Summed Stress Score Research Articles

Clinical Utility of SPECT in the Heart Transplant Population: Analysis From a Single Large-volume Center.

Survival after heart transplant has greatly improved, with median survival now over 12 years. Cardiac allograft vasculopathy (CAV) has become a major source of long-term morbidity and mortality. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is used for CAV surveillance, but there is limited data on its prognostic utility. We retrospectively identified patients undergoing SPECT MPI for CAV surveillance at a single, large-volume center. Images were assessed with semiquantitative visual scoring (summed stress score [SSS] and summed rest score) and quantitatively with total perfusion defect (TPD). We studied 503 patients (mean age 62.5, 69.3% male) at a median of 9.0 years post-transplant. During mean follow-up of 5.1 ± 2.5 years, 114 (22.6%) patients died. The diagnostic accuracy for significant CAV (ISHLT grade 2 or 3) was highest for SSS with an area under the curve of 0.650 and stress TPD (area under the curve, 0.648), with no significant difference between SSS and stress TPD (P = 0.061). Stress TPD (adjusted hazard ratio, 1.07; P = 0.018) was independently associated with all-cause mortality, while SSS was not (P = 0.064). The prognostic accuracy of quantitative assessment of perfusion tended to be higher compared with semiquantitative assessment, with the highest accuracy for stress TPD (area under the receiver operating curve 0.584). While SPECT MPI identified a cohort of higher risk patients, with quantitative analysis of perfusion demonstrating higher prognostic accuracy. However, the overall prognostic accuracy was modest and alternative noninvasive modalities may be more suitable for CAV surveillance.

Diagnostic value of clinical risk scores for predicting normal stress myocardial perfusion imaging in subjects without coronary artery calcium

BackgroundWe evaluated if risk scores commonly used to predict the absence of significant stenosis at coronary computed tomography (CT) angiography are useful to predict a normal stress myocardial perfusion imaging (MPI) study. MethodsOur cohort included a total of 1422 consecutive patients with zero coronary artery calcium score (ZCS) who underwent 82Rb PET/CT for evaluation of suspected coronary artery disease (CAD). Predictive models were constructed as reported by Genders et al. and Alshahrani et al., and the probability of abnormal summed stress score (SSS) and of reduced myocardial perfusion reserve (MPR) based on these risk scores was assessed. ResultsIn the overall population, the prevalence of abnormal SSS was 0.10 and the prevalence of reduced MPR was 0.17 (both P < .001).The observed frequencies of abnormal SSS and reduced MPR vs the probabilities predicted by the Genders and Alshahrani models were above the diagonal identity line, highlighting an underestimation of the observed occurrence by these models. The areas under the receiver operating characteristic curve of the Genders and Alshahrani models indicated lack of discriminative ability for predicting abnormal SSS (0.547 and 0.527) and reduced MPR (0.509 and 0.538). The Hosmer–Lemeshow test revealed that both models underestimated the observed occurrence of abnormal SSS and reduced MPR. ConclusionsAvailable models were unable to identify among patients with ZCS those with a low probability of a normal stress MPI study. Thus, an optimal approach to rule out from MPI patients without detectable coronary calcium still needs to be improved.

Static CT myocardial perfusion imaging: image quality, artifacts including distribution and diagnostic performance compared to 82Rb PET

BackgroundRubidium-82 positron emission tomography (82Rb PET) MPI is considered a noninvasive reference standard for the assessment of myocardial perfusion in coronary artery disease (CAD) patients. Our main goal was to compare the diagnostic performance of static rest/ vasodilator stress CT myocardial perfusion imaging (CT-MPI) to stress/ rest 82Rb PET-MPI for the identification of myocardial ischemia.MethodsForty-four patients with suspected or diagnosed CAD underwent both static CT-MPI and 82Rb PET-MPI at rest and during pharmacological stress. The extent and severity of perfusion defects on PET-MPI were assessed to obtain summed stress score, summed rest score, and summed difference score. The extent and severity of perfusion defects on CT-MPI was visually assessed using the same grading scale. CT-MPI was compared with PET-MPI as the gold standard on a per-territory and a per-patient basis.ResultsOn a per-patient basis, there was moderate agreement between CT-MPI and PET-MPI with a weighted 0.49 for detection of stress induced perfusion abnormalities. Using PET-MPI as a reference, static CT-MPI had 89% sensitivity (SS), 58% specificity (SP), 71% accuracy (AC), 88% negative predictive value (NPV), and 59% positive predictive value (PPV) to diagnose stress-rest perfusion deficits on a per-patient basis. On a per-territory analysis, CT-MPI had 73% SS, 65% SP, 67% AC, 90.8% NPV, and 34% PPV to diagnose perfusion deficits.ConclusionsCT-MPI has high sensitivity and good overall accuracy for the diagnosis of functionally significant CAD using 82Rb PET-MPI as the reference standard. CT-MPI may play an important role in assessing the functional significance of CAD especially in combination with CCTA.

