Quantitative Perfusion SPECT Software Research Articles

Effect of Beta-Blocker Consumption on the Severity and Extension of Perfusion Defects in Dipyridamole Myocardial Perfusion Single-Photon Emission Computed Tomography.

Background Regarding the less-known effects of beta-blocker consumption on the diagnostic value of the myocardial perfusion scan with dipyridamole stress in coronary artery disease (CAD), we aimed to compare the findings of the scans done on the beta-blocker consumption course and after discontinuation of this medications. Materials and Methods Thirty patients with probably CAD and abnormal myocardial perfusion scans (presence of reversible defect), who had been treated with beta-blockers for at least 3 months, were studied. Dipyridamole stress phase of myocardial perfusion single-photon emission computed tomography (SPECT) was performed two times with an interval of about 1 week, once after discontinuation of all antianginal and anti-ischemic medications, statins, and beta-blockers for 72 hours prior to the study, and again after discontinuation of all these medications except for beta-blockers. Imaging was done with the same protocol, radiopharmaceutical dose, and imaging parameters. Summed stress score (SSS), summed stress rest, and summed difference scores (SDS), total perfusion deficit (TPD), severity, and extension of myocardial perfusion defects in three coronary artery territories were analyzed, using quantitative perfusion SPECT software. Results Most variables such as SSS, SDS, TPD, severity, and extension of defects showed a significant difference between the two conditions including beta-blocker consumption and after discontinuing beta-blocker consumption before stress imaging ( p < 0.05). Moreover, in patients on treatment with metoprolol, all studied factors including SSS, SDS, TPD, severity, and extension of perfusion defects were significantly reduced when patients consumed beta-blockers before SPECT evaluation ( p < 0.05). Conclusion Beta-blocker consumption can lead to a decrease in the severity and extent of myocardial perfusion defects and therefore probably a decrease in the sensitivity of myocardial scans. Discontinuation of beta-blocker prior to the dipyridamole myocardial perfusion scan can improve diagnostic accuracy.

Upper reference limits of transient ischemic dilation ratio for different protocols on new-generation cadmium zinc telluride cameras: A report from REFINE SPECT registry

BackgroundUpper reference limits for transient ischemic dilation (TID) have not been rigorously established for cadmium-zinc-telluride (CZT) camera systems. We aimed to derive TID limits for common myocardial perfusion imaging protocols utilizing a large, multicenter registry (REFINE SPECT). MethodsOne thousand six hundred and seventy-two patients with low likelihood of coronary artery disease with normal perfusion findings were identified. Images were processed with Quantitative Perfusion SPECT software (Cedars-Sinai Medical Center, Los Angeles, CA). Non-attenuation-corrected, camera-, radiotracer-, and stress protocol-specific TID limits in supine position were derived from 97.5th percentile and mean + 2 standard deviations (SD). Reference limits were compared for different solid-state cameras (D-SPECT vs. Discovery), radiotracers (technetium-99m-sestamibi vs. tetrofosmin), different types of stress (exercise vs. four different vasodilator-based protocols), and different vasodilator-based protocols. ResultsTID measurements did not follow Gaussian distribution in six out of eight subgroups. TID limits ranged from 1.18 to 1.52 (97.5th percentile) and 1.18 to 1.39 (mean + 2SD). No difference was noted between D-SPECT and Discovery cameras (P = 0.71) while differences between exercise and vasodilator-based protocols (adenosine, regadenoson, or regadenoson-walk) were noted (all P < 0.05). ConclusionsWe used a multicenter registry to establish camera-, radiotracer-, and protocol-specific upper reference limits of TID for supine position on CZT camera systems. Reference limits did not differ between D-SPECT and Discovery camera.

