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

Adjustment of acquisition arc in cardiac malposition during myocardial perfusion SPECT imaging: computer simulation based on deterministic modeling

OBJECTIVES

To simulate cardiac malpositions, leftward and rightward shift and dextrocardia, and also to compare distribution of activity of septal and lateral walls of left ventricle acquired in standard acquisition arc and after relevant adjustment.

METHODS

In this study, digital phantoms with cardiac malpositions are designed and procedure of acquisition of scan in standard arc (from right anterior oblique to left posterior oblique) and adjusted acquisition arc is simulated. The three situations of malposition including leftward and rightward shift and dextrocardia are considered. For all types, acquisition is conducted in standard and then adjusted arcs (from anterior to posterior and also from right to left for leftward and rightward shifts, respectively, and for dextrocardia, from left anterior oblique to right posterior oblique). All obtained projections are reconstructed using the algorithm of filtered back projection. During forward projection to obtain sinograms, radiation attenuation is also modeled by incorporation of a simplified transmission map to emission map. The resulting tomographic slices of the LV (septum, apex, and lateral wall) are presented visually and are compared by plotting intensity profiles of the walls. Finally, normalized error images are also computed. All the computations are performed in MATLAB software package.

RESULTS

In transverse slice, septum and lateral wall are attenuated progressively from apex, which is closer to the camera, to the base in similar fashion. In tomographic slices of standard acquisition arc, the septum shows remarkably higher activity compared to lateral wall. However, after adjustment, both seems equally intense and progressively being attenuated from apex to base, similar to that found in phantom with normally positioned heart. Likewise, for the phantom with rightward shift, when the scanning was done in standard arc, the septum is more intense than the lateral wall. And similarly, adjustment of the arc renders both walls equally intense. In dextrocardia, level of attenuation of basal parts of septum and lateral wall is higher in 360° arc compared to adjusted 180° arc.

CONCLUSION

Adjustment of acquisition arc exerts perceptible changes in distribution of activity over LV walls which are more compatible with normally positioned heart.

Iodine-123 β-methyl-P-iodophenyl-pentadecanoic Acid (123I-BMIPP) Myocardial Scintigraphy for Breast Cancer Patients and Possible Early Signs of Cancer-Therapeutics-Related Cardiac Dysfunction (CTRCD)

(1) Background: The mortality of breast cancer has decreased due to the advancement of cancer therapies. However, more patients are suffering from cancer-therapeutics-related cardiac dysfunction (CTRCD). Diagnostic and treatment guidelines for CTRCD have not been fully established yet. Ultrasound cardiogram (UCG) is the gold standard for diagnosis of CTRCD, but many breast cancer patients cannot undergo UCG due to the surgery wounds or anatomical reasons. The purpose of the study is to evaluate the usefulness of myocardial scintigraphy using Iodine-123 β-methyl-P-iodophenyl-pentadecanoic acid (123I-BMIPP) in comparison with UCG. (2) Methods: 100 breast cancer patients who received chemotherapy within 3 years underwent Thallium (201Tl) and 23I-BMIPP myocardial perfusion and metabolism scintigraphy. The images were visually evaluated by doctors and radiological technologists, and the grade of uptake reduction was scored by Heart Risk View-S software (Nihon Medi-Physics). The scores were deployed in a 17-segment model of the heart. The distribution of the scores were analyzed. (3) Results: Nine patients (9%) could not undergo UCG. No correlation was found between left ventricular ejection fraction (LVEF) and Heart Risk View-S scores of 201Tl myocardial perfusion scintigraphy nor those of BMIPP myocardial metabolism scintigraphy. In a 17-segment model of the heart, the scores of the middle rings were higher than for the basal ring. (4) Conclusions: Evaluation by UCG is not possible for some patients. Myocardial scintigraphy cannot serve as a perfect alternative to UCG. However, it will become the preferable second-choice screening test, as it could point out the early stage of CTRCD.

Integration of quantitative absolute myocardial blood flow estimates from dynamic CZT-SPECT improves the detection of coronary artery disease

BACKGROUND

Balanced ischemia with multi-vessel coronary artery disease (CAD) is difficult to diagnose with semiquantitative single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Dynamic cardiac SPECT provides quantitative estimations of stenosis severity and ischemic burden by assessing myocardial flow reserve (MFR) and myocardial blood flow (MBF). The aim of this study was to evaluate the incremental value of dynamic SPECT in multi-vessel coronary artery disease (CAD).

METHODS

Patients with suspected CAD who underwent dynamic ECG-gated dipyridamole MPI and coronary angiography within 6 months were retrospectively reviewed. The performance of summed stress, rest and difference scores (SSS, SRS, SDS), post-stress and resting MBF (MBFs, MBFr) and MFR were compared at both patient level and vessel level.

RESULTS

In 32 patients with 39 stenotic vessels, 12 had three-vessel disease (38%). Globally increased SSS and impaired MBF values were significantly associated with significant CAD at the patient level, but SDS and MFR were not. Regional increases in SSS and reductions in both MBFs and MBFr were significantly associated with stenotic vessels. The best cutoff value of global MBFs to predict CAD was 3.5 ml·g-1·min-1 (area under the curve, AUC = .84, P = .002). The best cutoff value of regional MBFs to detect significant stenosis was 3.6 ml·g-1·min-1 (AUC = .74, P < .001). However, the best possible cut-off values of MFR were not found. Sex-difference in both global and regional MBFr but MBFs was found, which might result in the non-significance in MFR.

CONCLUSIONS

This study validated a clinically available method to quantify MFR using dynamic CZT-SPECT. This method improved the detectability of multi-vessel CAD, and absolute MBFs was superior to MFR and other semiquantitative MPI parameters.

Clinical Validation of Japanese Normal Myocardial Perfusion Imaging Databases Using Semi-conductor Gamma Camera (D-SPECT): Japanese Society of Nuclear Cardiology Working Group Reports

Objective: A working group (WG) of the Japanese Society of Nuclear Cardiology (JSNC) determined Japanese normal databases of myocardial perfusion single-photon emission computed tomography (SPECT) on semi-conductor gamma camera (D-SPECT), and the aim of this study was to validate its clinical utility. Materials and methods: The normal myocardial perfusion SPECT (MPS) databases of Japanese patients in the ²⁰¹Tl stress/redistribution protocol (²⁰¹Tl protocol), ^99mTc stress/rest or rest/stress protocol (^99mTc protocol), and rest ^99mTc/stress ²⁰¹Tl simultaneous acquisition dual-isotope protocol (SDI protocol) were created by JSNC WG. The WG collected clinical cases for the ²⁰¹Tl protocol (male/female [m/f], 8/8), ^99mTc protocol (m/f, 9/7), and SDI protocol (m/f, 10/10) from WG participating hospitals. Four WG members read those clinical cases on a 17-segment and 5-point scale (0-4). Using the most frequent values as the score for each segment, weighted κ values were calculated with the scores obtained from quantitative perfusion software (QPS). Results: Weighted κ values were as follows; ²⁰¹Tl stress/female, 0.77; ²⁰¹Tl rest/female, 0.74; ²⁰¹Tl stress/male, 0.81; ²⁰¹Tl rest/male, 0.68; ^99mTc stress/female, 0.77; ^99mTc rest/female, 0.62; ^99mTc stress/male, 0.77; ^99mTc rest/male, 0.75; SDI stress/female, 0.87; SDI rest/female, 0.82; SDI stress/male, 0.87; SDI rest/male, 0.85. Conclusions: The diagnostic accuracy of Japanese MPS normal databases on D-SPECT were comparable with nuclear cardiology expert reading and further clinical applications are expected.

