MRI-compatible breast/rib phantom for evaluating ultrasonic thermal exposures.

INTRODUCTION

The target of this study was the development of a magnetic resonance imaging (MRI) compatible breast phantom for focused ultrasound which includes plastic (ABS) ribs. The objective of the current study was the evaluation of a focused ultrasound procedure using the proposed phantom that eliminates rib heating.

MATERIAL AND METHODS

The proposed phantom was evaluated using two different focused ultrasound exposures. The surrounding breast tissue was mimicked using an agar-silica-evaporation milk gel (2% w/v - 2% w/v - 40% v/v).

RESULTS

The attenuation of the ABS was similar to that of ribs. MR thermometry of focused ultrasound exposures were acquired using the breast/rib phantom. In one exposure focused ultrasound was applied with far-field targeting of the ribs. In the other exposure, the transducer was positioned laterally, thus avoiding exposure of the rib to focused ultrasound.

CONCLUSIONS

Due to growing interest in using MRI guided focused ultrasound (MRgFUS) for patients with breast cancer, the proposed breast/rib phantom can be utilized as a very useful tool for evaluating ultrasonic protocols.