Serial examination of cardiac function and perfusion in growing rats using SPECT/CT for small animals

Few studies have evaluated myocardial perfusion and ventricular function in normal, growing rats. We, therefore, evaluated serial changes in cardiac perfusion and function during the growth of normal rats using single photon emission computed tomography (SPECT) with technetium (99mTc)-sestamibi. Gated SPECT was serially performed in six normal rats. The left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) were calculated with Quantitative Gated SPECT software. The perfusion distribution was calculated as the percentage uptake of each of the 17 segments using Quantitative Perfusion SPECT software. As expected, the body weight (BW) of the rats increased with growth, but their heart rates (HR) did not change over time. EF decreased very slowly over time and showed a negative correlation with BW. EDV, ESV and SV showed strong positive correlations with BW. There were no significant differences in the percentage segmental uptake in 13 of the 17 segments during growth, except for three basal and one apical segments. Therefore, a single normal database could be applied for the evaluation of perfusion abnormalities in rats of at least 8 to 28 weeks old.

Personalized Models for Injected Activity Levels in SPECT Myocardial Perfusion Imaging.

We propose a patient-specific ("personalized") approach for tailoring the injected activities to individual patients in order to achieve dose reduction in SPECT-myocardial perfusion imaging (MPI). First, we develop a strategy to determine the minimum dose levels required for each patient in a large set of clinical acquisitions (857 subjects) such that the reconstructed images are sufficiently similar to that obtained at conventional clinical dose. We then apply machine learning models to predict the required dose levels on an individual basis based on a set of patient attributes which include body measurements and various clinical variables. We demonstrate the personalized dose models for two commonly used reconstruction methods in clinical SPECT-MPI: 1) conventional filtered backprojection (FBP) with post-filtering and 2) ordered-subsets expectation-maximization (OS-EM) with corrections for attenuation, scatter and resolution, and evaluate their performance in perfusion-defect detection by using the clinical Quantitative Perfusion SPECT software package. The results indicate that the achieved dose reduction can vary greatly among individuals from their conventional clinical dose and that the personalized dose models can achieve further reduction on average compared with a global (non-patient specific) dose reduction approach. In particular, the average personalized dose level can be reduced to 58% and 54% of the full clinical dose, respectively, for FBP and OS-EM reconstruction, while without deteriorating the accuracy in perfusion-defect detection. Furthermore, with the average personalized dose further reduced to only 16% of full dose, OS-EM can still achieve a detection accuracy level comparable to that of FBP with full dose.

Transient Ischemic Dilation Ratio in Regadenoson, Single Isotope Gated Single-photon Emission Computed Tomography Myocardial Perfusion Imaging.

Single isotope 99mTc single-photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) is the most commonly used protocol for nuclear stress testing. Transient ischemic dilation of the left ventricle (TID) has been considered a specific marker of severe coronary artery disease (CAD). Recent publications have questioned the clinical utility of TID, specifically with regadenoson as a stressor and 4DM-SPECT software for TID analysis. These findings have not been demonstrated using other imaging packages. The goal of our study was to establish the TID threshold in the identification of Multi-vessel CAD using Quantitative Perfusion SPECT (QPS) software. Included in this study are 190 patients that had undergone regadenoson-stress, same day, single-isotope 99mTc MPI and had a coronary angiography within a designated 3-month period. QPS (Cedars-Sinai, LA, CA) automated image analysis software was used to calculate TID ratios which were compared across different CAD categories. Coronary angiograms were reviewed to identify both obstructive and nonobstructive CAD. The mean TID for patients with nonobstructive CAD (n = 91) was 1.02 ± 0.11, and the threshold for TID was 1.24. A receiver operating characteristic curve showed that TID had a poor discriminatory capacity to identify MVD (area under the curve 0.58) with a sensitivity of 3% and a specificity of 97%. In our study with regadenoson MPI in a predominantly African-American population, TID was found to be a poor predictor of MVD using QPS software. The reason is unclear but possibly related to the significant decline in the prevalence of severe CAD in the area where our study took place.

Regadenoson in Myocardial Perfusion Study - First Institutional Experiences in Bosnia and Herzegovina.

