Summary:
Researchers from the UCLA Department of Radiological Sciences have developed a novel magnetic resonance thermometry technique that rapidly obtains 3D images and temperature maps with high spatial and temporal resolution and without breath holds for better treatment guidance in organs with motion and fatty tissue content.
Background:
Magnetic resonance imaging (MRI) is an important technology that provides crucial information to plan, guide, monitor, and assess minimally invasive thermal therapies. Thermal therapy is a growing area of interest in the clinic for its application in treating a wide range of disorders that had previously required surgery to treat. The technique allows clinicians to ablate aberrant tissue in a less invasive manner. Importantly, MRI can measure temperature distribution and estimate thermal dosage during procedures to help determine a treatment endpoint and prevent thermal damage to non-target tissues. The most widely used strategy today for MRI temperature mapping is based on the proton resonance frequency shift (PRF), but PRF temperature mapping is susceptible to phase errors and image artifacts caused by motion, including from breathing. This limits spatial coverage and makes MRI thermometry difficult for sick, elderly or pediatric patients. Additionally, PRF cannot measure temperature change in adipose tissues, which are often present in or near organs such as the breast, liver, and prostate. While more recent progress has been made to achieve MRI temperature measurement in both aqueous and adipose tissues, the majority of these methods only provide measurements in a few slices and do not achieve 3D coverage. Thus, a technique allowing for free-breathing dual MR thermometry of aqueous and adipose tissues with high spatiotemporal resolution and 3D coverage fulfills a great need in the field.
Innovation:
UCLA researchers led by Holden Wu in the Department of Radiological Sciences have developed a new method for free-breathing MRI mapping of temperature in aqueous and adipose tissues. They found that their new method performed better than currently available methods and demonstrated good agreement with reference measurements in phantom. In healthy humans, the new free-breathing method achieved 3D coverage of the brain, breast, prostate, or liver with fast (<5 seconds) temporal resolution. The temperature maps were stable over time during the 20-30 minute non-heating scans despite potential motion and were consistent across subjects. The researchers also used the proposed technique to monitor high-intensity focused ultrasound (HIFU) ablation in ex vivo porcine fat/muscle tissues and found that the technique achieved 3D coverage with high spatial and temporal resolution and measured temperatures consistent with temperature probe readings. Taken together, Wu and team’s novel MRI technique could improve MRI-guided thermal procedures, particularly for organs with motion and fat tissue content.
Potential Applications:
● High resolution temperature mapping for guiding thermal therapy in aqueous and adipose tissues
● Free-breathing MRI for patients with breath-holding difficulties
Advantages:
● Fast imaging (<5 sec/volume) with 3D spatial coverage
● Eliminates breath holding
● Measures accurate temperature values in aqueous and adipose tissues
Patent Application:
System and method for free-breathing quantitative multiparametric mri
Development to Date:
Researchers have successfully acquired images with high 3D spatial and temporal resolution and accurate temperature maps in phantom and in healthy human subjects. They have also successfully demonstrated use of the technique to accurately monitor temperature during high-intensity focused ultrasound ablation in ex vivo porcine fat/muscle tissues.