Towards the direct quantitative monitoring of the dynamic of cryosurgery iceballs with open-field MRI

Presents the results of a series of experiments towards the direct quantitative monitoring of the growth of cryosurgery iceballs in fat under open-field MRI. The study was conducted using the near-real-time mode of a SIGNA SP/sup TM/ 0.5 T open-field MRI system from General Electric Medical Systems. The study reports the dynamic course of the iceball growth process sampled simultaneously in the temperature, MR signal and spatial domains. Algorithms to automatically estimate the diameter of the growing iceball from the time series of sagittal MR images are presented. Building on these direct measurements, a prescription is introduced to predict the cryogenic temperatures reached within the iceball which are beyond the range of sensitivity of the MR signal itself. Results show that the approach is quite promising especially when the range of sensitivity of the MR signal is sufficiently extended to allow for a parametric fit of the iceball dynamics to the sample temperature.