The American Association of Physicists in Medicine (AAPM) held their annual meeting from July 30 through August 2 in Denver. The focused ultrasound presentations covered topics ranging from the history of cancer immunotherapy and the role FUS can play in immunomodulation; clinical case studies in the use of FUS for the treatment of bone tumors and movement disorders; and the development of new FUS devices for brain treatments. “Many of the clinicians who attended this meeting share our views on open science and collaboration,” said the Foundation’s Director of Extramural Research, Matt Eames, PhD, after attending the sessions. “I was pleased to hear how the principles that are permeating our work at the Foundation (and other medical not-for-profit organizations) are also being advocated in the medical physicist community.”
The Focused Ultrasound Foundation was a primary sponsor of the AAPM’s Ultrasound Special Program, a dedicated 3-day ultrasound track at the meeting that allowed attendees hands-on experience with focused ultrasound systems and a full day of talks on each of focused ultrasound and ultrasound for guiding therapy.
Summary of Talks:
MO-AB-708-0 Hands-on Workshop for Diagnostic Ultrasound Imaging Quality Control, High Intensity Focused Ultrasound Therapy and Ultrasound-guided Therapy by J Zagzebski1*, S Sammet2* (1) University of Wisconsin, Madison, WI, (2) University of Chicago , Chicago, IL
TU-A-708Therapeutic Ultrasound and Immunotherapy: A Primer by Elizabeth Repasky, Roswell Park Cancer Institute, Buffalo, NY, presented an overview of immunotherapy and specifically discussed the ways in which focused ultrasound may be used to modulate existing immunotherapy approaches. Checkpoint inhibitors can permit a powerful immune response by competitively binding receptors or molecules that would otherwise inhibit an immune response.
- TU-B-708-01 Towards a Completely Non-Invasive Treatment of Benign as well as Recurrent or Relapsed Malignant Tumors in Children. K Sharma1*, G ter Haar2*, (1) Children’s National Medical Center, Washington, DC, Dr. Sharma presented information on the osteoid osteoma clinical trial and a new study that plans to use liposomal carrier vehicles to delivery chemotherapy for osteoid osteoma and desmoid tumors.
- TU-B-708-02 Physics aspects of HIFU clinical trials for cancer treatments. The Institute of Cancer Research, London, UK.Dr. ter Haar presented the physical aspects of Sonalleve clinical trials for cancer treatments. She stressed the role of an attending ultrasound physicist: the clinician has expertise for the disease and the anatomy, but the ultrasound physicist understands how the energy interacts with the anatomy. Dr. ter Haar explained the sonication patterns (hyperthermia mode) and how the focus moves in a spiral pattern, which is useful for treating bone. Quality assurance is also an important component of a successful program. An AAPM task group has been formed on phantoms. Logging how treatments progress from patient to patient to gather information on treatment response is the basis of another AAPM task group (#241 led by Allison Payne) for quality assurance processes. Dr. ter Haar is an expert in and proponent of measuring acoustic output for focused ultrasound systems.
- TU-D-708-01 Advances in MR-guided FUS Induced Ablations, Hyperthermia, and Drug Delivery Kullervo Hynynen, University of Toronto, discussed focused ultrasound for thalamotomy, covering accuracy of MR thermometry and thermal dose. He described the physics behind these topics and then described his new work developing a prototype for a send/receive brain transducer. Because inertial cavitation may be a potential treatment for ischemic stroke (to break up the blood clot), the technique would require real-time acoustic monitoring. The newly developed transducer would allow this type of approach.
- TU-D-708-02 Comparison of MR and US Thermometry for Monitoring Tissue Temperature During Hyperthermia Rajiv Chopra, University of Texas Southwestern Medical Center at Dallas, explained that for MR-guided focused ultrasound, long exposures with a gradual temperature rise involve monitoring relative temperature and correcting for signal drift. Ultrasound thermometry is preferable for cases with long exposures and for cases where sonication might occur between breaths, and its temperature accuracy is equivalent to or better than MR. Ultrasound thermometry is also accurate for hyperthermia applications (reaching temperatures of 40C to 45C with a 0.4 degree error and a 1 mm spatial resolution), and this function is also equivalent to or better than MR.