Diagnostic Performance of PET Versus SPECT Myocardial Perfusion Imaging in Patients with Smaller Left Ventricles: A Substudy of the 18F-Flurpiridaz Phase III Clinical Trial

The performance of SPECT myocardial perfusion imaging (MPI) may deteriorate in smaller hearts, primarily because of the lower resolution of conventional Anger cameras. ¹⁸F-flurpiridaz is a novel PET MPI agent with superior image and defect resolution. We sought to determine the diagnostic performance of ^99mTc-labeled SPECT MPI compared with ¹⁸F-flurpiridaz PET MPI according to left ventricle (LV) size. Methods: We conducted a substudy of the phase III clinical trial of flurpiridaz (n = 750) and stratified diagnostic performance according to the median PET LV end-diastolic volume (LVEDV), with smaller LVs defined as having an LVEDV of less than 113 mL (n = 369) and larger LVs defined as having an LVEDV of at least 113 mL (n = 381). Images were interpreted by the majority rule of 3 independent masked readers. The reference standard was quantitative invasive angiography, with at least 50% stenosis in at least 1 coronary artery considered significant. Results: SPECT performance decreased significantly from an area under the curve (AUC) of 0.75 in larger LVs to 0.67 in smaller LVs (P = 0.03), whereas PET performance was similar in larger and smaller LVs (AUC, 0.79 vs. 0.77, P = 0.49). Accordingly, in smaller LVs, PET had a higher AUC (0.77) than the SPECT AUC (0.67) (P < 0.0001), a phenomenon driven by female patients (P < 0.0001). In smaller LVs, there was a degradation of SPECT sensitivity that was highly significant (P < 0.001), whereas there was no significant change in PET sensitivity according to LV size (P = 0.07). Overall, PET had significantly higher sensitivity than SPECT in both smaller LVs (67% vs. 43%, P < 0.001) and larger LVs (76% vs. 61%, P < 0.001). The specificities of PET and SPECT were similar in larger LVs (76% vs. 83%, P = 0.11). Although SPECT specificity improved in smaller compared with larger LVs (90% vs. 83%, P = 0.03), the PET specificity did not change with LV size (76% vs. 76%, P = 0.9). Conclusion: The diagnostic performance of ¹⁸F-flurpiridaz PET MPI is not affected by LV size and is superior to SPECT MPI in patients with smaller LVs, highlighting the importance of appropriate test selection in these patients.

Ability of artificial intelligence to diagnose coronary artery stenosis using hybrid images of coronary computed tomography angiography and myocardial perfusion SPECT

BACKGROUND

Detecting culprit coronary arteries in patients with ischemia using only myocardial perfusion single-photon emission computed tomography (SPECT) can be challenging. This study aimed to improve the detection of culprit regions using an artificial neural network (ANN) to analyze hybrid images of coronary computed tomography angiography (CCTA) and myocardial perfusion SPECT.

METHODS

This study enrolled 59 patients with stable coronary artery disease (CAD) who had been assessed by coronary angiography within 60 days of myocardial perfusion SPECT. Two nuclear medicine physicians interpreted the myocardial perfusion SPECT and hybrid images with four grades of confidence, then drew regions on polar maps to identify culprit coronary arteries. The gold standard was determined by the consensus of two other nuclear cardiology specialist based on coronary angiography findings and clinical information. The ability to detect culprit coronary arteries was compared among experienced nuclear cardiologists and the ANN. Receiver operating characteristics (ROC) curves were analyzed and areas under the ROC curves (AUC) were determined.

RESULTS

Using hybrid images, observer A detected CAD in the right (RCA), left anterior descending (LAD), and left circumflex (LCX) coronary arteries with 83.6%, 89.3%, and 94.4% accuracy, respectively and observer B did so with 72.9%, 84.2%, and 89.3%, respectively. The ANN was 79.1%, 89.8%, and 89.3% accurate for each coronary artery. Diagnostic accuracy was comparable between the ANN and experienced nuclear medicine physicians. The AUC was significantly improved using hybrid images in the RCA region (observer A: from 0.715 to 0.835, p = 0.0031; observer B: from 0.771 to 0.843, p = 0.042). To detect culprit coronary arteries in perfusion defects of the inferior wall without using hybrid images was problematic because the perfused areas of the LCX and RCA varied among individuals.

CONCLUSIONS

Hybrid images of CCTA and myocardial perfusion SPECT are useful for detecting culprit coronary arteries. Diagnoses using artificial intelligence are comparable to that by nuclear medicine physicians.

Characteristics of iodine-123 IQ-SPECT/CT imaging compared with conventional SPECT/CT

OBJECTIVES

Although the utility of IQ-SPECT imaging using ^99mTc and ²⁰¹Tl myocardial perfusion SPECT has been reported, ¹²³I-labeled myocardial SPECT has not been fully evaluated. We determined the characteristics and utility of ¹²³I IQ-SPECT imaging compared with conventional SPECT (C-SPECT).

METHODS

Two myocardial phantom patterns were used to simulate normal myocardium and myocardial infarction. SPECT acquisition was performed using a hybrid dual-head SPECT/CT system equipped with a SMARTZOOM collimator for IQ-SPECT or a low-medium energy general purpose collimator for C-SPECT. Projection data were reconstructed using ordered subset expectation maximization with depth-dependent 3-dimensional resolution recovery for C-SPECT and ordered subset conjugate gradient minimizer method for IQ-SPECT. Three types of myocardial image were created; namely, no correction (NC), with attenuation correction (AC), and with both attenuation and scatter corrections (ACSC). Five observers visually scored the homogeneity of normal myocardium and defect severity of the myocardium with inferior defects by a five-point scale: homogeneity scores (5 = homogeneous to 1 = inhomogeneous) and defect scores (5 = excellent to 1 = poor). We also created a 17-segment polar map and quantitatively assessed segmental %uptake using a myocardial phantom with normal findings and defects.

