 22% of those with a positive PYP SPECT.<br /><b>Conclusion</b><br />When read by experienced readers, chest and cardio-focal reconstruction of PYP SPECT have comparable diagnostic performance. A substantial proportion of patients with a positive PYP SPECT have a non-diffuse distribution of PYP. Given the possibility of misclassification of non-diffuse myocardial uptake on cardio-focal reconstruction alone, chest reconstruction of PYP scintigraphy should be strongly considered.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 03 Apr 2023; epub ahead of print</small></div>

<div><h4>Ga-FAPI PET/CT for molecular assessment of fibroblast activation in right heart in pulmonary arterial hypertension: a single-center, pilot study.</h4><i>Gu Y, Han K, Zhang Z, Zhao Z, ... Wang L, Fang W</i><br /><b>Background</b><br />Positron emission tomography (PET) imaging with radiolabeled fibroblasts activation protein inhibitor (FAPI) provides the opportunity to directly visualize fibrosis. This study aimed to investigate the feasibility of <sup>68</sup>Ga-FAPI PET imaging in assessing right ventricular (RV) fibrotic remodeling and the relationship between FAPI uptake with parameters of pulmonary hemodynamics and cardiac function in pulmonary arterial hypertension (PAH) patients.<br /><b>Methods</b><br />In this pilot study, sixteen PAH patients were enrolled to participate in cardiac <sup>68</sup>Ga-FAPI PET/CT imaging. All patients underwent right heart catheterization and echocardiography for assessment of pulmonary hemodynamics and cardiac function within seven days. Cardiac FAPI uptake was visually assessed and quantified as maximum standardized uptake value (SUVmax).<br /><b>Results</b><br />Twelve PAH patients exhibited FAPI uptake in RV free wall and insertion point. The overall activity of FAPI accumulated in the RV free wall (SUVmax: 2.5 ± 1.8, P < 0.001) and insertion point (SUVmax:2.5 ± 1.7, P < 0.001) was significantly upregulated compared to left ventricle (SUVmax:1.5 ± 0.5). Patients with tricuspid annular plane systolic excursion (TAPSE) < 17 mm presented significantly higher uptake than those with TAPSE ≥ 17 mm in both RV free wall (SUVmax: 3.4 ± 1.9 vs 1.7 ± 1.1, P = 0.010) and insertion point (SUVmax: 3.4 ± 1.9 vs 1.6 ± 0.7, P = 0.028), indicating RV uptake of FAPI was associated with RV dysfunction. There was significant positive correlation between cardiac FAPI uptake and total pulmonary resistance and the level of N-terminal pro b-type natriuretic peptide.<br /><b>Conclusions</b><br /><sup>68</sup>Ga-FAPI PET/CT imaging is feasible to directly visualize fibrotic remodeling of RV in patients with PAH.<br /><br />© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 01 Apr 2023; 30:495-503</small></div>

<div><h4>External validation of the CRAX2MACE model.</h4><i>Hijazi W, Leslie W, Filipchuk N, Choo R, ... Slomka PJ, Miller RJH</i><br /><b>Background</b><br />Single-photon emission computed tomography (SPECT) myocardial perfusion is frequently used to predict risk of major adverse cardiovascular events (MACE). We performed an external validation of the CRAX2MACE score, developed to estimate 2-year risk of MACE in patients with suspected coronary artery disease (CAD).<br /><b>Methods</b><br />Patients who underwent clinically indicated SPECT with available follow-up for MACE were included (N = 2,985). The prediction performance for MACE (revascularization, myocardial infarction, or death) within 2 years for CRAX2MACE was compared with stress and ischemic total perfusion deficit (TPD) using area under the receiver operating characteristic curve (AUC). Calibration was assessed with calibration plots, Brier score, and the Hosmer-Lemeshow test.<br /><b>Results</b><br />MACE occurred within 2 years in 243 (8.1%) patients. The AUC for CRAX2MACE (0.710, 95% CI 0.677-0.743) was significantly higher compared to stress TPD (AUC 0.669, 95% CI 0.632-0.706, P = .010) and ischemic TPD (AUC 0.664, 95% CI 0.627-0.700, P < .001). The model had acceptable goodness-of-fit (P = .103) and was well-calibrated with Brier score of 0.071.<br /><b>Conclusion</b><br />CRAX2MACE had higher predictive performance for 2-year MACE than quantitative perfusion in an external population. The current model is simple to use and could be implemented to assist physicians when estimating patient risk.<br /><br />© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 01 Apr 2023; 30:702-707</small></div>

