The role of the diffuse-weighted magnetic resonance imaging for quality control of radiosurgical treatment of secondary liver tumor lesions
Summary. The aim: to determine the role of diffuse-weighted magnetic resonance imaging (DW-MRI) quality control at the radiosurgical treatment of metastatic liver lesions. The study of the dynamics of quantitative diffusion indices of histologically verified liver metastases in 37 patients undergoing radiosurgical treatment was conducted. The parameters of diffuse-weighted images with the SE-planar image (EPI) are used: the matrix 192×128, TR — 8464, TE — 80, the thickness of the cut — 2 mm, the gap — 8 mm. The value of the b-factor is used: b=0.800 s/mm. 88 metastatic lesions were found, that visualized at diffuse-weighted images for all values of b-factor (0.800) and had a high signal intensity and more clear contours, even in the case of fuzzy imaging lesions on T1, T2. On ADC-maps, metastatic lesions were heterogeneous, reduced rate, quantitative measure of ADC ranged 0.9±0,2•10 s/mm. The mean ADC value in the postoperative stage was 1.5±0,4•10 s/mm. In contrast to metastatic lesions, ADC average value for cysts was 2,4±0,2•10 s/mm, for hemangiomas — 2,1±0,2•10 s/mm. The method of DWI-MRI is fast pulse sequence, which significantly improves the informative value in the detection and differentiation of lesions of benign origin from metastatic, the prognostic value of the positive result compared to contrast-enhanced images. The apparent diffusion coefficient (ADC) as a quantitative indicator allows to differentiate the continuation or processes of regression of the local focus before and after radiosurgical treatment.
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