High-intensity focused ultrasound therapy in the uterine fibroid: a clinical case study of poor heating efficacy

TL;DR

This study investigates why high-intensity focused ultrasound therapy was less effective in heating a uterine fibroid, identifying high local perfusion and deep location as key factors affecting treatment efficacy.

Contribution

It combines MRI perfusion analysis and ultrasound simulations to identify causes of poor heating in HIFU treatment of uterine fibroids.

Findings

High local perfusion rate in the fibroid compared to surrounding tissue

Deep location of the fibroid contributed to ultrasound attenuation

Small focal point shift observed during ultrasound simulation

Abstract

A clinical case study of high-intensity focused ultrasound (HIFU) treatment in the uterine fibroid was conducted. During the therapy, poor heating efficacy was observed which could be attributed to several factors such as the local perfusion rate, patient-specific anatomy or changes in acoustic parameters of the ultrasound field. In order to determine the cause of the diminished heating, perfusion analyses and ultrasound simulations were conducted using the magnetic resonance imaging (MRI) data from the treatment. The perfusion analysis showed high local perfusion rate in the myoma (301.0 +- 25.6 mL/100 g/min) compared to the surrounding myometrium (233.8 +- 16.2 mL/100 g/min). The ultrasound simulations did not show large differences in the focal point shape or the acoustic pressure (2.07 +- 0.06 MPa) when tilting the transducer. However, a small shift (-2.2 +- 1.3 mm) in the axial location of the focal point was observed. The main causes for the diminished heating were likely the high local perfusion and ultrasound attenuation due to the deep location of the myoma.