Stress Single-photon Emission Computed Tomography Research Articles

Disparities in Noninvasive Traditional and Advanced Testing for Coronary Artery Disease: Findings from the INCAPS-COVID 2 Study

The COVID-19 pandemic disrupted the delivery of cardiovascular care, including noninvasive testing protocols and test selection for the evaluation of coronary artery disease (CAD). Trends in test selection in traditional versus advanced noninvasive tests for CAD during the pandemic and in countries of varying income status have not been well studied. The International Atomic Energy Agency conducted a global survey to assess the pandemic-related changes in the practice of cardiovascular diagnostic testing. Site procedural volumes for noninvasive tests to evaluate CAD from March 2019 (prepandemic), April 2020 (onset), and April 2021 (initial recovery) were collected. We considered traditional testing modalities, such as exercise electrocardiography, stress echocardiography, and stress single-photon emission computed tomography, and advanced testing modalities, such as stress cardiac magnetic resonance, coronary computed tomography angiography, and stress positron emission tomography. Survey data were obtained from 669 centers in 107 countries, reporting the performance of 367,933 studies for CAD during the study period. Compared with 2019, traditional tests were performed 14% less frequently (recovery rate 82%) in 2021 versus advanced tests, which were performed 15% more frequently (128% recovery rate). Coronary computed tomography angiography, stress cardiac magnetic resonance, and stress positron emission tomography showed 14%, 25%, and 25% increases in volumes from 2019 to 2021, respectively. The increase in advanced testing was isolated to high- and upper middle-income countries, with 132% recovery in advanced tests by 2021 compared with 55% in lower income nations. The COVID-19 pandemic exacerbated economic disparities in CAD testing practice between wealthy and poorer countries. Greater recovery rates and even new growth were observed for advanced imaging modalities; however, this growth was restricted to wealthy countries. Efforts to reduce practice variations in CAD testing because of economic status are warranted.

Enhancing the diagnostic performance of CZT SPECT myocardial perfusion imaging with myocardial blood flow information

Abstract Background The use of cadmium-zinc-telluride (CZT) single photon emission computed tomography (SPECT) for measuring myocardial blood flow (MBF) has been established as a valuable tool for improving diagnostic accuracy. However, the clinical significance of incorporating MBF into the interpretation of stress SPECT myocardial perfusion imaging (MPI) remains largely unknown. Purpose The objective of this study is to determine the effect of MBF information on the interpretation of CZT SPECT MPI. Methods A cohort of 411 patients underwent a rest/stress gated perfusion and MBF imaging procedure using full-dose 99mTc-tetrofosmin. MBF and flow reserve were calculated using the Corridor4DM v2018 software (INVIA, Ann Arbor, MI). The SPECT data were analyzed twice, once without and once with MBF results. The criteria for abnormal myocardial flow reserve were set at 2.0, while stress flow was set at 1.8 ml/min/g. The interpretations were categorized into normal, equivocal, or abnormal and interpretive certainty was classified into five groups: definitely normal/abnormal, probably normal/abnormal, or equivocal. The overall results were evaluated, along with differences between men and women. Statistical significance was determined using contingency table analysis and chi-squared testing. Results The study cohort had a mean age of 62.5 ± 9.8 years, with 71% of the participants being male. The addition of MBF altered the MPI interpretation in 10.7% of patients (44/411), with a change from abnormal or equivocal to normal in 45.5% (20/44) of cases. The frequency of equivocal MPI interpretations dropped significantly from 4.6% without MBF to 1.5% with MBF (P=0.008). Interpretive certainty improved with a significant decrease in equivocal scans (P=0.006). 89.1% of MPI with MBF were reported as definitely normal or abnormal, compared to 83.0% without MBF (P=0.012) (Figure 1). Further analysis by gender showed similar results for men, while no significant changes were observed in women's MPI interpretation and certainty (Figure 2). Conclusion The inclusion of MBF had a significant impact on the interpretation of CZT SPECT MPI scans, with changes observed in 10.7% of cases. Interpretative certainty improved with fewer equivocal scans and a higher proportion of definitely normal or definitely abnormal interpretations. These findings were evident in men, but not in women (possible due to smaller sample size).Figure 1Figure 2

Radiation dose to patients and public exposure in cardiac rest and stress single photon emission computed tomography examinations

Cardiovascular nuclear medicine (NM) imaging examinations expose patients to extremely high absorbed doses of ionizing radiation, which necessitates extensive efforts to reduce the doses without compromising the quality of images. This study aims to assess patients' radiation doses to patients and public exposure in Cardiac rest and stress single photon emission computed tomography (SPECT) scans. The patients' exposure was calculated for 21 patients using the administered activity (AA, MBq). (GE SPECT) was the device used for all patients. AA (MBq) mean and range were 370 for Rest and 1110 for Stress. The average range of the dose rate was 1.59 (0.67–2.34) mR/h for rest and 7.29 (4.2–9.98) mR/h for stress when computed at 30 cm from the patient's chest level after injection. At 100 cm from the patient, the mean dose rate values were 0.37 (0.16–0.73) mR/h for rest and 1.39 (1.01–2.0) mR/h for stress. The overall effective dose is 12.1 mSv per rest and stress SPECT procedure. The mean effective dose for cardiac rest is comparable with previously published studies while the effective dose from cardiac stress is higher than previously published studies. The variation in the effective dose depends on several factors, including the department's clinical indication imaging protocols and radiation safety measures.

