Volume-based 18F-FDG PET analysis of cardiac sarcoidosis using the descending aorta as a reference tissue.

OBJECTIVE: 18F-FDG PET can be used to calculate the threshold value of myocardial volume based on the mean standardised uptake value (SUVmean) of the aorta to detect highly integrated regions of cardiac sarcoidosis. The present study investigated the myocardial volume when the position and number of volumes of interest (VOIs) were changed in the aorta.

METHODS: The present study examined PET/computed tomography images of 47 consecutive cardiac sarcoidosis cases. VOIs were set at three locations in the myocardium and aorta (descending thoracic aorta, superior hepatic margin and near the pre-branch of the common iliac artery). The volume was calculated for each threshold using 1.1-1.5 times the SUVmean (median of three cross-sections) of the aorta as the threshold to detect high myocardial 18F-FDG accumulation. The detected volume, correlation coefficient with the visually manually measured volume and the relative error were also calculated.

RESULTS: The optimum threshold value for detecting high 18F-FDG accumulation was 1.4 times that of the single cross-section of the aorta and showed the smallest relative errors of 33.84% and 25.14% and correlation coefficients of 0.974 and 0.987 for single and three cross-sections, respectively.

CONCLUSION: The SUVmean of the descending aorta may be detected in good agreement with the visual high accumulation by multiplying the same threshold constant for both single and multiple cross-sections.