MRI characteristics of ovarian metastasis: differentiation from stomach and colorectal cancer

Purpose To evaluate the efficacy of MRI findings for differentiating between ovarian metastasis from stomach cancer (OMSC) and colorectal cancer (OMCC). Methods Twenty-six patients with histopathologically proven ovarian metastasis (n = 8 with 12 OMSCs and n = 18 with 25 OMCCs) were enrolled in the study. All patients had undergone pelvic MRI before surgery. We retrospectively reviewed MRI findings and compared them between the two pathologies. The black scrunchie sign was defined as a thick (> 5 mm) and lobulated hypointense rim (> 180 degrees) with central hyperintense areas on T2-weighted images. Results Predominantly solid lesions (100% vs. 20%, p < 0.01), black scrunchie sign (33% vs. 0%, p < 0.01), and flow void (67% vs. 20%, p < 0.01) were frequently observed in OMSCs than in OMCCs. The signal intensity ratio of solid components on T2-weighted images (3.30 +/- 0.70 vs. 2.52 +/- 0.77, p < 0.01) and gadolinium-enhanced T1-weighted images (2.21 +/- 0.57 vs. 1.43 +/- 0.32, p < 0.01) were significantly higher in OMSCs than in OMCCs. Furthermore, hyperintense areas within cystic components on T1-weighted images (71% vs. 18%, p < 0.01) and stained-glass appearance (44% vs. 0%, p < 0.01) were frequently observed in OMCCs than in OMSCs. Conclusion The black scrunchie sign was only observed in OMSCs. OMSCs always exhibited predominantly solid lesions and had higher signal intensity of solid components on T2- and gadolinium-enhanced T1-weighted images. OMCCs usually presented as cystic lesions, usually accompanied by hyperintense areas within the cystic components on T1-weighted images.