Aim/Introduction: SPECT myocardial perfusion imaging (MPI) is a clinical mainstay with static imaging protocol and semi-quantitatively assessed for perfusion abnormalities. Dynamic cardiac SPECT is a new quantitative index of stenosis severity and ischemic burden by the assessment of myocardial flow reserve (MFR) and myocardial blood flow (MBF). Our aim is to evaluate the incremental value of dynamic SPECT in the detectability of multi-vessel coronary artery disease (CAD). Materials and Methods: Consecutive patients with suspected CAD, who underwent dynamic ECG-gated dipyridamole MPI using a cardiac-dedicated CZT camera (D-SPECT) and invasive/or computed tomography coronary angiography within 6 months were retrospectively reviewed. Subjects with history of coronary interventions in the past 90 days were excluded. Dynamic imaging data were analyzed using commercial Corridor 4DM software package, and static perfusion and volumetric data were analyzed utilizing QPS/QGS software, which provided automatically plots according to the 17-segment model, and subsequently divided into three main vascular territories (LAD, LCX, RCA). Significant stenosis was defined as ≥ 50% luminal stenosis. The performance of static perfusion data, including summed stress, rest and difference scores (SSS, SRS and SDS), and dynamic perfusion data, namely post-stress and resting MBF (MBFs, MBFr) and MFR were compared at the vessel-level. The statistical significance was p<0.05. Results: A total of 50 patients with 139 stenotic vessels were included, 29 with multi-vessel disease (58%), and 11 patients (22%) with myocardial infarction (MI). Both global and regional MBFs showed a significant correlation with global and regional SSS (r=-0.67 and -0.38~-0.68, p≤0.001, respectively). Globally increased SSS, SDS and impaired MBFs, MFR were significantly associated with significant CAD. In vessel-based analysis, SSS and SDS failed to detect LAD, LCX diseases, except SSS in RCA disease. Post-stress MBF successfully detected LAD, LCX and RCA diseases, while MFR could only detect LAD disease. Using receiver operating characteristic (ROC) curve analyses, the best cutoff value of global MBFs to predict CAD was 2.4ml/g/min (area under the curve: 0.569, p=0.005), but the best cut-off value of MFR was not found. Conclusion: We validated a clinically available method for MFR quantification by dynamic 99mTc-perfusion SPECT utilizing a CZT camera, which improves the detectability of multi-vessel CAD, and post-stress MBF is a better parameter than MFR and static data. References: none
Aim/Introduction: Spline fitting allows to interpolate a sequence of temporal data, generating temporal and spatial smoothing of dynamic perfusion studies. We aimed to assess the impact of spline fitting on the assessment of myocardial blood flow and flow reserve using dynamic CZT perfusion SPECT. Materials and Methods: We retrospectively analyzed CZT dynamic myocardial perfusion SPECT previously acquired in 28 consecutive patients in the framework of the Waterday  study (clinicaltrials.gov: NTC 02278497) using a DSPECT camera (Spectrum Dynamics, Caesarea, Israel). The CZT SPECT data were processed without (DY) and with (SF) applying a spline fitting function using a commercially available software (4DM, Invia, Ann Arbor, MI). All reconstructed frames were automatically segmented to extract the vascular input function and the myocardial uptake curve, and a one-compartment model was used to estimate global uptake values. SPECT myocardial blood flow (MBF) derived using Leppo correction and flow reserve (MFR) were compared to 15O-water PET data quantified using the Carimas 2.4 software (Turku PET Centre, Turku, Finland). Results: Rest and stress SPECT MBF values were similar with or without spline fitting (rest: 1.178 ± 0.385 vs 1.120 ± 0.457; and stress: 3.209 ± 0.880 vs 3.151 ± 0.758 for DY and SF respectively). At stress, both DY and SF MBF were increased compared to PET MBF (2.882 ± 0.967, p<0.05 vs SF, p<0.01 vs. DY). At rest, DY but not SF MBF was significantly increased vs. PET MBF (1.027 ± 0.237, p<0.05 vs DY). Correlations to PET MBF were similar using DY (r= 0.90, p<0.0001) or SF (r= 0.88, p<0.0001) but the difference between SPECT and PET was optimized using SF (0.18±0.58, p<0.05) compared to DY (0.24±0.51, p<0.001). The differences observed in terms of MBF yielded no difference on the assessment of MFR (DY: 2.93 ±1.13, SF: 3.15±1.15, PET: 2.83±0.81, all p-values= ns). Conclusion: Spline fitting had only a limited impact on the quantitative assessment of myocardial blow flow and flow reserve using dynamic CZT SPECT. References:  Agostini D et al. Eur J Nucl Med Mol Imaging. 2018;45(7):1079-1090.
