Single-photon Emission Computed Tomography Software Research Articles

Cardiac motion correction with a deep learning network for perfusion defect assessment in single-photon emission computed tomography myocardial perfusion imaging

BackgroundIn myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT), ungated studies are used for evaluation of perfusion defects despite motion blur. We investigate the potential benefit of motion correction using a deep-learning (DL) network for evaluating perfusion defects. MethodsWe employed a DL network for cardiac motion correction in ECG-gated SPECT-MPI images, wherein the image data from different cardiac phases are combined with respect to a reference gate to reduce motion blur. For training the DL network, 197 cases were used. Given the variability of gated images during the cardiac cycle, we investigated the detectability of perfusion defects in two distinct reference gates. To assess perfusion defect detection, we performed receiver-operating characteristic (ROC) analyses on the motion-corrected images using a separate test dataset of clinical 194 subjects, in which studies were created from actual patient data with inserted simulated-lesions as ground truth. The reconstructed images were assessed by the quantitative-perfusion SPECT (QPS) software. We also evaluated the performance on reduced-count studies (by two and four folds). ResultsThe quantitative results, measured by area-under-the-ROC curve (AUC), demonstrated that DL motion correction improves the detectability of perfusion defects significantly on both standard- and reduced-count studies, and that the detectability can vary with reference cardiac phases. A joint assessment from two reference phases achieved AUC = 0.841 on the quarter-count data, higher than with ungated full-count data (AUC = 0.795, P-value = 0.0054). ConclusionsDL motion correction can benefit assessment of perfusion defects in standard- and reduced-count SPECT-MPI studies. It can also be beneficial to evaluate perfusion images over multiple cardiac phases.

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.

Prognostic value of summed motion score assessed by gated SPECT myocardial perfusion imaging in patients with dilated cardiomyopathy.

The prognosis of patients with dilated cardiomyopathy (DCM) is poor and new indicators are urgently needed to predict lethal cardiac events. This study aimed to investigate the value of summed motion score (SMS) in predicting cardiac death of DCM patients using gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Eighty-one patients with DCM who underwent 99mTc-MIBI gated SPECT MPI were retrospectively enrolled and were divided into cardiac death and survivor groups. The functional parameters of left ventricle including SMS were measured using quantitative gated SPECT software. During the follow-up period of 44 (25, 54) months, 14 (17.28%) cardiac deaths were observed. Compared with the survivor group, SMS was significantly higher in the cardiac death group. Multivariate cox regression analysis showed that SMS was an independent predictor for cardiac death (HR 1.34, 95% CI 1.02-1.77, P = 0.034). SMS also provided incremental prognostic value over other variables in the multivariate model as determined by likelihood ratio global chi-squared test. In the Kaplan-Meier survival analysis, the event-free survival rate was significantly lower in the high-SMS (HSMS) group than the low-SMS (LSMS) (log-rank P < 0.001). Furthermore, the area under curve (AUC) of SMS was larger than that of LVEF at the 12th month of follow-up (0.85 vs. 0.80, P = 0.045). SMS is an independent predictor of cardiac death in DCM patients and provides incremental prognostic value. SMS might have higher predictive value than LVEF for early cardiac death.

Quantitative bone single photon emission computed tomography analysis of the effects of duration of bisphosphonate administration on the parietal bone

Effects of long-term bisphosphonate (BP) administration on the metabolism of healthy bone and the concomitant changes in imaging are unclear. Hence, we aimed to retrospectively investigate the effects of long-term BP administration on the intact parietal bone using the standardised uptake value (SUV) derived from single photon emission computed tomography (SPECT). We enrolled 29 patients who had odontogenic infection, osteoporosis, bone metastasis cancer, or rheumatoid arthritis, and classified them into BP-naïve: A (14 patients) and BP-treated: B, < 4 years (7 patients) and C, ≥ 4 years (8 patients) groups. We measured the maximum bilateral SUV (SUVmax) of the parietal bone using quantitative bone SPECT software. There were significant differences in the duration of BP administration and SUVmax of the parietal bone among the diseases (P < 0.0001 and P = 0.0086, respectively). There was a positive correlation between the duration of BP administration and SUVmax of the parietal bone (rs = 0.65, P = 0.0002). The SUVmax was significantly different between A and B (P = 0.02) and between A and C (P = 0.0024) groups. This is the first report on the correlation between long-term BP administration and the SUVmax of the parietal bone using the quantitative bone SPECT analysis.