Stress Perfusion Cardiac Magnetic Resonance vs SPECT Imaging for Detection of Coronary Artery Disease

BackgroundGadaCAD2 was 1 of 2 international, multicenter, prospective, Phase 3 clinical trials that led to U.S. Food and Drug Administration approval of gadobutrol to assess myocardial perfusion and late gadolinium enhancement (LGE) in adults with known or suspected coronary artery disease (CAD). ObjectivesA prespecified secondary objective was to determine if stress perfusion cardiovascular magnetic resonance (CMR) was noninferior to single-photon emission computed tomography (SPECT) for detecting significant CAD and for excluding significant CAD. MethodsParticipants with known or suspected CAD underwent a research rest and stress perfusion CMR that was compared with a gated SPECT performed using standard clinical protocols. For CMR, adenosine or regadenoson served as vasodilators. The total dose of gadobutrol was 0.1 mmol/kg body weight. The standard of reference was a 70% stenosis defined by quantitative coronary angiography (QCA). A negative coronary computed tomography angiography could exclude CAD. Analysis was per patient. CMR, SPECT, and QCA were evaluated by independent central core lab readers blinded to clinical information. ResultsParticipants were predominantly male (61.4% male; mean age 58.9 ± 10.2 years) and were recruited from the United States (75.0%), Australia (14.7%), Singapore (5.7%), and Canada (4.6%). The prevalence of significant CAD was 24.5% (n = 72 of 294). Stress perfusion CMR was statistically superior to gated SPECT for specificity (P = 0.002), area under the receiver operating characteristic curve (P < 0.001), accuracy (P = 0.003), positive predictive value (P < 0.001), and negative predictive value (P = 0.041). The sensitivity of CMR for a 70% QCA stenosis was noninferior and nonsuperior to gated SPECT. ConclusionsVasodilator stress perfusion CMR, as performed with gadobutrol 0.1 mmol/kg body weight, had superior diagnostic accuracy for diagnosis and exclusion of significant CAD vs gated SPECT.

Automatic reorientation by deep learning to generate short-axis SPECT myocardial perfusion images

BackgroundSingle photon emission computed tomography (SPECT) myocardial perfusion images (MPI) can be displayed both in traditional short-axis (SA) cardiac planes and polar maps for interpretation and quantification. It is essential to reorient the reconstructed transaxial SPECT MPI into standard SA slices. This study is aimed to develop a deep-learning-based approach for automatic reorientation of MPI. MethodsA total of 254 patients were enrolled, including 226 stress SPECT MPIs and 247 rest SPECT MPIs. Fivefold cross-validation with 180 stress and 201 rest MPIs was used for training and internal validation; the remaining images were used for testing. The rigid transformation parameters (translation and rotation) from manual reorientation were annotated by an experienced nuclear cardiologist and used as the reference standard. A convolutional neural network (CNN) was designed to predict the transformation parameters. Then, the derived transform was applied to the grid generator and sampler in spatial transformer network (STN) to generate the reoriented image. A loss function containing mean absolute errors for translation and mean square errors for rotation was employed. A three-stage optimization strategy was adopted for model optimization: (1) optimize the translation parameters while fixing the rotation parameters; (2) optimize rotation parameters while fixing the translation parameters; (3) optimize both translation and rotation parameters together. ResultsIn the test set, the Spearman determination coefficients of the translation distances and rotation angles between the model prediction and the reference standard were 0.993 in X axis, 0.992 in Y axis, 0.994 in Z axis, 0.987 along X axis, 0.990 along Y axis and 0.996 along Z axis, respectively. For the 46 stress MPIs in the test set, the Spearman determination coefficients were 0.858 in percentage of profusion defect (PPD) and 0.858 in summed stress score (SSS); for the 46 rest MPIs in the test set, the Spearman determination coefficients were 0.9 in PPD and 0.9 in summed rest score (SRS). ConclusionsOur deep learning-based LV reorientation method is able to accurately generate the SA images. Technical validations and subsequent evaluations of measured clinical parameters show that it has great promise for clinical use.

Standardized Radiomics Analysis of Clinical Myocardial Perfusion Stress SPECT Images to Identify Coronary Artery Calcification.

