A new MRI method, tested in vitro for the assessment of thermal coagulation and demonstrated in vivo on focused ultrasound ablation.

A new MRI method is described. It is implemented for the assessment of thermal coagulation after thermal treatment. The method does not require injection of a contrast agent. The image is based on the amount of magnetization exchange between macromolecules and water in the tissue. Coagulated tissue has a faster magnetization exchange rate, forming the new contrast. In this study, the new imaging method is shown to have good contrast between coagulated and untreated excised tissues of porcine liver and muscle. The method is also successfully demonstrated in vivo in rat thigh muscle thermally treated with focused ultrasound.