Machine Learning for Multi-Vessel Coronary Artery Disease Prediction on Electrocardiogram Gated Single-Photon Emission Computed Tomography.

Background: Single-photon emission computed tomography (SPECT) encounters difficulties in diagnosing severe multi-vessel coronary artery disease (svMVD) because of balanced ischemia. We estimated the predictive value of electrocardiogram-gated SPECT for svMVD and improved it using machine learning (ML). Methods and results: We enrolled consecutive 335 patients (median age, 74 years; 255 men) who underwent adenosine stress-gated SPECT (99mTechnesium) and coronary angiography. svMVD was defined as three-vessel disease or left main tract stenosis. Predictive models were constructed using statistical and ML methods. Eighteen cases (5%) showed svMVD, and diabetes, summed stress score (SSS), and the max difference among segmental time of stroke volume per cardiac cycle (MDSV: a parameter of left ventricular [LV] end-systolic dyssynchrony) on adenosine stress were independent significant predictors. The area under the receiver operating characteristic curve (AUC) of SSS and MDSV on stress were 0.759 and 0.763, respectively. Conversely, the extra trees classifier and light gradient boosting machine had improved AUC values of 0.826 and 0.870, respectively, and the MDSV on stress and diabetes showed high feature values in the ML models. Conclusion: ML on SPECT helped to improve the diagnostic performance of svMVD and diabetes, and the parameters of LV dyssynchrony played essential roles in the ML predictive models.

Semi-quantitative assessment of ischemia with rubidium-82 PET myocardial perfusion imaging

PurposeSemi-quantitative scores can be used as an adjunct to visual assessment in rubidium-82 positron emission tomography (82Rb PET). The semi-quantitative cut-off values used in 82Rb PET are derived from single-photon emission computed tomography (SPECT). It is unknown whether these cut-off values can be extrapolated to 82Rb PET. We compared the semi-quantitative with the visual assessment of ischemia and determined which summed difference score (SDS) score predicts ischemia best. MethodsWe included 108 patients who underwent 82Rb PET imaging and performed visual and semi-quantitative assessment. A scan with a SDS ≥ 2 and a summed stress score (SSS) ≥ 4 was considered to demonstrate ischemia. We compared the semi-quantitative with the visual assessment. Results41 (38%) Normal scans, and 67 (62%) scans with ischemia and/or an irreversible defect were included. The semi-quantitative assessment showed ischemia more often than the visual assessment (51% vs 29%, P < .001). Patients with a low or intermediate pre-test probability of coronary artery disease (CAD) and a SDS < 4 did not demonstrate ischemia by visual assessment. ConclusionSemi-quantitative assessment in 82Rb PET imaging clearly demonstrates the presence of ischemia. Ischemia is unlikely in patients with low and intermediate pre-test probability of CAD and a SDS < 4.

Technical note: Partitioning of gated single photon emission computed tomography raw data for protocols optimization.

PurposeMethodologies for optimization of SPECT image acquisition can be challenging due to imaging throughput, physiological bias, and patient comfort constraints. We evaluated a vendor‐independent method for simulating lower count image acquisitions.MethodsWe developed an algorithm that recombines the ECG‐gated raw data into reduced counting acquisitions. We then tested the algorithm to simulate reduction of counting statistics from phantom SPECT image acquisition, which was synchronized with an ECG simulator. The datasets were reconstructed with a resolution recovery algorithm and the summed stress score (SSS) was assessed by three readers (two experts and one automatic).ResultsThe algorithm generated varying counting levels, simulating multiple examinations at the same time. The error between the expected and the simulated countings ranged from approximately 5% to 10% for the ungated simulations and 0% for the gated simulations.ConclusionsThe vendor‐independent algorithm successfully generated lower counting statistics datasets from single‐gated SPECT raw data. This method can be readily implemented for optimal SPECT research aiming to lower the injected activity and/ or to shorten the acquisition time.