Myocardial perfusion (MP) stress single-photon emission computed tomography (SPECT) is an established diagnostic test for patients suspected of coronary artery disease (CAD). Meanwhile, coronary artery calcification (CAC) scoring obtained from diagnostic CT is a highly sensitive test, offering incremental diagnostic information in identifying patients with significant CAD yet normal MP stress SPECT (MPSS) scans. However, after decades of wide utilization of MPSS, CAC is not commonly reimbursed (e.g. by the CMS), nor widely deployed in community settings. We studied the potential of complementary information deduced from the radiomics analysis of normal MPSS scans in predicting the CAC score. We collected data from 428 patients with normal (non-ischemic) MPSS (99mTc-sestamibi; consensus reading). A nuclear medicine physician verified iteratively reconstructed images (attenuation-corrected) to be free from fixed perfusion defects and artifactual attenuation. Three-dimensional images were automatically segmented into four regions of interest (ROIs), including myocardium and three vascular segments (left anterior descending [LAD]-left circumference [LCX]-right coronary artery [RCA]). We used our software package, standardized environment for radiomics analysis (SERA), to extract 487 radiomic features in compliance with the image biomarker standardization initiative (IBSI). Isotropic cubic voxels were discretized using fixed bin-number discretization (eight schemes). We first performed blind-to-outcome feature selection focusing on a priori usefulness, dynamic range, and redundancy of features. Subsequently, we performed univariate and multivariate machine learning analyses to predict CAC scores from i) selected radiomic features, ii) 10 clinical features, and iii) combined radiomics + clinical features. Univariate analysis invoked Spearman correlation with Benjamini-Hotchberg false-discovery correction. The multivariate analysis incorporated stepwise linear regression, where we randomly selected a 15% test set and divided the other 85% of data into 70% training and 30% validation sets. Training started from a constant (intercept) model, iteratively adding/removing features (stepwise regression), invoking the Akaike information criterion (AIC) to discourage overfitting. Validation was run similarly, except that the training output model was used as the initial model. We randomized training/validation sets 20 times, selecting the best model using log-likelihood for evaluation in the test set. Assessment in the test set was performed thoroughly by running the entire operation 50 times, subsequently employing Fisher's method to verify the significance of independent tests. Unsupervised feature selection significantly reduced 8×487 features to 56. In univariate analysis, no feature survived the false-discovery rate (FDR) to directly correlate with CAC scores. Applying Fisher's method to the multivariate regression results demonstrated combining radiomics with the clinical features to enhance the significance of the prediction model across all cardiac segments. Conclusions: Our standardized and statistically robust multivariate analysis demonstrated significant prediction of the CAC score for all cardiac segments when combining MPSS radiomic features with clinical features, suggesting radiomics analysis can add diagnostic or prognostic value to standard MPSS for wide clinical usage.

Predictive value of a positive stress single-photon emission computed tomography or stress cardiac magnetic resonance for ruling in obstructive coronary artery disease in a real-world setting

Introduction and objectivesRandomized controlled trials comparing stress cardiac magnetic resonance (CMR) and single-photon emission computed tomography (SPECT) suggest similar diagnostic accuracy for detecting obstructive coronary artery disease (CAD). There are few data on whether this remains true in routine clinical practice.The aim of this study was to assess clinical and angiographic characteristics of patients undergoing invasive coronary angiography (ICA) after stress CMR or SPECT, and to compare their positive predictive value with published results from the CE-MARC trial. MethodsIn this retrospective tertiary-center analysis, we included 429 patients undergoing ICA after a positive stress CMR or positive SPECT performed within the previous 12 months. Obstructive CAD was defined as any coronary artery stenosis ≥50% in a vessel compatible with the ischemic territory on stress testing. ResultsOf the total 429 patients, 356 (83%) were referred after a positive SPECT, and 73 (17%) after a positive stress CMR. Patients did not differ according to age, cardiovascular risk factors, previous revascularization or left ventricular dysfunction, but patients with SPECT were more frequently male (p=0.046). The prevalence of obstructive CAD was similar in patients with positive SPECT vs. positive stress CMR (76.1% vs. 80.8%, respectively, p=0.385). The positive predictive values of both techniques were similar to those reported in the CE-MARC trial. ConclusionIn this tertiary center analysis, stress CMR and SPECT showed similar positive predictive values, comparable to those reported in the CE-MARC trial. This finding supports the emerging adoption of CMR in clinical practice for the diagnosis and management of CAD.

