Diagnostic performance of dual-energy Rho/Z CT and cinematic rendering in Achilles tendon rupture: a prospective...

To evaluate the diagnostic performance of dual-energy computed tomography (DECT) Rho/Z mapping and cinematic rendering (CR) for detecting Achilles tendon rupture.

In this prospective study, 117 consecutive patients (median age, 40 years; IQR, 32.8-44.0; range, 17-62) underwent DECT between January and September 2024. MRI served as the reference for rupture diagnosis and quantitative measures (location and gap). For complex/atypical tears (partial tears, avulsion fractures, intratendinous calcifications), operative findings were used as the reference standard. Three independent readers, blinded to the reference, interpreted images in three sessions (grayscale CT, DECT Rho/Z, and CR) to determine rupture presence, location, and gap. Diagnostic metrics (AUC, sensitivity, specificity, accuracy, PPV/NPV) were calculated; Rho/Z cutoffs were derived by ROC analysis.

In total, 194 DECT/CR datasets were analyzed (77 bilateral = 154; 40 unilateral = 40). DECT Rho/Z and CR outperformed grayscale CT for rupture detection with AUCs > 0.90 (all P < 0.001). Consensus reader accuracy was higher for DECT (94.9%) and CR (91.8%) than for grayscale CT (66.0%). In exploratory subgroup analyses, DECT showed favorable sensitivity and specificity for avulsion fractures and calcifications; for partial tears, DECT/CR achieved high accuracy (99.1%, 116/117). Measurements of rupture location and gap showed substantial agreement with the reference (κ > 0.80). Quantitative parameters (80-keV, Sn150-keV, Rho, Z_eff) differed significantly between ruptured and intact tendons (all P < 0.001).

DECT Rho/Z and CR showed strong diagnostic performance versus grayscale CT using MRI/operative findings as references and may provide complementary value in complex cases.