[Paper Review] Cardiac CT perfusion imaging of pericoronary adipose tissue (PCAT) highlights potential confounds in coronary CTA

Hao Wu, Yingnan Song+11 more|arXiv (Cornell University)|Jun 27, 2023

Cardiovascular Disease and AdiposityMedicine3 citations

TL;DR

This study uses dynamic cardiac CT perfusion (CCTP) to investigate how contrast dynamics affect pericoronary adipose tissue (PCAT) assessment in coronary CTA. It reveals that HU, apparent volume, and radiomic features in PCAT are highly sensitive to acquisition timing and hemodynamic changes due to stenosis, introducing significant confounds in PCAT quantification that may compromise clinical interpretation unless corrected via data normalization.

ABSTRACT

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.

Motivation & Objective

• To investigate the impact of contrast enhancement dynamics on pericoronary adipose tissue (PCAT) assessment in coronary CTA.
• To evaluate how hemodynamic changes due to coronary stenosis affect PCAT HU, blood flow, and radiomic features.
• To assess temporal variability in PCAT features across different phases of contrast enhancement.
• To identify potential confounding factors in PCAT quantification that may affect diagnostic accuracy in CCTA.

Proposed method

• Dynamic cardiac CT perfusion (CCTP) was used to track HU changes in PCAT, myocardium, and other adipose depots over time.
• Hemodynamic parameters including blood flow and time-to-peak enhancement were estimated in PCAT and compared to contiguous myocardium.
• Contrast enhancement dynamics were analyzed relative to peak aortic enhancement time (Pa), used as a reference for standard CCTA acquisition.
• Radiomic features were extracted from PCAT at multiple time points and compared for temporal stability.
• Apparent PCAT volume was calculated using a conventional fat window and tracked from the first scan (P1) to Pa.
• Statistical comparisons were made between PCAT regions proximal and distal to significant stenoses to assess hemodynamic effects.

Experimental results

Research questions

• RQ1 How does contrast enhancement timing affect HU measurements in pericoronary adipose tissue (PCAT) relative to other adipose depots?
• RQ2 To what extent does the presence of a coronary stenosis alter PCAT enhancement dynamics and blood flow?
• RQ3 How do radiomic features of PCAT change over time during dynamic contrast enhancement?
• RQ4 What is the magnitude of apparent PCAT volume change between early and standard CCTA acquisition times?
• RQ5 How sensitive are PCAT features to hemodynamic changes, and what implications does this have for clinical interpretation?

Key findings

• PCAT HU increased significantly more than in other adipose depots, with a 4-HU increase before Pa and a 3-HU increase after Pa, indicating strong contrast sensitivity.
• Estimated blood flow in PCAT was approximately 23% of that in contiguous myocardium, confirming its vascular perfusion.
• PCAT distal to a significant stenosis showed less enhancement and longer time-to-peak compared to proximal regions.
• Apparent PCAT volume decreased by approximately 15% from the first scan (P1) to peak aortic enhancement (Pa) when using a conventional fat window.
• 78% of radiomic features in PCAT changed by more than 10% relative to P1, indicating high temporal variability.
• Contrast dynamics and hemodynamic changes due to stenosis introduce substantial confounds in PCAT assessment, necessitating data normalization for reliable quantification.