<div><h4>F-FDG/N-ammonia cardiac PET findings in ATTR cardiac amyloidosis.</h4><i>Young KA, Lyle M, Rosenbaum AN, Chang IC, ... Blauwet L, Bois JP</i><br /><AbstractText><sup>18</sup>F-flurodeoxyglycose (FDG)/<sup>13</sup>N-ammonia positron emission tomography/computed tomography (PET/CT) is frequently utilized to evaluate cardiac sarcoidosis (CS) but findings can reflect other forms of myocardial inflammation or altered myocardial metabolic activity. Herein, we present five cases where cardiac PET findings suggested CS, but right ventricular endomyocardial biopsy samples revealed ATTR-type cardiac amyloidosis.</AbstractText><br /><br />© 2022. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 01 Apr 2023; 30:726-735</small></div>

<div><h4>Quantitation of diffuse myocardial ischemia with mental stress and its association with cardiovascular events in individuals with recent myocardial infarction.</h4><i>Almuwaqqat Z, Garcia EV, Cooke CD, Garcia M, ... Quyyumi AA, Vaccarino V</i><br /><AbstractText>Microcirculatory dysfunction during psychological stress may lead to diffuse myocardial ischemia. We developed a novel quantification method for diffuse ischemia during mental stress (dMSI) and examined its relationship with outcomes after a myocardial infarction (MI). We studied 300 patients ≤ 61 years of age (50% women) with a recent MI. Patients underwent myocardial perfusion imaging with mental stress and were followed for 5 years. dMSI was quantified from cumulative count distributions of rest and stress perfusion. Focal ischemia was defined in a conventional fashion. The main outcome was a composite outcome of recurrent MI, heart failure hospitalizations, and cardiovascular death. A dMSI increment of 1 standard deviation was associated with a 40% higher risk for adverse events (HR 1.4, 95% CI 1.2-1.5). Results were similar after adjustment for viability, demographic and clinical factors and focal ischemia. In sex-specific analysis, higher levels of dMSI (per standard deviation increment) were associated with 53% higher risk of adverse events in women (HR 1.5, 95% CI 1.2-2.0) but not in men (HR 0.9, 95% CI 0.5-1.4), P 0.001. A novel index of diffuse ischemia with mental stress was associated with recurrent events in women but not in men after MI.</AbstractText><br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 29 Mar 2023; epub ahead of print</small></div>

<div><h4>A quick glance at selected topics in this issue.</h4><i>Bhambhvani P, Hage FG, Iskandrian AE</i><br /><AbstractText>\"A quick glance at selected topics in this issue\" aims to highlight contents of the Journal and provide a quick review to the readers.</AbstractText><br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 24 Mar 2023; epub ahead of print</small></div>