Characteristics and key differences between patient populations receiving imaging modalities for coronary artery disease diagnosis in the US

BackgroundThere are limited data on the impact of imaging modality selection for the assessment of coronary artery disease (CAD) risk on downstream resource utilisation. This study sought to identify differences between patient populations in the US undergoing stress echocardiography, single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), positron emission tomography (PET) MPI, and coronary computed tomography angiography (cCTA) for the assessment of CAD risk, and associated physician referral patterns.MethodsClaims and electronic health records data for 2.5 million US patients who received stress echocardiography, cCTA, SPECT MPI or PET MPI between January 2016 and March 2018, from the Decision Resources Group Real-World Evidence US Data Repository, were analysed. Patients were stratified into suspected and existing CAD cohorts, and further stratified by pre-test risk and presence and recency of interventions or acute cardiac events (within 1–2 years pre-index test). Linear and logistic regression were used to compare numeric and categorical variables.ResultsPhysicians were more likely to refer patients to standalone SPECT MPI (77%) and stress echocardiography (18%) than PET MPI (3%) and cCTA (2%). Overall, 43% of physicians referred more than 90% of their patients to standalone SPECT MPI. Just 3%, 1% and 1% of physicians referred more than 90% of their patients to stress echocardiography, PET MPI or cCTA. At the aggregated imaging level, patients who underwent stress echocardiography or cCTA had similar comorbidity profiles. Comorbidity profiles were also similar for patients who underwent SPECT MPI and PET MPI.ConclusionMost patients underwent SPECT MPI at the index date, with very few undergoing PET MPI or cCTA. Patients who underwent cCTA at the index date were more likely to undergo additional imaging tests compared with those who underwent other imaging modalities. Further evidence is needed to understand factors influencing imaging test selection across patient populations.

Endovascular aortic repair impact on myocardial contractility: A prospective study.

This study aimed to estimate if the altered sphygmic wave transmission may affect the left ventricular (LV) contractile function in patients undergoing endovascular aortic repair (EVAR). A prospective single-centre study was carried out on consecutive patients undergoing EVAR for abdominal aortic aneurysm. A preoperative and 6-month single photon emission computed tomography (SPECT) with arterial stiffness measurement were performed to evaluate variations in pressure wave curve and myocardial perfusion parameters. From 2018 to 2020 a total of 16 patients were included in the study. Among the parameters evaluated, we found a measurable reduction of the reflected wave transit time from pre- to postoperative period, for both stress (115.13 ± 7.2 ms-111.1 ± 7.0 ms, p = .08) and rest SPECT acquisitions (115.3 ± 6.2 ms-112.2 ± 5.6 ms, p = .1). Unidirectional increase of both LV end-systolic volume (34 ± 9 mL-39 ± 8 mL, p = .02) and end-diastolic volume (85 ± 34 mL-89 ± 29 mL, p = .6) was also observed. Lastly, the ratio between the end-systolic pressure and the end-systolic volume (maximal systolic myocardial stiffness) decreased from 3.6 ± 1.5 mmHg/mL to 2.66 ± .74 mmHg/mL (p = .03). Our data showed that EVAR induced an altered transmission of the sphygmic wave associated with an early LV contractile impairment.

Abstract TMP66: Correlation Of Cerebrovascular Reserve Assessed By Acetazolamide-stress Spect With Collaterals On Arterial Spin-labeling MRI In Patients With Carotid Occlusive Disease

Introduction: We investigated the relationship between the level of cerebral collateral circulation on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) and cerebrovascular reserve (CVR) on acetazolamide (ACZ)-stress single photon emission computed tomography (SPECT) brain scans in internal carotid artery (ICA) stenosis. Methods: This study enrolled 129 patients with severe ICA stenosis (&gt;70%). Collateral circulation was assessed in pulsed ASL images based on the presence of arterial transit artifact (ATA) that late-arriving flow appears as serpiginous high ASL signal within cortical vessels. CVR based on rest-SPECT and ACZ-stress SPECT with Tc-99m-ECD was calculated. The ASL CBF maps were independently assessed by two neuroradiologists blinded to clinical information. The two neuroradiologists graded on two slices of ASL images corresponding to Alberta Stroke Program Early Computed Tomography Score (ASPECTS) location using a 4-point scale for ASL intensity. Results: With ACZ-stress SPECT, the 88/129 (68%) patients showed normal CVR and 41/129 (32%) patients showed decreased CVR. In 73/88 (82%) of the normal CVR group patients, ASL showed ATA in ipsilateral to the stenosis. In 19/41 (46%) of the decreased CVR group patients, ASL showed no evidence of ATA in ipsilateral to the stenosis. Significant positive relationship was observed between the normal CVR group and the ATA showing group in ICA stenosis patients (p = 0.001, chi-square test). The ASL-based ASPECTS scores of brain in the ipsilateral side was lower than the scores in the contralateral side to the ICA stenosis (p &lt; 0.0001, Wilcoxon signed rank test). The ASL-based ASPECTS scores of brain ipsilateral side to the ICA stenosis was lower in the reduced CVR group than normal CVR group (p = 0.005). Conclusion: This study demonstrated the statistically significant positive correlation between good collaterals on ASL MRI and intact CVR in patients with ICA stenosis.

