Prognostic value of lung sestamibi uptake in myocardial perfusion imaging of patients with known or suspected coronary artery disease.

OBJECTIVES: We sought to determine whether lung uptake of technetium-99m (99mTc)-based myocardial perfusion tracers predicts cardiac events. BACKGROUND: Increased lung uptake of thallium-201 during myocardial perfusion scintigraphy can predict important clinical outcomes. It is unclear whether lung uptake of 99mTc-based myocardial perfusion tracers can be used in a similar way. METHODS: Stress lung-to-heart ratio (sLHR) was determined in 718 patients undergoing 99mTc-sestamibi single-photon emission computed tomographic stress imaging. The primary outcome was acute myocardial infarction or death. RESULTS: During a mean follow-up of 5.6 years, a primary end point occurred in 114 patients (16%). The sLHR was significantly greater in those with an adverse outcome (p < 0.00001). The likelihood of an adverse outcome increased by a factor of 1.5 (95% confidence interval 1.2 to 1.7) for each standard deviation increase in sLHR after adjustment for all other variables. The sLHR provided a small but significant improvement in risk stratification when added to clinical, stress test, perfusion, and left ventricular volume information (global chi-square 168.6 vs. 150.7, p < 0.00001). CONCLUSIONS: Stress LHR is an adjunctive prognostic measure in patients with known or suspected coronary artery disease.

Prognostic value of automated quantification of 99mTc-sestamibi myocardial perfusion imaging.

UNLABELLED: Although human interpretation of (99m)Tc-sestamibi SPECT myocardial perfusion imaging has been repeatedly validated in the diagnostic and prognostic assessment of coronary artery disease, it remains unclear if automated computer-derived quantitative indices of perfusion have similar or independent prognostic information. METHODS: We studied 718 patients referred for (99m)Tc-sestamibi SPECT myocardial perfusion imaging who were followed for 5.6 +/- 1.1 y (mean +/- SD). The SPECT studies were initially interpreted visually without benefit of computer-based analysis and were then subjected to a blinded reprocessing to extract quantitative indices of perfusion. Follow-up was through the Manitoba Population Health Research Data Repository. Acute myocardial infarction or cardiac death occurred in 79 individuals (11.0% of the cohort). RESULTS: Visual and quantitative categorization of scan perfusion abnormalities showed similar prognostic value for predicting acute myocardial infarction or cardiac death. Discordance between the visual and quantitative categorizations defined a group at intermediate risk. There was a gradient of risk with increasing severity of the summed stress score (SSS) or summed difference score (SDS). The automated SSS and SDS provided incremental prognostic information over that obtained from visual interpretation. CONCLUSION: Automated quantification of (99m)Tc-sestamibi SPECT myocardial perfusion scans provides objective prognostic information and may complement the conventional visual image interpretation.

Automated quantification of 99mTc sestamibi myocardial perfusion compared with visual analysis.

OBJECTIVES: The visual interpretation of 99mTc sestamibi single photon emission computed tomography (SPECT) myocardial perfusion images can be challenging due to the quantity of scan information generated, the large number of normal variants, attenuation artifacts and gender differences. The development of automated, computer derived, quantitative indices of perfusion can assist in this interpretation by providing an objective measure. It is important to verify that similar results can be obtained when the software is used in centres outside those where the algorithms were initially developed. Our objective was to assess the degree of concordance between the visual and automated diagnostic assessments of 99mTc sestamibi SPECT. METHODS: We studied 718 patients referred for 99mTc sestamibi SPECT myocardial perfusion imaging. The SPECT studies were initially interpreted visually without benefit of computer based analysis, and were then subjected to blinded reprocessing to extract quantitative indices of perfusion. RESULTS: There was very good agreement between the visual and quantitative diagnostic classifications. When a visual abnormality was taken to be the reference standard, the automated summed stress score (SSS) showed agreement (SSS>3) in 80% (kappa 0.60, P<0.0001). The area under the receiver operating characteristic (ROC) curve was 0.89 (95% confidence interval (CI), 0.86-0.91). Concordance was greater in those with previous myocardial infarction or severe perfusion defects, but was not affected by age, prior revascularization, stress procedure or heart rate. Concordance over the presence or absence of visual reversibility and the summed difference score (SDS) in abnormal scans was slightly lower (overall agreement 73% (kappa 0.36, P<0.00001) and ROC area 0.84 (95% CI, 0.77-0.90)). CONCLUSION: Automated quantification of 99mTc sestamibi SPECT myocardial perfusion with the SSS and SDS provides objective diagnostic information and concordance when compared with conventional visual image interpretation.