Introduction:Myocardial perfusion imaging (MPI) is widely used in the evaluation of known and suspected coronary artery disease (CAD). Imaging of heart in stress and rest enables the comparison of myocardial uptake of radiotracer in proportion to the needs and coronary flow, which is used for detection of perfusion defects. Exercise stress and pharmacologic agents are used for the stressing purpose. Novel pharmacologic stressor regadenoson is A2A selective adenosine agonist, which selectively binds to the adenosine receptors in coronary arteries causing coronary dilatation.Materials and methods:We analyzed 50 myocardial perfusion studies performed with regadenoson as a pharmacologic agent that was injected before Tc99m-sestamibi in stress imaging. Stress and rest sets of images were evaluated for relative uptake of Tc99m-sestamibi in order to detect and characterize perfusion defects. After the injection of regadenoson, hemodynamic parameters and potential side-effects were closely monitored. Side-effects were stratified per severity as mild, moderate and severe. Studies were read by nuclear medicine physicians using quantitative perfusion SPECT software. Additional diagnostic information such as wall motion and wall thickening were provided by gating.Results:Thirty-three patients (66%) experienced one or more side-effects upon the administration of regadenoson, most commonly warmth and chest discomfort. In all patients but one (98%), the symptoms were mild, of short duration and self-limiting. Out of all side-effects registered, 44 (96%) were mild, and 2 (4%) were moderate. Two moderate side-effects developed in one patient with a prior history of asthma, and included shortness of breath and cough. Heart rate changed by 16 +- 31 bpm. Highest increase in blood pressure was 30 mm Hg for systolic, and 10 mm Hg for diastolic. One case of significant decrease in blood pressure was noted from the hypertensive basal values, 50 mm for systolic, and 30 mm Hg for diastolic. ST segment depression of up to 1 mm occurred in 4 cases (8%), and T-wave changes in 3 cases (6%). No conduction abnormalities, significant hypotension, symptomatic bradycardia or cardiac arrest ocurred.Conclusion:Our first institutional experiences proved regadenoson as A2A selective adenosine agonist as a pharmacologic stressor to be safe, tolerable and easily used. Its safety profile enabled the study to be performed in patients with respiratory disease also.

Variabilidade introduzida pelo operador no processamento dos estudos Gated-SPECT do miocárdio

Introduction – Gated - Single Photon Emission Computed Tomography (SPECT) is one of cardiac imaging techniques with more development over last decades. For image analysis, the use of quantification software leads to increased reproducibility and accuracy of interpretations. The purpose of this study was to assess, in Gated-SPECT studies, intra and inter-operator variability of quantitative parameters of myocardial perfusion and function, obtained with the software Quantitative Gated SPECT (QGS) and Quantitative Perfusion SPECT (QPS). Material and methods – We used a non-probability sample of convenience of 52 patients who underwent myocardial Gated-SPECT studies for clinical indications and that formed ESTeSL’s Xeleris workstation database. The fifty-two studies were divided into two groups: Group I (GI) of 17 patients with normal myocardial perfusion images; Group II (GII) of 35 patients with perfusion defects in Gated-SPECT images. All studies were processed 5 times by 4 independent operators (with 3 years of experience in Nuclear Medicine Services with a sample mean of 15 Gated-SPECT studies per week). Friedman´s statistical test was used to assess intra and inter-operator variability, considering α = 0.01. Results and discussion – To all variables, the respective p values did not reflected statistically significant differences (p> α). Thus, there was no significant intraor inter-operator variability in processing myocardial Gated-SPECT studies. Conclusion – QGS and QPS software allow a reproducible quantification of the evaluated function and perfusion parameters, with no variability introduced by the operator.

