Objective: This study was undertaken to clarify the relationship between the signal intensity of T2-weighted magnetic resonance images and the therapeutic effect of magnetic resonance-guided focused ultrasound surgery (MRgFUS) on uterine fibroids. Study design: Ninety-five fibroids in 63 patients were classified into 3 types based on the signal intensity of T2-weighted magnetic resonance images as follows: type 1, low intensity
type 2, intermediate intensity
type 3, high intensity. The treated area ratio of MRgFUS and the volume reduction ratio 6 months after treatment were used as the indices of therapeutic effect. Results: The treated area ratio of type 3 fibroids was the lowest among the 3 types (P &lt
.01). The volume reduction ratio correlated with the treated area ratio (r = 0.64
P &lt
.01). Conclusion: The efficacy of MRgFUS correlates with the signal intensity of T2-weighted magnetic resonance images. Type 1 and type 2 fibroids are suitable candidates for MRgFUS, whereas type 3 fibroids are not. © 2007 Mosby, Inc. All rights reserved.