  Features of pericoronary adipose tissue (PCAT) assessed from coronary
computed tomography angiography (CCTA) are associated with inflammation and
cardiovascular risk. As PCAT is vascularly connected with coronary vasculature,
the presence of iodine is a potential confounding factor on PCAT HU and
textures that has not been adequately investigated. Use dynamic cardiac CT
perfusion (CCTP) to inform contrast determinants of PCAT assessment. From CCTP,
we analyzed HU dynamics of territory-specific PCAT, myocardium, and other
adipose depots in patients with coronary artery disease. HU, blood flow, and
radiomics were assessed over time. Changes from peak aorta time, Pa, chosen to
model the time of CCTA, were obtained. HU in PCAT increased more than in other
adipose depots. The estimated blood flow in PCAT was ~23% of that in the
contiguous myocardium. Comparing PCAT distal and proximal to a significant
stenosis, we found less enhancement and longer time-to-peak distally.
Two-second offsets [before, after] Pa resulted in [ 4-HU, 3-HU] differences in
PCAT. Due to changes in HU, the apparent PCAT volume reduced ~15% from the
first scan (P1) to Pa using a conventional fat window. Comparing radiomic
features over time, 78% of features changed >10% relative to P1. CCTP
elucidates blood flow in PCAT and enables analysis of PCAT features over time.
PCAT assessments (HU, apparent volume, and radiomics) are sensitive to
acquisition timing and the presence of obstructive stenosis, which may confound
the interpretation of PCAT in CCTA images. Data normalization may be in order.
