Study Of The Histology And Grade Of Gliomas Using The DTI And FT Parameters

Gliomas are the most common primary tumors of the brain, so it's important to perform accurate preoperative diagnosis of the tumor histology and grade for planning neurosurgical strategies and appraising patient's prognosis. DTI and FT provide us with the unique technique that can noninvasively identify specific white matter tracts in the brain in vivo. So the DTI and FT make the study of normal microstructure and pathological state using MRI deep into to a more microscopic level. Although DTI metrics have been used for preoperative diagnosis of the gliomas histology and grade, the previous results regarding their efficacy are apparently inconsistent. In addition, the study of the regions using the FT metrics have not present until now.Objective:To retrospectively evaluate whether DTI parameter FA and FT parameter FDi using different FA threshold depicts the status of the structure and function of the peritumoral fibers; To retrospectively evaluate whether the FDi using FA threshold of 0.15 and 0.25 and fractional anisotropy (FA) via DTI can be helpful for the preoperative diagnosis of the gliomas grade. To determine whether the DTI metrics including tensor shape measures such as linear, planar and spherical anisotropy coefficients (CL, CP and CS), can help preoperative evaluation of tumor grade in gliomas.Material and Method:DTI was performed on some patients with histologically confirmed gliomas using a 1.5-T MR scanner, and then using two methods to deal with the DTI image. Method 1:The ROIs could be placed in the specified peritumoral fibers according to the DTI anatomic atlas created by Wakana et al, and then the statistical analysis were employed among the FA values, FDi values and ratios derived from these ROIs to obtain the information of the gliomas histology and grade. Meanwhile, the correlation between FDi and FA was assessed by using the Spearman correlation coefficient. Method 2:CE T1WI, BO and DTI maps were co-registered and each lesion was subdivided into two regions:central, peritumoral using Self-developed software. DTI metrics (FA/MD/CL/CP/CS) were measured from the two ROI and compared with receiver operating characteristic (ROC) curves.Results: 1. The most of fiber tracts of healthy volunteers and peritumoral fibers were 2D depicted on the FA color mapping based on the DTI according the according to the DTI anatomic atlas created by Wakana et al. Meanwhile, these fiber tracts were 3D verified using FT technology.2. Differences in FA values between the peritumoral and contralateral fiber tracts in the unaffected side were significant.3. Differences of FDi values of the peritumoral fibers derived from FA threshold of 0.15,0.2 and 0.25 were significant.4. Differences in FDi values between the peritumoral derived from the FA threshold of 0.2,0.25 and 0.3 and contralateral fiber tracts in the unaffected side derived from the FA threshold of 0.15 and 0.25, respectively.5. In the peritumoral fibers, differences in FA ratios and FDi ratios using FA threshold of 0.25 between the low-grade gliomas and high-grade gliomas were significant.6. FDi was shown to correlate significantly with fractional anisotropy in peritumoral fibers and contralateral fiber tracts in the unaffected side.7. The areas under the ROC curves (AUC) of FA, CL, CS were all larger than 0.5 and P<0.05, and The AUC of FA was the largest.Conclusions:1. Combined the FA and FDi could analysis the pathological conditions of the peritumoral fibers.2. FA and FDi can be used to distinguish between high-grade and low-grade gliomas. This may be useful in developing surgical strategies and appraising patient's prognosis.3. FA,CL,CS all have good effect to distinguish between high-grade and low-grade gliomas and the effect of FA is best.