Differences in Prognostic Value of Myocardial Perfusion Single-Photon Emission Computed Tomography Using High-Efficiency Solid-State Detector Between Men and Women in a Large International Multicenter Study.

Semiquantitative assessment of stress myocardial perfusion defect has been shown to have greater prognostic value for prediction of major adverse cardiac events (MACE) in women compared with men in single-center studies with conventional single-photon emission computed tomography (SPECT) cameras. We evaluated sex-specific difference in the prognostic value of automated quantification of ischemic total perfusion defect (ITPD) and the interaction between sex and ITPD using high-efficiency SPECT cameras with solid-state detectors in an international multicenter imaging registry (REFINE SPECT [Registry of Fast Myocardial Perfusion Imaging With Next-Generation SPECT]). Rest and exercise or pharmacological stress SPECT myocardial perfusion imaging were performed in 17 833 patients from 5 centers. MACE was defined as the first occurrence of death or myocardial infarction. Total perfusion defect (TPD) at rest, stress, and ejection fraction were quantified automatically by software. ITPD was given by stressTPD-restTPD. Cox proportional hazards model was used to evaluate the association between ITPD versus MACE-free survival and expressed as a hazard ratio. In 10614 men and 7219 women, with a median follow-up of 4.75 years (interquartile range, 3.7-6.1), there were 1709 MACE. In a multivariable Cox model, after adjusting for revascularization and other confounding variables, ITPD was associated with MACE (hazard ratio, 1.08 [95% CI, 1.05-1.1]; P<0.001). There was an interaction between ITPD and sex (P<0.001); predicted survival for ITPD<5% was worse among men compared to women, whereas survival among women was worse than men for ITPD≥5%, P<0.001. In the international, multicenter REFINE SPECT registry, moderate and severe ischemia as quantified by ITPD from high-efficiency SPECT is associated with a worse prognosis in women compared with men.

Abstract 9727: Predictive Value of Machine Learning on Adenosine Stress Single Photon Emission Computed Tomography for Multivessel Coronary Artery Stenosis

Introduction: Adenosine stress single photon emission computed tomography (SPECT) is utilized to detect coronary artery stenosis, but the diagnostic performance is recognized not to be enough in patients with multivessel disease (MVD). Estimation of left ventricular (LV) dysfunction on electrocardiography gated SPECT including LV dissynchrony was reported to be valuable to predict MVD, but prognostic value of machine learning of those data was not studied. Hypothesis: Machine learning of gated SPECT data has high diagnostic performance for MVD. Methods: We enrolled consecutive 256 patients (78±11 years, 188 male) who underwent adenosine stress gated SPECT (99mTechnesium) and coronary angiography in one month. LV function and myocardial perfusion score were evaluated by Heart Risk View (Nihon Medi-Physics Co.,Ltd.). First, multivariate logistic regression analysis underwent with minimum Akaike’s information critetion by stepwise regression. Propensity score (PS) was calculated with the selected predictors, and receiver operation characteristics (ROC) curve analysis was performed to evaluate the predictive value. Next, we constructed prediction model for MVD by machine learning (random forest method and deep learning). Results: Thirty-five cases (14%) showed MVD. Stepwise regression with AIC showed 7 predictors as the Figure. Their accuracy and area under ROC were in 0.527-0.809, 0.599-0.689, respectively. PS of the 7 predictors showed the accuracy 0.691 and AUROC 0.758. Random forest method and deep learning built prediction models, and their accuracy and AUROC were 0.840 and 0.788, 0.846 and 0.760, respectively. The top two feature importance of random forest were SD od TES on stress and Phase SD on stress, which indicate the degree of LV dyssynchrony. Conclusions: Machine learning of adenosine stress gated STECT had powerful predictive value for MVD, and the degree of LV dyssynchrony on stress played essential role in the prediction.

Patients undergoing invasive coronary angiography after a positive single-photon emission computed tomography or a positive stress cardiac magnetic resonance - What to expect at the cath lab

