Application Study Of Diffusion Tensor Imaging In Deep Brain Tumor Preoperative Evaluation

Objective:To investigate the alteration of water molecule diffusion characteristics in the white matter tract near deep brain tumor by MR diffusion tensor imaging (DTI) and to explore the application of DTI in the preoperative surgical planning for deep brain tumors.Materials and Methods:10 cases of deep brain tumor patents were included in the study. Routine T1WI/T2WI and DTI scan were performed on a Siemens Magnetom Trio A Tim system I-Class 3.0 T magnetic resonance scanner using single-shot echo - planar imaging (single shotSE EPI) sequence. DTI scan parameters: TR 3000 ms, TE was 93ms, FOV230mm×230mm, Slice thickness 5 mm, diffusion gradient encoding in 20 directions. b =0s/mm2 and 1000 s/mm2, matrix size 256×256, number of signal intensity acquired=4. Fractional anisotropy (FA) maps and apparent diffusion coefficient (ADC) maps were generated automatically using the syngo MMWP VE27 soft in the imaging work station. FA value and ADC value were measured after circling region of interest (ROI) in the corresponding area of bilateral white matter fiber bundles. The relationship between the white matter tracts and tumor mass was observed on the three-dimension reconstructed tracts tracing maps and FA maps. Information of space structure relationship from DTI was employed to guide the preoperative planning.Results:FA value decreased in the white matter tracts near the tumor,mean 0.3416±0.089, range 0.1964∽0.4801. The mean FA value in the normal tracts was 0.4899±0.061, range 0.3865∽0.567. There was a significant statistical different between the FA value in normal tracts and that in tracts near tumor(p<0.01). The mean ADC values of normal tracts and tracts near tumor were 0.72937±0.061×10-3mm2/s (range 0.3865∽0.8311×10-3 mm2/s)and 0.93245±0.1630×10-3mm2/s (range 6947∽1.1810×10-3 mm2/s) respectively. ADC value of tracts near tumor was prodominantly high than that of the normal tracts(p<0.01). The relationship between tracts and tumors was classified according to the tract tracing maps and FA maps: simple displacement in three cases, displacement with disruption in six cases and simple disruption in one case. Preoperative muscle gradeⅤin 4 cases, gradeⅣin 4 cases and gradeⅢin 2 cases. Tumor was totally resected in 4 cases of them, subtotal resection in 6 cases and partial resection in one case.Conclusion:The FA value decreased and the ADC value increased significantly in the white matter tracts near deep brain tumor.Alterations of water molecule diffusion tensor characteristics were observed. The space structure relationship between the tracts and tumor could be shown by combination of FA maps and tracts tracing maps. DTI can provide objective reference for preoperative planning.