Suk Kim MD, Abstract Co-Author: Nothing to Disclose

Ga Jin Han, Presenter: Nothing to Disclose

Nam Kyung Lee MD, Abstract Co-Author: Nothing to Disclose

Tae un Kim, Abstract Co-Author: Nothing to Disclose

Dong Soo Suh, Abstract Co-Author: Nothing to Disclose

Do Youn Park, Abstract Co-Author: Nothing to Disclose

 Classic MRI features of endometriosis are a cystic lesion with hyperintensity on T1-weighted image and hypointensity (shading) on T2-weighted image. However, because these findings are infrequently seen in hemorrhagic cysts, hemorrhagic cysts may be misdiagnosed as endometriosis. Thus, the purpose of our study was to investigate the value of DWI in the distinction of endometriosis from hemorrhagic cyst in the ovary.

 In 198 patients with T1 hyperintense ovarian cystic masses who underwent MR with respiratory-triggered breath-hold DWI at 1.5 T, 75 endometriotic lesions were confirmed at surgery in 61 patients (14: bilateral, 47: unilateral involvement). As control, 13 hemorrhagic cysts were confirmed at surgery in 13 patients. A total of 88 ovarian lesions (75 endometriosis and 13 hemorrhagic cysts) were enrolled in this retrospective study. Ovarian lesions were analyzed for size, the pattern of shading (no signal loss, a signal loss of the entire lesion, a fluid-fluid level with hypointesity of the dependent portion), signal intensity (SI) ratio (SI of the lesion/ SI of the gluteus maximus muscle) on T2-weighted image, in consensus by two radiologists. ADC values were also calculated in ovarian lesions, particularly focusing on shading. The comparison of ADC values between endometriosis and hemorrhagic cysts was used by the Mann-Whitney U test. Optimal cutoff values of ADC values for differentiating endometriosis from hemorrhagic cyst were obtained with receiver operating characteristic analysis.

 On T2-weighted image, endometriosis showed no signal loss (n=3, 4.0%), signal loss of the entire lesion (n=53, 70.7%), fluid-fluid level (n=19, 25.3%), and all hemorrhagic cysts showed signal loss of the entire lesion. The mean ADC values of endometriosis and hemorrhagic cyst were 1.09 ± 0.32 × 10−3  and 0.77 ± 0.42 × 10−3 mm2/sec, respectively  (P < .005). Optimum cutoff values of ADC for differentiating endometriosis from hemorrhagic cyst were 0.80 × 10−3 mm2/sec (sensitivity, 76%; specificity, 70%).

 The addition of DWI to T2-weighted image could be helpful in the differentiation of endometriosis from hemorrhagic cyst in the ovary.

 The addition of DWI to T2-weighted image may be useful to differentiate endometriosis from hemorrhagic cyst in the ovary, which can enable patients to avoid unnecessary surgery.

Kim, S, Han, G, Lee, N, Kim, T, Suh, D, Park, D, Diffusion-weighted MR Imaging (DWI) in the Differentiation of Endometriosis from Hemorrhagic Cyst in the Ovary.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11008792.html