Magnetic resonance imaging characteristics of ovarian torsion: insights into diagnostic features

We aimed to describe the magnetic resonance imaging (MRI) features of adnexal torsion, additional radiological findings and apparent diffusion coefficient (ADC) measurements of the affected and non-affected ovaries.

We retrospectively examined the MRI of 34 torsed adnexa of 34 cases. We specifically examined the peripherally displaced follicle sign, stromal edema, lack of stromal contrast enhancement, follicular rim sign, T2 hypointense rim sign, uterine deviation, adnexal displacement, whirlpool sign, T2 hypointense dot sign, and tubal thickening. These signs were systematically compared between the torsed and non-torsed adnexa. In addition to that, the presence of free fluid was recorded. As a quantitative analysis, ovarian size and stromal ADC values in torsed and non-torsed ovaries were measured.

The average age was 36.6 years. The right ovary was torsed in 21 (61.8%) of the cases, and the left ovary was torsed in 13 (38.2%). There were significant differences between groups in all signs except the follicular rim sign. The highest accuracy was at the whirlpool sign (0.93). This was followed by uterine deviation and stromal edema (0.85). The accuracy rates of other findings are, respectively, lack of stromal contrast enhancement (0.81), T2 hypointense dot sign (0.79), peripherally displaced follicle sign (0.77), displacement of the adnexa (0.66), tubal thickening (0.66), T2 hypointense rim sign (0.62) and follicular rim sign (0.54). The largest size of ovary in patients with torsion was significantly larger, with an average of 67.5 ± 16.3 mm, compared to 38.8 ± 7.7 mm in non-torsed adnexa (p < 0.001). Additionally, the stromal ADC value was significantly higher in torsed ovarian stroma, averaging 1930.5 ± 455.4 (10⁻⁶ mm²/s) compared to 1655.7 ± 349.3 (10⁻⁶ mm²/s) in non-torsed ovarian stroma (p < 0.001).

In our study, we conducted a comprehensive evaluation of various imaging signs associated with adnexal torsion. The most reliable indicators of adnexal torsion, based on their high accuracy rates, include an enlarged ovary, the presence of the whirlpool sign, uterine deviation, and stromal edema.