Validation of automated quantification of nuclear cardiology in Japanese patients using total perfusion deficits: Comparison with visual assessment

BackgroundAutomated quantitative assessment based on a total perfusion deficit (TPD) has been recognized to be useful for detection of coronary artery disease (CAD). We, therefore, aimed to validate reproducibility of the automated quantification with the TPD on myocardial perfusion single photon emission computed tomography (SPECT) images in Japanese patients with history of stable CAD. MethodsPatients (n=47, age 67±10) underwent rest 201Tl and stress 99mTc-tetrofosmin myocardial perfusion SPECT on two separate occasions with the same protocol within 3–26 months. They had abnormal findings on the first SPECT imaging by visual analysis and had no changes in symptoms, cardiac medications, coronary risk factors, and electrocardiogram findings at the time of the second imaging. They had no intervening coronary revascularization and myocardial infarction between the first and second imaging. The TPD was automatically derived from SPECT images through quantitative perfusion SPECT software with the Japanese normal database. A visual summed stress score (SSS) was estimated with the 5-point visual scoring model for 20 segments of SPECT images by independent expert interpreters. Abnormal criteria for the stress TPD and SSS were defined as ≥5% and ≥4, respectively. ResultsThe stress TPD determined by the quantitative analysis well correlated between the first and second imaging (r=0.985) as well as the SSS by the visual analysis showed good correlation (r=0.978). The correlation coefficients were similar between the visual and quantitative analyses. Bland–Altman analyses indicated extremely good reproducibility in both assessments. ConclusionThe TPD is evidently a quantitative index having high reproducibility and the automated quantification with it provides comparable results to the visual assessment by experienced interpreters. The automated quantification with the TPD is highly significant for clinical assessment of CAD, and allows easily performing myocardial perfusion SPECT imaging without expert interpreters.

Diagnostic value of automated quantification of nuclear cardiology in Japanese patients with single vessel coronary artery disease: Comparison between Japanese and American normal databases

BackgroundThe Japanese diagnostic assessment of nuclear cardiology has usually been based on semi-quantitative visual analyses but not on automated quantification with a total perfusion deficit (TPD). We, therefore, aimed to determine whether automated TPD quantification is useful to detect coronary artery disease (CAD) in Japanese patients in comparison with conventional visual segmental analysis, and to compare results from the automated assessment between the Japanese and American normal databases (NDBs). MethodsPatients with suspected CAD underwent rest 201Tl and stress 99mTc-tetrofosmin myocardial perfusion single photon emission computed tomography (SPECT) and coronary angiography within three months. The TPD was automatically derived from the SPECT image through quantitative perfusion SPECT software with the Japanese and American NDBs. The visual summed stress scores (SSS) were estimated with the 5-point visual scoring model for 20 segments of SPECT images. An abnormal criteria for the stress TPD and SSS were defined as ≥5% and ≥4, respectively. ResultsDetection sensitivity of CAD was 87% with the stress TPD score derived from the Japanese NDB and 85% with the SSS in visual analysis. In contrast, the detection sensitivity with the stress TPD score derived from the American NDB was 75%, which was significantly lower than that with the Japanese TPD (p=0.0004). Specificity of the automated Japanese TPD assessment was similar to that of the visual SSS assessment (87% vs. 80%). Thus, sensitivity and specificity of the automated quantitative assessment based on the TPD scores derived from the Japanese NDB were consistent with that of visual quantification based on the segmental defect scores. ConclusionThe automated quantitative assessment with the Japanese NDB is useful for the detection of CAD when experts in visual interpretation of a myocardial perfusion SPECT image were absent in a clinical setting.

Diagnostic evaluation of three cardiac software packages using a consecutive group of patients

PurposeThe aim of this study was to compare the diagnostic performance of the three software packages 4DMSPECT (4DM), Emory Cardiac Toolbox (ECTb), and Cedars Quantitative Perfusion SPECT (QPS) for quantification of myocardial perfusion scintigram (MPS) using a large group of consecutive patients.MethodsWe studied 1,052 consecutive patients who underwent 2-day stress/rest 99mTc-sestamibi MPS studies. The reference/gold-standard classifications for the MPS studies were obtained from three physicians, with more than 25 years each of experience in nuclear cardiology, who re-evaluated all MPS images. Automatic processing was carried out using 4DM, ECTb, and QPS software packages. Total stress defect extent (TDE) and summed stress score (SSS) based on a 17-segment model were obtained from the software packages. Receiver-operating characteristic (ROC) analysis was performed.ResultsA total of 734 patients were classified as normal and the remaining 318 were classified as having infarction and/or ischemia. The performance of the software packages calculated as the area under the SSS ROC curve were 0.87 for 4DM, 0.80 for QPS, and 0.76 for ECTb (QPS vs. ECTb p = 0.03; other differences p < 0.0001). The area under the TDE ROC curve were 0.87 for 4DM, 0.82 for QPS, and 0.76 for ECTb (QPS vs. ECTb p = 0.0005; other differences p < 0.0001).ConclusionThere are considerable differences in performance between the three software packages with 4DM showing the best performance and ECTb the worst. These differences in performance should be taken in consideration when software packages are used in clinical routine or in clinical studies.