Abstract Funding Acknowledgements Type of funding sources: None. Background Randomized controlled trials comparing stress cardiac magnetic resonance (CMR) and single-photon emission computed tomography (SPECT) suggest similar diagnostic accuracy for detecting obstructive coronary artery disease (CAD). However, there are few data on whether or not this remains true in routine clinical practice. The aim of this study was to assess the clinical and angiographic characteristics of patients undergoing invasive coronary angiography (ICA) after a positive stress CMR or positive SPECT, and to compare their positive predictive value with published results from the CE-MARC trial. Methods In this retrospective tertiary-center analysis, we included 429 patients (mean age 67 ± 10 years, 28% women, 42% diabetic) undergoing ICA between January 2016 and December 2020, after a positive stress CMR or positive SPECT. Regarding stress test, an adenosine protocol was performed in all stress CMR and in 76.4% (n = 272) of stress SPECT. Stress test results, including ischemia location and severity, were classified as reported by their primary readers. Patients with missing data on key variables, and those in whom microvascular disease was considered likely in the original stress test report were excluded. Obstructive CAD was defined as any coronary artery stenosis ≥ 50% in a vessel compatible with the ischemic territory on stress testing. Results Out of the total 429 patients, 356 (83%) were referred after a positive SPECT, and 73 (17%) after a positive stress CMR. Patients did not differ regarding age, cardiovascular risk factors, previous revascularization or left ventricular dysfunction, but patients with SPECT were more frequently male (p = 0.046). Overall, 320 patients (75%) had obstructive CAD on ICA. The prevalence of obstructive CAD was similar in patients with positive SPECT vs. positive stress CMR (76.1% vs. 80.8%, respectively, p = 0.385). There were also no significant differences in the prevalence of left main or 3-vessel disease (9.0% vs. 9.6%, p = 0.871, and 19.7% vs. 23.3% p = 0.483, respectively). Revascularization was performed or planned in 59.3% of patients in the SPECT group, and 52.1% of those in the stress CMR group (p = 0.255). The positive predictive values of both techniques were similar to those reported in the CE-MARC trial (Figure), and would increase to 88.1% and 89.4% for SPECT and stress CMR, respectively, if patients reported as having only mild ischemia were excluded. Conclusion In this tertiary center analysis, stress CMR and SPECT showed similar positive predictive values, comparable to those reported in the CE-MARC trial.

CORRELATION BETWEEN MYOCARDIAL PERFUSION IMAGING AND CAROTID ULTRA-SONOGRAPHY IN PATIENTS WITH CHEST PAIN

Background: Atherosclerosis is a major risk factor for coronary artery disease (CAD). Carotid ultrasound (U/S) may be a useful method for prediction of CAD through measurement of intimio-media thickness (IMT) of right and left common carotic arteries. Objective: To emphasize the correlation between myocardial perfusion imaging using single photon emission computed tomography (SPECT) and carotid ultrasound through measuring IMT in early prediction and diagnosis of CAD. Patients and methods: The study included 80 patients complaining from chest pain. Single photon emission computed tomography (SPECT) and carotid U/S were done to each of them. All Patients were recruited from El-Hussein university hospital outpatient clinic and Kobry El-Koba military hospital outpatient clinic between February 2020 and November 2020. Results: The study included 80 patients, 57 of them were males while 23 of them were females. 52 patients were hypertension (HTN), 31 patients were diabetes mellitus (DM), 33 patients were smokers, 15 patients of them had positive family history. 52 patients had positive SPECT stress test revealing CAD “ischemic group”, while 28 of them had negative SPECT stress test “Non-ischemic group”. For the ischemic group, 43 patients (82.7%) had increased intimio-media thickness IMT. Right IMT mean ± SD “0.69±0.10”, t-test “7.771”, weighted Kappa test 0.655 substantial agreement and P-value “p <0.001”. Lefy IMT mean ± SD “0.77±0.12”, t-test “5.122” , weighted Kappa test 0.614 substantial agreement and p-value “p <0.001”. Only 9 patients (17.3%) from the ischemic group had below 75th percentile IMT. For Non-ischemic group, only 9 patients (32.1%) had abnormal IMT while the other 19 patients (67.9%) had normal IMT. Conclusion: Carotid ultrasound and intimio-media thickness are good predictors and highly correlated to coronary artery disease.

Prevalence of abnormal SPECT myocardial perfusion imaging during the COVID-19 pandemic.

PurposeThe aim of this study is to evaluate the rate of abnormal myocardial perfusion imaging (MPI) studies at a single medical center during the COVID-19 pandemic compared to prior to the pandemic.MethodsWe retrospectively studied stress single-photon emission computed tomography (SPECT)-MPI studies performed during the peak of COVID-19 restrictions at the University of Alabama Medical Center in comparison to the same time period in 2019.ResultsSPECT-MPI volume was reduced from 553 per month in 2019 to 105 per month in 2020. The proportion of abnormal SPECT-MPI for the 2020 cohort (61 ± 13 years, 48% men, 41% black) was not different from the 2019 cohort (62 ± 12 years, 48% men, 42% black) (31% vs. 27%, p = 0.4). Similar proportion of patients in the 2 cohorts had abnormal myocardial perfusion, moderate-large perfusion defects, myocardial ischemia, myocardial scar, and abnormal left ventricular ejection fraction. The proportion of abnormal SPECT-MPIs was not different based on whether patients were evaluated face-to-face or by telemedicine (28% vs. 27%, p > 0.9) but was higher for cardiology providers (40% vs. 20%, p < 0.001).ConclusionsThere was a significant reduction in the number of SPECT-MPI studies performed during the peak restrictions from the pandemic. Despite this restriction, the rate of abnormal studies remained stable. Our study suggests that it remains difficult to predict which patients will have abnormal SPECT-MPI even when providers and stress laboratories are forced to prioritize the performance of studies to high-yield patients.