Aim/Introduction: Multi-vessel disease is frequently a cause of false negative myocardial perfusion SPECT. The global reduction of perfusion is difficult to see on the images. Scintigraphic measurement of Coronary Flow Reserve (CFR), usually performed by dynamic SPECT or dynamic PET can decrease false negative study. We developed an original method to evaluate the CFR, using routine SPECT 99mTc-tetrofosmin (1 day Stress-Rest protocol), without 1st pass acquisition. Materials and Methods: Myocardial uptake being related to myocardial perfusion, the counts ratio stress/rest represents CFR. Successively, 5 corrective factors are applied (completely automatic) at stress and rest , on myocardial short axis slices (Software Aladdin language - Xeleris GE) 1. Subtraction of the stress residual activity in the rest images 2. Normalization of the injected tracer activity 3. Normalization of the time duration acquisition 4. Consideration of the flow depending tetrofosmin myocardial extraction. 5. Normalization of the central ventricular pixel counts The 5 cumulative applications produce global Coronary Reserve Index (CRI), and regional CRI (rCRI) corresponding to the 3 coronary territories (LAD, LCx and RCA). These processings have been applied to 32 patients addressed to our institution for routine myocardial stress (exercise, dipyridamole, or regadenoson) and rest SPECT; they underwent also Invasive Coronary Angiography (ICA). Results: The CRI evaluations were compared to ICA considered as gold standard. ICA indicates 7 normal patients and 25 Coronary Artery Disease (CAD) patients. CRI mean is 3.65 ± 2.10 for normal patients, and 1.57 ± 0.56 for CAD patients. We found 14 CAD patients with normal perfusion SPECT and low CRI. The optimal cut-off CRI to separate normal and CAD patients is 2.20 . Considering this CRI value, we obtain: Sensitivity 92%, Specificity 86%, Positive Predictive Value 96%, and Negative Predictive Value 75%. Among the 25 CAD patients, 8 present multi-vessel epicardial disease with abnormal global CRI. Analysis of the 3 regional CRI, shows that the difference between the maximal and the minimal rCRI, normalized with the global CRI, is smaller for the multi-vessel disease (0.36 ± 0.45) than for the 17 others CAD patients (0.11 ± 0.08). A diffuse decrease of rCRI may indicate multi-vessel epicardial disease and/or microvascular disease. Conclusion: Evaluation of global CRI and rCRI by routine 99mTc-tetrofosmin SPECT is feasible. Using this evaluation after the routine SPECT reconstruction ,with no additional time (fully automatic process) improves efficiency of perfusion SPECT analysis. Sensitivity and Positive Predictive Value are excellent. References: None
Aim/Introduction: To assess relative myocardial perfusion, absolute myocardial blood flow (MBF) and coronary flow (CFR) reserve by dynamic single photon emission computed tomography on cadmium-zinc-telluride gamma camera in patients with multivessel coronary artery disease (MVCAD). Materials and Methods: 38 patients with coronary artery disease (mean age 60±9,5 years; 52 men;) were enrolled. According to quantitative invasive coronary angiography results all the patients were divided into two groups: 1) multivessel CAD: 12 patients with the two-vessel disease and 24 patients with three-vessel disease; 2) non-multivessel CAD: consisted of 22 patients with nonobstructive disease and 12 patients with one vessel disease. Within one week all patients underwent the assessment of myocardial perfusion (SSS, SRS, SDS), stress and rest MBF (ml/min/g), CFR and flow difference (FD) by dynamic 99mTc-Sestamibi CZT SPECT. Results: The mean SYNTAX score was 16.5±11. The values of summed stress score were significantly (p< 0.01) different in patients with and without multivessel CAD: 7.5 (IQR 5;10) and 4 (IQR 4;8), respectively. Summed rest score and difference score did not differ significantly in these two groups. The values of global stress MBF, CFR and FD were significantly (p<0.01) lower in patients with multivessel disease than in non multivessel CAD group: 0.43 ml/g/min (IQR 0.29; 0.52) versus 0.67 ml/g/min (IQR 0.53; 0.81); 1.38 (IQR 1.13; 1.64) versus 2.09 (IQR 1.59; 2.7); 0.1 ml/g/min (IQR 0.04; 0.19) versus 0.32 ml/g/min (IQR 0.19; 0.53), respectively. The correlations between SYNTAX and stress MBF (r=-0.6; p=0.00006), CFR (r=-0.58; p=0.0001), FD (r=-0.6; p=0.00009), were stronger than between SYNTAX and SSS (r=0.37; p=0.02), SDS(r=0.39; p=0.02). Based on univariate logistic regression the following indexes allow to predict MVCAD significantly: stress MBF per 0.1 unit increase (OR 0.75; CI 0.62-0.91; p=0.005); CFR (OR 0.12; CI 0.04-0.38; p=0.0003); FD per 0.1 unit increase (OR 0.72; CI 0.57-0.91; p=0.0016 and SSS (OR 1.21; CI 1.06-1.39; p=0.004); SDS (OR 1.19; CI 1.01-1.14; p=0.03). Based on the ROC analysis it was revealed that the areas under the ROC curves were higher for stress MBF (0.81;CI 0,71-0,9) CFR (0.8; CI 0,68-0,88) and FD (0.78; CI 0,67-0,87) than for SSS (0.68; CI 0,55-0,79) and SDS (0.64; CI 0,51-0,75). Conclusion: Our results found out that dynamic SPECT indexes reflect the severity of coronary artery lesion better than standard MPI. Absolute myocardial blood flow indexes derived by CZT could be useful in clinical practice in the management of patients with multivessel CAD. References: none
Aim/Introduction: Dynamic CZT-SPECT may be used to measure myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). The aim of our study was to evaluate MBF and MPR using a low-dose CZT-SPECT protocol in patients with suspected or known coronary artery disease (CAD) and to investigate the accuracy of dynamic data in predicting obstructive CAD. Materials and Methods: We analyzed 150 patients (102 men, mean age 65±8 years) with suspected or known CAD. All patients underwent dynamic CZT-SPECT after the injection of 185 MBq and 555 MBq of 99mTc-sestamibi for rest and stress imaging, respectively. Standard rest and stress acquisition were performed at the end of each dynamic scan. Summed stress score (SSS) >3 was considered as abnormal. Obstructive CAD was defined as ≥75% stenosis at coronary angiography. Results: In the overall population, global MPR was significantly lower (P<0.05) in patients with abnormal (2.4±0.7) as compared to those with normal (2.7±0.8) myocardial perfusion imaging. Significant correlations between MPR and SSS (r=-0.213, P<0.01) and between MPR and total perfusion defect (TPD) (r=-0.217, P<0.01) were found. In a subgroup of 60 patients with available coronary angiographic data, MPR (2.11±0.56 vs. 2.72±0.65, P=0.001) and stress MBF (2.71±0.85 vs. 3.43±0.95 ml/min/g, P=0.009) were significantly lower in patients with (n=17) compared to those without (n=43) obstructive CAD. At univariable logistic regression analysis, male gender, SSS, TPD, stress MBF, and MPR resulted significant predictors of obstructive CAD. At multivariable regression analysis only male gender (P<0.01) and MPR (P<0.005) were significant predictors of obstructive CAD. Accordingly, in the 180 individual vessels analyzed, regional stress MBF (2.79±0.94 vs. 3.35±1.07 ml/min/g, P=0.015) and regional MPR (2.18±0.81 vs. 2.74±0.81, P=0.002) were significantly lower in vessels with (n=25) compared to those without (n=155) obstructive CAD. Conclusion: MPR assessed by low-dose dynamic CZT-SPECT showed good correlation with myocardial perfusion imaging findings in patients with suspected or known CAD and it could be useful in predicting obstructive CAD. References: None
Aim/Introduction: Evaluation of myocardial ischemia is crucial for patients with intermediate coronary stenosis disease. Quantification myocardial blood flow (MBFQ) using technetium labeled myocardial perfusion tracers and dedicated SPECT cameras has become clinically feasible. Comparison of SPECT MBFQ, myocardial flow reserve (MFR) and myocardial perfusion imaging (MPI) has not been studied. Materials and Methods: Patients with suspected or known coronary artery disease who were scheduled for SPECT MPI were consented to receive an adjunct dynamic SPECT (DySPECT) scan for MBFQ under the same rest and stress test. Subjects with intermediate disease defined as a coronary lesion with a visually estimated percentage diameter stenosis ranging from between 50 and 80% were included. Image processing of MBFQ employed full physical corrections for reconstruction of DySPECT images, one-tissue compartment for kinetic modeling, and corrections for 99mTc-Sestamibi extraction and rest rate-pressure-product to quantify stress MBF, rest MBF and MFR using a dedicated SPECT MBFQ software. Flow values in myocardium were further converted to corresponded flow