Evaluation of a Reduced-Radiation and Reduced-Contrast Photon-Counting CT Angiography Protocol for Preoperative Abdominal Wall Artery Mapping
2Gray School of Medicine, Tel Aviv University
Background
CT angiography (CTA) is the reference standard for preoperative deep inferior epigastric artery (DIEA) perforator mapping before DIEP flap reconstruction. We evaluated whether photon-counting detector CT (PCD-CT) could enable reductions in radiation and iodinated contrast while maintaining diagnostic image quality.
Methods
This matched study included 12 PCD-CT examinations and two cohorts of 12 energy-integrating detector CT examinations acquired using GE and Philips scanners. Each PCD-CT patient was matched by age and body mass index to one patient from each comparison cohort. Two blinded reviewers independently rated vessel clarity, diagnostic acceptability, and bilateral small-branch visualization using five-point scales. Bilateral arterial and muscle attenuation and subcutaneous-fat noise were measured at proximal and periumbilical levels to calculate examination-level signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Radiation exposure was assessed using dose-length product (DLP). Matched cohorts were compared using paired t-tests.
Results
PCD-CT enabled a 33% reduction in administered iodinated contrast volume, from 90 to 60 mL. Compared with Philips CT, mean DLP was 240±69 versus 1,451±326 mGy·cm, an 83% reduction (P<.001). Vessel clarity was similar between PCD-CT and GE CT (3.75±0.97 versus 3.83±0.58, P=.795) but lower than with Philips CT (4.50±0.67, P=.043). Diagnostic acceptability and small-branch visualization were lower with PCD-CT than with both conventional systems (all P≤.039). SNR was lower with PCD-CT than with GE and Philips CT (P=.003 and P<.001, respectively). CNR was similar to GE CT (P=.075) but lower than Philips CT (P=.007).
Conclusions
PCD-CT enabled substantial reductions in radiation and iodinated contrast. Despite lower quantitative and subjective image-quality measures, vessel clarity was comparable to GE CT, and the examinations remained clinically acceptable for preoperative DIEA mapping. These findings highlight the challenges of introducing new technology and the need for continuous protocol evaluation to balance patient safety and comfort with diagnostic image quality.