Ultra-high-resolution photon-counting detector CT for visualization of the brachial plexus.

Objectives: To investigate the use of photon-counting detector CT (PCD-CT) to improve brachial plexus depiction.

Materials And Methods: This retrospective study included patients who underwent neck CT from March to December 2023. To assess the optimal reconstruction condition in PCD-CT, the signal-to-noise ratios (SNRs) on images using various quantitative regular (Qr) kernels and strengths of quantum iterative reconstruction (QIR) were evaluated. Next, images obtained by ultra-high-resolution mode in PCD-CT (PCD-UHR), standard mode in PCD-CT (PCD-STD), and standard mode in energy-integrating detector CT (EID-STD) of 20 patients each were compared regarding brachial plexus depiction. A qualitative evaluation was performed using a 5-point Likert scale regarding sharpness, noise, and overall image quality. The standard deviations (SDs), SNRs, and contrast-to noise ratios (CNRs) were quantitatively evaluated.

Results: Overall, 60 patients (mean age, 63 years ± 18; 30 males) were included. The SNRs for the Qr40 and QIR4 (means ± SDs) were 3.6 ± 1.1 and 4.1 ± 1.2, respectively, significantly higher than others (P < 0.05). The scores for overall image quality were 4 [4-5], 3 [3-4], and 2 [2-3], and those for sharpness were 4 [3-5], 3 [3-3], and 2 [1-3] for PCD-UHR, PCD-STD, and EID-STD, respectively (all, P < 0.05). Those for noise were 3 [3-4], 4 [3-4], and 2 [2-2], the SDs were 6.6 ± 1.6, 5.4 ± 0.8, and 8.8 ± 1.7, SNRs were 5.0 ± 1.4, 6,1 ± 1.2, and 3.5 ± 1.6, and CNRs were 5.6 ± 1.9, 7.9 ± 1.7, and 4.4 ± 1.8, respectively (between either of the PCD groups and EID-STD, P < 0.05).

Conclusion: PCD-CT showed superior delineation for brachial plexus to EID-CT.