An optimised multi-baseline approach for on-line MR-temperature monitoring on commodity graphics hardware

Magnetic resonance Imaging (MRI) can be used for non invasive temperature mapping and is therefore a promising tool to monitor and control interventional therapies based on thermal ablation. The proton resonance frequency shift MRI technique gives an estimate of the temperature by comparing phase changes between dynamically acquired images. These temperature measurements are prone to motion induced errors however, particularly in abdominal organs due to breathing. Several computational approaches have been proposed previously to correct for these motion related errors on the measured temperature. They have required significant time to compute however, and have not been sufficiently fast for several real-time temperature mapping applications. This paper proposes to use modern graphics cards (GPUs) to assess on-line motion corrected thermal maps. The computation times obtained on the GPU are compared to an existing CPU reference implementation. An acceleration factor close to 7 was obtained for the processing of one slice (resolution 128 times 128 pixels), and higher than 21 for 12 slices, allowing a real-time implementation.