RESULTS

The average visual homogeneity scores of the IQ-SPECT with NC and ACSC were significantly higher than that of C-SPECT, whereas the average visual defect scores of IQ-SPECT with AC and ACSC were significantly lower. The %uptake of all segments for IQ-SPECT with NC was significantly higher than that of C-SPECT. Furthermore, the subtraction of %uptake for C-SPECT and IQ-SPECT was the largest in inferior wall, which was approximately 10.1%, 14.7% and 14.4% for NC, AC and ACSC, respectively. The median % uptake values of the inferior wall with defect areas for C-SPECT and IQ-SPECT were 46.9% and 50.7% with NC, 59.8% and 69.2% with AC, and 54.7% and 66.5% with ACSC, respectively.

CONCLUSION

¹²³I IQ-SPECT imaging significantly improved the attenuation artifact compared with C-SPECT imaging. Although the defect detectability of IQ-SPECT was inferior to that of C-SPECT, ¹²³I IQ-SPECT images with NC and ACSC met the criteria for defect detectability. Use of ¹²³I IQ-SPECT is suitable for routine examinations.

Myocardial perfusion and left ventricular quantitative parameters obtained using gated myocardial SPECT: Comparison of three software packages

BACKGROUND

The aim of the present study was to compare Emory Cardiac Toolbox, Myovation, and Quantitative Gated SPECT software regarding the automatic measurements of perfusion and functional left ventricular (LV) quantitative parameters, summed stress score (SSS), perfusion defect score, LV ejection fraction (LVEF), end-diastolic volume, and end-systolic volume (ESV).

METHODS AND RESULTS

99mTc-tetrofosmin gated SPECT studies were performed in 634 consecutive patients based on the one-day stress/rest protocol. Participants were divided into subgroups according to heart size (ESV cut-off value: 25 mL), perfusion (SSS >/≤3), and other patient/protocol-related factors. LVEF was categorized as normal (≥50%), mildly moderately impaired (35-49%), and severely abnormal (<35%). The concordance between the packages was good to excellent, in overall population, ESV ≤25 mL, ESV >25 mL, and SSS >3 subgroups (intraclass correlation coefficients, ICCs 0.73-0.93). In SSS ≤3 subgroup, the correlation was excellent for LV functional parameters, but suboptimal for perfusion variables (ICCs 0.30-0.83). LVEF categorization revealed similar variability (discordance 18.1 and 11.1% for stress/rest LVEF values, respectively). Pair comparisons demonstrated considerable differences concerning all parameters for all patient subgroups. The statistical significance of our findings by ESV and SSS classifications was evaluated.

CONCLUSIONS

Despite the significant concordance between software packages, considerable differences in mean values of myocardial perfusion and LV functional parameters were demonstrated.

Artificial neural network retrained to detect myocardial ischemia using a Japanese multicenter database

Purpose

An artificial neural network (ANN) has been applied to detect myocardial perfusion defects and ischemia. The present study compares the diagnostic accuracy of a more recent ANN version (1.1) with the initial version 1.0.

Methods

We examined 106 patients (age, 77 ± 10 years) with coronary angiographic findings, comprising multi-vessel disease (≥ 50% stenosis) (52%) or old myocardial infarction (27%), or who had undergone coronary revascularization (30%). The ANN versions 1.0 and 1.1 were trained in Sweden (n = 1051) and Japan (n = 1001), respectively, using ^99mTc-methoxyisobutylisonitrile myocardial perfusion images. The ANN probabilities (from 0.0 to 1.0) of stress defects and ischemia were calculated in candidate regions of abnormalities. The diagnostic accuracy was compared using receiver-operating characteristics (ROC) analysis and the calculated area under the ROC curve (AUC) using expert interpretation as the gold standard.

Results

Although the AUC for stress defects was 0.95 and 0.93 (p = 0.27) for versions 1.1 and 1.0, respectively, that for detecting ischemia was significantly improved in version 1.1 (p = 0.0055): AUC 0.96 for version 1.1 (sensitivity 87%, specificity 96%) vs. 0.89 for version 1.0 (sensitivity 78%, specificity 97%). The improvement in the AUC shown by version 1.1 was also significant for patients with neither coronary revascularization nor old myocardial infarction (p = 0.0093): AUC = 0.98 for version 1.1 (sensitivity 88%, specificity 100%) and 0.88 for version 1.0 (sensitivity 76%, specificity 100%). Intermediate ANN probability between 0.1 and 0.7 was more often calculated by version 1.1 compared with version 1.0, which contributed to the improved diagnostic accuracy. The diagnostic accuracy of the new version was also improved in patients with either single-vessel disease or no stenosis (n = 47; AUC, 0.81 vs. 0.66 vs. p = 0.0060) when coronary stenosis was used as a gold standard.

Conclusion

The diagnostic ability of the ANN version 1.1 was improved by retraining using the Japanese database, particularly for identifying ischemia.

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

Purpose

Traditionally, 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).

Methods

206 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.

Results

Sensitivity 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%).

Conclusion

Automated analysis of myocardial perfusion SPECT can be as accurate as visual interpretation by an expert reader in detecting significant CAD defined by FFR.

Electronic supplementary material

The online version of this article (10.1007/s00259-018-3951-1) contains supplementary material, which is available to authorized users.

Diagnostic accuracy of an artificial neural network compared with statistical quantitation of myocardial perfusion images: a Japanese multicenter study

PURPOSE

Artificial neural networks (ANN) might help to diagnose coronary artery disease. This study aimed to determine whether the diagnostic accuracy of an ANN-based diagnostic system and conventional quantitation are comparable.

METHODS

The ANN was trained to classify potentially abnormal areas as true or false based on the nuclear cardiology expert interpretation of 1001 gated stress/rest 99mTc-MIBI images at 12 hospitals. The diagnostic accuracy of the ANN was compared with 364 expert interpretations that served as the gold standard of abnormality for the validation study. Conventional summed stress/rest/difference scores (SSS/SRS/SDS) were calculated and compared with receiver operating characteristics (ROC) analysis.

RESULTS

The ANN generated a better area under the ROC curves (AUC) than SSS (0.92 vs. 0.82, p < 0.0001), indicating better identification of stress defects. The ANN also generated a better AUC than SDS (0.90 vs. 0.75, p < 0.0001) for stress-induced ischemia. The AUC for patients with old myocardial infarction based on rest defects was 0.97 (0.91 for SRS, p = 0.0061), and that for patients with and without a history of revascularization based on stress defects was 0.94 and 0.90 (p = 0.0055 and p < 0.0001 vs. SSS, respectively). The SSS/SRS/SDS steeply increased when ANN values (probability of abnormality) were >0.80.