Anxiety and hemodynamic reactivity during cardiac stress testing: The role of gender and age in myocardial ischemia

BackgroundThe prevalence of myocardial ischemia is associated with anxiety. State and trait anxiety are more common in younger women compared to men, and high anxiety levels could affect hemodynamic reactivity during cardiac stress testing. The aim is to examine whether anxiety plays a role in gender differences in patients ≤ 65 and > 65 years in hemodynamic reactivity and ischemia during cardiac stress testing. Methods and resultsIncluded were 291 patients (66.8 ± 8.7 years, 45% women) with suspect ischemia undergoing myocardial perfusion single-photon emission computed tomography (MPI-SPECT). Primary outcomes were semi-quantitative summed difference score (SDS) and summed stress score (SSS), as continuous indicators of myocardial ischemia. Analyses were stratified by age. Trait anxiety was measured using a validated questionnaire (GAD-7) and state anxiety using facial expression analyses software. Overall, trait and state anxiety were not associated with the prevalence of ischemia (N = 107, 36%). A significant interaction was found between gender and trait anxiety in women ≤ 65 years for SDS (F(1,4) = 5.73, P = .019) and SSS (F(1,10) = 6.50, P = .012). This was not found for state anxiety. ConclusionSDS and SSS were significantly higher in women younger than 65 years with high trait anxiety. This interaction was not found in men and women over 65 years.

CZT camera systems may provide better risk stratification for low-risk patients

BackgroundThe photon sensitivity and spatial resolution of single-photon emission-computed tomography (SPECT) has been significantly improved by solid-state camera systems using cadmium zinc telluride (CZT) detectors. While the diagnostic accuracy of these systems is well established, there is little evidence directly comparing the prognostic utility to conventional NaI cameras. Methods and ResultsRetrospective analysis of patients undergoing SPECT between 2008 and 2012. Visual SPECT assessment was performed utilizing the 17-segment model to determine summed stress scores (SSS). We identified 12,830 consecutive patients, mean age 63.2 ± 13.7 and 56.1% male, 5072 of whom underwent CZT and 7758 NaI imaging. During a median follow-up duration of 7.0 years (IQR 5.5-8.2), a total of 2788 (21.7%) patients died. Compared to SSS 0, minimal perfusion abnormality (SSS 1-3) was associated with increased all-cause mortality with CZT camera (adjusted HR 1.32, P = .017) and NaI camera (adjusted HR 1.29, P = .001, interaction P = .803). Increasing stress abnormality was associated with a similar increase in risk with CZT or NaI imaging (interaction P > .500). In a propensity matched analysis, patients with normal perfusion stress perfusion assessed with a CZT was associated with decreased mortality compared to normal perfusion assessed by a NaI camera system (hazard ratio .88, 95% CI .78-.99, P = .040). ConclusionsIncreasing stress perfusion abnormality was associated with similar increase in all-cause mortality with CZT or NaI cameras. CZT and NaI camera systems provide similar risk stratification, however, normal myocardial perfusion may be associated with a more benign prognosis when assessed with a CZT camera system.

Prognostic value of coronary risk factors, exercise capacity and single photon emission computed tomography in liver transplantation candidates: A 5-year follow-up study