<div><h4>Visualization of fibroblast activation using Ga-FAPI PET/CT after pulmonary vein isolation with pulsed field compared with cryoballoon ablation.</h4><i>Kupusovic J, Kessler L, Bruns F, Bohnen JE, ... Rischpler C, Siebermair J</i><br /><b>Background</b><br />Pulsed-field ablation (PFA) is a novel ablation modality for atrial fibrillation (AF) ablating myocardium by electroporation without tissue-heating. With its different mechanism of tissue ablation, it is assumed that lesion creation is divergent to thermal energy sources. <sup>68</sup>Ga-fibroblast-activation protein inhibitor (FAPI) PET/CT targets FAP-alpha expressed by activated fibroblasts. We aimed to assess <sup>68</sup>Ga-FAPI uptake in pulmonary veins as surrogate for ablation damage after PFA and cryoballoon ablation (CBA).<br /><b>Methods</b><br />26 patients (15 PFA, 11 CBA) underwent <sup>68</sup>Ga-FAPI-PET/CT after ablation. Standardized uptake values (SUV) and fibroblast-activation volumes of localized tracer uptake were assessed.<br /><b>Results</b><br />Patient characteristics were comparable between groups. In PFA, focal FAPI uptake was only observed in 3/15 (20%) patients, whereas in the CBA cohort, 10/11 (90.9%) patients showed atrial visual uptake. We observed lower values of SUV<sub>max</sub> (2.85 ± 0.56 vs 4.71 ± 2.06, P = 0.025) and FAV (1.13 ± 0.84 cm<sup>3</sup> vs 3.91 ± 2.74 cm<sup>3</sup>, P = 0.014) along with a trend towards lower SUV<sub>peak</sub> and SUV<sub>mean</sub> in PFA vs CBA patients, respectively.<br /><b>Conclusion</b><br />Tissue response with respect to fibroblast activation seems to be less pronounced in PFA compared to established thermal ablation systems. This functional assessment might contribute to a better understanding of lesion formation in thermal and PFA ablation potentially contributing to better safety outcomes.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 21 Mar 2023; epub ahead of print</small></div>

<div><h4>Extensive cardiac FDG uptake in a patient with AL amyloidosis.</h4><i>Hatipoglu S, Wechalekar AD, Wechalekar K</i><br /><AbstractText>Cardiac AL amyloidosis is a medical emergency causing rapid deterioration of cardiac function; however, it remains to be a diagnostic challenge especially when presenting with unusual symptoms and clinical findings. We present case of a 44-year-old patient with typical angina, persistently elevated troponin and normal epicardial coronary arteries. He was initially treated for myocarditis due to chest pain with troponin rise. However, CMR finding of subendocardial enhancement, increased native T1 values as well as extensive diffuse FDG uptake on PET-CT also suggested inflammatory cardiac conditions. Rapid decline in LV function and clinical deterioration led to further investigations including serum free light chains and bone marrow biopsy which confirmed systemic AL amyloidosis. Although the pathophysiology of unusual FDG PET-CT findings remains unknown, marked myocardial FDG uptake might have been caused by various features that were associated with AL amyloidosis including myocardial cell toxicity/inflammation or microvascular dysfunction. Awareness of these features specific to AL amyloidosis among physicians and description of associated cardiac FDG uptake findings has a potential to aid early diagnosis.</AbstractText><br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 17 Mar 2023:1-7; epub ahead of print</small></div>

