Low dose contrast CT for transcatheter aortic valve replacement assessment: Results from the prospective SPECTACULAR study (spectral CT assessment prior to TAVR).

Abstract

BACKGROUND\nComputed tomographic angiography (CTA) based planning for transcatheter aortic valve replacement (TAVR) is essential for reduction of periprocedural complications. Spectral CT based imaging provides several advantages, including better contrast/signal to noise ratio and increased soft tissue contrast, permitting better delineation of contrast filled structures at lower doses of iodinated contrast media. The aim of this prospective study was to assess the initial feasibility of a low dose iodinated contrast protocol, utilizing monoenergetic 40\u202fkeV reconstruction, using a dual-layer CT scanner (DLCT) for CTA in patients undergoing TAVR planning.\n\n\nMETHODS\n116 consecutive TAVR patients underwent a gated chest and a non-gated CTA of the abdomen and pelvis. 40\u202fkeV virtual monoenergetic images (VMI) were reconstructed and compared with conventional polychromatic images (CI). The proximal aorta and access vessels were scored for image quality by independent experienced cardiovascular imagers.\n\n\nRESULTS\nProximal aortic image quality as assessed by signal to noise (SNR) and contrast to noise ratio (CNR), were significantly better with 40\u202fkeV VMI relative to CI (SNR 14.65\u202f±\u202f7.37 vs 44.16\u202f±\u202f22.39, p\u202f<\u202f0.001; CNR 15.84\u202f±\u202f9.93 vs 59.8\u202f±\u202f40.83, p\u202f<\u202f0.001). Aortic root dimensions were comparable between the two approaches with a bias towards higher measurements at 40\u202fkeV (Bland Altman). SNR and CNR in all access vessel segments at 40\u202fkeV were substantially better (p\u202f<\u202f0.001 for all peripheral access vessel segments) with comparable image quality.\n\n\nCONCLUSION\n40\u202fkeV VMI with low dose contrast dose spectral imaging is feasible for comprehensive preprocedural evaluation of access vessels and measurements of aortic root dimensions in patients undergoing TAVR.