MR-guided focused ultrasound surgery, present and future

Abstract

MR-guided focused ultrasound surgery (MRgFUS) is a quickly developing technology with potential applications across a spectrum of indications traditionally within the domain of radiation oncology. Especially for applications where focal treatment is the preferred technique (for example, radiosurgery), MRgFUS has the potential to be a disruptive technology that could shift traditional patterns of care. While currently cleared in the United States for the noninvasive treatment of uterine fibroids and bone metastases, a wide range of clinical trials are currently underway, and the number of publications describing advances in MRgFUS is increasing. However, for MRgFUS to make the transition from a research curiosity to a clinical standard of care, a variety of challenges, technical, financial, clinical, and practical, must be overcome. This installment of the Vision 20∕20 series examines the current status of MRgFUS, focusing on the hurdles the technology faces before it can cross over from a research technique to a standard fixture in the clinic. It then reviews current and near-term technical developments which may overcome these hurdles and allow MRgFUS to break through into clinical practice.

Preliminary experience with a transcranial magnetic resonance–guided focused ultrasound surgery system integrated with a 1.5-T MRI unit in a series of patients with essential tremor and Parkinson’s disease

“…6,7,13,36,43 The HI-FU adopted in MRgFUS generates its effects on target tissues through several mechanisms: direct heating, cavitation, and shear stress. 52 Since its development, the most recent technologies have allowed the use of HI-FU in neurosurgical practice. 1,21,28,30,31,52 MRI guidance is used for both the planning and the thermal monitoring of the targeted area, thanks to water proton resonance frequency-shift thermometry.…”

“…52 Since its development, the most recent technologies have allowed the use of HI-FU in neurosurgical practice. 1,21,28,30,31,52 MRI guidance is used for both the planning and the thermal monitoring of the targeted area, thanks to water proton resonance frequency-shift thermometry. 30,35 At the beginning, MRgFUS was used to treat both benign and malignant neoplasms.…”

Improving thermal dose accuracy in magnetic resonance-guided focused ultrasound surgery: Long-term thermometry using a prior baseline as a reference

“…Targeting already treated tissue also prolongs the procedure time, which is a major criticism of volumetric MRgFUS compared to alternative therapies. [13][14][15] Another consequence of inaccurate thermometry is the commonly reported mismatch between thermal dose treatment volume (TDV) and nonperfused volume (NPV), which is the clinically accepted standard of in vivo ablation efficacy. 7,[16][17][18][19] There is potential for disagreement between the two in vivo measures (TDV, NPV) of treatment volume, as they are derived from different physical phenomena; TDV is based on temperature-dependent image-based phase accrual during treatment surpassing the threshold of 240 equivalent minutes, while NPV is based on the ability of contrast agent to reach the tissue after treatment.…”

MRI-guided focused ultrasound surgery in musculoskeletal diseases: the hot topics

“…MRgFUS offers several advantages in comparison with these techniques, since it is a radiation-free technique not requiring any surgical incision or invasive/mini-invasive approach; however, a large variety of technical, financial, clinical and practical challenges must be overcome to allow MRgFUS to break through into clinical practice and to make the transition from a research curiosity to a clinical standard of care. 25,26 …”