Hybrid Magnetic Resonance & Ultrasound (MR-US) Imaging as a Novel Method of High Intensity Focused Ultrasound Treatment Guidance and Monitoring

Victoria Bull¹, John Civale¹, Ian Rivens¹, David J. Collins², Gail ter Haar¹, Martin O. Leach²

Although MRI is considered the gold standard for HIFU treatment guidance, it lacks the ability to interrogate blood flow and monitor cavitation during treatments. A hybrid MR-ultrasound (MR-US) imaging system has shown promise as an improved technique, allowing real-time Doppler ultrasound and B-mode cavitation detection to be performed simultaneously with MR thermometry. A comparative study of truly simultaneous MR-US thermometry has also been conducted, showing good correlation between measurements of temperature change. The appearance of cavitation correlated with fluctuations in MR thermometry, and colour Doppler added dynamic information to MR angiographs. This system is a strong candidate for clinical use.