Carotid Body Detection Rate and Size on Photon-Counting Versus Energy-Integrating Detector CT

PURPOSE: To compare the carotid body (CB) detection rate and size measured on photon-counting CT (PCCT) versus energy-integrating detector CT (EIDCT), and to evaluate the effects of laterality and contrast phase. METHODS: This retrospective study was conducted at a single institution on 48 adult patients who underwent head and neck CTA on both PCCT and EIDCT on arterial and venous phase imaging. CB detection was analyzed as a binary outcome using a mixed-effects logistic regression model with modality, phase, side, and modality-by-phase interaction as fixed effects, and patient as a random effect. CB size was analyzed using a linear mixed-effects model with the same fixed effects and patient as a random effect. Sensitivity analysis for CB size adjusted for age, sex, and hypertension. RESULTS: CB detection rates were higher on PCCT than on EIDCT, particularly on the right side (arterial, 96% vs 77%; venous, 96% vs 82%), and slightly higher on the left side (arterial, 85% vs 81%; venous, 83% vs 82%). In mixed-effects logistic regression, PCCT was associated with higher odds of CB detection than EIDCT (OR, 3.97; P = .009). CB size was significantly smaller when measured on PCCT than on EIDCT (estimated difference, -2.7 mm³; P = .01). The right CB was larger than the left across modalities (estimated difference, +4.7 mm³; P < .001). There was no significant difference in CB measurements between arterial and venous phases (P = .53), and no significant modality-by-phase interaction (P = .98). In sensitivity analysis, the modality and side effects remained significant after adjustment for age, sex, and hypertension. CONCLUSION: PCCT improves CB detection compared with EIDCT but yields smaller CB measurements. CB size is greater on the right than on the left, with minimal effect of contrast phase. These findings remained robust after adjustment for age, sex, and hypertension.