Diagnostic limitations in advanced stage peripheral arterial disease in a cadaveric study comparing photon-counting and energy-integrating CT detectors

To evaluate the limits of 1st-generation dual-source photon-counting detector CT (PCD-CT) and 3rd-generation dual-source energy-integrating-detector (EID-CT) regarding imaging of advanced stage peripheral arterial disease (ASPAD) of the femoral runoff. One human cadaver with ASPAD of the superficial femoral arteries was surgically prepared to establish continuous extracorporeal perfusion of the right upper leg. In addition to one stent already in place, three more stents were deployed in positions with severe calcification and stenosis to create thirteen different scenarios of ASPAD. CT angiographies with different radiation dose (CTDI_vol 10, 5, 3 mGy) and matching convolution kernels were performed with PCD-CT and EID-CT. In-stent lumen visibility, signal-to-noise ratio (SNR), and luminal attenuation were assessed quantitatively. Results were compared using analyses of variance with a PCD-CT maximum dose and resolution scan (96 mGy, BV89) serving as standard of reference. Highest and lowest stent lumen visibility was observed with PCD-CT BV76 (97 ± 2%) and EID BV40 (77 ± 5%), respectively. Severe stent underexpansion in conjunction with heavy calcification resulted in the worst lumen visibility. PCD-CT displayed superior dose efficiency, yielding comparable SNR at 3 mGy to EID-CT at 10 mGy (p = 0.27). Luminal attenuation was higher for PCD-CT regardless of dose and reconstruction settings (max. 369 ± 19 HU, BV76, 5 mGy vs. 329 ± 12 HU for EID, BV59, 5 mGy; p < 0.001). PCD-CT realises substantially higher image quality than EID-CT, thereby enhancing assessment of the femoral vasculature in ASPAD. Furthermore, this indicates substantial radiation dose and contrast agent volume saving potential. Both scanners show limitations in very low luminal diameters.