BackgroundAlthough consensus-based guidelines support noninvasive stress testing prior to orthotopic liver transplantation (OLT), the optimal screening strategy for assessment of coronary artery disease in patients with end-stage liver disease (ESLD) is unclear. This study sought to determine the relative predictive value of coronary risk factors, functional capacity, and single photon emission computed tomography (SPECT) on major adverse cardiovascular events and all-cause mortality in liver transplantation candidates. MethodsPrior to listing for transplantation, 404 consecutive ESLD patients were referred to a University hospital for cardiovascular (CV) risk stratification. All subjects met at least one of the following criteria: inability to perform > 4 METs by history (62%), insulin-treated diabetes mellitus (53%), serum creatinine > 1.72 mg/dL (8%), history of MI, PCI or CABG (5%), stable angina (3%), cerebrovascular disease (1%), peripheral vascular disease (1%). Subjects underwent Technetium-99m SPECT with multislice coronary artery calcium scoring (CACS) using exercise treadmill or standard adenosine stress in those unable to achieve 85% maximal heart rate (Siemens Symbia T16). Abnormal perfusion was defined as a summed stress score (SSS) ≥ 4. ResultsOf the 404 patients, 158 (age 59 ± 9 years; male 68%) subsequently underwent transplantation and were included in the primary analysis. Of those, 50 (32%) died after a mean duration follow-up of 5.4 years (maximal 10.9 years). Most deaths (78%) were attributed to noncardiovascular causes (malignancy, sepsis, renal failure). Of the 32 subjects with abnormal perfusion (20%), nine (6%) had a high-risk perfusion abnormality defined as a total perfusion defect size (PDS) ≥ 15% and/or an ischemic PDS ≥ 10%. Kaplan–Meier survival curves demonstrated abnormal perfusion was associated with increased CV mortality (generalized Wilcoxon, P = 0.014) but not all-cause death. Subjects with both abnormal perfusion and an inability to exercise > 4 METs had the lowest survival from all-cause death (P = 0.038). Abnormal perfusion was a strong independent predictor of CV death (adjusted HR 4.2; 95% CI 1.4 to 12.3; P = 0.019) and MACE (adjusted HR 7.7; 95% CI 1.4 to 42.4; P = 0.018) in a multivariate Cox regression model that included age, sex, diabetes, smoking and the ability to exercise > 4 METs. There was no association between CACS and the extent of perfusion abnormality, nor with outcomes. ConclusionsMost deaths following OLT are noncardiovascular. Nonetheless, abnormal perfusion is prevalent in this high-risk population and a stronger predictor of cardiovascular morbidity and mortality than functional status. A combined assessment of functional status and myocardial perfusion identifies those at highest risk of all-cause death. (Exercise Capacity and Single Photon Emission Computed Tomography in Liver Transplantation Candidates [ExSPECT]; ClinicalTrials.gov Identifier: NCT03864497).

Post-reconstruction attenuation correction for SPECT myocardium perfusion imaging facilitated by deep learning-based attenuation map generation

BackgroundAttenuation correction can improve the quantitative accuracy of single-photon emission computed tomography (SPECT) images. Existing SPECT-only systems normally can only provide non-attenuation corrected (NC) images which are susceptible to attenuation artifacts. In this work, we developed a post-reconstruction attenuation correction (PRAC) approach facilitated by a deep learning-based attenuation map for myocardial perfusion SPECT imaging. MethodsIn the PRAC method, new projection data were estimated via forwardly projecting the scanner-generated NC image. Then an attenuation map, generated from NC image using a pretrained deep learning (DL) convolutional neural network, was incorporated into an offline reconstruction algorithm to obtain the attenuation-corrected images from the forwardly projected projections. We evaluated the PRAC method using 30 subjects with a DL network trained with 40 subjects, using the vendor-generated AC images and CT-based attenuation maps as the ground truth. ResultsThe PRAC methods using DL-generated and CT-based attenuation maps were both highly consistent with the scanner-generated AC image. The globally normalized mean absolute errors were 1.1% ± .6% and .7% ± .4% and the localized absolute percentage errors were 8.9% ± 13.4% and 7.8% ± 11.4% in the left ventricular (LV) blood pool, respectively, and − 1.3% ± 8.0% and − 3.8% ± 4.5% in the LV myocardium for PRAC methods using DL-generated and CT-based attenuation maps, respectively. The summed stress scores after PRAC using both attenuation maps were more consistent with the ground truth than those of the NC images. ConclusionWe developed a PRAC approach facilitated by deep learning-based attenuation maps for SPECT myocardial perfusion imaging. It may be feasible for this approach to provide AC images for SPECT-only scanner data.