The impact of frame numbers on cardiac ECG-gated SPECT images with interpolated extra frames using echocardiography.

Background: Cardiac echocardiography and cardiac ECG-gated single-photon emission computed tomography (SPECT) are the most common modalities for left ventricle (LV) volumes and function assessment. The temporal resolution of SPECT images is limited and an ECG provides better temporal resolution. This study investigates the impact of frame numbers on images in terms of qualitative and quantitative assessments. Methods: In this study, 5 patients underwent echocardiography and cardiac ECG-gated SPECT imaging, and 5 standard views of the LV were recorded to determine LV walls boundaries and volumes. Also, 2 original images with 8 frames and 16 frames per cardiac cycle were recorded simultaneously in a single gantry orbit. Using the data extracted from the LV model, 8 extra new frames were created with interpolation between existing frames of the original 8-frame image. Three series of images (8 and 16 original and 16 interpolated) were reconstructed separately. LV volumes and ejection fraction (EF) were calculated using Quantitative Gated SPECT (QGS) software. Results: Compared to the original 8-frame gating, original 16-frame gated images resulted in larger end-diastole volume (EDV) (mean ± SD: 68.6 ± 27.11 mL vs 66.2±25.41 mL, p<0.001), smaller end-systole volume (ESV) (mean ± SD: 24.6±8.7 mL vs 26±7.3 mL, p<0.001), and higher EF (64% vs 60.2%, p<0.001). The results for the interpolated series were also different from the original images (closer to the original 16-frame series rather than 8-frame). Conclusion: Changing the frame number from 8 to 16 in cardiac ECG-gated SPECT images caused a significant change in LV volumes and EF. Frame interpolation with sophisticated algorithms can be used to improve the temporal resolution of SPECT images.

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.

Cardiac Resynchronization Therapy for Improving Non-Uniform Thickening of Left Ventricular Wall: Assessment by Quantitative Gated Myocardial Perfusion SPECT.

Cardiac resynchronization therapy (CRT) improves cardiac dyssynchrony in heart failure patients with a wide QRS electrocardiogram (ECG). Assessment of left ventricular (LV) dyssynchrony using echocardiography or other imaging modalities is important to predict CRT effectiveness. In this study, we retrospectively evaluated cardiac nuclear imaging of ECG-gated myocardial perfusion single-photon emission computed tomography (SPECT) with 99mTc-sestamibi for CRT candidate (n = 120) with severe heart failure and wide QRS (> 120 msec) in ECG. To analyze LV non-uniformity, we used the quantitative gated SPECT (QGS) software to calculate changes in regional LV wall thickness during a cardiac cycle (i.e., wall thickening scores). Cardiac events (heart failure, ventricular arrhythmias and cardiac death) after CRT during 38 ± 22 (SD) months were also evaluated. In 97 of 120 patients who underwent QGS before and 6 months after CRT, CRT homogenized non-uniform wall thickening between septal and lateral of the LV especially in CRT responders. This observation was indicated as increase in the lateral deflection (XWT) of wall thickening scores before CRT and its decrease after CRT. In 120 patients with QGS before CRT, the larger XWT before CRT (≥ 16.5) predicted better prognoses after CRT. This finding was similarly observed even in patients with narrower baseline QRS (≤ 140 msec; n = 41 of 120), who usually have less benefits from CRT. In conclusion, CRT improved non-uniformity of wall thickening between the LV septal and lateral regions evaluated using QGS, which is predictive of better prognosis in the chronic phase after CRT.

Risk factors of non-sustained ventricular tachycardia by technetium-perfusion imaging in patients with coronary artery lesions caused by Kawasaki disease

