Improved magnetic resonance thermal imaging by combining proton resonance frequency shift (PRFS) and apparent diffusion coefficient (ADC) data

Effective thermal therapy for cancer is dependent on adequate tumor heating. Adequate heating, in turn, is dependent on reliable volumetric measurement of temperature to guide heating. Proton resonance frequency shift (PRFS) magnetic resonance imaging is frequently used for the purpose of three-dimensional temperature imaging. However, this method is susceptible to drift in the imaging magnetic field, leading to a corresponding drift in the measured temperature. A new approach to correcting for this drift is presented. It combines PRFS imaging alternated with water apparent diffusion coefficient (ADC) imaging to yield resulting thermal images that are drift corrected and possess the complementary strengths of the two methods. The drift-corrected PRFS images retain the high resolution and relatively noise-free characteristic of PRFS imaging while adding on the drift-free stability of ADC imaging. This technique is successfully demonstrated in a phantom experiment. This technique is also applicable to correcting motion-induced sudden large discontinuities in PRFS imaging, although not explicitly demonstrated in this work.