Dual-energy CT in diagnosing sacral fractures: assessment of diagnostic accuracy and intra- and inter-rater reliabilities.

Abstract

Purpose: Evaluating sacral fractures is crucial in fragility fractures of the pelvis. Dual-energy CT (DECT) is considered useful for diagnosing unclear fractures on single-energy CT (SECT). This study aims to investigate the effectiveness of DECT in diagnosing sacral fractures.

Methods: Thirty cases with suspected sacral fractures underwent SECT, DECT, and MRI. The exams were evaluated by two groups: three inexperienced surgeons (Group I) and three experienced surgeons (Group E). Diagnoses were made initially using SECT (pre-DECT) and then reassessed including DECT (post-DECT). This process was repeated twice. Presence of fractures was determined based on MRI. Sensitivity, specificity, inter-rater and intra-rater reliability, and diagnostic accuracy were calculated. Diagnostic accuracy was statistically compared between two groups.

Results: Sensitivity was 0.73 in pre-DECT and 0.9 in post-DECT, while specificity was 0.83 in pre-DECT and 0.91 in post-DECT. Sensitivity significantly improved with the addition of DECT (McNemar test: p < 0.001). Intra-rater reliability (Fleiss' kappa coefficient) was 0.44 in pre-DECT and 0.76 in post-DECT. Inter-rater reliability (Cohen's kappa coefficient) was 0.6 in pre-DECT and 0.81 in post-DECT. Diagnostic accuracy was significantly lower in group I than group E in pre-DECT (P = 0.019, 0.048), but there was no significant difference between two groups in post-DECT.

Conclusion: Combined use of DECT with SECT improved the detection rate of sacral fractures and enhanced intra-rater and inter-rater reliability. High diagnostic accuracy was achieved regardless of the observer's experience. These results indicate that DECT is a useful imaging modality for diagnosing sacral fractures.