BackgroundSudden death can occur in some patients with non-sustained ventricular tachycardia (NSVT) after myocardial infarction (MI) in those with coronary artery lesions (CAL) caused by Kawasaki disease (KD). The aim of this study was to determine the risk factors for NSVT in the late period after KD by technetium-99m-tetrofosmin myocardial perfusion imaging (MPI). MethodsWe retrospectively analyzed the relation between the appearance of NSVT and the findings in MPI single-photon-emission computed tomography (SPECT) in 75 patients (55 males and 20 females) who had had CAL caused by KD. All the patients had undergone MPI and 24-h Holter electrocardiogram at the same time between 2003 and 2012. The age at MPI ranged from 2 to 44 years (median 19 years), and the time from the onset of KD to MPI ranged from 1 to 44 years (median 18 years). We evaluated extent score (ES), summed rest score (SRS), summed stress score (SSS), summed difference score (SDS), and left ventricular ejection fraction (LVEF) by quantitative gated SPECT software. We analyzed which factors related to NSVT using multivariate logistic regression. Further, we calculated the cut-off point for NSVT using receiver operating characteristic curve. ResultsThe affecting factors were ES (OR, 0.63, 95%CI, 0.35–0.92, p=0.013) and the interval from the onset of KD to MPI (OR, 0.82, 95%CI, 0.69–0.96, p=0.004). The cut-off points for ES and the interval from the onset of KD were 11% (AUC, 0.931, p<0.001) and 18 years (AUC, 0.732, p=0.007), respectively. ConclusionsES is the strongest parameter for predicting NSVT in the late period. In patients with post-KD, adolescence and young adults with ES ≥11% are at risk of fatal ventricular arrhythmia.

Respiratory motion reduction with a dual gating approach in myocardial perfusion SPECT: Effect on left ventricular functional parameters

BackgroundRespiratory motion (RM) complicates the analysis of myocardial perfusion (MP) single-photon emission computed tomography (SPECT) images. The effects of RM on left ventricular (LV) functional variables have not been thoroughly investigated. Methods and resultsThoracic electrical bioimpedance and electrocardiographic signals were recorded from eighteen patients undergoing the rest phase of a 1-day stress/rest cardiac-gated MP-SPECT examination. The signals and list-mode emission data were retrospectively processed to yield standard cardiac- and dual-gated (respiratory and cardiac gating) image sets applying a novel algorithm. LV volume, MP, shape index (SI), wall motion (WM), wall thickening (WT), and phase analysis parameters were measured with Quantitative Perfusion SPECT/Quantitative Gated SPECT software (Cedars-Sinai Medical Center). Image quality was evaluated by three experienced physicians. Dual gating increased LV volume (77.1 ± 26.8 vs 79.8 ± 27.6 mL, P = .006) and decreased SI (0.57 ± 0.05 vs 0.56 ± 0.05, P = .036) and global WT (39.0 ± 11.8% vs 36.9 ± 9.4%, P = .034) compared to cardiac gating, but did not significantly alter perfusion, WM or phase analysis parameters or image quality (P > .05). ConclusionsRM reduction has an effect on LV volume, shape, and WT parameters. RM exerts no significant effect on phase analysis parameters.

Automated SPECT analysis compared with expert visual scoring for the detection of FFR-defined coronary artery disease

PurposeTraditionally, interpretation of myocardial perfusion imaging (MPI) is based on visual assessment. Computer-based automated analysis might be a simple alternative obviating the need for extensive reading experience. Therefore, the aim of the present study was to compare the diagnostic performance of automated analysis with that of expert visual reading for the detection of obstructive coronary artery disease (CAD).Methods206 Patients (64% men, age 58.2 ± 8.7 years) with suspected CAD were included prospectively. All patients underwent 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) and invasive coronary angiography with fractional flow reserve (FFR) measurements. Non-corrected (NC) and attenuation-corrected (AC) SPECT images were analyzed both visually as well as automatically by commercially available SPECT software. Automated analysis comprised a segmental summed stress score (SSS), summed difference score (SDS), stress total perfusion deficit (S-TPD), and ischemic total perfusion deficit (I-TPD), representing the extent and severity of hypoperfused myocardium. Subsequently, software was optimized with an institutional normal database and thresholds. Diagnostic performances of automated and visual analysis were compared taking FFR as a reference.ResultsSensitivity did not differ significantly between visual reading and most automated scoring parameters, except for SDS, which was significantly higher than visual assessment (p < 0.001). Specificity, however, was significantly higher for visual reading than for any of the automated scores (p < 0.001 for all). Diagnostic accuracy was significantly higher for visual scoring (77.2%) than for all NC images scores (p < 0.05), but not compared with SSS AC and S-TPD AC (69.8% and 71.2%, p = 0.063 and p = 0.134). After optimization of the automated software, diagnostic accuracies were similar for visual (73.8%) and automated analysis. Among the automated parameters, S-TPD AC showed the highest accuracy (73.5%).ConclusionAutomated analysis of myocardial perfusion SPECT can be as accurate as visual interpretation by an expert reader in detecting significant CAD defined by FFR.