Quantification of myocardial perfusion SPECT using freeware package (cardioBull)

We have developed freeware package for automatically quantifying myocardial perfusion and (123)I-labeled radiopharmaceutical single-photon emission computed tomography (SPECT), which is called "cardioBull". We aim to evaluate diagnostic performance of the detection of coronary artery disease (CAD) on the developed software in comparison with commercially available software package [Quantitative Perfusion SPECT (QPS)]. Stress-rest (99m)Tc-sestamibi myocardial perfusion SPECT was performed in 36 patients with CAD and 35 control patients. A ≥ 75% stenosis in the coronary artery was identified by coronary angiography in the CAD group. Segmental perfusion defect score was automatically calculated by both cardioBull and QPS software. Summed stress score (SSS) was obtained to detect CAD by the receiver operator characteristic (ROC) analysis. Areas under the ROC curves (AUC) were calculated in patient-based and coronary-based analyses. Mean SSSs showed no significant difference between cardioBull and QPS (6.0 ± 7.1 vs. 5.6 ± 7.0). The AUC for cardioBull was equivalent to that for QPS (0.91 ± 0.04 vs. 0.87 ± 0.04, p = n.s.). Sensitivity, specificity, and accuracy for cardioBull were 89, 74, and 82%, respectively. For the regional detection of CAD, the AUC showed largest value in left anterior descending coronary artery (LAD) territory (0.86 ± 0.06 for cardioBull, 0.87 ± 0.06 for QPS, p = n.s.). Sensitivity, specificity and accuracy of cardioBull were 70, 88, and 83% for the LAD; 91, 62, and 66% for the left circumflex coronary artery (LCx); and 78, 69, and 70% for the right coronary artery (RCA), respectively. The AUC, sensitivity, specificity and accuracy for the detection of CAD showed high diagnostic performance on the developed software. In addition, the developed software provided comparable diagnostic performance to the commercially available software package.

Attenuation correction of myocardial SPECT by scatter-photopeak window method in normal subjects

Segmentation with scatter and photopeak window data using attenuation correction (SSPAC) method can provide a patient-specific non-uniform attenuation coefficient map only by using photopeak and scatter images without X-ray computed tomography (CT). The purpose of this study is to evaluate the performance of attenuation correction (AC) by the SSPAC method on normal myocardial perfusion database. A total of 32 sets of exercise-rest myocardial images with Tc-99 m-sestamibi were acquired in both photopeak (140 keV +/- 10%) and scatter (7% of lower side of the photopeak window) energy windows. Myocardial perfusion databases by the SSPAC method and non-AC (NC) were created from 15 female and 17 male subjects with low likelihood of cardiac disease using quantitative perfusion SPECT software. Segmental myocardial counts of a 17-segment model from these databases were compared on the basis of paired t test. AC average myocardial perfusion count was significantly higher than that in NC in the septal and inferior regions (P < 0.02). On the contrary, AC average count was significantly lower in the anterolateral and apical regions (P < 0.01). Coefficient variation of the AC count in the mid, apical and apex regions was lower than that of NC. The SSPAC method can improve average myocardial perfusion uptake in the septal and inferior regions and provide uniform distribution of myocardial perfusion. The SSPAC method could be a practical method of attenuation correction without X-ray CT.

