Correlation Between Diffusion-weighted Imaging And Histopathologic State Of Gliomas

IntroductionGliomas is the most frequent primary tumor in central nervous system,which life span is short and prognosis is fairly bad. Conventional MR imaging helps to characterize the location and extent of these tumors, but MR imaging provides limited information regarding tumor type and grade. Consequently, conventional MR imaging falls short as a definitive diagnostic examination; that role is reserved for histopathologic evaluation after biopsy. Biopsy" selective inaccurate or too small location all may lead to incorrect classification,and effect treatment project choice, and influence prognosis,Therefore, to develop a technology which can accurately describe pathology information is very important to choose pertinent treatment plan . Diffusion weighted imaging, a technique that measures the mobility of water within tissues at the cellular level, reflects micromolecule substance Brownian movement state within tissues,which provides information related to the microscopic cellular environment in solid tumors. Our experiment is to clarify the correlation between apparent diffusion coefficient (ADC) and microscopic histopathologic state of gliomas through MR DWI technology, to evaluate the value of clinical application of ADC value of brain gliomas.Materials and Methods1. Research object:Thirty cases with biopsy-proved gliomas were divided into A group(I grade), B group( II grade) and C group(III-IV grade) according to biological behaviour(30 cases ; 5 evaluated as WHO grade I,12 as WHO grade II tumors, 9 evaluated as WHO grade III and 4 as WHO grade IV tumors).2. Instrument and method:All examinations were performed on Signa 1.5T Excite HDMR with circularly polarized head coils. All patients underwent MR imaging, which included conventional MR imaging ,DWI and contrast -enhancement T1-weighted imaging. ADC values of the solid components of the tumors were estimated by functool image postprocessing workstation. The MR images were analyzed as follows: we used T2-weighted images and enhanced T1-weighted images to define the slice to be analyzed, to exclude regions of hemorrhage, and to distinguish cystic from enhancing solid portions of the mass. As many as three ROIs were drawn on every slice. Areas of edema, cystic change, and central necrosis were excluded from the analysis.Tumor cellularity and Nuclear-to-cytoplasm ratio were analyzed by MetaMorph/DP10/BX41 microgram analytical system. Areas of blood vessel, central necrosis, phlegmonosis cells and histological section onstructed defect were excluded from the analysis. The cellularity of each tumor was represented by the N/C ratio, which was calculated by dividing the percentage of the nuclear area by the percentage of the cytoplasmic area. Tumor cellularity was defined as the number of cells across a single representative high-power field. We measured average cellular and nuclear diameters for each tumor, using an ocular micrometer. Total cellular area was computed from the measured cell area of each tumor cell type multiplied by the number of cells per high-power field. Total nuclear area was computed from the measured nuclear area of each tumor cell type multiplied by the number of cells per high-power field.3. Statistics analysis:We made statistical comparisons of apparent diffusion coefficient ratio to normal brain with tumor type, using one-way analysis of variance. Statistical comparisons of the absolute apparent diffusion coefficient values with tumor cellularity and with total nuclear area were made with linear regression analysis and Pearson's correlation coefficient.ResultsThe ADC value in solid tumor of group A,groupB and group C was (12. 80±0. 73 ),(11. 30±1. 27) ,and (9. 55±1. 21)×10^-4 mm²/s, there was significant difference among these three groups (P < 0. 05 ).The cellularity in each group of glioma was (128±18) (235±86) (386±46) ,respectively. The N/ C ratio in each group of glioma was (0.06±0.01 ) (0.12±0.03), (0.33±0.05), respectively. There are significant difference in both cellularity and N/ C ratio of gliomas among all groups (P < 0. 05), A negative correlation existed between the absolute ADC value and both the cellularity (r = - 0.80, P < 0. 01) and the N/ C ratio (r = - 0. 73 , P < 0. 01). The apparent diffusion coefficient ratio correlated well with tumor classification (r = - 0. 73 , P < 0. 01).ConclusionThe apparent diffusion coefficient may be a useful tool in characterizing tumor cellularity and Nuclear-to-cytoplasm ratio and may be predictive of tumor classification. These parameters are not available in standard MR imaging. Therefore, diffusion-weighted imaging may enhance the diagnostic process in glioma.