Comparison of Left Ventricular Phase Parameters Analysis between Two Software Programs in Patients with Normal Gated Single-photon Emission Computed Tomography-Myocardial Perfusion Imaging.

Background:Phase analysis can be easily performed by different software to assess the left ventricular dyssynchrony from gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) with high precision. However, the normal values of histogram bandwidth (HBW) and phase standard deviation (PSD) and their comparison using different programs have not been fully elucidated and actively being evaluated at present. The aim of this study was to determine the phase analysis parameters values and to compare the phase indices of two commonly used programs in a group of patients with normal gated SPECT-MPI.Methods:Phase parameters were retrospectively evaluated in 138 consecutive nondiabetic patients having a normal gated SPECT-MPI using the quantitative gated SPECT (QGS) and Emory Cardiac Toolbox (ECTb) software. HBW, PSD, and phase entropy were calculated separately using both programs.Results:The fair correlation between software programs was observed. HBW and PSD in QGS and ECTb were 26.20 ± 9.7 and 25.46 ± 8.0 (r-value. 56, SEE 6.65) and 6.64 ± 2.5 and 7.65 ± 2.5 (r = 0.54, SEE 2.14), respectively. The value of phase entropy in QGS program was 45.08 ± 6.3. A fair correlation between phase entropy and PSD in QGS was observed (r = 0.44, 95% confidence interval-0.29–0.56).Conclusion:Phase analysis parameters derived from gated SPECT-MPI in patients with normal myocardial perfusion are program dependent and may differ. The results cannot be interchangeably used in the same patients.

Prediction of Flow-Limiting Fractional Flow Reserve in Patients With Stable Coronary Artery Disease Based on Quantitative Myocardial Perfusion Imaging

Although fractional flow reserve (FFR) and myocardial perfusion imaging (MPI) findings fundamentally differ, several cohort studies have revealed that these findings correlate. Here, we investigated whether flow-limiting FFR could be predicted from adenosine stress thallium-201 MPI with single-photon emission computed tomography (SPECT) findings derived from 84 consecutive, prospectively identified patients with stable coronary artery disease and 212 diseased vessels. Among them, FFR was measured in 136 diseased vessels (64%). The findings were compared with regional perfusion abnormalities including stress total perfusion defect (TPD)- rest TPD determined using quantitative perfusion single-photon emission computed tomography software. The FFR inversely correlated the most accurately with stress TPD- rest TPD (r=-0.552, p <0.001). Predictors of major vessels of interest comprising FFR <0.80, included stress TPD- rest TPD, the transient ischemic dilation ratio, left ventricular ejection fraction at rest and beta blockers for left anterior descending artery (LAD) regions, and stress TPD- rest TPD, left ventricular mass, left ventricular ejection fraction at rest, right coronary artery lesions, the transient ischemic dilation ratio, and age for non-LAD regions. The diagnostic accuracy of formulas to predict major vessels of interest with FFR <0.80 was high (sensitivity, specificity and accuracy for LAD and non-LAD: 84%, 87% and 86%, and 75%, 93% and 87%, respectively). In conclusion, although somewhat limited by a sample size and a single-center design, flow-limiting FFR could be predicted from MPI findings with a defined probability. A cohort study might validate our results and provide a novel adjunctive tool with which to diagnose functionally significant coronary artery disease from MPI findings.

Development of Digital Myocardial Phantom to Evaluate Software for Gated SPECT

Background: Real cardiac phantoms are often used to assess the performance of software for gated single-photon emission computed tomography(SPECT) . However, these phantoms have disadvan- tages in that they are not very similar to actual hearts and setting a perfusion defect is not easy. To overcome these problems, we developed a digital myocardial phantom, named%Myo-Simu' . The aims of this study were to check its operation when being incorporated into gated SPECT software and to elucidate its usefulness to assess properties of software. Methods: Myo-Simu yields a simulated left ventricle(LV)approximated as a moving spheroid that preserves shape similarity during the cardiac cycle with a fixed total myocardial volume. Wall thickness, background activity, spatial resolution, statistical noise, and perfusion defects are incorporated into the phantom, and these conditions can be modified by changing the input parameters. We generated various types of hearts by changing the length of the short and long axes, patterns of perfusion defects, spatial resolution, and image noise. Generated SPECT images were applied to Quantitative Gated SPECT(QGS) , Heart Function View, and EXINI Heart software to check the adaptability to gated SPECT analyses. We also evaluated the influences of wall thickness and spatial resolution on QGS analyses. Results: Myo-Simu successfully generated SPECT images of various geometries. These images can be applied to gated SPECT analyses without any problems in operation. In QGS, measured LV volumes changed greatly depending on wall thickness and spatial resolution. Conclusions: Myo-Simu is a feasible phantom for assessing gated SPECT software.