<div><h4>Quantitative flow ratio derived pullback pressure gradient and CZT-SPECT measured longitudinal flow gradient for hemodynamically significant coronary artery disease.</h4><i>Dai N, Zhang B, Gong Z, Dong Z, ... Shi H, Ge J</i><br /><b>Background</b><br />Whether physiological coronary diffuseness assessed by quantitative flow reserve (QFR) pullback pressure gradient (PPG) correlates with longitudinal myocardial blood flow (MBF) gradient and improves diagnostic performances for myocardial ischemia remains unknown.<br /><b>Methods and results</b><br />MBF was measured in mL g<sup>-1</sup> min<sup>-1</sup> with <sup>99m</sup>Tc-MIBI CZT-SPECT at rest and stress, corresponding myocardial flow reserve (MFR = MBF stress/MBF rest) and relative flow reserve (RFR = MBF stenotic area/MBF reference) were calculated. Longitudinal MBF gradient was defined as apical and basal left ventricle MBF gradient. △longitudinal MBF gradient was calculated by longitudinal MBF gradient at stress and rest. QFR-PPG was acquired from virtual QFR pullback curve. QFR-PPG significantly correlated with hyperemic longitudinal MBF gradient (r = 0.45, P = 0.007) and △longitudinal MBF gradient (stress-rest) (r = 0.41, P = 0.016). Vessels with lower RFR had lower QFR-PPG (0.72 vs. 0.82, P = 0.002), hyperemic longitudinal MBF gradient (1.14 vs. 2.22, P = 0.003) and △longitudinal MBF gradient (0.50 vs. 1.02, P = 0.003). QFR-PPG, hyperemic longitudinal MBF gradient and △longitudinal MBF gradient showed comparable diagnostic performances for predicting decreased RFR (area under curve [AUC]: 0.82 vs. 0.81 vs. 0.75, P = NS) or QFR (AUC: 0.83 vs. 0.72 vs. 0.80, P = NS). In addition, QFR-PPG and QFR in combination showed incremental value compared with QFR for predicting RFR (AUC = 0.83 vs. 0.73, P = 0.046, net reclassification index = 0.508, P = 0.001).<br /><b>Conclusion</b><br />QFR-PPG significantly correlated with longitudinal MBF gradient and △longitudinal MBF gradient when used for physiological coronary diffuseness assessment. All three parameters had high accuracy in predicting RFR or QFR. Adding physiological diffuseness assessment increased accuracy for predicting myocardial ischemia.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 16 Mar 2023; epub ahead of print</small></div>

<div><h4>Comparison of 2D-QCA, 3D-QCA and coronary angiography derived FFR in predicting myocardial ischemia assessed by CZT-SPECT MPI.</h4><i>Tang X, Dai N, Zhang B, Cai H, ... Xu Y, Ge J</i><br /><b>Background</b><br />Angiography derived fractional flow reserve (angio-FFR) has been proposed. This study aimed to assess its diagnostic performance with cadmium-zinc-telluride single emission computed tomography (CZT-SPECT) as reference.<br /><b>Methods and results</b><br />Patients underwent CZT-SPECT within 3 months of coronary angiography were included. Angio-FFR computation was performed using computational fluid dynamics. Percent diameter (%DS) and area stenosis (%AS) were measured by quantitative coronary angiography. Myocardial ischemia was defined as a summed difference score ≥ 2 in a vascular territory. Angio-FFR ≤ 0.80 was considered abnormal. 282 coronary arteries in 131 patients were analyzed. Overall accuracy of angio-FFR to detect ischemia on CZT-SPECT was 90.43%, with a sensitivity of 62.50% and a specificity of 98.62%. The diagnostic performance (= area under ROC = AUC) of angio-FFR [AUC = 0.91, 95% confidence intervals (CI) 0.86-0.95] was similar as those of %DS (AUC = 0.88, 95% CI 0.84-0.93, p = 0.326) and %AS (AUC = 0.88, 95% CI 0.84-0.93 p = 0.241) by 3D-QCA, but significantly higher than those of %DS (AUC = 0.59, 95% CI 0.51-0.67, p < 0.001) and %AS (AUC = 0.59, 95% CI 0.51-0.67, p < 0.001) by 2D-QCA. However, in vessels with 50-70% stenoses, AUC of angio-FFR was significantly higher than those of %DS (0.80 vs. 0.47, p < 0.001) and %AS (0.80 vs. 0.46, p < 0.001) by 3D-QCA and %DS (0.80 vs. 0.66, p = 0.036) and %AS (0.80 vs. 0.66, p = 0.034) by 2D-QCA.<br /><b>Conclusion</b><br />Angio-FFR had a high accuracy in predicting myocardial ischemia assessed by CZT-SPECT, which is similar as 3D-QCA but significantly higher than 2D-QCA. While in intermediate lesions, angio-FFR is better than 3D-QCA and 2D-QCA in assessing myocardial ischemia.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 16 Mar 2023; epub ahead of print</small></div>

