Clinical validation of dual-source dual-energy computed tomography (DECT) for coronary and valve imaging in patients undergoing transcatheter aortic valve implantation (TAVI)

AIM: To assess the validity of virtual non-contrast (VNC) reconstructions for coronary artery calcium (CACS) and aortic valve calcium scoring (AVCS) in patients undergoing trans-catheter aortic valve implantation (TAVI). MATERIALS AND METHODS: Twenty-three consecutive TAVI patients underwent a three-step computed tomography (CCT) acquisition: (1) traditional CACS; (2) dual-energy (DE) CT coronary angiogram (CTCA); and (3) DE whole-body angiogram. Linear regression was used to model calcium scores generated from VNC images with traditional scores to derive a conversion factor [2.2 (95% CI: 1.97-2.58)]. The effective radiation dose for the TAVI protocol was compared to a standard control group. Bland-Altman analysis and weighted k-statistic were used to assess inter-method agreement for absolute score and risk centiles. RESULTS: CACS and AVCS from VNC reconstructions correlated well with traditional scores (r = 0.94 and r = 0.86; both p < 0.0001). There was excellent agreement between VNC and non-contrast coronary calcium scores [mean difference -71.8 (95% limits of agreement -588.7 to 445.1)], with excellent risk stratification into risk centiles (k = 0.99). However, the agreement was weaker for the aortic valve [mean difference -210.6 (95% limits of agreement -1233.2 to 812)]. Interobserver variability was excellent for VNC CACS [mean difference of 6 (95% limits of agreement 134.1-122.1)], and AVCS [mean difference of -16.4(95% limits of agreement 576 to -608.7)]. The effective doses for the DE TAVI protocol was 16.4% higher than standard TAVI protocol (22.7 versus 19.5 mSv, respectively) accounted for by the DE CTCA dose being 47.8% higher than that for a standard CTCA [9.9(5.6-14.35) versus 6.7 (1.17-13.72) mSv; p < 0.01). CONCLUSIONS: CACS and AVCS can be accurately quantified, and patients can be risk stratified using DECT VNC reconstructions. However, the dose from DE CTCA is significantly greater than the standard single-energy CTCA precluding the use of this technology in routine clinical practice. (C) 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.