The Comparison of Quantitative Evaluation Results of the MPS SPECT/CT and Coronary Angiography: Determining the Most Valuable Quantitative Evaluation Score

Objectives:This study aimed to determine the most important perfusion score in patient selection for coronary angiography (CA) by quantitatively evaluating myocardial perfusion scintigraphy (MPS).Methods:Patients who underwent MPS single-photon emission computerized tomography/computed tomograph imaging in our clinic between December 2017 and January 2019, without coronary artery disease (CAD) history, followed by CA were included in the study. CA was considered positive when there is a stenosis of 70% or more in at least one coronary vessel. The summed stress score, rest score, and differential score; total perfusion deficit (TPD); and the defect’s extent obtained from non-attenuation-corrected (NC) and attenuation-corrected (AC) images of 80 patients were evaluated using the Mann-Whitney U test. A p value of <0.05 was considered significant. Receiver operating characteristic (ROC) analysis was performed.Results:The scores obtained from NC and AC images showed a significant difference between the two groups for all scores except for the extent and TPD scores at rest from AC images. The applied ROC curves’ highest diagnostic value was determined as the TPD score at stress (TPDS) obtained from NC images (area under the curve: 0.880, 95% confidence interval, 0.807-0.952, p<0.001). The cut-off value obtained for the TPDS from the ROC curve was found to be 5.5.Conclusion:The scores obtained from NC images have more power to detect CAD than those obtained from AC images. Patients with no prior CAD history with TPDS score higher than 5 in MPS should be referred for CA with priority.

PROGNOSTIC VALUE OF PET MPI MYOCARDIAL FLOW RESERVE IN CABG PATIENTS

<h3>BACKGROUND</h3> Positron emission tomography (PET) myocardial perfusion imaging (MPI) is a well-validated non-invasive imaging technique for the assessment of coronary artery disease (CAD). Amongst its many advantage, it permits quantitative, non-invasive assessment of myocardial blood flow (MBF) and myocardial flow reserve (MFR). While the diagnostic and prognostic value of MFR has been extensively validated in the general CAD population, only limited data is available when it comes to its prognostic value in patients with prior coronary artery bypass grafting (CABG). Our study aim was to evaluate if diminished MFR on 13N-Ammonia PET MPI is associated with increased risk of major adverse cardiovascular events (MACE) amongst patients with prior CABG. <h3>METHODS AND RESULTS</h3> A retrospective study was performed at the Montréal University Hospital Centre (CHUM) between February 2018 and September 2020. Patients (n=62) with prior CABG (at least 3 months) who had an 13N-Ammonia PET/CT scan performed were included. The main endpoint was to evaluate if myocardial perfusion values were associated with increased risk of MACE. MACE was defined as death, re-infarction, repeat revascularization or hospitalization for heart failure. In patients with multiple MACE, only the first event was considered for analysis. Our cohort was subdivided in two groups: patients with MACE and patients without MACE. The main indications for performing PET MPI are displayed in the figure. Baseline characteristics (table) were comparable between both groups except for the number of graft (3.0 [2.0,3.0] vs. 3.0 [3.0,4.0], p=0.005). Risk factors were similar between both groups except for presence of chronic kidney disease (CKD) (11 (55%) vs. 10 (23.8%), p=0.02). There was no difference between both groups regarding drug regimen. In patients with MACE as compared to no-MACE, both global MFR (1.8 ± 0.5 vs. 2.1 ± 0.5, p=0.03, respectively) and the global stress MBF (1.2 [0.9,1.4] vs. 1.4 [1.1,1.8] mL/min/g, p=0.049, respectively) were significantly lower. Sum Stress Score was higher in the MACE group (2.5 [1.0,10.0] vs. 0.0 [0.0,3.5], p=0.04). Low left ventricular ejection fraction (LVEF) reserve had no prognostic value in our study (p=0.20). <h3>CONCLUSION</h3> In patients with prior CABG, both reduced global MFR and global stress MBF were associated with increased risk of MACE. Therefore, PET MPI with flow quantification can help identifying patients at risk of MACE after CABG. Our findings need to be confirmed in a larger cohort of patients.

