Background: The prognostic value of aortic valve calcium in patients prior to transcatheter aortic valve replacement (TAVR) is well established. Its reliable quantification requires a non-contrast computed tomography (CT) of the heart (‘true non contrast’, TNC) which in this cohort is not regularly performed at all centers. Photon Counting Detector CT (PCD-CT) permits the routine derivation of ‘virtual non-contrast’ (VNC) and ‘virtual non-iodine’ (VNI) series from CT Angiography (CTA) acquisitions due to its intrinsic spectral sensitivity. These might render separate non-contrast acquisitions unnecessary. The aim of our study was to evaluate the feasibility of quantification of aortic valve calcification on VNC/ VNI series derived from CTA scans.

Methods: 45 consecutive patients underwent pre TAVR CT on a novel PCD-CT (NAEOTOM Alpha, Siemens Healthineers, Erlangen, Germany) comprising a non-contrast CT of the heart, followed by a CTA of the heart, aorta, and iliac arteries. VNC series were derived from CTA acquisitions and two readers independently quantified aortic valve calcium using the Agaston calcium score and the Volume Score on VNC-, VNI- and TNC-series.

Results: A total of 41 patients (41.46% female) were included in the study. In comparison with the "true" avarage calcium scores and the volume derived from TNC series (i.e., 2800[2075-3681] vs. 2206[1645-2894] mm³), calcium scores and volume scores derived from VNC (i.e., 752[390-1357] vs. 653.3[319.5-1052.3] mm³) and VNI (i.e., 1986[1270-3278] vs. 1515[971-2480] mm³) series were consistently lower but correlation was excellent for both, i.e., calcium and volume score, respectively (r’s: 0.96 and 0.96 for VNC; r’s: 0.92 and 0.91 for VNI, p< 0.05).

Conclusion: Our initial patient experience with TAVR planning CT on a novel PCD-CT showed significant correlation of aortic valve calcium scores and volumes derived from VNC and VNI series, as compared with those derived from TNC series, thus rendering non-contrast acquisitions for TAVR planning redundant.