Magnetic Resonance Imaging to Rule out Leiomyosarcoma in Patients Undergoing Surgery for Leiomyomas: A Real World Experience in an Unenhanced Patient Population

Objective: Surgery for leiomyomas is common; yet, no reliable test can help distinguish a benign leiomyoma and malignant leiomyosarcoma (LMS). Materials and Methods: This retrospective observational cohort study evaluated patients before and after implementation of a protocol to identify LMS, which included magnetic resonance imaging (MRI) with diffusion-weighted imaging. Results: This study revealed the incidence of uterine pathology, as well as MRI, lactate dehydrogenase (LDH), and pathology results, in 1085 patients - 479 before and 606 after implementation of the protocol. Two cases of LMS were identified in the postprotocol cohort, and 70% of the patients underwent MRI. Test statistics for MRI to detect LMS in this cohort were: sensitivity of 100%; specificity of 67%; positive predictive value of 1%; negative predictive value of 100%; false-positive rate of 33%; and false-negative rate of 0%. For patients with both MRI and LDH results (358/606, 59%), 56.7% had normal MRI and LDH, 9.8% had negative MRI but high LDH, 6.4% had abnormal MRI and high LDH, and 27.1% had abnormal MRI and normal LDH. Conclusion: Preoperative MRI for detecting LMS had high a sensitivity and a high false-positive rate, which warrants caution in interpreting MRI results, particularly in women of childbearing age.