MRガイド下集束超音波による子宮筋腫治療のための自己参照型温度分布画像化法の最適化

概要

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The self-reference method is a magnetic resonance (MR) thermometry method for mapping temperature changes in a target organ using the baseline phase field in a region of interest (ROI) estimated by the polynomial extrapolation of the field in the surrounding region (s) for estimating (RFE) and subtracting the baseline from the measured field. In the present work, optimization of the ROI and RFE to adopt this technique to MR-guided focused ultrasound surgery (MRgFUS) of uterine fibroid was examined. Both numerical simulation with the Gaussian-profiled heating region and application to clinical data showed that the optimal radius of the ROI should be larger than or equal to 2.7-times of σ, the radius of the temperature field with 1/e of the highest temperature at the heat center, whereas the optimal ratio of the areas of the ROI and RFE should be larger than or equal to 1.5. Use of multiple, isolated RFEs in place of a single, doughnut-like RFE surrounding the ROI was proposed to reduce temperature error due to the unfavorable phase inhomogeneity included in the RFE. The error induced in the isolated RFE was equivalent to that induced in the single RFE in the simulation when the ROI size and ROI to RFE ratio were identical. In the clinical data, the isolated RFEs yielded better agreement with the conventional, baseline subtraction method in Bland-Altman plots.
社団法人日本生体医工学会の論文
2005-12-10