CONCLUSION

The ANN was diagnostically accurate in various clinical settings, including that of patients with previous myocardial infarction and coronary revascularization. The ANN could help to diagnose coronary artery disease.

CT-based SPECT attenuation correction and assessment of infarct size: results from a cardiac phantom study

RATIONALE

Myocardial perfusion SPECT is a commonly performed, well established, clinically useful procedure for the management of patients with coronary artery disease. However, the attenuation of photons from myocardium impacts the quantification of infarct sizes. CT-Attenuation Correction (AC) potentially resolves this problem. This contention was investigated by analyzing various parameters for infarct size delineation in a cardiac phantom model.

METHODS

A thorax phantom with a left ventricle (LV), fillable defects, lungs, spine and liver was used. The defects were combined to simulate 6 infarct sizes (5-20% LV). The LV walls were filled with 100120 kBq/ml ^99mTc and the liver with 10-12 kBq/ml ^99mTc. The defects were filled with water of 50% LV activity to simulate transmural and non-transmural infarction, respectively. Imaging of the phantom was repeated for each configuration in a SPECT/CT system. The defects were positioned in the anterior as well as in the inferior wall. Data were acquired in two modes: 32 views, 30 s/view, 180° and 64 views, 15 s/view, 360° orbit. Images were reconstructed iteratively with scatter correction and resolution recovery. Polar maps were generated and defect sizes were calculated with variable thresholds (40-60%, in 5% steps). The threshold yielding the best correlation and the lowest mean deviation from the true extents was considered optimal.

RESULTS

AC data showed accurate estimation of transmural defect extents with an optimal threshold of 50% [non attenuation correction (NAC): 40%]. For the simulation of non-transmural defects, a threshold of 55% for AC was found to yield the best results (NAC: 45%). The variability in defect size due to the location (anterior versus inferior) of the defect was reduced by 50% when using AC data indicating the benefit from using AC. No difference in the optimal threshold was observed between the different orbits.

CONCLUSION

Cardiac SPECT/CT shows an improved capability for quantitative defect size assessment in phantom studies due to the positive effects of attenuation correction.

Prognostic Value of 123I-BMIPP SPECT in Patients with Nonischemic Heart Failure with Preserved Ejection Fraction

Imaging of myocardial fatty acid metabolism using ¹²³I-betamethyl-p-iodophenyl-pentadecanoic acid (¹²³I-BMIPP) SPECT is useful for identifying high-risk patients with known ischemic heart disease. However, its utility for patients who have nonischemic heart failure with preserved ejection fraction is not well known. This study aimed to evaluate the prognostic value of the ¹²³I-BMIPP defect score in such patients. Methods: Of 804 consecutive patients who were admitted to the hospital because of acute heart failure and underwent ¹²³I-BMIPP SPECT, we identified 133 (mean age ± SD, 73 ± 13 y) who had normal coronary arteries by invasive coronary angiography and preserved left ventricular ejection fraction (≥50%) by echocardiography. ¹²³I-BMIPP defects were quantitatively scored to obtain summed defect scores in 17 segments of ¹²³I-BMIPP SPECT images. The patients were divided into 2 groups based on their score. The multivariate Cox model was used to assess a possible correlation between a higher score (≥4, n = 46) and major adverse cardiac events, including cardiac death, cardiovascular events, and hospitalization for heart failure, compared with a lower score (<4, n = 87). Results: During a mean follow-up of 2.5 y, 35 major adverse cardiac events occurred. The median scores in the high-score and low-score groups were 7.13 ± 4.21 and 1.29 ± 0.80, respectively. By multivariate Cox analysis, a higher score was associated with increased major adverse cardiac events, compared with a lower score (hazard ratio, 11.04; 95% confidence interval, 4.93-24.74; P < 0.001). Conclusion: This study demonstrated that the defect score by ¹²³I-BMIPP SPECT may have potential prognostic value in patients who have nonischemic heart failure with preserved ejection fraction.

Reducing the small-heart effect in pediatric gated myocardial perfusion single-photon emission computed tomography

BACKGROUND

We compared two reconstruction algorisms and two cardiac functional evaluation software programs in terms of their accuracy for estimating ejection fraction (EF) of small hearts (SH).

METHODS

The study group consisted of 66 pediatric patients. Data were reconstructed using a filtered back projection (FBP) method without the resolution correction (RC) and an iterative method based on an ordered subset expectation maximization (OSEM) algorithm with the RC. EF was evaluated using two software programs of quantitative gated single-photon emission computed tomography (SPECT) (QGS) and cardioREPO. We compared the EF of gated myocardial perfusion SPECT to echocardiographic measurement (Echo).

RESULTS

Forty-eight of 66 patients had an end-systolic volume < 20 mL which was used as the criterion for being included in the SH group, and the SH effect led to an overestimation of EF. While significant differences were observed between Echo (66.9 ± 5.0%) and QGS-FBP without RC (76.9 ± 8.4%, P < .0001), QGS-OSEM with RC (76.6 ± 8.6%, P < .0001), and cardioREPO-FBP without RC (72.1 ± 10.0%, P = .0011), no significant difference was observed between Echo and cardioREPO-OSEM with RC (67.4 ± 6.1%) in SH group.

CONCLUSIONS

In pediatric gated myocardial perfusion SPECT, the SH effect can be significantly reduced when an OSEM algorithm is used with RC in combination with the specific cardioREPO algorithm.

IQ-SPECT for thallium-201 myocardial perfusion imaging: effect of normal databases on quantification

OBJECTIVE

Although IQ-single-photon emission computed tomography (SPECT) provides rapid acquisition and attenuation-corrected images, the unique technology may create characteristic distribution different from the conventional imaging. This study aimed to compare the diagnostic performance of IQ-SPECT using Japanese normal databases (NDBs) with that of the conventional SPECT for thallium-201 (²⁰¹Tl) myocardial perfusion imaging (MPI).

METHODS

A total of 36 patients underwent 1-day ²⁰¹Tl adenosine stress-rest MPI. Images were acquired with IQ-SPECT at approximately one-quarter of the standard time of conventional SPECT. Projection data acquired with the IQ-SPECT system were reconstructed via an ordered subset conjugate gradient minimizer method with or without scatter and attenuation correction (SCAC). Projection data obtained using the conventional SPECT were reconstructed via a filtered back projection method without SCAC. The summed stress score (SSS) was calculated using NDBs created by the Japanese Society of Nuclear Medicine working group, and scores were compared between IQ-SPECT and conventional SPECT using the acquisition condition-matched NDBs. The diagnostic performance of the methods for the detection of coronary artery disease was also compared.

