MRI-guided HIFU surgery for treatment of brain lesions

Abstract

MRI guided HIFU is non-invasive therapy that used to ablate the brain lesion disorder such as essential tremor and MRI is used for planning and monitoring the procedure of the HIFU treatment. Essential tremor (ET) is the most common movement disorders that occur during activity or rest time. Two types of mechanisms are commonly required to explain the effects of therapeutic ultrasound. These are categorised as thermal effects and mechanical effects. HIFU is utilised for local ablation therapy on different types of tissues using an intensity more than 1000 W/cm2. Hence, other tissues can behave differently when exposed to heat, necessitating accurate monitoring of thermal feedback during treatment.

The HIFU transducer has 1,024 elements with frequency 650-kHz, which are transmitted through the intact skull to a focal point. As the beams are concentrated and converge, the target brain tissue becomes ablated at the Maximum temperature 60°C. Continuous, real-time thermal data input by using the MRI machine helps the clinical staff reliably to change the position and temperature parameters during the procedure. The widely used MRI mapping to measure temperature changes in tissue during a hyperthermia procedure is proton resonance frequency (PRF) of water tissue at field strength 3T.