Proton, diffusion‐weighted imaging, and sodium ( 23 Na) MRI of uterine leiomyomata after MR‐guided high‐intensity focused ultrasound: A preliminary study

Abstract Purpose To determine the feasibility of using combined proton ( 1 H), diffusion‐weighted imaging (DWI), and sodium ( 23 Na) magnetic resonance imaging (MRI) to monitor the treatment of uterine leiomyomata (fibroids). Materials and Methods Eight patients with uterine leiomyomata were enrolled and treated using MRI‐guided high‐intensity frequency ultrasound surgery (MRg‐HIFUS). MRI scans collected at baseline and posttreatment consisted of T2‐, T1‐, and 1 H DWI, as well as posttreatment 23 Na MRI. The 23 Na and 1 H MRi were coregistered using a replacement phantom method. Regions of interest in treated and untreated uterine leiomyoma tissue were drawn on 1 H MRI and DWI, wherein the tissue apparent diffusion coefficient of water (ADC) and absolute sodium concentrations were measured. Results Regions of treated uterine tissue were clearly identified on both DWI and 23 Na images. The sodium concentrations in normal myometrium tissue were 35.8 ± 2.1 mmol (mM), in the fundus; 43.4 ± 3.8 mM, and in the bladder; 65.3 ± 0.8 mM with ADC in normal myometrium of 2.2 ± 0.3 × 10 −3 mm 2 /sec. Sodium concentration in untreated leiomyomata were 28 ± 5 mM, and were significantly elevated (41.6 ± 7.6 mM, P < 0.05) after treatment. Apparent diffusion coefficient values in the treated leiomyomata (1.30 ± 0.38 × 10 −3 mm 2 /sec) were decreased compared to areas of untreated leiomyomata (1.75 ± ‐4048μ‐4050μ36 × 10− 3 mm 2 /sec; P = 0.04). Conclusion Multiparametric imaging permits identification of uterine leiomyomata, revealing altered 23 Na MRI and DWI levels following noninvasive treatment that provides a mechanism to explore the molecular and metabolic pathways after treatment. J. Magn. Reson. Imaging 2009;29:649–656. © 2009 Wiley‐Liss, Inc.