- TU-D-708-03 Design of a Low-Power, Minimally Invasive High Intensity Focused Ultrasound Device for Ablative Applications in Neuro-Oncology: A Simulation Study A cross-departmental group from Johns Hopkins University School of Medicine (Biomedical Engineering, Radiology and Radiological Science, and Neurosurgery) presented their work in simulating the development of a minimally invasive device that would be inserted into the ventricle of the brain through a burr hole and used to apply focused ultrasound ablation from inside. The idea is to address expanding the current treatment envelope in the brain. X Zhang1*, N Ellens2 , M Belzberg3 , P Miller3 , A Cohen3 , H Brem3, J Siewerdsen1,3 , A Manbachi1,3 (1) Department of Biomedical Engineering; (2) Department of Radiology and Radiological Science; (3) Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD.
- TU-D-708-4 Normal-Tissue Toxicity Assessment of Drug-Loaded Nanodroplets Used for Treating Prostate Cancer with MR-Guided Pulsed Focused-Ultrasound To delay prostate tumor growth, this group is testing the use of chemotherapy-loaded nanoemulsions in a mouse model. The drug is released using pulsed focused ultrasound under MR guidance, and tissue toxicity was tested and found to be nontoxic. R Gupta1*, D Cvetkovic2 , C Ma2 , L Chen2(1) UPMC Cancer Centers, Altoona, PA (2) Fox Chase Cancer Center, Philadelphia, PA
Therapeutic Strategies and Image Guidance in HIFU
A session designed to provide a broad understanding and the current status of ongoing research efforts in the area of therapeutic ultrasound.
- TU-FG-708-01 Modulating Brain Circuits with Ultrasound by Charles Caskey, Vanderbilt University Institute of Imaging Science, Nashville, TN
- TU-FG-708-02 Immune-Priming Using Ultrasound by Chandan Guha, Albert Einstein College of Medicine, New York, NY
- TU-FG-708-03 Advancing the Role of MRI in HIFU Treatments by Allison Payne, University of Utah Hospitals, Salt Lake City, UT
- TU-FG-708-04 Mechanisms and Applications of Boiling Histotripsy for Mechanical Tissue Ablation in HIFU by Tatiana Khokhlova, University of Washington, Seattle, WA–As an emerging application for focused ultrasound, histotripsy is unlikely to trigger a clinically meaningful immune response, but it also does not stimulate tumor proliferation (a fact that has not yet been confirmed for ablation). Histotripsy has also proven effective at lysing large blood clots, and so may be a future treatment for cases such as hemorrhagic stroke.
- TU-FG-708-05 Targetability of Adult Soft Tissue Sarcomas for Mild Hyperthermia Treatments Using Magnetic Resonance Imaging-Guided High-Intensity Focused Ultrasound by J Cammin1*, S Kothapalli2, H Chen2, A Partanen3, I Zoberi1, M Altman1 (1) Washington University Department of Radiation Oncology, St. Louis, MO, (2) Washington University Department of Biomedical Engineering, St. Louis, MO, (3) Philips Clinical Science, MR Therapy, Andover, MA
- TU-H-708-01 Advanced Model Based HIFU Therapy Planning and Conduction for the Treatment of Moving Organs by J Jenne, Fraunhofer MEVIS Institute for Medical Image Computing, Bremen, Germany. Dr. Jenne provided an update on the European FUSIMO (Focused Ultrasound In Moving Organs) project.
- TU-H-708-02 Rapid Modeling of HIFU Beam Propagation through Inhomogeneous Tissues by D Christensen, University of Utah, Salt Lake City, UT. Dr. Christensen described his group’s HAS (Hybrid Angular Spectrum) acoustic simulation tool for FUS applications.
- TU-H-708-03 HIFU in Radiation Oncology – Dosimetry and Workflow Consideration by D Schlesinger, University of Virginia Health Systems, Charlottesville, VA. Dr. Schlesinger described radiation dose and FUS thermal dose and discussed how the two can be compared directly based on fraction of cell death.