WE-G-220-07: Treatment Assessment for Pulsed Focused Ultrasound Therapy of Prostate Tumor Using a Clinical 1.5T MRI

Abstract

Purpose: Recent in vivo experiments have showed non‐thermal effects of pulsed focused ultrasound (pFUS) on tumor growth delay. This study investigates the application of a clinical 1.5T MR scanner for treatment assessment of prostate tumors after pFUS treatment, which provides a non‐ invasive and accurate way to measure tumor volume for treatment efficacy evaluation, and also an alternative way for small animaltumor model study that generally requires high‐magnetic‐field MRI facility (e.g., the Bruker NMR system). Methods: A mouse tumor model was developed by implanting LNCaP tumor cells in nude mice prostates. When tumor volume reached ∼130 mm3 on MRI, mice were randomly assigned into two groups (n=8): (1) pFUS treatment; (2) control. MRI‐guided pFUS treatment was performed using InSightec ExAblate 2000 with a 1.5T GE MR scanner. Non‐thermal pFUS was delivered for 60 sec per sonication (1MHz; 25W acoustic power; 10% duty cycle, on/off=0.1/0.9 sec). The body temperature was kept 40% reduction in tumor volume was shown in mice treated with pFUS compared to that for the control mice Conclusion: Clinical 1.5T MRI is able to assess the tumor volume change after pFUS treatment for a small animal model (tumor size: 3–10mm). It may provide an alternative way for treatment assessment for small animal studies. This work is supported by Focused Ultrasound Surgery Foundation, Varian Medical Systems, DOD PC073127 and DOD BC102806.