Precision imaging biomarkers for gout: artifact-specific spectral CT parameters for personalized differentiation of...

Spectral computed tomography (CT) enables non-invasive visualization and quantification of monosodium urate deposits and has an important role in gout diagnosis and monitoring. However, artifact-related false-positive findings may reduce diagnostic confidence, particularly when artifacts show attenuation features overlapping with tophi.

To evaluate advanced spectral CT parameters as quantitative imaging biomarkers for differentiating tophi from common artifacts.

Prospective cross-sectional study.

Consecutive participants with suspected foot gout were prospectively recruited from May 2023 to May 2024 and underwent foot spectral CT scans. Participants were classified into gout and non-gout groups. Regions of interest (ROIs) were delineated on index tophi in the gout group and on artifact regions in the non-gout group, including nail bed, skin, beam-hardening, vascular, and tendon artifacts. Conventional attenuation (HU_120-kV) and three advanced spectral parameters (effective atomic number (Zeff), electron density (ED), and dual-energy ratio (DER)) were measured and compared. Diagnostic performance of each parameter was assessed using receiver operating characteristic curves and the area under the curve (AUC).

The final analysis included 82 tophus ROIs and 243 artifact ROIs. Tophi differed significantly from beam-hardening, vascular, and tendon artifacts across all parameters (p < 0.001). ED (AUC = 0.848-0.939) and HU_120-kV (AUC = 0.819-0.935) showed the most consistent performance for overall artifacts, beam-hardening, vascular, and tendon artifacts, with no significant difference between them. In contrast, discrimination of nail bed and skin artifacts was more limited. DER (AUC = 0.728) and Zeff (AUC = 0.722) provided complementary values for nail bed artifacts, while ED showed the highest AUC for skin artifacts (AUC = 0.740).

Spectral CT parameters may support artifact-specific tophus differentiation in gout. An artifact-specific parameter selection approach may help reduce false-positive interpretations and improve confidence in spectral CT-based gout assessment.

Chinese Clinical Trial Registry, ChiCTR2300069114, https://www.chictr.org.cn/showproj.html?proj=185804.