Improved diagnosis of the number of stenosed coronary artery vessels by segmentation with scatter and photo-peak window data for attenuation correction in myocardial perfusion SPECT

Diagnostic Effect of Attenuation Correction in Myocardial Perfusion Imaging in Different Coronary Arteries: A Systematic Review and Meta-Analysis

Background: The aim of this study was to determine whether, and if so how, attenuation correction (AC) improves the diagnostic performance of myocardial perfusion imaging (MPI) in different coronary artery-supplied territories, using coronary angiography as the reference standard.

Methods: PubMed and EMBASE were searched until December 2020 for studies evaluating AC MPI for the diagnosis of coronary artery disease (CAD) with vessel-based data. Methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. For each study, the sensitivity, specificity, diagnostic odds ratios and areas under summary receiver operating characteristic curves (AUC) with 95% confidence intervals were calculated to determine the diagnostic accuracy of AC compared to non-AC MPI. A bivariate mixed-effects model was used to pool the data. Subgroup analyses considering the type of radiotracer and type of AC were performed.

Results: A total of 264 articles were screened, of which 22 studies (2,608 patients) were enrolled. Significant improvements in specificity [0.78 vs. 0.58 in overall CAD, 0.87 vs. 0.61 in right coronary artery (RCA)] and diagnostic odds ratios (16 vs. 8 in overall CAD, 18 vs. 7 in RCA) after AC were shown in overall CAD at a patient level and RCA stenosis. Improvements in AUC were also noted. MPI had a similar diagnostic performance for detecting left anterior descending and left circumflex coronary artery stenosis with or without AC. There were trends of decreased sensitivity after AC, but none were significant. Diagnostic odds ratio showed significant improvement after AC only in the technetium-99m subgroup.

Conclusion: The results of this study suggest that AC should be applied to MPI to improve the diagnosis of CAD regardless of which type of radiotracer, and that AC MPI can improve the specificity of detecting RCA stenosis.

Long-term prognostic value of computed tomography-based attenuation correction on thallium-201 myocardial perfusion imaging: A cohort study

BACKGROUND

Myocardial perfusion imaging (MPI) is a well-established diagnostic tool to evaluate coronary artery disease (CAD) and also an effective prognostic tool for patients with CAD. However, few studies investigated the prognostic value of attenuation correction (AC) in MPI, and the results were controversial.

OBJECTIVES

To investigate the prognostic value of computed tomography (CT)-based AC thallium-201 (Tl-201) MPI.

METHODS

A total of 108 consecutive patients who underwent Tl-201 MPI and received coronary angiography within 90 days were included. Medical records were reviewed and missing information was completed after telephone contact. The prognostic value was evaluated by Kaplan-Meier analysis, univariable and multivariable Cox proportional hazards model.

RESULTS

After a mean follow-up of 7.72 ± 3.72 years, 27 patients had died, 41 had been readmitted for cardiovascular (CV)-related events and 44 had reached the composite of death plus CV-related re-admission. Kaplan-Meier curves for all-cause mortality for SSS with a cutoff value of 13 for AC and 16 for non-AC (NAC) images showed a significant difference between the two curves for both AC and NAC images (p = 0.011 for AC and p = 0.021 for NAC). In the multivariable model, SSS and SRS showed similar independent predictive values in predicting all-cause mortality and composite of all-cause mortality plus CV-related re-admission, in both AC and NAC images. Subgroup analysis implicated that AC MPI possibly provided better risk stratification in obese patients.

CONCLUSION

CT-based AC and NAC MPI showed similar value and were the only significant predictors for the composite of mortality and CV events.

Comparison of Myocardial Ischemia Detection Between Semiconductor and Conventional Anger-type Three-detector SPECT

Objective: Although semiconductor single-photon emission computed tomography (D-SPECT) has been used for myocardial perfusion imaging, few studies have compared its ability to detect myocardial ischemia with that of 3-detector SPECT (GCA9300R). This study used invasive coronary angiography to determine whether the detectability of myocardial ischemia differs between D-SPECT and GCA9300R. Materials and methods: This study included 24 patients who were assessed by coronary angiography within 60 days of myocardial perfusion D-SPECT and GCA9300R. Two nuclear medicine physicians interpreted myocardial perfusion D-SPECT and GCA9300R images with five grades of confidence, then defined regions of ischemia on polar maps. The gold standard was determined by another nuclear cardiology specialist based on integrated assessment of the coronary angiography findings and other clinical information derived from medical charts. The concordance rate and the Cohen kappa (κ) between D-SPECT and GCA9300R were calculated. Results: The sensitivity, specificity, negative and positive predictive values, and the accuracy of patient-based diagnoses were 66.7%, 91.7%, 89.2%, 72.8%, and 85.5%, respectively, for GCA9300R, and 83.3%, 83.3%, 93.7%, 62.4%, and 83.3%, respectively, for D-SPECT. Interpretations of ischemia did not uncover any significant differences between D-SPECT and GCA9300R. The Cohen κ values of D-SPECT and GCA9300 agreed substantially, moderately and marginally for the left circumflex coronary artery (LCX) (0.68), right coronary artery (RCA) (0.43), and left anterior descending coronary artery (LAD) (0.39), respectively. Conclusions: The detectability of myocardial ischemia is comparable between D-SPECT and GCA9300R. Sensitivity is better for D-SPECT than GCA9300R. However, false-positive D-SPECT findings, especially in the apex and inferior wall should be interpreted with caution.