Background: Endometriomas and functional hemorrhagic cysts (FHCs) are a common
Objective: This study aimed to assess the diagnostic efficiency of magnetic resonance imaging (MRI)
using signal intensity measurements in differentiating endometriomas from FHCs.
Methods: Forty-six patients who underwent pelvic MRI examinations (endometriomas, n=28;
FHCs, n=18) were retrospectively included. The “T2 shading” sign was evaluated subjectively and
quantitatively by measuring the T1-T2 signal intensity difference and calculating the percentage of
signal decrease between T1 and T2-weighted sequences. The resulted values, along with the measurement
of the Apparent Diffusion Coefficient (ADC) and the signal intensity on three diffusion-
weighted sequences (DWI) (b50, b400, and b800), were compared between groups by using the
Mann–Whitney U test. Also, the receiver operating characteristic analysis was performed for the
statistically significant results (P<0.016), and the area under the curve (AUC) was also calculated.
Results: The two quantitative assessment methods showed similar efficiency in detecting endometriomas
(P<0.001; sensitivity, 100%; specificity, 81.82%; AUC>0.86), outperforming the classic
subjective evaluation of the “T2 shading” sign (sensitivity, 92.86%; specificity, 66.67%). ADC
(P=0.52) and DWI measurements (P=0.49, P=0.74, and P=0.78) failed to distinguish between the
Conclusion: The quantitative analysis and interpretation of the “T2 shading” sign can significantly
improve the differential diagnosis between endometriomas and FHCs.