Towards Reference Values of Pericoronary Adipose Tissue Attenuation: Impact of Coronary Artery and Tube Voltage in Coronary Computed Tomography Angiography

Objectives: To determine normal pericoronary adipose tissue mean attenuation (PCAT) values for left the anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) in patients without plaques on coronary CT angiography (cCTA), taking into account tube voltage influence.

Methods: This retrospective study included 192 patients (76 (39.6%) men; median age 49 years (range, 19-79)) who underwent cCTA with third-generation dual-source CT for the suspicion of CAD between 2015 and 2017. We selected patients without plaque on cCTA. PCAT was measured semi-automatically on cCTA images in the proximal segment of the three main coronary arteries with 10 mm length. Paired t-testing was used to compare PCAT between combinations of two coronary arteries within each patient, and one-way ANOVA testing was used to compare PCAT in different kV groups.

Results: The overall mean ± standard deviation (SD) PCAT was - 90.3 ± 11.1 HU. PCAT in men was higher than that in women: - 88.5 ± 10.5 HU versus - 91.5 ± 11.3 HU (p = 0.001). PCAT of LAD, LCX, and RCA was - 92.4 ± 11.6 HU, - 88.4 ± 9.9 HU, and - 90.2 ± 11.4 HU, respectively. Pairwise comparison of the arteries showed significant difference in PCAT: LAD and LCX (p < 0.001), LAD and RCA (p = 0.009), LCX and RCA (p = 0.033). PCAT of the 70 kV, 80 kV, 90 kV, 100 kV, and 120 kV groups was - 95.6 ± 9.6 HU, - 90.2 ± 11.5 HU, - 87.3 ± 9.9 HU, - 82.7 ± 6.2 HU, and - 79.3 ± 6.8 HU, respectively (p < 0.001).

Conclusions: In patients without plaque on cCTA, PCAT varied by tube voltage, with minor differences in PCAT between coronary arteries (LAD, LCX, RCA). PCAT values need to be interpreted taking into account tube voltage setting.

Key Points: • In patients without plaque on cCTA, PCAT differs slightly by coronary artery (LAD, LCX, RCA). • Tube voltage of cCTA affects PCAT measurement, with mean PCAT increasing linearly with increasing kV. • For longitudinal cCTA analysis of PCAT , the use of equal kV setting is strongly recommended.