Decreased attenuation difference between non-contrast and portal-venous phases of CT predicts the ultrasonography-unspecified adnexal torsion

Objectives To evaluate the value of contrast-enhanced CT in diagnosing ultrasonography-unspecified adnexal torsion (AT). Methods Surgically confirmed patients with painful pelvic masses ( n = 165) were retrospectively collected from two institutes. Two senior radiologists independently reviewed the CT images and determined the Hounsfield unit difference between non-contrast vs portal venous phases (ΔHU PV-NC ) in both derivation and validation samples. The cutoff value, sensitivity, specificity, predictivity, and reproducibility of the ΔHU PV-NC and other visually assessed CT signs were analyzed and compared using the receiver-operating characteristic curve, multivariable regression, and inter-rater agreement assays, respectively. Results Women with twisted ( n = 73 [47 ± 19 years]) or untwisted ( n = 92 [40 ± 15 years]) adnexal lesions were reviewed. The ΔHU PV-NC ≤ 17.5 HU (AUC: 0.91 [95% CI: 0.86, 0.96]; sensitivity: 95% [95% CI: 87, 98]; and specificity: 88% [95% CI: 80, 94]) was the independent predictor of AT (OR: 137 [95% CI: 39, 481], p