Comparison of Diagnostic Performance of Fractional Flow Reserve Derived from Coronary Computed Tomographic Angiography Versus Single-Photon Emission Computed Tomographic Myocardial Perfusion Imaging

Fraction flow reserve (FFR) derived from computed tomography (FFRCT) has been proposed to be an effective gatekeeper for invasive angiographic referral. The purpose of the present study is to examine the real-world diagnostic performance of FFRCT and myocardial perfusion imaging as well as to assess the utility of FFRCT as a gatekeeper for invasive coronary angiography in patients suspected of having obstructive coronary artery disease. Total of 146 consecutive patients underwent both single-photon emission computed tomography (SPECT) and invasive FFR were evaluated. An FFRCT value 1 to 2 cm distal to a stenosis ≤0.80 was defined as positive for ischemia and a summed stress score ≥2 or transient ischemic dilatation ≥1.2 were positive for ischemia with the invasive FFR value of <0.80 serving as the gold standard. The patient-based sensitivity of FFRCT was significantly higher than SPECT (91 vs 52%, p <0.001) and exhibited similar positive predictive value (82 vs 82%, p=0.91). These trends were observed even in patients with multivessel and left main trunk disease and those with severe coronary calcification. In conclusion, our data suggest that FFRCT has higher diagnostic performance characteristics than SPECT and details the superior FFRCT analysis in detecting patients with hemodynamically significant coronary artery disease. Our results support the clinical utility of FFRCT analysis as a gatekeeper for invasive coronary angiography in clinical practice.

Low coronary flow relative to myocardial mass predicts heart failure in symptomatic hypertensive patients with no obstructive coronary artery disease.

The transition from hypertension to heart failure (HF) remains poorly understood. We hypothesized that insufficient perfusion to match global metabolic demand, reflected by a low ratio of myocardial blood flow to global myocardial mass, may be a HF risk marker. A retrospective cohort (n = 346) of patients with hypertension who underwent clinical positron emission tomography (PET) myocardial perfusion imaging for chest pain and/or dyspnoea at Brigham and Women's Hospital (Boston, MA, USA) were studied. Patients without obstructive coronary artery disease by history or PET perfusion (summed stress score <3), HF, cardiomyopathy, or ejection fraction (EF) <40% were followed for HF hospitalization (primary outcome), all-cause death, and their composite. Myocardial blood flow, left ventricular (LV) mass, volumes, and EF were obtained from PET, and a 'flow/mass ratio' was determined as hyperaemic myocardial blood flow over LV mass indexed to body surface area. A lower flow/mass ratio was independently associated with larger end-diastolic (β = -0.44, P < 0.001) and end-systolic volume (β = -0.48, P < 0.001) and lower EF (β = 0.33, P < 0.001). A flow/mass ratio below the median was associated with an adjusted hazard ratio of 2.47 [95% confidence interval (CI) 1.24-4.93; P = 0.01] for HF hospitalization, 1.95 (95% CI 1.12-3.41; P = 0.02) for death, and 2.20 (95% CI 1.39-3.49; P < 0.001) for the composite. An integrated physiological measure of insufficient myocardial perfusion to match global metabolic demand identifies subclinical hypertensive heart disease and elevated risk of HF and death in symptomatic patients with hypertension but without flow-limiting coronary artery disease.

Assessing the prevalence and predicting factors of an abnormal gated myocardial perfusion SPECT in asymptomatic patients with type 2 diabetes.

Considering the significant prevalence of silent myocardial ischemia and its related morbidity and mortality in asymptomatic type 2 diabetic patients, it is not well known whether early screening with MPI is cost-effective and predicting factors are not well elucidated. This was a cross-sectional study including 63 asymptomatic patients with type 2 diabetes mellitus (T2DM), with normal ECG and ejection fraction. Patients with any history of documented valvular, congestive or ischemic heart disease, renal or hepatic failure were excluded. At first all patients were interviewed and checked for risk factors and then patients underwent a two-day rest/stress 99mTc-MIBI gated MPI SPECT. Data was assessed by QPS/QGS and 4DM software and evaluated by a nuclear medicine specialist with summed stress score (SSS) of more than 4 defined as CAD. There were 42 females (67%) and 21 males (33%), with a mean age of 61.33 ± 6.98years and 7.97 ± 4.86years history of T2DM. CAD was detected in 26 (41.3%) patients and was significantly associated with male gender, smoking and requiring insulin therapy (P-value = 0.019, 0.046, 0.05, respectively). A significant association was found between the duration of diabetes, especially when > 15years, and the probability of having CAD. Multivariable logistic regression revealed that smoking; male gender and diabetes duration were the strongest independent predictors of abnormal MPI results. We found a high (46%) prevalence of abnormal stress MPI SPECT in patients with type 2 diabetes mellitus, despite being asymptomatic. Asymptomatic patients with a history of smoking, long duration of diabetes, being under insulin treatment and male gender might benefit from MPI for early detection of silent ischemia.