<div><h4>Simultaneous assessment of left ventricular mechanical dyssynchrony using integrated N-ammonia PETMR system: direct comparison of PET phase analysis and MR feature tracking.</h4><i>Fukushima K, Endo K, Yamakuni R, Kiko T, ... Ito H, Takeishi Y</i><br /><b>Background</b><br />To compare phase analysis with positron emission tomography (PA) and magnetic resonance feature tracking derived myocardial strain (FT) for left ventricular (LV) mechanical dyssynchrony using PETMR system in patients with ischemic heart disease.<br /><b>Methods and results</b><br />Patients who underwent rest-pharmacological stress <sup>13</sup>N ammonia PETMR were enrolled. Histogram bandwidth (BW) and phase standard deviation (PSD) were compared to global longitudinal, long axis radial, short axis circumferential, and radial strain (GLS, GRS, SA Circ, and SA Rad) obtained from FT. LV dyssynchrony index (SDI) derived from PA and FT were compared. BW and PSD showed significant correlations with FT (a Pearson\'s coefficient r = 0.64, P < .0001, and r = 0.51, P < .0001 for SA Circ; r = 0.67, P < .0001, and r = 0.74, P < .0001 for GLS; r = - 0.60, P < .0001, r = - 0.61, P < .0001 for SA Rad; r = - 0.62, P < .0001, and r = - 0.68, P < .0001 for GRS, respectively). Bland-Altman plots for SDI showed a preferable agreement (95% limit of agreement - 0.12 to 0.075, - 0.20 to 0.098, - 0.38 to 0.077, and - 0.37 to 0.032; bias 0.0068 ± 0.056, 0.026 ± 0.068, 0.11 ± 0.088, and 0.13 ± 0.079 for SA Circ, SA Rad, GLS, and GRS, respectively).<br /><b>Conclusion</b><br />In simultaneous acquisition using PETMR, comparison of PET phase analysis and MR strain showed a good correlation.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 14 Mar 2023; epub ahead of print</small></div>

<div><h4>Lung-to-heart ratio analysis using virtual planar images obtained from myocardial perfusion SPECT data: A phantom and clinical studies.</h4><i>Imoto A, Tateishi E, Murakawa K, Ohta Y, Fukuda T</i><br /><b>Backgrounds</b><br />The lung-to-heart ratio (L/H ratio) in myocardial perfusion scintigraphy (MPS) is a useful marker that complements the sensitivity of ischemia detection. However, it requires planar imaging acquired following a separate protocol in addition to single-photon emission computed tomography (SPECT). We developed a novel method for constructing virtual planar image (VPI) from SPECT data.<br /><b>Methods</b><br />Myocardial phantoms using Tl-201 were built with different amounts of radioactivity in the lungs. SPECT data and conventional planar images of these phantoms were collected with an Anger-type gamma camera. VPIs were constructed by adding all coronal images reconstructed from SPECT data. The clinical utility of VPIs obtained from 52 patients who underwent MPS with Tc-99m sestamibi was evaluated.<br /><b>Results</b><br />The radioactivity linearity of VPIs was satisfactory, with a correlation coefficient of r ≥ .99 between the measured amounts of radioactivity and image counts. The L/H ratios obtained from VPI analysis were strongly correlated with those of conventional planar images with a correlation coefficient of r ≥ .99 in the phantom study and r = .929 in clinical application.<br /><b>Conclusion</b><br />The accuracy of VPI-based L/H ratio analysis was comparable to that of conventional planar image-based analysis. VPIs could be used as an alternative method of obtaining planar images in clinical settings.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 14 Mar 2023; epub ahead of print</small></div>

