DOES PELVIC MAGNETIC-RESONANCE-IMAGING DIFFERENTIATE AMONG THE HISTOLOGIC SUBTYPES OF UTERINE LEIOMYOMATA

Objective: To evaluate if pelvic magnetic resonance imaging (MRI) is r eliable for differentiating leiomyoma subtypes. Design: Prospective st udy. Setting: Academic center. Patient(s): Forty-five patients underwe nt MRI before surgery for leiomyomata. Intervention(s): One radiologis t blinded to patient history and histologic diagnosis recorded the MRI characteristics and classification of the largest leiomyoma. Main Out come Measure(s): Comparison of MRI and histologic diagnoses. Result(s) : Leiomyoma subtypes were diagnosed accurately by MRI in 69% of cases. Magnetic resonance imaging had a 95% sensitivity and 72% specificity for diagnosing an uncomplicated leiomyoma and a 10% sensitivity and 10 0% specificity for a cellular leiomyoma. For cystic leiomyomata, the s ensitivity was 80% and specificity was 98%, and for hemorrhagic leiomy omata, 100% and 86%, respectively. Magnetic resonance imaging correctl y diagnosed all malignant tumors and did not incorrectly diagnose a le iomyoma as a leiomyosarcoma in any case. nl-defined MRI margins were s ignificantly more likely to be leiomyosarcoma, whereas well-defined ma rgins were characteristic of benign lesions. Hemorrhagic leiomyomata w ere significantly more likely to be hyperintense on T1-weighted images than other subtypes. Conclusion(s): Although MRI is only fairly accur ate in differentiating the subtypes of benign uterine smooth muscle tu mors, signal intensities and margin characteristics are useful to dist inguish accurately benign from malignant tumors. (Fertil Steril(R) 199 8;70:580-7. (C) 1998 by American Society for Reproductive Medicine.).