Acoustic Coupling Bath Using Heavy Water For Transranial Magnetic Resonance-Guided Focused Ultrasound Surgery

In transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) treatments, the degassed water flowing between the gap of the skull and the focused ultrasound (FUS) transducer was used for acoustic coupling and skull skin cooling. However, the circulating water may affect the magnetic resonance (MR) images, such as introducing uncertain artifacts or reducing signal-to-noise ratio (SNR). This study, tested the feasibility of using heavy water (D2O) as a coupling bath for tcMRgFUS. Phantom studies were conducted to examine the validity of heavy water on eliminating image artifacts and improving SNR. Meanwhile, the acoustic properties of D2O in coupling were measured. The results suggested that the acoustic attenuation of heavy water can be neglected and the acoustic velocity in heavy water is close to that of pure water. Thus, heavy water is a suitable material for tcMRgFUS coupling baths replacing the regular cooling and coupling water (H2O).