Prevalence of myocardial viability and ischemic burden in chronic total occluded coronary artery disease

Abstract Aims We assessed the viable myocardium status and investigated the relationship between collaterals with the ischemia burden and myocardial viability utilizing cardiac magnetic resonance imaging (CMR) and adenosine stress single-photon emission computed tomography (SPECT). Methods and results 150 consecutive patients with at least one native CTO artery, as confirmed by coronary arteriography or coronary CT angiography, were prospectively recruited. SPECT examination was accepted by only 50 patients while declined by the other 100 patients for reasons such as financial problems. Of all segments in the 173 CTO artery territories, only 10.4% exhibited transmural myocardial infarction and 60.2% showed no late gadolinium enhancement. Among 50 patients who completed SPECT examination, 36 patients showed inducible perfusion defect in CTO territory, and the proportion of the ischemic area of 42% patients was over 10%. Conclusion Most patients with CTO had different degrees of myocardial infarction detected by CMR, but only a minority of them showed transmural infarction and cardiac function in patients with transmural infarction declined compared to those without transmural infarction. Approximately half of CTO patients exhibited inducible ischemia in CTO territory. Based on this, a large proportion of patients potentially benefit from CTO-PCI. Figure 1. Relationship between WMSI, LVE Funding Acknowledgement Type of funding source: Other. Main funding source(s): Beijing Municipal Education Commission Science and Technology Plan for 2020, Capital Health Development Research Project (no. 2018-2-2063)

Effects of the COVID-19 pandemic on myocardial perfusion imaging for ischemic heart disease

PurposeWe assessed the effects of the COVID-19 pandemic on myocardial perfusion imaging (MPI) for ischemic heart disease during the lockdown imposed by the Italian Government.MethodsWe retrospectively reviewed the number and the findings of stress single-photon emission computed tomography (SPECT)-MPI performed between February and May 2020 during the COVID-19 pandemic at the University of Napoli Federico II. The number and the findings of stress SPECT-MPI studies acquired in the corresponding months of the years 2017, 2018, and 2019 were also evaluated for direct comparison.ResultsThe number of stress SPECT-MPI studies performed during the COVID-19 pandemic (n = 123) was significantly lower (P < 0.0001) compared with the mean yearly number of procedures performed in the corresponding months of the years 2017, 2018, and 2019 (n = 413). Yet, the percentage of abnormal stress SPECT-MPI studies was similar (P = 0.65) during the pandemic (36%) compared with the mean percentage value of the corresponding period of the years 2017, 2018, and 2019 (34%).ConclusionThe number of stress SPECT-MPI studies was significantly reduced during the COVID-19 pandemic compared with the corresponding months of the previous 3 years. The lack of difference in the prevalence of abnormal SPECT-MPI studies between the two study periods strongly suggests that many patients with potentially abnormal imaging test have been missed during the pandemic.

Cardiac Magnetic Resonance Versus Single-Photon Emission Computed Tomography for Detecting Coronary Artery Disease and Myocardial Ischemia: Comparison with Coronary Angiography.

Background: This study aimed to compare the diagnostic accuracy of stress single-photon emission computed tomography (SPECT) and stress cardiac magnetic resonance (CMR) for the assessment of coronary artery disease (CAD) in the same patients, using coronary angiography as the reference standard. Methods: Thirty patients with known or suspected CAD who were referred for exercise SPECT myocardial perfusion imaging (MPI) for the evaluation of myocardial ischemia underwent stress CMR MPI and computed tomography coronary angiography (CTCA) or selective coronary angiography (SCA). The data from the two stress modalities were compared against the data from angiography. Results: In our study population, 30% of the recruited subjects had significant CAD. The CMR sensitivity for the detection of significant CAD and/or myocardial ischemia was 89% and specificity was 76%. For SPECT, the corresponding sensitivity was 78% and specificity was 52%. The negative predictive value was 92% for CMR and 83% for SPECT. The receiver-operating characteristic (ROC) analysis evaluating the presence of significant CAD, CMR (area under the curve (AUC) 0.78) outperformed SPECT (AUC 0.59) (p < 0.01). The ROC analysis evaluating the presence of myocardial ischemia was also in favor of CMR (AUC 0.82) versus SPECT (AUC 0.67) (p < 0.01). Conclusions: CMR has high diagnostic accuracy for the detection of CAD and stress-induced ischemia and appears to outperform SPECT. CMR may thus be the preferred noninvasive imaging modality to assess patients with known or suspected CAD.

