Feasibility study on energy prediction of microwave ablation upon uterine adenomyosis and leiomyomas by MRI

Abstract

Objective: To evaluate the feasibility of energy prediction of percutaneous microwave ablation (PMWA) upon uterine leiomyomas and adenomyosis by MRI.

Methods: 63 patients (49 patients with 49 uterine leiomyomas and 14 patients with adenomyosis) who underwent ultrasound-guided PMWA treatment were studied during the period from June 2011 to December 2012. Before PMWA, contrast-enhanced MRI (ceMRI) was performed for all of the patients. Based on the signal intensity (SI) of T2 weighted MRI, uterine leiomyomas were classified as hypointense, isointense and hyperintense. During ablation, the output energy of the microwave was set at 50 W, and T11a microwave antennas were used. ceMRI was performed within 7 days after PMWA treatment. Non-perfused volume and energy required per unit volume were analysed statistically.

Results: When unit volume of lesions was ablated, uterine adenomyosis needed more energy than did uterine leiomyomas, and hyperintense uterine leiomyomas needed more energy than did hypointense pattern.

Conclusions: MRI SI of uterine leiomyomas and uterine adenomyosis can be used to predict PMWA energy.

Advances in knowledge: The conclusions indicate that MRI SI can be used to perform pre-treatment planning, which will make the treatment more precise.

Figures

Figure 1.

MR images of adenomyosis before and after percutaneous microwave ablation (PMWA) in a 41-year-old female with a lesion located in the posterior uterine wall. (a) T2 weighted sagittal MR image of adenomyosis before PMWA (arrow). (b) Contrast-enhanced MRI (ceMRI) of the same lesion before PMWA showing homogeneous contrast enhancement (arrow). (c) ceMRI of the same lesion after PMWA; the length and height of the non-perfusion area were measured on sagittal ceMRI. (d) ceMRI of the same lesion after PMWA; the width of the non-perfusion area was measured on axial ceMRI.

Figure 2.

MR images of hypointense leiomyomas before and after percutaneous microwave ablation (PMWA) in a 32-year-old female, measuring 5.5 × 5.2 × 4.9 cm and 5.4 × 5.0 × 4.6 cm, respectively. (a) T2 weighted sagittal MR image of a patient before PMWA shows two hypointense leiomyomas (arrows). (b) Two hypointense leiomyomas show minor enhancement on contrast-enhanced MRI (ceMRI) before PMWA (arrows). (c) ceMRI of the same patient after PMWA; the length and height of the non-perfusion area of a leiomyoma were measured on sagittal ceMRI. (d) ceMRI of the same patient after PMWA; the width of the non-perfusion area of a leiomyoma was measured on axial ceMRI.

Figure 3.

MR images of hyperintense leiomyomas before and after percutaneous microwave ablation (PMWA) in a 36-year-old female, measuring 6.4 × 5.9 × 6.4 cm, and the method of measurement for non-perfusion area after PMWA. (a) T2 weighted sagittal MR image of hyperintense leiomyomas before PMWA (arrow). (b) Contrast-enhanced MRI (ceMRI) of the same leiomyoma before PMWA shows homogeneous contrast enhancement (arrow). (c) ceMRI of the same leiomyoma after PMWA; the length and height of the non-perfusion area were measured on sagittal ceMRI. (d) ceMRI of the same leiomyoma after PMWA; the width of the non-perfusion area was measured on axial ceMRI.