Feasibility of photon-counting CT for femoroacetabular impingement syndrome evaluation: lower radiation dose and improved diagnostic confidence

Andrea Ferrero, Garret M. Powell, Dennis K. Adaaquah, Kishore Rajendran, Jamison E. Thorne, Aaron J. Krych, Kelly K. Horst, Cynthia H. McCollough, Francis I. Baffour

Research output: Contribution to journalArticlepeer-review


Objective: The feasibility of low-dose photon-counting detector (PCD) CT to measure alpha and acetabular version angles of femoroacetabular impingement (FAI). Material and methods: FAI patients undergoing an energy-integrating detector (EID) CT underwent an IRB-approved prospective ultra-high-resolution (UHR) PCD-CT between 5/2021 and 12/2021. PCD-CT was dose-matched to the EID-CT or acquired at 50% dose. Simulated 50% dose EID-CT images were generated. Two radiologists evaluated randomized EID-CT and PCD-CT images and measured alpha and acetabular version angles on axial image slices. Image quality (noise, artifacts, and visualization of cortex) and confidence in non-FAI pathology were rated on a 4-point scale (3 = adequate). Preference tests of standard dose PCD-CT, 50% dose PCD-CT, and 50% dose EID-CT relative to standard dose EID-CT were performed using Wilcoxon Rank test. Results: 20 patients underwent standard dose EID-CT (~ CTDIvol, 4.5 mGy); 10 patients, standard dose PCD-CT (4.0 mGy); 10 patients, 50% PCD-CT (2.6 mGy). Standard dose EID-CT images were scored as adequate for diagnostic task in all categories (range 2.8–3.0). Standard dose PCD-CT images scored higher than the reference in all categories (range 3.5–4, p < 0.0033). Half-dose PCD-CT images also scored higher for noise and cortex visualization (p < 0.0033) and equivalent for artifacts and visualization of non-FAI pathology. Finally, simulated 50% EID-CT images scored lower in all categories (range 1.8–2.4, p < 0.0033). Conclusions: Dose-matched PCD-CT is superior to EID-CT for alpha angle and acetabular version measurement in the work up of FAI. UHR-PCD-CT enables 50% radiation dose reduction compared to EID while remaining adequate for the imaging task.

Original languageEnglish (US)
Pages (from-to)1651-1659
Number of pages9
JournalSkeletal Radiology
Issue number9
StatePublished - Sep 2023


  • Femoroacetabular impingement
  • Pelvis CT
  • Photon-counting CT
  • Radiation dose reduction

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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