Search

Background: Computed tomography aortic valve calcium (AVC) score has accepted value for diagnosing and predicting outcomes in aortic stenosis (AS). Multi-energy CT (MECT) allows virtual non-contrast (VNC) reconstructions from contrast scans. We aim to compare the VNC-AVC score to the true non-contrast (TNC)-AVC score for assessing AS severity., Methods: We prospectively included patients undergoing a MECT for transcatheter aortic valve replacement (TAVR) planning. TNC-AVC was acquired before contrast, and VNC-AVC was derived from a retrospectively gated contrast-enhanced scan. The Agatston scoring method was used for quantification, and linear regression analysis to derive adjusted-VNC values., Results: Among 109 patients (55% female) included, 43% had concordant severe and 14% concordant moderate AS. TNC scan median dose-length product was 116 ​mGy∗cm. The median TNC-AVC was 2,107 AU (1,093-3,372), while VNC-AVC was 1,835 AU (1293-2,972) after applying the coefficient (1.46) and constant (743) terms. A strong correlation was demonstrated between methods (r ​= ​0.93; p ​< ​0.001). Using accepted thresholds (>1,300 AU for women and >2,000 AU for men), 65% (n ​= ​71) of patients had severe AS by TNC-AVC and 67% (n ​= ​73) by adjusted-VNC-AVC. After estimating thresholds for adjusted-VNC (>1,564 AU for women and >2,375 AU for men), 56% (n ​= ​61) had severe AS, demonstrating substantial agreement with TNC-AVC (κ ​= ​0.77)., Conclusions: MECT-derived VNC-AVC showed a strong correlation with TNC-AVC. After adjustment, VNC-AVC demonstrated substantial agreement with TNC-AVC, potentially eliminating the requirement for an additional scan and enabling reductions in both radiation exposure and acquisition time., Competing Interests: Declaration of competing interest L.S. has received consulting honorarium from Amgen, BMS and Philips; and grant support from Amgen and Philips. D. L and P.P are supported by grants from Amgen and Philips. D.D. have received software royalties from Cedars-Sinai Medical Center. D.D. was supported by grants from National Heart, Lung and Blood institute (1R01HL133616 and 1R01HL148787-01A1). S.S.H. is an employee of Philips Healthcare. Other authors declare no conflict., (Copyright © 2023 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Purpose: Virtual non-contrast (VNC) coronary artery calcium scoring (CAC) may obviate the need for traditional non-contrast (TNC) CAC. There is no data on the influence of body mass index (BMI) on VNC reliability. We aimed to evaluate the influence of BMI on VNC CAC agreement with TNC., Materials and Methods: All patients who underwent sequential CAC and coronary CT angiography (CCTA) using spectral CT with TNC CAC > 0 between August 2020 and December 2021 were included. Agatston CAC scores were calculated manually by 2 blinded readers from VNC scans. A correction factor was calculated from the slope of the linear regression using the method of least squares and applied to the VNC scores. Bland-Altman plots and Cohen's weighted Kappa were utilized., Results: We included 174 patients (57.5% female). Mean BMI was 32.6 ± 7.02 kg/m 2 [BMI < 30 (39.7%); BMI 30-40 (45.4%); and BMI > 40 kg/m 2 (14.9%)]. Mean TNC CAC was 177.8 ± 316.86 and mean VNC CAC after applying the correction factor 149.34 ± 296.73. The TNC value strongly correlated with VNC (r = 0.94; p < 0.0001). As BMI increased there was a progressive reduction in signal-to-noise ratio, contrast-to-noise ratio and coronary enhancement (p < 0.05). The degree of agreement between VNC and TNC CAC decreased as BMI increased (agreement = 91.79 (weighted Kappa = 0.72), 91.14 (weighted Kappa = 0.58) and 88.46% (weighted Kappa = 0.48) (all P values < 0.001) for BMI < 30; 30-40 and > 40 kg/m 2 , respectively)., Conclusion: BMI has a significant influence on the accuracy of VNC CAC. VNC CAC shows substantial agreement in non-obese patients but performs poorly in BMI > 40 kg/m 2 . This is the first study to evaluate the influence of body mass index (BMI) on virtual non-contrast (VNC) coronary artery calcium scoring (CAC) as compared to traditional non-contrast (TNC). We retrospectively evaluated 174 patients with TNC CAC and two blinded reviewers manually calculated the VNC CAC. All cases were included without specific selection for quality. The ratio between the two directly proportional values was determined using the slope from the linear regression through the method of least squares. This correction factor of 2.65 was applied to the calcium scores obtained from VNC images. We found that VNC CAC shows substantial risk-class agreement with TNC in non-obese patients (agreement = 91.79 and weighted Kappa = 0.72) but performs poorly in BMI > 40 kg/m 2 (agreement: 88.46% and weighted Kappa = 0.48). These findings show the potential use of VNC CAC to avoid additional radiation in non-obese patients. However, further research on potential improvement strategies for VNC CAC in obese patients is needed., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)