A 2-Year Prospective Study on the Differences in Prognostic Factors for Major Adverse Cardiovascular, Cerebrovascular and Renal Events Between Patients with Mild and Severe Chronic Kidney Disease.

Purpose/Method: No studies have reported on prognostic markers in patients with chronic kidney disease (CKD) according to the severity of the disease. Therefore, in this multicenter, prospective trial performed as part of the Gunma CKD SPECT Multicenter Study, we recruited 311 patients with CKD (eGFR < 60 min/mL/1.73 m2) including 50 patients on hemodialysis and followed them for 2 years. The study sample underwent stress 99mTc-tetrofosmin SPECT for suspected or possible ischemic heart disease. We evaluated the summed stress score (SSS), summed rest score (SRS), summed difference score (SDS) and cardiac function with electrocardiogram-gated SPECT. Then, we compared the differences in prognostic markers for major adverse cardiac, cerebrovascular, and renal events (MACCRE) between patients with mild CKD (30 min/mL/1.73 m2 ≤ eGFR <60 min/mL/1.73 m2; n=184) and those with severe CKD (eGFR <30 min/mL/1.73 m2; n=97). Results: Of 281 patients available for analysis, 91 experienced MACCRE. In a multivariate Cox proportional hazards analysis of factors related to MACCRE, in patients with mild CKD the significant prognostic markers were SDS (P=0.002) and end-systolic volume (ESV, P=0.034); and in the patients with severe CKD, they were eGFR (P=0.03) and diabetes-mellitus (DM, P=0.023). Conclusions: Our findings indicate that SDS and ESV are significant prognostic markers for MACCRE in patients with mild CKD and eGFR and DM are significant prognostic markers in patients with severe CKD.

Simulating dose reduction for myocardial perfusion SPECT using a Poisson resampling method.

The purpose of this study was to determine the lowest Tl-201 dose that does not reduce the image quality of myocardial perfusion SPECT (MPS) by Poisson resampling simulation. One hundred and twelve consecutive MPS data from patients with suspected or known coronary artery disease were collected retrospectively. Stress and rest MPS data were resampled using the Poisson method with 33%, 50%, 67%, and 100% count settings. Two nuclear medicine physicians assessed the image quality of reconstructed data visually by giving grades from - 2 to + 2. The summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) were obtained on the workstation. Image quality grades and semi-quantitative scores were then compared among these resampled images. The proportions of "adequate" image quality were 0.48, 0.75, 0.92, and 0.96 for the groups of images with 33%, 50%, 67%, and 100% data, respectively. The quality of the resampled images was significantly degraded at 50% and 33% count settings, while the image quality was not different between 67 and 100% count settings. We also found that high body mass index further decreased image quality at 33% count setting. Among the semi-quantitative parameters, SSS and SRS showed a tendency to increase with a decline in count. Based on the simulation results, Tl-201 dose for MPS can be reduced to 74MBq without significant loss of image quality. However, the SSS and SRS can be changed significantly, and it needs to be further verified under the different conditions.

Effects of gender and defect reversibility on detection of coronary disease with an upright and supine cadmium-zinc-telluride camera

BackgroundLimited data address the roles of gender, perfusion defect reversibility, and imaging position in interpretation of images acquired on an upright/supine cadmium-zinc-telluride (CZT) cardiac imaging system. Methods and ResultsFrom a consecutive cohort of patients imaged on an upright/supine CZT camera, 260 patients with coronary angiograms were studied. Multivariable models identified gender as a significant effect modifier for imaging variables of CAD. For males, a supine summed stress score (SSS) ≥ 3 provided high accuracy (sensitivity 70.7%, specificity 72.2%), and highest contribution to multivariable models. In females, supine SSS ≥ 2 provided the best cut-off for defect size and severity (sensitivity 90%, specificity 35.9%), but specificity was improved substantially to 53.3% with decrease in sensitivity to 80% by also requiring quantitative identification of perfusion defect reversibility in the supine position. Eight variables, accurate for predicting coronary disease, were more accurate with supine than upright imaging. ConclusionsPerfusion defect reversibility improved specificity in female patients for detection of coronary disease compared to perfusion defect size and extent alone. Supine images provided superior accuracy for detection of coronary disease compared to upright images.