The importance of population-specific normal database for quantification of myocardial ischemia: comparison between Japanese 360 and 180-degree databases and a US database

ObjectivesWe aimed to develop a Japanese normal database for specific acquisition conditions, to compare US and Japanese normal populations, and to examine effects of camera rotation angle range on the normal limits. Methods and ResultsStress-rest 99mTc myocardial perfusion databases for 360° (Jp360) and 180° (Jp180) acquisitions were created by the working group activity of the Japanese Society of Nuclear Medicine using Japanese patients. A standard 180° database (US180) had been previously generated by the Cedars Sinai Medical Center based on American patients. Additionally, 90 Japanese patients underwent coronary arteriography and stress-rest 99mTc perfusion study with 360° acquisition for validation purposes, and quantitative evaluation was performed by QPS software using the above three normal database sets. Major differences between US180 and Jp360 databases were found in the apex and in the anterior wall in females and in the inferior wall in males. When the diagnostic performance was evaluated by receiver-operating characteristic analysis, area under the curve was the highest for Jp360 (0.842), followed by Jp180 (0.758) and US180 (0.728) databases (P = .019, Jp360 vs US180; P = .035, Jp360 vs Jp180). The coronary territory score at stress was highest with the Jp360 database in male patients with right coronary artery stenosis (n = 26, Jp360: 4.92 ± 4.61 [mean ± SD], Jp180: 4.23 ± 4.29, US180: 2.92 ± 3.53; P < .0001 between Jp360 and US180) and in female patients with left anterior descending artery stenosis (n = 12, Jp360: 6.33 ± 4.76, Jp180: 5.25 ± 4.83, US180: 4.50 ± 4.15; P = .0076 between Jp360 and US180). ConclusionBecause of the differences between US and Japanese normal databases, it is essential to use population- and acquisition-specific databases when using quantitative perfusion SPECT software.

An Improved Method for Automatic Segmentation of the Left Ventricle in Myocardial Perfusion SPECT

This study describes and validates a new method for automatic segmentation of left ventricular mass (LVM) in myocardial perfusion SPECT (MPS) images. This is important for estimating the size of a perfusion defect as percentage of the left ventricle. A total of 101 patients with known or suspected coronary artery disease underwent both rest and stress MPS and MRI. A new automated algorithm was trained in 20 patients (40 MPS studies) and tested in 81 patients (162 MPS studies). The algorithm, which segmented the left ventricle in the MPS images, is based on Dijkstra's algorithm and finds an optimal mid-mural line through the left ventricular wall. From this line, the endocardium and epicardium are identified on the basis of an individually estimated wall thickness and signal intensity. The algorithm was validated by comparing LVM in both stress and rest MPS, with LVM of the manually segmented left ventricle from MRI as the reference standard. For comparison, LVM was quantified using the software quantitative perfusion SPECT (QPS). The mean difference+/-SD in LVM between MPS and MRI was lower for the new method (6%+/-15% LVM) than for QPS (18%+/-19% LVM) for both mean difference (P<0.001) and SD (P=0.015). Linear regression analysis of LVM, comparing MPS and MRI, yielded R2=0.83 using the new method and R2=0.80 using QPS. Interstudy variability, measured as the coefficient of variance between rest MPS and stress MPS, was 6% for both the new method and QPS. Both the new algorithm and QPS systematically overestimated LVM in hearts with thin myocardium and underestimated LVM in hearts with thick myocardium. The new segmentation algorithm quantifies LVM with a significantly lower bias and variability than does the commercially available QPS software, when compared to manually segmented LVM by MRI. This makes the new algorithm an attractive method to use for estimating the size of the perfusion defect when expressing it as percentage of the left ventricle. This study shows that inaccurate estimation of wall thickness is the main source of error in automatic segmentation.

