ARRS 2022 Abstracts

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E1435. Photon-Counting vs. Energy-Integrating CT Imaging of the Wrist
Authors
  1. Jan-Peter Grunz; University Hospital Würzburg
  2. Andreas Kunz; University Hospital Würzburg
Objective:
Detailed display of bone microarchitecture is essential for evaluating subtle wrist fractures in CT. The goal of this study was to compare the performance of a novel CT with clinical cadmium-telluride-based photon-counting detector (PCD-CT) to a third-generation dual-source CT scanner with energy-integrating detector build (EID-CT).

Materials and Methods:
Eight cadaveric wrists were examined with both systems using radiation dose equivalent acquisition protocols (low-dose, standard-dose, and full-dose [volume CT dose index = 1.5, 5.8, and 8.7 mGy, respectively). All wrists were scanned with the two operating modes of the photon-counting CT (standard resolution mode and ultrahigh-resolution mode). After reformation with comparable convolution kernels, three radiologists performed subjective evaluation of image quality for each dataset. To estimate the interrater agreement, the intraclass correlation coefficient (ICC) was calculated based on absolute agreement in a two-way random-effects model. Signal-to-noise and contrast-to-noise ratios were computed based on Hounsfield unit measurements in predefined ROIs to provide an additional semiquantitative measure of image quality.

Results:
Subjective image quality of standard-dose PCD-CT scans in ultrahigh-resolution mode was superior compared to full-dose EID-CT (p = 0.040) and full-dose PCD-CT in standard resolution (p = 0.016). No difference was ascertained between low-dose PCD-CT in ultrahigh-resolution and standard-dose scans with either EID-CT (p = 0.470) or PCD-CT in standard resolution mode (p = 0.108). Observer evaluation of EID-CT and standard resolution PCD-CT delivered similar results in full-dose and standard dose examinations (p = 0.248 and 0.509, respectively). ICC was 0.876 (95% confidence interval: 0.744–0.925; p < 0.001), indicating good reliability. Between dose equivalent studies, signal-to-noise and contrast-to-noise ratios were substantially higher in PCD-CT examinations (all p < 0.001).

Conclusion:
High-resolution imaging of the appendicular skeleton is feasible with a cadmium-telluride-based PCD-CT. Compared to energy-integrating detector builds, the novel technique enables superior image quality, hence allowing for considerable dose reduction.