RESULTS

SSSs were 6.6 ± 8.2 for the conventional SPECT, 6.6 ± 9.4 for IQ-SPECT without SCAC, and 6.5 ± 9.7 for IQ-SPECT with SCAC (p = n.s. for each comparison). The SSS showed a strong positive correlation between conventional SPECT and IQ-SPECT (r = 0.921 and p < 0.0001), and the correlation between IQ-SPECT with and without SCAC was also good (r = 0.907 and p < 0.0001). Regarding diagnostic performance, the sensitivity, specificity, and accuracy were 80.8, 78.9, and 79.4%, respectively, for the conventional SPECT; 80.8, 80.3, and 82.0%, respectively, for IQ-SPECT without SCAC; and 88.5, 86.8, and 87.3%, respectively, for IQ-SPECT with SCAC, respectively. The area under the curve obtained via receiver operating characteristic analysis were 0.77, 0.80, and 0.86 for conventional SPECT, IQ-SPECT without SCAC, and IQ-SPECT with SCAC, respectively (p = n.s. for each comparison).

CONCLUSIONS

When appropriate NDBs were used, the diagnostic performance of ²⁰¹Tl IQ-SPECT was comparable with that of the conventional system regardless of different characteristics of myocardial accumulation in the conventional system.

Artifacts in Quantitative analysis of myocardial perfusion SPECT, using Cedars-Sinai QPS Software

Quantitative analysis of myocardial perfusion Single photon emission computerized tomography (SPECT) images is increasingly applied in modern nuclear cardiology practice, assisting in the interpretation of myocardial perfusion images (MPI). There are different extensively validated state-of-the-art software packages, including QPS (cedars-Sinai), Corridor 4DM (University of Michigan) and Emory cardiac toolbox (Emory university), providing highly accurate and reproducible data. However, these software packages may suffer from potential artifacts related to patient or technical factors. By recognizing the source of such artifacts, the interpreting physician can avoid misinterpretation of MPI study. In this review, we discuss some of technical pitfalls that may occur in Quantitative Perfusion SPECT software (QPS, cedars-Sinai Medical center).

The value of local normal limits in quantitative Thallium-201 CZT MPI SPECT

BACKGROUND

Considering the distinctive characteristics of CZT detectors, automatic quantification of ischemia using normal limits included with software package may deliver suboptimal results for CAD detection. The present study aims to evaluate the benefits of creating normal limits specific to a local population and laboratory protocol.

METHODS AND RESULTS

Two groups were selected from patients who had undergone a CZT MPI. Normal limits were generated with the QPS application based on the population with low likelihood of CAD. Using the vendor-supplied and the population-specific normal limits i-TPD and vessel-specific SDS results obtained for patients who had subsequently undergone coronary angiography were compared with coronary angiography data. A weak correlation was observed for low i-TPD (stress TPD minus rest TPD) and SDS values. Both databases gave similar values for the area under the ROC curve concerning i-TPD (0.75 to 0.74) and SDS results (0.72 to 0.75 for the LAD, 0.62 to 0.64 for the LCx, and 0.63 to 0.67 for the RCA). Sensitivity (60%), specificity (78%), and predictive positive (84%) and negative (52%) values were also similar with a diagnostic and prognostic threshold value.

CONCLUSION

The use of a population-specific created database did not influence the diagnostic value of thallium-201 MPI QPS results using a CZT camera.

Influence of acquisition orbit on phase analysis of gated single photon emission computed tomography myocardial perfusion imaging for assessment of left ventricular mechanical dyssynchrony

OBJECTIVE

The association between left ventricular (LV) dyssynchrony parameters, given by phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), and acquisition orbits is unclear. The aim of this study was to assess the dependence of LV dyssynchrony parameters on acquisition orbits.

METHODS

Ninety-nine patients who underwent ²⁰¹Tl-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. Forty-four patients who underwent ^99mTc-tetrofosmin-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. The major hypoperfusion group with ²⁰¹Tl was divided into inferior or non-inferior wall hypoperfusion subgroups, and anteroseptal or non-anteroseptal wall hypoperfusion subgroups. Gated SPECT MPI data over a 360° acquisition orbit (360° images) and a 180° acquisition orbit (180° images) were reconstructed, and histogram bandwidth (HBW) and phase standard deviation (PSD) were compared.

RESULTS

Between 360° and 180° images with ²⁰¹Tl, there were significant differences in HBW and PSD both globally (HBW 34.8 ± 16.6 vs. 29.1 ± 10.2; PSD 8.8 ± 4.9 vs. 7.0 ± 2.3, p < 0.05 for both) and in the inferior wall (HBW 29.5 ± 15.5 vs. 23.3 ± 9.0; PSD 7.6 ± 4.6 vs. 5.6 ± 2.4, p < 0.001 for both) in the major hypoperfusion group, and also in the inferior wall in all subgroups of the major hypoperfusion group. In contrast, no segment had any significant differences in HBW or PSD between 360° and 180° images with ^99mTc.

CONCLUSION

Differences in acquisition orbit had a significant influence on HBW and PSD with ²⁰¹Tl-gated SPECT MPI in the inferior wall in patients with major hypoperfusion myocardium.

Normal Databases for the Relative Quantification of Myocardial Perfusion

PURPOSE OF REVIEW

Myocardial perfusion imaging (MPI) with SPECT is performed clinically worldwide to detect and monitor coronary artery disease (CAD). MPI allows an objective quantification of myocardial perfusion at stress and rest. This established technique relies on normal databases to compare patient scans against reference normal limits. In this review, we aim to introduce the process of MPI quantification with normal databases and describe the associated perfusion quantitative measures that are used.

RECENT FINDINGS

New equipment and new software reconstruction algorithms have been introduced which require the development of new normal limits. The appearance and regional count variations of normal MPI scan may differ between these new scanners and standard Anger cameras. Therefore, these new systems may require the determination of new normal limits to achieve optimal accuracy in relative myocardial perfusion quantification. Accurate diagnostic and prognostic results rivaling those obtained by expert readers can be obtained by this widely used technique.

SUMMARY

Throughout this review, we emphasize the importance of the different normal databases and the need for specific databases relative to distinct imaging procedures. use of appropriate normal limits allows optimal quantification of MPI by taking into account subtle image differences due to the hardware and software used, and the population studied.

