“Flow void sign” on MRI: Differentiation of uterine leiomyomas from other solid pelvic masses

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Objective: To assess the usefulness of demonstrating flow void sign on conventional MRI sequences in differentiating uterine leiomyomas from other solid pelvic masses which have same signal intensity to myometrium.
Methods: This descriptive study was conducted in the Department of Radiology, University Hospital, Karachi from April 2014 to May 2015. It comprised female patients of all ages who had Magnetic Resonance Imaging (MRI) pelvis with diagnosis of a solid appearing pelvic mass followed by surgery and histopathology at our institution. Flow void sign was described as demonstration of feeding vessels appearing as flow void between the uterine leiomyomas and uterus. Histopathology was taken as gold standard.
Results: Flow void sign was observed in 66 out of 73 pelvic masses on MRI. Out of 66 patients 65 were diagnosed histologically as leiomyomas. When the flow void sign was seen on MRI and subsequent histopathology confirmed the diagnosis of leiomyoma. In all such cased the sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of the flow void sign for diagnosing leiomyomas were calculated as 97% (65/67), 83% (65/66), 98% (65/66), 71% (65/67) and 95% (70/73), respectively.
Conclusion: Flow void sign is an important ancillary sign for the radiological diagnosis of leiomyoma on MRI and useful in differentiating leiomyoma from focal adenomyosis or ovarian tumors (fibromas) which show signal intensity similar to uterine leiomyomas.


Pakistan Journal of Radiology