Changes in left ventricle myocardial volume during stress test using cadmium-zinc-telluride cardiac imaging: Implications in coronary artery disease

BackgroundCadmium-zinc-telluride (CZT) SPECT allows the estimation of left ventricle myocardial volume (LVMV). We tested the clinical relevance of rest-stress LVMV changes (Δ LVMV) in detecting coronary artery disease (CAD, coronary stenosis > 70%), using CZT-SPECT. MethodsWe prospectively enrolled 512 consecutive patients with known or suspected CAD (mean age: 70.3 ± 9.2 years, 72% male) for stress-rest myocardial perfusion imaging (MPI, single-day stress-rest protocol). We quantified summed stress scores (SSS), summed rest scores, and summed difference scores, together with LVMV and ejection fraction (EF) after stress and at rest. All patients underwent coronary angiography within 30 days. ResultsTwo hundred seventy-two patients had CAD at coronary angiography. ΔLVMV ≤ 5 mL, corresponding to 6% of change from rest LVMV, was the best predictor of CAD (AUC = 0.831, 79% sensitivity, 82% specificity), irrespective of the stress protocol (dipyridamole or exercise stress) and independently of MPI-SSS, LV EF, and clinical history (P = 0.004). Integrated discrimination improvement (IDI) and net reclassification improvement (NRI) were significant for the addition of ΔLVMV ≤ 5 mL (IDI = 6.1%, P < 0.0001; NRI = 29.7%, P = 0.02) to MPI-SSS, whereas the other parameters were not. ConclusionsThe evaluation of ΔLVMV using CZT-SPECT can improve the diagnostic accuracy in predicting the presence of CAD when added to conventional MPI.

Vitamin D Deficiency as a Risk Factor for Myocardial Ischemia

Background and Objectives: Vitamin D (Vit D) deficiency has been implicated in various conditions, including cardiovascular disease. The purpose of this retrospective study was to investigate the incidence of patients with myocardial ischemia in relation to their serum levels of vitamin D. Materials and Methods: A 64-month search (January 2016 to April 2021) in our database of the Nuclear Medicine Laboratory revealed 113 patients who had both myocardial perfusion imaging with single photon emission computed tomography (MPI SPECT) and Vit D measurements. MPI SPECT obtained myocardial images during both stress (summed stress score, SSS) and rest (summed rest score, SRS). Abnormal MPI SPECT was when the SSS was ≥4. Vit D was determined by radioimmunoassay (RIA). Patients with Vit D values <10 ng/mL, 10–29 ng/mL and ≥30 ng/mL were defined as having a deficiency, insufficiency and sufficiency, respectively. Results: Among patients, 46/113 (40.7%) were male and 67/113 (59.3%) were female. Abnormal MPI was found in 58/113 (51.3%) patients. Vit D deficiency was noted in 20/113 (17.7%) patients, insufficiency in 86/113 (76.1%) patients, and normal Vit D was noted in only 7/113 (6.2%) patients. Sixteen of the 20 patients (80%) with Vit D deficiency, and 38/86 (44.2%) with insufficiency had an abnormal MPI SPECT. In contrast, only 1/7 (14.3%) patients with sufficient Vit D levels had an abnormal MPI SPECT. The Mann-Whitney U-test showed that ischemia reduced the values of Vit D. Correlation analysis showed a negative association of Vit D levels with SSS (rho = −0.232, p = 0.014) and SRS (rho = −0.250, p = 0.008). Further evaluation with a Vit D cut off 20 ng/mL retrieved no statistical significance. Finally, Vit D and gender were independently associated with myocardial ischemia. Conclusions: Low Vit D levels may represent a risk factor for myocardial ischemia.