Normal values and standardization of parameters in nuclear cardiology: Japanese Society of Nuclear Medicine working group database

As a 2-year project of the Japanese Society of Nuclear Medicine working group activity, normal myocardial imaging databases were accumulated and summarized. Stress-rest with gated and non-gated image sets were accumulated for myocardial perfusion imaging and could be used for perfusion defect scoring and normal left ventricular (LV) function analysis. For single-photon emission computed tomography (SPECT) with multi-focal collimator design, databases of supine and prone positions and computed tomography (CT)-based attenuation correction were created. The CT-based correction provided similar perfusion patterns between genders. In phase analysis of gated myocardial perfusion SPECT, a new approach for analyzing dyssynchrony, normal ranges of parameters for phase bandwidth, standard deviation and entropy were determined in four software programs. Although the results were not interchangeable, dependency on gender, ejection fraction and volumes were common characteristics of these parameters. Standardization of ¹²³I-MIBG sympathetic imaging was performed regarding heart-to-mediastinum ratio (HMR) using a calibration phantom method. The HMRs from any collimator types could be converted to the value with medium-energy comparable collimators. Appropriate quantification based on common normal databases and standard technology could play a pivotal role for clinical practice and researches.

Nuclear myocardial perfusion imaging using thallium-201 with a novel multifocal collimator SPECT/CT: IQ-SPECT versus conventional protocols in normal subjects

OBJECTIVE

A novel multifocal collimator, IQ-SPECT (Siemens) consists of SMARTZOOM, cardio-centric and 3D iterative SPECT reconstruction and makes it possible to perform MPI scans in a short time. The aims are to delineate the normal uptake in thallium-201 ((201)Tl) SPECT in each acquisition method and to compare the distribution between new and conventional protocol, especially in patients with normal imaging.

METHODS

Forty patients (eight women, mean age of 75 years) who underwent myocardial perfusion imaging were included in the study. All patients underwent one-day protocol perfusion scan after an adenosine-stress test and at rest after administering (201)Tl and showed normal results. Acquisition was performed on a Symbia T6 equipped with a conventional dual-headed gamma camera system (Siemens ECAM) and with a multifocal SMARTZOOM collimator. Imaging was performed with a conventional system followed by IQ-SPECT/computed tomography (CT). Reconstruction was performed with or without X-ray CT-derived attenuation correction (AC). Two nuclear physicians blinded to clinical information interpreted all myocardial perfusion images. A semi-quantitative myocardial perfusion was analyzed by a 17-segment model with a 5-point visual scoring. The uptake of each segment was measured and left ventricular functions were analyzed by QPS software.

RESULTS

IQ-SPECT provided good or excellent image quality. The quality of IQ-SPECT images without AC was similar to those of conventional LEHR study. Mid-inferior defect score (0.3 ± 0.5) in the conventional LEHR study was increased significantly in IQ-SPECT with AC (0 ± 0). IQ-SPECT with AC improved the mid-inferior decreased perfusion shown in conventional images. The apical tracer count in IQ-SPECT with AC was decreased compared to that in LEHR (0.1 ± 0.3 vs. 0.5 ± 0.7, p < 0.05). The left ventricular ejection fraction from IQ-SPECT was significantly higher than that from the LEHR collimator (p = 0.0009).

CONCLUSION

The images of IQ-SPECT acquired in a short time are equivalent to that of conventional LEHR. The results indicated that the IQ-SPECT system with AC is capable of correcting inferior artifacts with high image quality.

Validation of automated quantification of myocardial perfusion single-photon emission computed tomography using Heart Score View in patients with known or suspected coronary artery disease

Heart Score View (HSV) is a free software package for automated quantification of myocardial single photon emission computed tomography (SPECT) imaging using a standard Windows computer. We compared scoring results of myocardial perfusion among visual analysis, Quantitative Perfusion SPECT (QPS), and HSV in patients with known or suspected coronary artery disease.This study included 75 consecutive patients with known or suspected coronary artery disease who underwent adenosive stress-rest Tl-201 SPECT. Analysis of myocardial perfusion SPECT was performed on a standard 17-segment model visually and using QPS and HSV.There were 54 male and 21 female patients with a mean age of 70.5 ± 10.7 years. Thirteen patients (17%) had prior myocardial infarction. Summed stress score (SSS) and summed rest score (SRS) in the mid and basal areas were significantly higher on HSV than visual analysis or QPS. There was no significant difference in SDS in the whole area among the 3 methods. Similar results were found even in patients without prior myocardial infarction. Manual setting of the left ventricular cavity improved the correlations of SSS, SRS and SDS between HSV and the other methods.Our data suggested that HSV was comparable with visual analysis or QPS in scoring myocardial perfusion when manual setting of the left ventricular cavity is applied.

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

BACKGROUND

The 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).

METHODS

Patients with suspected CAD underwent rest (201)Tl and stress (99m)Tc-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.

RESULTS

Detection 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.

CONCLUSION

The 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.

Normal stress databases in myocardial perfusion scintigraphy--how many subjects do you need?

BACKGROUND

Commercial normal stress databases in myocardial perfusion scintigraphy (MPS) commonly consist of 30-40 individuals. The aim of the study was to determine how many subjects are needed.

METHODS

Four normal stress databases were developed using patients who underwent 99mTc MPS: non-corrected images (NC) for male, NC for female, attenuation-corrected images (AC) for male and AC for female subjects. 126 male and 205 female subjects were included. The normal database was created by alternatingly computing the mean of all normal subjects and normalizing the subjects with respect to this mean, until convergence. Coefficients of variation (CV) were created for increasing number of included patients in the four different normal stress databases.

RESULTS

Normal stress databases with < 35 subjects had a high CV. Mean CV -2 standard deviations (SD) decreased with 28% between two and five included subjects, 71% between two and 35 subjects and 83% between two and 100 included subjects for NC man.

CONCLUSIONS

We conclude that the commonly used 30-40 individuals for making a normal stress database might not be enough due to the high CV. We propose that normal stress databases should consist of more than 30-40 individuals, preferably more than 50 individuals, both for NC and AC studies.

Computer-aided diagnosis system for bone scintigrams from Japanese patients: importance of training database

AIM

Computer-aided diagnosis (CAD) software for bone scintigrams have recently been introduced as a clinical quality assurance tool. The purpose of this study was to compare the diagnostic accuracy of two CAD systems, one based on a European and one on a Japanese training database, in a group of bone scans from Japanese patients.

METHOD

The two CAD software are trained to interpret bone scans using training databases consisting of bone scans with the desired interpretation, metastatic disease or not. One software was trained using 795 bone scans from European patients and the other with 904 bone scans from Japanese patients. The two CAD softwares were evaluated using the same group of 257 Japanese patients, who underwent bone scintigraphy because of suspected metastases of malignant tumors in 2009. The final diagnostic results made by clinicians were used as gold standard.