<div><h4>Impact of respiratory gating and ECG gating on F-FDG PET/CT for cardiac sarcoidosis.</h4><i>Hanaoka K, Watanabe S, Morimoto-Ishikawa D, Kaida H, ... Md , Ishii K</i><br /><b>Background</b><br />The aim of this study was to estimate the impact of respiratory and electrocardiogram (ECG)-gated FDG positron emission tomography (PET)/computed tomography (CT) on the diagnosis of cardiac sarcoidosis (CS).<br /><b>Methods and results</b><br />Imaging from thirty-one patients was acquired on a PET/CT scanner equipped with a respiratory- and ECG-gating system. Non-gated PET images and three kinds of gated PET/CT images were created from identical list-mode clinical PET data: respiratory-gated PET during expiration (EX), ECG-gated PET at end diastole (ED), and ECG-gated PET at end systole (ES). The maximum standardized uptake value (SUVmax) and cardiac metabolic volume (CMV) were measured, and the locations of FDG accumulation were analyzed using a polar map. The mean SUVmax of the subjects was significantly higher after application of either respiratory-gated or ECG-gated reconstruction. Conversely, the mean CMV was significantly lower following the application of respiratory-gated or ECG-gated reconstruction. The segment showing maximum accumulation was shifted to the adjacent segment in 25.8%, 38.7%, and 41.9% of cases in EX, ED, and ES images, respectively.<br /><b>Conclusion</b><br />In FDG PET/CT scanning for the diagnosis of CS, gated scanning is likely to increase quantitative accuracy, but the effect depends on the location and synchronization method.<br /><br />© 2023. The Author(s) under exclusive licence to American Society of Nuclear Cardiology.<br /><br /><small>J Nucl Cardiol: 14 Mar 2023; epub ahead of print</small></div>

<div><h4>Diagnostic accuracy for CZT gamma camera compared to conventional gamma camera technique with myocardial perfusion single-photon emission computed tomography: Assessment of myocardial infarction and function.</h4><i>Hedeer F, Akil S, Oddstig J, Hindorf C, ... Carlsson M, Engblom H</i><br /><b>Background</b><br />The solid-state cadmium-zinc-telluride (CZT) gamma camera for myocardial perfusion single-photon emission computed tomography (MPS) has theoretical advantages compared to the conventional gamma camera technique. This includes more sensitive detectors and better energy resolution. We aimed to explore the diagnostic performance of gated MPS with a CZT gamma camera compared to a conventional gamma camera for detection of myocardial infarct (MI) and assessment of left ventricular (LV) volumes and ejection fraction (LVEF), using cardiac magnetic resonance (CMR) as the reference method.<br /><b>Methods</b><br />Seventy-three patients (26% female) with known or suspected chronic coronary syndrome were examined with gated MPS using both a CZT gamma camera and a conventional gamma camera as well as with CMR. Presence and extent of MI on MPS and late gadolinium enhancement (LGE) CMR was evaluated. For LV volumes, LVEF and LV mass, gated MPS images and cine CMR images were evaluated.<br /><b>Results</b><br />MI was found in 42 patients on CMR. The overall sensitivity, specificity, positive and negative predictive values for the CZT and the conventional gamma camera were the same (67%, 100%, 100% and 69%). For infarct size > 3% on CMR, the sensitivity was 82% for the CZT and 73% for the conventional gamma camera, respectively. LV volumes were significantly underestimated by MPS compared to CMR (P ≤ .002 for all measures). The underestimation was slightly less pronounced for the CZT compared to the conventional gamma camera (2-10 mL, P ≤ .03 for all measures). For LVEF, however, accuracy was high for both gamma cameras.<br /><b>Conclusion</b><br />Differences between a CZT and a conventional gamma camera for detection of MI and assessment of LV volumes and LVEF are small and do not appear to be clinically significant.<br /><br />© 2023. The Author(s).<br /><br /><small>J Nucl Cardiol: 13 Mar 2023; epub ahead of print</small></div>