statuses defined by the Gould’s flow diagram with slight modification. The patient-based positive diagnosis of MBFQ met one of two independent criteria as 1) ≥3.01% extent of myocardium within ischemia-steal combined flow status or 2) ≥20.3% extent of myocardium within moderate abnormal and ischemia-steal combined status. MFR alone as criteria defined ischemia when MFR <1.74. Interpretation of MPI images were conducted by three experienced readers in a consented reading session. MPI was considered abnormal when SSS ≥4 or SDS ≥2 or index of transient ischemia dilation ≥1.19. The patient-based diagnostic performance SPECT MBFQ, MFR and MPI for detecting myocardial ischemia were compared. Results: A total of 126 patients were included. Among this population, 71 patients presented with multi-vessel disease and 55 patients showed one-vessel disease. 68 patients (50.0%) showed abnormal results on MBFQ, which was significantly higher than the abnormal rate of MFR (58/126, 46.0%, p=0.000) and MPI (30/126, 23.8%, p-0.012). In patients with multi-vessel intermediate disease, MBFQ also showed more abnormal results (40/71, 56.3%) than MFR (28/71, 39.4%, p=0.000) and MPI (33.3%, 14/71, p=0.013), suggesting more myocardial ischemia was found by MBFQ. In patients with one-vessel disease, there was no significant difference in diagnosing myocardial ischemia of three methods. Conclusion: SPECT MBFQ detected more myocardial ischemia than MFR alone and traditional MPI for patients with intermediate disease, especially for patients with multi-vessel intermediate disease. References:  JACC Cardiovasc Imaging. 2012 Apr;5(4):430-40.
Aim/Introduction: Stress myocardial perfusion imaging (MPI) with SPECT accounts for the majority of tests currently performed for ischemia detection in patients with known or suspected coronary artery disease (CAD). The novel gamma cameras with semiconductor cadmium-zinc-telluride (CZT) detectors allowed an improvement in image accuracy and acquisition time. We performed a meta-analysis to compare the diagnostic performance of conventional SPECT (C-SPECT) and CZT-SPECT systems in detecting angiographically proven CAD. Materials and Methods: Studies published between January 2000 and February 2018 were identified by PubMed and Web of Science databases search. We included studies assessing C-SPECT or CZT-SPECT as a diagnostic test to evaluate patients for the presence of CAD, defined as at least 50% diameter stenosis on invasive coronary angiography. A study was eligible regardless of whether patients were referred for suspected or known CAD. For each eligible study, data were extracted to estimate sensitivity, specificity, and diagnostic odds ratio (OR) with 95% confidence interval (CI). The bivariate random-effects model was used to calculate the pooled summary estimates for sensitivities and specificities for both cameras. Results: We identified 40 eligible articles (25 C-SPECT and 15 CZT-SPECT studies) including 7334 patients (4997 in C-SPECT and 2337 in CZT-SPECT studies). The pooled sensitivity and specificity were 85% (95% CI 79-89) and 66% (95% CI 56-74) for C-SPECT and 89% (95% CI 86-91) and 69% (95% CI 61-75) for CZT-SPECT imaging studies. The area under the curve was slightly higher for CZT-SPECT (0.89, 95% CI 0.86-0.92), compared to C-SPECT (0.83, 95% CI 0.80-0.86) (P=0.03); accordingly, the summary diagnostic OR was 17 (95% CI 13-22) for CZT-SPECT and 11 (95% CI 7-15) for C-SPECT (P=0.04). The accuracy of the two tests slightly differs between C-SPECT and CZT-SPECT (chi-square 11.28, P=0.04). However, we were unable to demonstrate if the subtle difference in global accuracy was due to sensitivity (chi-square 2.13, P=0.14) or specificity (chi-square 0.21, P=0.65), also when separate variances for each test were allowed in the models. At meta-regression analysis, no significant association between both sensitivity and specificity and demographical and clinical variables considered was found for C-SPECT and CZT-SPECT studies. Conclusion: C-SPECT and CZT-SPECT have good diagnostic performance in detecting angiographically proven CAD, with a slightly higher accuracy for CZT-SPECT. This result supports the use of the novel gamma cameras in clinical routine practices also considering the improvements in acquisition time and radiation exposure reduction. References: None