RESULTS

The Japanese CAD software showed a higher specificity and accuracy compared to the European CAD software [81 vs. 57 % (p < 0.05) and 82 vs. 61 % (p < 0.05), respectively]. The sensitivity was 90 % for the Japanese CAD software and 83 % for the European CAD software (n.s).

CONCLUSION

The CAD software trained with a Japanese database showed significantly higher performance than the corresponding CAD software trained with a European database for the analysis of bone scans from Japanese patients. These results could at least partly be caused by the physical differences between Japanese and European patients resulting in less influence of attenuation in Japanese patients and possible different judgement of count intensities of hot spots.

Quantitative analysis of perfusion studies: strengths and pitfalls

Tools for automated quantification of myocardial perfusion are available to nuclear cardiology practitioners and researchers. These methods have demonstrated superior reproducibility with comparable diagnostic and prognostic performance, when compared with segmental visual scoring by expert observers. A particularly useful application of the quantitative analysis can be in the detection of subtle changes or in precise determination of ischemia. Some challenges remain in the routine application of perfusion quantification. Multiple quantitative parameters may need to be reconciled by the expert reader for the final diagnosis. Computer analysis may be sensitive to imaging artifacts, resulting in false positive scans. Perfusion quantification may require site specific normal limits and some degree of manual interaction. New software improvements have been proposed to address some of these challenges.

Small average differences in attenuation corrected images between men and women in myocardial perfusion scintigraphy: a novel normal stress database

Background

The American Society of Nuclear Cardiology and the Society of Nuclear Medicine state that incorporation of attenuation-corrected (AC) images in myocardial perfusion scintigraphy (MPS) will improve image quality, interpretive certainty, and diagnostic accuracy. However, commonly used software packages for MPS usually include normal stress databases for non-attenuation corrected (NC) images but not for attenuation-corrected (AC) images. The aim of the study was to develop and compare different normal stress databases for MPS in relation to NC vs. AC images, male vs. female gender, and presence vs. absence of obesity. The principal hypothesis was that differences in mean count values between men and women would be smaller with AC than NC images, thereby allowing for construction and use of gender-independent AC stress database.

Methods

Normal stress perfusion databases were developed with data from 126 male and 205 female patients with normal MPS. The following comparisons were performed for all patients and separately for normal weight vs. obese patients: men vs. women for AC; men vs. women for NC; AC vs. NC for men; and AC vs. NC for women.

Results

When comparing AC for men vs. women, only minor differences in mean count values were observed, and there were no differences for normal weight vs. obese patients. For all other analyses major differences were found, particularly for the inferior wall.

Conclusions

The results support the hypothesis that it is possible to use not only gender independent but also weight independent AC stress databases.

Estimation of cardiac event risk by gated myocardial perfusion imaging and quantitative scoring methods based on a multi-center J-ACCESS database

BACKGROUND

Myocardial perfusion imaging (MPI) has been used to estimate cardiac event risk. The aim of the present study is to achieve stable risk estimation based on perfusion scoring and a multi-center prognostic database.

METHODS AND RESULTS

Multivariate logistic regression analysis was performed to estimate cardiac event risk based on a J-ACCESS study. A stress-MPI was performed in 45 patients with coronary artery disease (CAD) and in 25 non-CAD patients. Perfusion defect scoring of summed stress score (SSS) was performed by 5 methods: (1) visual scoring; (2) automatic scoring of 3 short-axis and 1 vertical long-axis slices; (3) visual modification of Method 2; (4) automatic polar map scoring based on a Japanese multi-center database; and (5) visual modification of Method 4. Agreement of SSS between 2 observers was good (r=0.87-0.97). Agreement of estimated cardiac event risk between observers and among 5 methods was very good (r=0.99-1.00). Regarding diagnostic accuracy for CAD, Method 5 showed optimal diagnostic yields (sensitivity 84%, accuracy 77%).

CONCLUSIONS

Estimation of cardiac event risk in conjunction with polar map segmentation and common normal databases resulted in stable risk values, and might be used for risk stratification in patients suspected of having CAD.

Validation of automated quantitation of myocardial perfusion and fatty acid metabolism abnormalities on SPECT images

BACKGROUND

Myocardial perfusion and fatty acid imaging have played important roles in the risk stratification of patients with coronary artery disease (CAD). However, visual image assessment requires considerable experience and training. Therefore, an automated program has been developed that can quantify perfusion and fatty acid uptake on myocardial single emission computed tomography (SPECT). The present study aimed to validate the automated quantitative program.

METHODS AND RESULTS

A total of 50 patients were studied with known or suspected CAD who underwent stress ²⁰¹Thallium (²⁰¹Tl) and resting ¹²³I-labelled β-methyl iodophenyl pentadecanoic acid (BMIPP) SPECT. The SPECT images were quantified in 17 segments visually and using our Heart Score View software. Values were compared with those in a normal Japanese database and calculated summed stress (SSS), summed rest (SRS), summed difference (SDS), and summed BMIPP scores for each modality. Summed scores obtained using standard visual analysis and Heart Score View significantly correlated (²⁰¹Tl: SSS: r=0.934; SRS: r=0.827; SDS: r=0.743 summed BMIPP score: r=0.913) (each P<0.001) and Bland-Altman analysis revealed good agreement between the 2 approaches.

CONCLUSIONS

Correlations between scores determined using Heart Score View software and standard visual interpretation were linear for both perfusion and fatty acid images. Thus, our new automated program might be useful for the risk stratification of patients with CAD in the clinical setting.

Quantification of myocardial perfusion SPECT using freeware package (cardioBull)

OBJECTIVE

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)].

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

[Study of collimator broad correction in myocardial perfusion imaging]

The purpose of this study was to evaluate the effect of myocardial perfusion imaging that is reconstructed using the ordered subsets-expectation maximization (OS-EM) method with collimator broad correction.

METHODS

A cardiac phantom and clinical data (with ten normal patients) were used. These projection data were reconstructed using OS-EM with collimator broad correction (OS-EM(+)), without collimator broad correction (OS-EM(-)), and with filtered back projection (FBP). We analyzed the reconstructed images using the following: FWHM of reoriented short-axis data, volume calculated using QGS software, and a polar map calculated using QPS software.

RESULTS AND CONCLUSION

On the important point of spatial resolution, OS-EM(+) was excellent compared with FBP. However, a difference in % uptake was seen in one segment. Therefore, when a quantitative myocardial SPECT evaluation is done, the treatment of the numerical value needs to be noted.

Normal myocardial perfusion SPECT database for the Spanish population

INTRODUCTION AND OBJECTIVES

The aims of this study were to create a Spanish database of normal myocardial perfusion SPECT (single-photon emission computed tomography) data, termed the normal Spanish database, and to compare it with a database of normal data from the North American population.