Feasibility and Diagnostic Accuracy of a Gated SPECT Early-Imaging Protocol: A Multicenter Study of the Myoview Imaging Optimization Group

The aim of this study was to investigate whether early (time 1, or T1) myocardial tetrofosmin imaging is feasible and as accurate in detecting coronary artery disease as is standard delayed (time 2, or T2) imaging. One hundred twenty patients (100 men and 20 women; mean age +/- SD, 61 +/- 10 y) with anginal symptoms underwent tetrofosmin gated SPECT. Stress/rest T1 imaging was performed at 15 min and T2 at 45 min after injection. Image quality was visually evaluated using a 4-point scale (from 0 = poor to 3 = optimal). Myocardial perfusion analysis was performed on a 20-segment model using quantitative perfusion SPECT software, and reversible ischemia was scored as a summed difference score (SDS). Coronary angiography was performed within 1 mo on all patients, and stenosis of more than 50% of the diameter was considered significant. Overall, quality was scored as optimal or good for 94% of T1 images and 95% of T2 images (P = not statistically significant). Heart, lung, liver, and subdiaphragmatic counts did not differ for stress and rest T1 and T2 imaging. A good linear relationship was seen between T1 and T2 SDS (r = 0.69; P < 0.0001), and Bland-Altman analysis showed good agreement between the 2 conditions. In terms of global diagnostic accuracy, areas under the receiver-operating-characteristic curve were comparable between T1 and T2 (0.80 vs. 0.81, P = not statistically significant). Discrepancies between T1 and T2 SDS were observed in 44% of patients (T1 - T2 SDS > 2). Linear regression analysis showed a good correlation between T1 and T2 SDS (r = 0.67; P < 0.0001), whereas the Bland-Altman method showed a shift in the mean value of the difference of +2.67 +/- 2.73. In patients with a T1 - T2 SDS of more than 2, areas under the receiver-operating-characteristic curves were significantly higher for T1 than for T2 images (0.79 vs. 0.70, P < 0.001). T1 imaging is feasible and as accurate as T2 imaging in identifying coronary artery disease. However, in a discrete subset of patients, early acquisition strengthens the clinical message of defect reversibility by permitting earlier, more accurate identification of more severe myocardial ischemia.

Preliminary clinical results of photon energy recovery in simultaneous rest Tl-201/stress Tc-99m sestamibi myocardial SPECT

Background. The purpose of this study is to report the first clinical results obtained with the spectral deconvolution technique photon energy recovery (PER) for crosstalk correction in simultaneous rest thallium 201/stress technetium 99m sestamibi myocardial perfusion single photon emission computed tomography (SPECT). Methods and Results. Thirty-four patients with suspected coronary artery disease received Tl-201 (111-130 MBq) at rest, followed by single SPECT. Tc-99m sestamibi (444-518 MBq) was then injected at stress, followed by dual SPECT. Single SPECT data were processed to obtain the following data sets: single raw (conventional) Tl-201 and single PER (scatter-corrected) Tl-201. Dual SPECT data were processed to obtain the following data sets: dual raw Tl-201, dual PER (scatter- and crosstalk-corrected) Tl-201, dual raw Tc-99m, and dual PER (scatter-corrected) Tc-99m. All data sets were automatically analyzed with Cedars-Sinai Quantitative Perfusion SPECT software to derive the relative segmental uptake, the summed score, and the summed difference score. The relative segmental uptake, the summed score, and the number of patients with significant reversibility (summed difference score >2) were 74.84% ± 12.79%, 3.44 ± 3.07, and 13, respectively, for single raw Tl-201; 80.5% ± 10.18%, 1.97 ± 2.25, and 20, respectively, for dual raw Tl-201; 69.47% ± 14.08%, 6.41 ± 3.68, and 17, respectively, for single PER Tl-201; and 69.99% ± 13.39%, 6.58 ± 3.63, and 17, respectively, for dual PER Tl-201. The differences between single and dual raw Tl-201 data sets were highly significant, whereas there was no significant difference between PER-corrected Tl-201 data sets. Conclusions. PER is quantitatively efficient to correct for crosstalk in patients investigated with simultaneous rest Tl-201/stress Tc-99m sestamibi myocardial SPECT. (J Nucl Cardiol 2001;8:144-51.)