Impact of low-energy virtual monoenergetic imaging in photon-counting CT for pre-TAVI pelvic arteries visualization

This study aimed to assess the impact of photon-counting computed tomography (PCCT) virtual monoenergetic images (VMI) on quantitative and qualitative parameters in abdominal and pelvic vascular imaging for transcatheter aortic valve implantation (TAVI) planning.

A retrospective analysis of 125 patients undergoing dual-source PCCT scans before TAVI procedures was conducted. Reconstructions included polychromatic (T3D) images, leveraging multiple photon energy levels and VMI series spanning 40-100 keV in 15 keV increments. Quantitative parameters (signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]) were evaluated. Qualitative assessments by three radiologists used clinically relevant five-point scales for overall image quality, TAVI access site suitability, and confidence in TAVI measurements.

VMI reconstructions, particularly at 40 and 55 keV, demonstrated significantly higher SNR and CNR than T3D reconstructions (p < 0.001). T3D reconstructions had a mean noise of 12.61 ± 6.12, comparable to 100 keV VMI reconstructions (14.77 ± 8.23, p > 0.05). In qualitative evaluation, 55 keV VMI images scored highest in overall image quality and TAVI access site assessability, followed by 70 keV VMI reconstructions.

Low-keV PCCT VMI reconstructions provided superior quantitative and qualitative image quality for abdominal and pelvic vascular imaging in TAVI planning. Notably, 55 keV reconstructions showed an image quality reserve over T3D images, aiding confidence in TAVI-related measurements and enabling possible future reductions in contrast agent use, emphasizing the relevance of VMI techniques in optimizing TAVI imaging protocols.