Achieving very-low-dose radiation exposure in cardiac computed tomography, single-photon emission computed tomography, and positron emission tomography.

During the past several years, the need to reduce radiation has become a central issue in cardiac imaging. During this time, radiation dose to the patient in cardiac computed tomography (CT), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) has seen significant reductions without compromising image quality, primarily because of new developments in scanner hardware and reconstruction software. Sub-mSv radiation doses have been reported for cardiac CT.1–5 Stress and rest SPECT myocardial perfusion imaging (MPI) traditionally required ≈15 minutes to register the required number of photon events. New SPECT camera instrumentation and software have now enabled acquisition times as short as 2 minutes, to increase counting efficiency by up to a factor of 7.6 These new systems can also be used to reduce radiation exposure to patients during the MPI scan, allowing a corresponding marked reduction in the administered dose of radioactivity when used with the standard imaging time.7 It is important to keep radiation exposure as low as reasonably achievable. In this review, therefore, we briefly summarize recent technical advances in scanner hardware and reconstruction software, as well as the steps recommended to achieve very low radiation dose in cardiac imaging. We also review the current status of radiation in cardiac CT, SPECT, and PET as reported in multicenter studies and registries, as well as current clinical reports of radiation dose reduction, which illustrate the potential of the newest technology. Direct imaging of the coronary arteries is challenging because of their small sizes and rapid motion. Cardiac CT requires high temporal resolution to freeze such motion and therefore has benefited from steadily increasing CT gantry rotation speed. Imaging of the coronary arteries also requires high spatial resolution and reconstruction of submillimeter slices. Multiple transaxial slices need to be acquired simultaneously for complete …

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.

Underestimation of the ejection fraction using the quantitative gated SPECT for patients with myocardial hypertrophy

The aim of the present study is to quantify the degree of the error as a function of the left ventricular (LV) wall thickness, in calculation of the ejection fraction (EF) using gated single-photon emission computed tomography (SPECT). The essential error of quantitative gated SPECT (QGS) software in patients with myocardial hypertrophy has not been quantitatively estimated. Forty-six patients with known or suspected hypertrophic cardiomyopathy underwent gated myocardial perfusion SPECT and cardiac magnetic resonance (MR) imaging. The EF value was automatically calculated from gated SPECT using the QGS software. Twelve points of regional LV wall thickness and the EF value were estimated from MR images. Only a fair correlation was found between the QGS-EF and the MR-EF values (r = 0.48, y = 0.49x + 26.80, p < 0.01), and the QGS-EF was underestimated (r = 0.25, y = 0.90x) in 30 patients with myocardial hypertrophy (mean wall thickness > 12 mm). The magnitude of the error of the EF quantification from gated SPECT showed a significant negative correlation with the mean 12-point LV wall thickness in all 46 patients (r = -0.67, y = -4.12x + 40.44, p < 0.0001). The degree of the error of the ESV and that of the EDV showed positive correlation with the mean LV wall thickness (r = 0.55, y = 5.46x - 56.13, p < 0.0001; r = 0.31, y = 4.20x - 55.28, p < 0.05, respectively). The underestimation of EF increases with the degree of myocardial hypertrophy, because of the overestimation of the LV cavity especially in the end-systolic phase.

