Young-Sun Kim MD, Presenter: Nothing to Disclose

Hyo Keun Lim MD, Abstract Co-Author: Research grant, Koninklijke Philips Electronics NV

Hyunchul Rhim MD, PhD, Abstract Co-Author: Nothing to Disclose

Herve Trillaud MD, Abstract Co-Author: Nothing to Disclose

Willem P. Mali MD, PhD, Abstract Co-Author: Nothing to Disclose

Joerg Barkhausen MD, Abstract Co-Author: Nothing to Disclose

To assess the accuracies of size and location of sonication in volumetric MR-HIFU ablation in the treatment of uterine fibroids based on MR thermometry analysis and to know whether or not treatment cell size or a feedback control algorithm affects the sonication accuracies

We treated 33 women (mean age 44.8) with 38 symptomatic uterine fibroids (volume 255±195.8mL) using the MR-HIFU system which was capable of performing volumetric feedback ablation. We analyzed the accuracies of size (diameter×length) and location (AP[anterior-pesterior], FH[foot-head], and LR[left-right] directions) of 527 sonications based on lethal thermal dose (240 equivalent minutes at 43°C[240EM]) in MR thermometry. The effects of treatment cell size and a feedback control were statically evaluated.

Ablation zone sizes of 4, 8, 12 and 16mm treatment cells at 240EM were 4.6±1.4mm×4.4±4.8mm (n=13), 8.9±1.9mm×20.2±6.5mm (n=248), 13.0±1.2mm×29.1±5.6mm (n=234) and 18.1±1.4mm×38.2±7.6mm (n=32). Absolute values of displacements (n=527) were 0.9±0.7mm, 1.2±0.9mm and 2.8±2.2mm in LR, FH and AP directions, respectively. Of 527 sonications, 99.6% (525/527) were within the prospectively defined acceptance range (LR and FH ±5mm; AP ±12mm). Augmentation of ablation zone diameter (p<0.001) and displacement in FH direction(p<0.001) significantly increased as the increments of treatment cell size. Adoption of a feedback control increased diameter (p=0.037) and decreased AP displacement (p=0.026) significantly.

Sonication accuracy of volumetric MR-HIFU ablation of uterine fibroids appears to be small enough to be clinically acceptable, which is affected by treatment cell size and a feedback control.

Volumetric MR-HIFU ablation therapy can be safely used for the treatment of symptomatic uterine fibroids. Safety margin for this therapy could be suggested based on the results of this study.

Kim, Y, Lim, H, Rhim, H, Trillaud, H, Mali, W, Barkhausen, J, Sonication Accuracy of Volumetric MR-HIFU Ablation for the Treatment of Symptomatic Uterine Fibroids Based on MR Thermometry Analysis.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11010731.html