Sensitivity of DECT in ACL tears. A prospective study with arthroscopy as reference method

BACKGROUND: CT is often used for fracture evaluation following knee trauma and to diagnose ACL injuries would also be valuable. PURPOSE: To investigate the diagnostic accuracy of dual energy CT (DECT) for detection of ACL tears in acute and subacute knee injuries. MATERIAL AND METHODS: Patients with suspected ACL injury were imaged with DECT and MRI. Clinically blinded DECT images were independently read twice by two radiologists. ACL was classified as normal or abnormal. Arthroscopy served as reference method. Sensitivity and positive predictive value (PPV) were calculated, and diagnostic performance between DECT and MRI was assessed. RESULTS: 48 patients (26 M, 22 F, mean age 23 years, range 15–37 years) were imaged with a mean of 25 days following trauma. Of these, 21 patients underwent arthroscopy with a mean of 195 days after trauma. Arthroscopy revealed 19 ACL tears and 2 ACLs with no tear. The combined sensitivity was 76.3% (95% CI 66.8–85.9) and 86.8 (95% CI 71.9–95.6) for DECT and MRI, respectively. There was no statistically significant difference between these two methods (p = .223). The positive predictive value (PPV) was 93.5 (95% CI 84.3–98.2) and 91.7 (95% CI 77.5–98.3) for DECT and MRI, respectively. CONCLUSION: DECT has lower sensitivity to detect an ACL rupture than MRI, but the difference is not statistically significant. The PPV is high in both methods.