Focused Ultrasound Lab

Our research is focused on the development of new advances in MR imaging methodology, real-time data acquisition/reconstruction, and therapeutic ultrasound techniques. We have projects to develop MRI-guided focused ultrasound techniques for hyperthermia, high-intensity focused ultrasound (HIFU), and low-intensity focused ultrasound (LIFU). Research in those areas will provide promise for treating a wide range of oncological and neurological diseases.

Technical Developments

  • Motion-robust, multi-slice, real-time MR thermometry in abdominal organs
  • Sonication strategies for volumetric ultrasound hyperthermia
  • Temperature mapping robust to motion
  • Real time integration (RTHawk) with InSightec system
  • Temperature mapping in bone and fat

Basic and Clinical Research

MRI-guided focused ultrasound is being investigated as a powerful modality to treat a wide variety of conditions and applications, including movement disorders (such as essential tremor and Parkinson’s disease), brain tumors (such as glioblastoma and brain metastases), bone tumors (including osteoid osteoma), desmoid tumors, and psychiatric illness.

  • Cardiac ablation with high-intensity ultrasound
  • Prostate hyperthermia
  • Pre-clinical studies:
    • Bone regeneration after FUS
    • Effect of sonication duration on ablation depth
    • Facet joint ablation
    • FUS-induced blood-brain barrier opening

Clinical Treatments and Trials

UCSF is consistently ranked amongst the top hospitals for the treatment of a wide variety of conditions. UCSF is a premier site for clinical trial enrollment and investigation because of strong collaborations between scientific and clinical enterprises. We are currently enrolling patients in clinical trials using focused ultrasound for the treatment of brain tumors, psychiatric illnesses, bone tumors, and others.

Focused Ultrasound Research Projects

Motion-robust, multi-slice, real-time MR thermometry

  • This project proposed an effective and practical reconstruction pipeline to achieve motion-robust, multi-slice, real-time MR thermometry for monitoring thermal therapy in abdominal organs.
  • The application includes a fast spiral MRI pulse sequence and a real-time reconstruction pipeline based on multi-baseline proton resonance frequency shift (PRFS) method with visualization of temperature imaging.
  • The pipeline supports multi-slice acquisition with minimal reconstruction lag. Simulations with a virtual motion phantom were performed to investigate the influence of the number of baselines and respiratory rate on the accuracy of temperature measurement.

The result of healthy volunteer experiments without heating (volunteer #1). (a) A coronal slice is acquired and shows the left and right kidney organs which are indicated with blue dashed lines. PRFS temperature maps show that a (c) multi-baseline PRFS reconstruction allows stable and homogeneous temperature measurements, compared to a (b) single baseline

Motion phantom

  • In this project, we developed a low-cost and simple MR-compatible respiratory motion simulator to support proof-of-concept studies of MR monitoring approaches with respiratory-induced abdominal organ motion.
  • The phantom motion system integrates pneumatic control via an actuator subsystem located outside the MRI and coupled via plastic tubing to a compressible bag for distention and retraction within the MRI safe motion subsystem and phantom positioned within the MRI scanner.


Advanced Beamforming Strategies for Volumetric Hyperthermia

  • This project proposed electronic beam steering, multi-focal patterns, and sector vortex beamforming approaches in conjunction with partial array activation.
  • Turning off a percentage of the outer array to increase the f-number increased the focal size with a decrease in focal gain.
  • Sonications with the vortex mode number 4 provided the focused pressure fields around the axis of the beam and the heated volume was enlarged, for higher mode numbers and for lower number of active elements.
  • We developed an acoustic and thermal simulation framework to calculate the 3D acoustic intensity and temperature distribution resulting from the proposed beamforming and scanning strategies.
  • This project demonstrated the feasibility of large volume hyperthermia beam patterns using the ExAblate body system.


MR Thermometry-guided Prostate Hyperthermia with Real-time Ultrasound Beamforming and Power Control

  • Feasibility of prostate hyperthermia with endorectal ultrasound applicators has been demonstrated in clinical trials
  • This project presents a real-time MR thermometry-guided system for hyperthermia delivery within constrained regions with the ExAblate prostate array and validated it in phantom experiments.
  • We developed real-time MR Thermometry platform to control the focus and power output of the ultrasound beam, ensuring constant and uniform heating within the region of treatment.


T2-based Temperature Monitoring in Bone Marrow

  • Proton resonant frequency shift (PRF) thermometry fails to detect temperature change in tissues with high lipid content, such as bone marrow.
  • Current clinical protocols rely on measurement of temperature change of adjacent muscle
  • Poor accuracy of temperature measurement, sub-optimal ablation
  • Here, we developed T2-based thermometry to monitor the temperature in bone marrow during focused ultrasound ablation.
  • We measured a T2 elevation of 269 ms. Assuming the T2/temp coefficient of 7 ms/°C, this corresponds to a temperature rise of 38°C. The ex-vivo experiment shows that it takes 10-15 minutes for the marrow to return to the baseline temperature.
  • The in-vivo experiment showed excellent correspondence between the area of T2 elevation in marrow during the ablation and the resulting non-enhancing area in the post-contrast images.


T2-Mapping as a Predictor for Non-Perfused Volume in MRgFUS Treatments of Desmoid Tumors

  • Desmoid tumors are benign but locally aggressive soft tissue tumors that arise from fibroblast cells.

  • The gold-standard assessment of the reduction of viable tumor volume post-treatment is non-perfused volume (NPV). Evaluation of NPV is typically performed with post-treatment gadolinium enhanced MR imaging. As gadolinium cannot be repeatedly administered during treatments, there is a need for alternative non-contrast monitoring of the tissue to prevent over and under treatment.

  • The objective of this study was to develop an alternative method of non-contrast monitoring of tissue ablation during focused ultrasound treatment.

  • Double-echo and multi-echo images were acquired before, during and after the MRgFUS treatment. T2 maps were generated with an exponential fit and T2 maps were compared to post-treatment post-contrast images. T2 mapping showed excellent qualitative agreement with the post-contrast NPV.

  • This study showed that T2 mapping may be used to visualize the extent of ablation with focused ultrasound and can be used as a predictor of NPV prior to the administration of contrast.


T2-based Temperature Monitoring in Abdominal Fat during Fibroid Treatments

  • The goal of this study was to investigate near-field heating in patients treated with the InSightec fibroid system.
  • Accurate measurement of near-field heating in adipose tissue: shorter treatments and preventing injury in healthy tissues


Focused Ultrasound Lab Researchers

Associate Professor
Associate Chair, Wellbeing and Professional Climate
Associate Professor In Res.
Assistant Professor
Department of Radiology
Asst Professor In Residence
Assistant Professor
Assistant Adjunct Professor