Quantifying perfusion-related energy losses during magnetic resonance-guided focused ultrasound

Background/introduction The focused ultrasound power required for successful ablation of uterine fibroid tissue varies substantially between patients and within single treatments.[1,2] Fibroids with high signal intensity in pretreatment T2-weighted MR images have been shown to require increased power to achieve adequate temperature elevation for ablation;[2,4] thus, T2-weighted signal intensity has been suggested as a predictor of MRgFUS treatment response.[2,3] Physiologically, the high intensity of T2weighted MR images of uterine fibroids may represent vascularization, fluid-rich tissues, or degeneration.[4,6] By quantifying perfusion-related energy losses (Qb) during MRgFUS treatments, this study is the first step in linking perfusion-related energy losses with MR perfusion imaging. This knowledge could be used to improve biothermal modeling of MRgFUS fibroid treatments and as a potential independent predictor of treatment response and outcome.