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Safety of Magnetic Resonance Imaging-Guided High Intensity Focused Ultrasound (MRgHIFU) Mild Hyperthermia Treatment of Porcine Muscle in Vivo

L Zhu*, H Chen , H Gach , I Zoberi , D Hallahan , M Altman , Washington University in St. Louis, St. Louis, MO


(Sunday, 7/29/2018) 5:05 PM - 6:00 PM

Room: Karl Dean Ballroom B1

Purpose: Mild hyperthermia therapy (MHT, 41-43°C for up to 1 hour), an effective radiosensitizer, requires accurate and homogenous tumor heating without damaging the surrounding tissues and skin. MRgHIFU can achieve noninvasive, localized, and accurate MHT. However, few studies have evaluated the safety of this technique in living tissues. An in vivo porcine leg model was used here to assess the safety of MRgHIFU-mediated MHT.

Methods: MHT treatment was performed with a clinical MRgHIFU system (Sonalleve V2, Profound Medical.) in porcine leg muscles for three times using focal cell sizes of 18mm and 32mm. Temperature maps acquired from multiple planes every 3s provide feedback control to the HIFU output to maintain the temperature at the desired level. T2-weighted MRIs of the treated region with gadolinium contrast were collected before and immediately after heating to assess any potential thermal damage. Muscles and skin within the heating region were collected for histological analysis and benchmarked against untreated muscle and skin. MR thermometry images were processed offline to evaluate the mean temperature (Tavg) and the standard deviation of the temperature in the target slice, near field, and far field.

Results: The Tavg in the focal region of the target slice was within 1.1°C of the target temperature in all cases. Tavg in the in both near and far field below 39.5°C. No non-perfused muscle within the ultrasound beam path was detected in the contrast-enhanced MR images . The H&E analysis found no significant lesions or congestion in the skin or muscle.

Conclusion: This study demonstrates that a commercial MRgHIFU system can be used for 1hr MHT treatments without causing tissue damage, implying the system may be safe for use in treating human patients.




IM- Ultrasound : Safety

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