Work

Ultra-high-resolution Photon-Counting CT for Leaflet-Specific Evaluation of Fibrosis and Calcification in Aortic Stenosis

Year: 2026

Type: preprint

Abstract: Objectives Ultra-high-resolution photon-counting detector (PCD)-CT may enable leaflet-specific analysis of aortic valve fibrosis and calcification, providing insights into early aortic stenosis (AS) disease progression. This study aimed to investigate how PCD-CT leaflet-specific calcific and fibrotic volumes influence cardiovascular magnetic resonance (CMR) leaflet mobility. Materials and methods Participants with moderate aortic AS prospectively underwent both PCD-CT (n=80) and CMR (n=58). Using PCD-CT, calcific and fibrotic volumes were segmented for right (RCC), left (LCC), and non-coronary cusps (NCC) and indexed to the aortic annulus area (ICV and IFV). CMR-derived leaflet mobility index (LMI) was assessed. Two raters compared image quality using a Likert-scale (1=poor to 5=excellent) and distinguishability of individual leaflets in PCD-CT with EID-CT (n=82). Results PCD-CT analysis showed that calcification was higher in males (e.g., ICV RCC : 15±16 vs. 4±7 µL/cm 2 ;p<0.001) while fibrosis was higher in females (e.g., IFV LCC ; 47±18 vs. 34±15 µL/cm 2 ;p=0.004) across all leaflets. Fibrocalcific ratio was higher in LCC (53±276) compared to RCC (19±48;p<0.001) and NCC (13.5±34;p<0.001). LMI of RCC was higher in females compared to men (0.66±0.21 vs. 0.38±0.33;p=0.008). LMI LCC and LMI NCC showed no sex differences. LMI RCC negatively correlated with ICV RCC (ρ=-0.64[-0.77, −0.46];p<0.001) and LMI NCC with ICV NCC (ρ=-0.69[-0.80, −0.53];p<0.001), whereas LMI LCC negatively correlated with IFV LCC (ρ=-0.35[-0.56,-0.10];p=0.007), particularly in females (ρ=-0.70[-0.89, −0.31];p = 0.003). PCD-CT yielded higher image quality (5[IQR4–5] vs. 3[3–4];p<0.001) and leaflet distinguishability (79/80[99%] vs. 42/82[51%];p<0.001) than EID-CT. Conclusions Ultra-high-resolution PCD-CT allows for leaflet-specific quantification of indexed fibrotic and calcific volume. These volumes demonstrate sex- and leaflet-specific differences that may distinctly contribute to AS pathophysiology. Key Points Detailed leaflet-level characterization of fibrotic and calcific remodeling in aortic stenosis remains limited with energy integrating CT. Photon-counting CT enabled reliable leaflet-specific quantification of fibrosis and calcification, identified sex-related tissue distribution patterns, and demonstrated associations between calcification and impaired leaflet mobility. Leaflet-specific photon-counting CT assessment may enhance our understanding of aortic stenosis progression and support more individualized imaging evaluation through improved differentiation of fibrotic and calcific valvular remodeling. Clinical Trials Registration NCT05851209

Source: medRxiv

DOI: 10.64898/2026.10.27.26366483