Abstract
1727
Introduction: Patients with ischemic left ventricle (LV) dysfunction may benefit from revascularization; however, accurate assessment of the extent of viable (hibernating) vs. scar tissue is required for appropriate patient selection for this invasive procedure. Interpretation of scarred versus viable areas of the LV myocardium is routinely performed using F-18-fluorodeoxyglucose positron emission tomography (FDG PET) myocardial viability images. This assessment can be suboptimal in patients with high residual tracer activity in the LV cavity blood-pool due to diabetes mellitus or glucose intolerance. The objective of this study was to evaluate the effect of an automated blood-background correction on the determination of myocardial scar and viability scores.
Methods: N=107 patients with known or suspected CAD were included from the previous PARR-2 randomized control trial (JNM 2010;51:567). Automated analysis of the reconstructed static ammonia and FDG images was performed using in-house-developed software to identify the mismatch (hibernating myocardium) and match (fibrotic scar) scores as a percentage of the global LV myocardium. Patient data was analyzed a second time by automatically subtracting the LV blood-background from the reconstructed images prior to score determination. Match and mismatch scores from both methods were compared to determine the impact of the blood-background subtraction.
Results: Across the population, the original ammonia perfusion-FDG match and mismatch scores were determined to be 14 ± 8 % and 3 ± 5 %, respectively. These values increased significantly to 25 ± 11 % (p < 0.0001) for match scores and 9 ± 9 % (p < 0.0001) for mismatch scores, following subtraction of the blood background, reflecting the detection of a greater extent and severity of disease. These results suggest that the automated contrast-recovery provided by this subtraction method may increase the sensitivity for quantification of the total hibernating myocardium and scar burden in the presence of residual blood background tracer activity.
Conclusions: Subtraction of the residual tracer activity in the blood-pool provides contrast recovery of the PET viability images, resulting in higher sensitivity for detection and quantification of scar and viable LV myocardium, which may allow for more appropriate selection of patients for revascularization or assessment of LV recovery following revascularization.