&lt;sup&gt;201&lt;/sup&gt;Tl心筋SPECTにおける三次元動画表示を用いた左室壁運動評価の検討─心臓CTとの比較─

Advances in computed tomography (CT) technology make it possible to obtain left ventricular wall motion using 3D reconstruction. In this study, we compared the images obtained from CT and (201)Tl electrocardiogram (ECG) gated single photon emission computed tomography (SPECT). In 20 patients with ischemic heart disease, we performed (201)Tl ECG gated SPECT (GE Healthcare Millennium VG) and ECG gated CT (Philips Medical Systems Brilliance iCT) to evaluate of left ventricular wall motion during the resting phase. In SPECT, left ventricular images were reconstructed using quantitative gated SPECT (QGS) software. In CT, the images were reconstructed using Virtual Place (AZE Software). The left ventricle was classified into five regions (anterior, lateral, inferior, septal, and apical). The amplitude of the wall motion was classified into five grades according to AHA classification. The values of the wall motion were separately checked by two radiographers. Assessment of left ventricular function myocardial wall movement using the three-dimensional movie display with ECG gated myocardial SPECT data was in agreement with the evaluation by cardiac CT inspection, and corresponded with wall motion in 88 of all 100 segments. SPECT analysis has the same quantity as that of obtained from CT for evaluation of left ventricular wall motion.

Performance of a semiconductor SPECT system: comparison with a conventional Anger-type SPECT instrument

ObjectiveThe performance of a new single photon emission computed tomography (SPECT) scanner with a cadmium-zinc-telluride (CZT) solid-state semiconductor detector (Discovery NM 530c; D530c) was evaluated and compared to a conventional Anger-type SPECT with a dual-detector camera (Infinia).MethodsThree different phantom studies were performed. Full width at half maximum (FWHM) was measured using line sources placed at different locations in a cylindrical phantom. Uniformity was measured using cylindrical phantoms with 3 different diameters (80, 120, and 160 mm). Spatial resolution was evaluated using hot-rod phantoms of various diameters (5, 9, 13, 16, and 20 mm). Three different myocardial phantom studies were also performed, acquiring projection data with and without defects, and evaluating the interference of liver and gallbladder radioactivity. In a clinical study, the D530c employed list-mode raw data acquisition with electrocardiogram (ECG)-gated acquisition over a 10-min period. From the 10-min projection data, 1-, 3-, 5-, 7- and 10-min SPECT images were reconstructed.ResultsThe FWHM of the D503c was 1.73–3.48 mm (without water) and 3.88–6.64 mm (with water), whereas the FWHM of the Infinia was 8.17–12.63 mm (without water) and 15.48–16.28 mm (with water). Non-uniformity was larger for the D530c than for the Infinia. Truncation artifacts were also observed with the D530c in a Φ160 mm phantom. The contrast ratio, as defined by myocardial defect/non-defect ratio, was better for the D530c than for the Infinia, and the influence from liver and gallbladder radioactivities was less. Quantitative gated SPECT (QGS) software demonstrated significant differences between data captured over a 10-min period, relative to those acquired over periods of <5 min; there was no difference between ejection fractions calculated using data capture for periods ≥5 min (p < 0.05).ConclusionsThe D530c is superior to the Infinia, with regard to both spatial resolution and sensitivity. In this study, these advantages were confirmed by the myocardial phantom and in a clinical setting, using the QGS software.

Reproducibility of Cerebral Blood Flow Assessment using a Quantitative SPECT Reconstruction Program and Split-Dose 123I-Iodoamphetamine in Institutions with Different γ-Cameras and Collimators

Single photon emission computed tomography (SPECT) is used widely in clinical studies. However, the technique requires image reconstruction and the methods for correcting scattered radiation and absorption are not standardized among SPECT procedures. Therefore, quantitation of cerebral blood flow (CBF) may not be constant across SPECT models. The quantitative SPECT (QSPECT) software package has been developed for standardization of CBF. Using the QSPECT/dual-table autoradiographic (DTARG) method, CBF and cerebral vascular reactivity (CVR) at rest and after acetazolamide challenge can be evaluated using (123)I-iodoamphetamine in a single SPECT session. In this study, we examined the reproducibility of quantitative regional CBF and CVR in QSPECT/DTARG using different SPECT models at two facilities. The subjects were nine patients with chronic cerebral ischemic disease who underwent QSPECT/DTARG at both facilities with use of different γ-cameras and collimators. There were significant correlations for CBF at rest and after acetazolamide challenge measured at the two facilities. The consistency of the CBFs of the patients measured at the two facilities were good in all cases. Our results show that CBF measured by QSPECT/DTARG in the same patients is reproducible in different SPECT models. This indicates that standardized evaluation of CBF can be performed in large multicenter studies.