Stenosis quantification in high-pitch photon-counting coronary CT angiography: in vitro and in vivo impact of reconstruction kernel types and sharpness levels.

Abstract

Background: We investigated the influence of different kernel types and sharpness levels on in vitro and in vivo coronary stenosis quantification in high-pitch photon-counting detector coronary CT angiography (PCD-CCTA).

Materials and methods: Coronary stenoses were evaluated in a phantom containing two stenosis grades (25% and 50%), and in a retrospective cohort of 30 patients who underwent high-pitch PCD-CCTA. Scans were reconstructed as virtual monoenergetic images at 55 keV using three different kernels (Br, Bv, and Qr) and four sharpness levels (36, 40, 44, and 48). Percent diameter stenosis (PDS) values were compared. In vitro measurements were additionally compared with the stenosis reference value. Two readers independently assessed the in vivo measurements.

Results: In vitro, PDS values of all stenoses showed no difference among various kernel types and sharpness levels (p ≥ 0.412). However, PDS measurements using kernel Bv40 showed the smallest cumulative deviation from the ground truth. In vivo, a total of 53 stenoses were identified in 30 patients, aged 63 ± 13 years (mean ± standard deviation), 8/30 (27%) females. There was no significant difference in PDS measurements among reconstructions, either when analyzed per stenosis or stratified by different plaque types (p = 1.000). Bv kernels showed higher interobserver reliability (intraclass correlation coefficient: Bv 0.91; Qr 0.88; Br 0.85).

Conclusion: With comparable diagnostic accuracy, different kernel types and sharpness levels can be used in high-pitch PCD-CCTA. Due to the in vivo advantage in interobserver reliability and the in vitro observed lowest cumulative deviation from ground truth, reconstruction with kernel Bv40 should be preferred.

Relevance statement: For image reconstruction in PCD-CCTA with high-pitch mode, kernel Bv40 should be considered to obtain the best diagnostic performance and reliability of stenosis quantification.

Key points: High-pitch PCD-CCTA images can be reconstructed with different kernels. Reconstructions with different kernels showed comparable accuracy on coronary stenosis quantification. In vitro, Bv40 reconstructions showed superior measurement accuracy to the reference. In vivo, reconstructions with the Bv kernel had the highest interobserver reliability. Reconstruction with kernel Bv40 should be considered in high-pitch PCD-CCTA.