TY  - JOUR
A1  - Gruschwitz, Philipp
A1  - Hartung, Viktor
A1  - Ergün, Süleyman
A1  - Peter, Dominik
A1  - Lichthardt, Sven
A1  - Huflage, Henner
A1  - Hendel, Robin
A1  - Pannenbecker, Pauline
A1  - Augustin, Anne Marie
A1  - Kunz, Andreas Steven
A1  - Feldle, Philipp
A1  - Bley, Thorsten Alexander
A1  - Grunz, Jan-Peter
T1  - Comparison of ultrahigh and standard resolution photon-counting CT angiography of the femoral arteries in a continuously perfused in vitro model
JF  - European Radiology Experimental
N2  - Background
With the emergence of photon-counting CT, ultrahigh-resolution (UHR) imaging can be performed without dose penalty. This study aims to directly compare the image quality of UHR and standard resolution (SR) scan mode in femoral artery angiographies.

Methods
After establishing continuous extracorporeal perfusion in four fresh-frozen cadaveric specimens, photon-counting CT angiographies were performed with a radiation dose of 5 mGy and tube voltage of 120 kV in both SR and UHR mode. Images were reconstructed with dedicated convolution kernels (soft: Body-vascular (Bv)48; sharp: Bv60; ultrasharp: Bv76). Six radiologists evaluated the image quality by means of a pairwise forced-choice comparison tool. Kendall’s concordance coefficient (W) was calculated to quantify interrater agreement. Image quality was further assessed by measuring intraluminal attenuation and image noise as well as by calculating signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR).

Results
UHR yielded lower noise than SR for identical reconstructions with kernels ≥ Bv60 (p < 0.001). UHR scans exhibited lower intraluminal attenuation compared to SR (Bv60: 406.4 ± 25.1 versus 418.1 ± 30.1 HU; p < 0.001). Irrespective of scan mode, SNR and CNR decreased while noise increased with sharper kernels but UHR scans were objectively superior to SR nonetheless (Bv60: SNR 25.9 ± 6.4 versus 20.9 ± 5.3; CNR 22.7 ± 5.8 versus 18.4 ± 4.8; p < 0.001). Notably, UHR scans were preferred in subjective assessment when images were reconstructed with the ultrasharp Bv76 kernel, whereas SR was rated superior for Bv60. Interrater agreement was high (W = 0.935).

Conclusions
Combinations of UHR scan mode and ultrasharp convolution kernel are able to exploit the full image quality potential in photon-counting CT angiography of the femoral arteries.

Relevance statement
The UHR scan mode offers improved image quality and may increase diagnostic accuracy in CT angiography of the peripheral arterial runoff when optimized reconstruction parameters are chosen.

Key points
• UHR photon-counting CT improves image quality in combination with ultrasharp convolution kernels.

• UHR datasets display lower image noise compared with identically reconstructed standard resolution scans.

• Scans in UHR mode show decreased intraluminal attenuation compared with standard resolution imaging.
KW  - CT angiography
KW  - femoral arteries
KW  - photon-counting computed tomography (CT)
KW  - small pixel effect
KW  - ultrahigh resolution
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-357905
VL  - 7
ER  -