"T2-Hypointense Dot Sign": A Novel and Highly Suggestive Clue for the Diagnosis of Ovarian Torsion

Abstract

Purpose: We aimed to describe "T2-hypointense dot sign" for the diagnosis of ovarian torsion and compare its diagnostic capability with whirlpool sign. Methods: Pelvic MRIs of 31 patients with surgically proven ovarian torsion were used for the analysis. The control group was comprised of 30 patients with adnexal neoplasm and 15 patients with tubo-ovarian abscess. The MRIs of all 76 patients were retrospectively evaluated by two independent radiologists for the presence of T2-hypointense dot sign and whirlpool sign using a three-point scale. Results: The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy values for the T2-hypointense dot sign for the diagnosis of ovarian torsion for observer 1 and observer 2 were 0.90, 1, 1, 0.93, and 0.96 and 0.87, 1, 1, 0.91, and 0.94, respectively. These same values for the whirlpool sign for observer 1 and observer 2 were 0.58, 1, 1, 0.77, and 0.82 and 0.42, 1, 1, 0.71, and 0.76, respectively. Both signs were definitely negative in patients with adnexal neoplasm and tubo-ovarian abscess. Interobserver agreement was excellent for the T2-hypointense dot sign (kappa = 0.83), but poor for the whirlpool sign (kappa = 0.31). Conclusions: The presence of T2-hypointense dot sign could be a valuable clue for the accurate and early diagnosis of ovarian torsion in non-contrast MRI scans.