Prognostic value of SPECT myocardial perfusion entropy in high-risk type 2 diabetic patients : The EVADIAB study

Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for the assessment of myocardial ischemia provides valuable prognostic value. However, the risk stratification of patients with type 2 diabetes mellitus (T2D) remains suboptimal. Recent studies have highlighted the role of coronary microvascular disease in the occurrence of coronary symptoms in this population. We hypothesized that enhanced signal analysis from SPECT myocardial perfusion images may allow insights into the status of the coronary microvasculature. More specifically, we hypothesized that myocardial perfusion entropy (MPE) as a surrogate marker of microvascular disease quantified from SPECT myocardial perfusion images may provide an incremental prognostic value in T2D patients independently from the routinely performed assessment of myocardial ischemia. T2D patients with very high cardiovascular risk were studied (n = 166, 65 ± 12 years). Ischemia was assessed by SPECT myocardial perfusion imaging (MPI). In addition, SPECT MPI was used for the quantification of rest and stress MPE using an original algorithm providing a global value of MPE from reconstructed rest and stress SPECT images. The primary end point was major adverse cardiac events (MACEs) defined as cardiac death, Q-wave myocardial infarction (MI) and myocardial revascularization > 3 months after SPECT. Forty-six patients underwent MACEs over a median follow-up of 4.6 years. Significant differences in stress MPE were observed between patients with and without MACEs (4.19 ± 0.46 vs. 3.93 ± 0.39; P ≤ 0.01). By Kaplan-Meier analysis, the risk of MACEs was significantly higher in patients with higher stress MPE (log-rank P ≤ 0.01). Stress MPE was significantly associated with the risk of MACEs (hazard ratio: 2.80, P ≤ 0.01) after adjustment for clinical and imaging risk factors as identified from preliminary, univariate analysis and including age, hypertension and ischemia. The risk of overfitting was controlled by internal validation procedures such as LASSO, stepwise and random forests selections on time-to-MACEs Cox models. A competing risk event (“other deaths”) slightly overestimated Cox estimates. However, the impact of informative censorship was assessed by Fine-Gray subdistribution hazard estimates and proved to be marginal. The incremental prognostic value of MPE over clinical risk factors was quantified using nested models showing improved AIC, reclassification (global continuous Net Reclassification Improvement [NRI]: 70.1, global Integrated Discrimination Improvement [IDI]: 6.6%), discrimination (change in c-statistic: 0.69 vs. 0.74), and time-dependent AUC (0.71 vs. 0.77 at 4 years of follow-up). Stress MPE provided independent and incremental prognostic information for the prediction of MACEs in diabetic patients.

Abstract WMP41: The Value of Arterial Spin-Labeling Imaging in the Cerebral Collateral Circulation Evaluation of Carotid Occlusive Disease; Correlation Study With Acetazolamide-Stress Single Photon Emission Computed Tomography

Introduction: We investigated the relationship between the level of cerebral collateral circulation on arterial spin-labeling (ASL) magnetic resonance imaging (MRI) and cerebrovascular reserve (CVR) on acetazolamide (ACZ)-stress single photon emission computed tomography (SPECT) brain scans in internal carotid artery (ICA) stenosis. Methods: This study enrolled 129 patients with severe ICA stenosis (&gt;70%). Collateral circulation was assessed in pulsed ASL images based on the presence of arterial transit artifact (ATA) that late-arriving flow appears as serpiginous high ASL signal within cortical vessels. CVR based on rest-SPECT and ACZ-stress SPECT with Tc-99m-ECD was calculated. The ASL CBF maps were independently assessed by two neuroradiologists blinded to clinical information. The two neuroradiologists graded on two slices of ASL images corresponding to Alberta Stroke Program Early Computed Tomography Score (ASPECTS) location using a 4-point scale for ASL intensity. Results: With ACZ-stress SPECT, the 88/129 (68%) patients showed normal CVR and 41/129 (32%) patients showed decreased CVR. In 73/88 (82%) of the normal CVR group patients, ASL showed ATA in ipsilateral to the stenosis. In 19/41 (46%) of the decreased CVR group patients, ASL showed no evidence of ATA in ipsilateral to the stenosis. Significant positive relationship was observed between the normal CVR group and the ATA showing group in ICA stenosis patients (p = 0.001, chi-square test). The ASL-based ASPECTS scores of brain in the ipsilateral side was lower than the scores in the contralateral side to the ICA stenosis (p &lt; 0.0001, Wilcoxon signed rank test). The ASL-based ASPECTS scores of brain ipsilateral side to the ICA stenosis was lower in the reduced CVR group than normal CVR group (p = 0.005). Conclusion: This study demonstrated the statistically significant positive correlation between good collaterals on ASL MRI and intact CVR in patients with ICA stenosis.