Work

Temperature Mapping During MR ‐Guided Cryoablation Using a FLORET UTE Sequence

Year: 2025

Type: article

Abstract: ABSTRACT Purpose To implement a three‐dimensional FLORET‐UTE sequence for rapid MR thermometry during cryoablation and to validate voxel‐wise temperature maps against fiber‐optic probes in ex vivo bovine liver. Methods A FLORET‐UTE trajectory (TE 50 μs, 1.6 mm isotropic, 18 s/volume) was executed on a 3 T scanner while dry‐ice cryoablation was applied to liver phantoms. Four fiber‐optic sensors provided reference temperatures. Magnitude signal was normalized to baseline and fitted to a mono‐exponential temperature model in the first experiment; the unchanged model was applied prospectively to the second dataset. Images were reconstructed offline with ‐regularized non‐Cartesian SENSE. Accuracy below 0°C was assessed with root‐mean‐square error (RMSE) and Bland–Altman analysis. Results Calibration yielded a strong signal–temperature relationship (). Prospective validation produced RMSEs of 0.93°C–1.73°C (overall 1.33°C). Bland–Altman bias was °C with limits of agreement °C to 2.23°C. Serial temperature maps captured three‐dimensional ice‐ball dynamics at 18‐s temporal resolution—substantially faster than previously reported radial‐UTE and STIR‐UTE approaches. Conclusion FLORET‐UTE enables quantitative 3‐D MR thermometry of frozen tissue with < 20 s temporal resolution and < 2°C accuracy, overcoming the speed limitations of earlier UTE methods. The technique is a promising candidate for real‐time MR‐guided cryoablation and warrants in vivo evaluation.

Source: Magnetic Resonance in Medicine

DOI: 10.1002/mrm.70152