METHODS

We selected 104 healthy volunteers (45 female, mean age 42+/-14 years) who underwent SPECT during stress and at rest. The findings were analyzed using the 4DM-SPECT commercial software package. The resulting normal Spanish database for males and females was compared with the North American population database (from 70 men and 60 women) provided with the 4DM-SPECT software.

RESULTS

In the Spanish database, the highest percentage uptake during both stress and rest was observed in medial-lateral region and the lowest, in the basal-septal region. The percentage uptake in the anterior-medial region was significantly lower in women than men, while uptake in the inferior, medial-septal and apical regions was lower in men than women. Data values in the Spanish database were significantly lower for the majority of heart regions than those in the database with the 4DM-SPECT software.

CONCLUSIONS

A Spanish database of normal myocardial perfusion SPECT data was created and included separate data for men and women. Significant differences were observed between this database and a commercial North American database that is commonly used in semiquantitative studies.

Clinical use of nuclear cardiology in the assessment of heart failure

A nuclear cardiology test is the most commonly performed non-invasive cardiac imaging test in patients with heart failure, and it plays a pivotal role in their assessment and management. Quantitative gated single positron emission computed tomography (QGS) is used to assess quantitatively cardiac volume, left ventricular ejection fraction (LVEF), stroke volume, and cardiac diastolic function. Resting and stress myocardial perfusion imaging, with exercise or pharmacologic stress, plays a fundamental role in distinguishing ischemic from non-ischemic etiology of heart failure, and in demonstrating myocardial viability. Diastolic heart failure also termed as heart failure with a preserved LVEF is readily identified by nuclear cardiology techniques and can accurately be estimated by peak filling rate (PFR) and time to PFR. Movement of the left ventricle can also be readily assessed by QGS, with newer techniques such as three-dimensional, wall thickening evaluation aiding its assessment. Myocardial perfusion imaging is also commonly used to identify candidates for implantable cardiac defibrillator and cardiac resynchronization therapies. Neurotransmitter imaging using (123)I-metaiodobenzylguanidine offers prognostic information in patients with heart failure. Metabolism and function in the heart are closely related, and energy substrate metabolism is a potential target of medical therapies to improve cardiac function in patients with heart failure. Cardiac metabolic imaging using (123)I-15-(p-iodophenyl)3-R, S-methylpentadecacoic acid is a commonly used tracer in clinical studies to diagnose metabolic heart failure. Nuclear cardiology tests, including neurotransmitter imaging and metabolic imaging, are now easily preformed with new tracers to refine heart failure diagnosis. Nuclear cardiology studies contribute significantly to guiding management decisions for identifying cardiac risk in patients with heart failure.

Comparison of diagnostic performances of three different software packages in detecting coronary artery disease

PURPOSE

Quantification of myocardial perfusion scintigraphy is frequently performed to assist physicians in detecting coronary artery disease (CAD). Software packages provide automated quantification of perfusion data. We aimed to compare the three commonly used software packages, Emory Cardiac Toolbox (ECT v2 and ECT v3), 4D-MSPECT (4DM v2 and 4DM v4) and Quantitative Perfusion SPECT (QPS v3 and QPS v4).

METHODS

We selected 283 patients who had a myocardial perfusion scintigraphy with (201)Tl followed by coronary angiography within 3 months. Summed stress score (SSS), summed difference score (SDS), total stress defect extent (TDE) and regional stress defect extent values were obtained from programs. A ≥70% stenosis in coronary arteries and their major branches was considered positive for CAD. A subgroup of patients was used to form an institutional normal database for QPS and 4DM. Receiver-operating characteristic (ROC) analysis to detect CAD was performed.

RESULTS

Mean SSS ± SD (vendor) for ECT v3, QPS v4 and 4DM v4 were 9.2 ± 7.1, 10.1 ± 6.8 and 5.5 ± 6.1, respectively. Area under the curve (AUC) values of SSS ROC analysis were 0.738 ± 0.031 for QPS v3, 0.755 ± 0.030 for QPS v4, 0.758 ± 0.030 for ECT v2, 0.778 ± 0.029 for ECT v3 and 0.771 ± 0.030 for 4DM v4. The AUC values for TDE were 0.755 ± 0.030 for QPS v4, 0.769 ± 0.030 for ECT v3 and 0.775 ± 0.029 for 4DM v4. The differences were not significant for both SSS and TDE. Differences of AUC between regional stress defect extent values of programs and AUC of SSS between institutional and vendor normal databases were not significant.

CONCLUSION

The diagnostic performances of programs to detect CAD are similar. However, there are differences in the magnitudes of the quantitative values produced by the programs.

Normal values for nuclear cardiology: Japanese databases for myocardial perfusion, fatty acid and sympathetic imaging and left ventricular function

Myocardial normal databases for stress myocardial perfusion study have been created by the Japanese Society of Nuclear Medicine Working Group. The databases comprised gender-, camera rotation range- and radiopharmaceutical-specific data-sets from multiple institutions, and normal database files were created for installation in common nuclear cardiology software. Based on the electrocardiography-gated single-photon emission computed tomography (SPECT), left ventricular function, including ventricular volumes, systolic and diastolic functions and systolic wall thickening were also analyzed. Normal databases for fatty acid imaging using ¹²³I-beta-methyl-iodophenyl-pentadecanoic acid and sympathetic imaging using ¹²³I-meta-iodobenzylguanidine were also examined. This review provides lists and overviews of normal values for myocardial SPECT and ventricular function in a Japanese population. The population-specific approach is a key factor for proper diagnostic and prognostic evaluation.

The validity of multi-center common normal database for identifying myocardial ischemia: Japanese Society of Nuclear Medicine working group database

PURPOSE

The Japanese Society of Nuclear Medicine (JSNM) working group has created a myocardial perfusion imaging database applicable to standard acquisition protocol. The aim of this study is to validate the diagnostic accuracy of the common normal database compared with the expert interpretation of each institute.

METHODS

Five institutions participated in this study and used different acquisition settings which included 360 degrees /180 degrees rotation, camera configuration and camera orbits. The software and its version used in each institution also varied. The working group database was applied to detect the culprit coronary territory from a total of 166 patients with coronary artery disease (CAD) and 145 patients with low-likelihood of CAD.

RESULTS

When summed stress score > or =4 was defined as significant abnormality, overall sensitivity, specificity and accuracy of patient-based analysis were 77, 72 and 75%, respectively, based on quantitative analysis using the common database, whereas those by institutional visual expert reading were 72, 79 and 75%, respectively.

CONCLUSION

The common database, which was created by a multi-center working group and separated between male/female with 180/360 degrees acquisitions, demonstrated comparable diagnostic accuracy to expert interpretation by each institute, and it may be applicable to multi-center studies.