The Study Of The Value Of ~1H-MR Spectroscopy 3D Multi-voxel And DWI In Grading Astrocytoma

Objective: To evaluate the grading effectiveness of 3D multi-voxel 1H- MR spectroscopy(MRS)and MR diffusion-weighted imaging(DWI) in patients with astrocytoma.Methods:60 patients with a primary astrocytoma underwent conventional MR examination, 3D multi-voxel 1H- MR spectroscopy (MRS) and MR diffusion-weighted imaging (DWI) examination on a 1.5T scanner (GE,Signa INFINITY) pre-operatively. Astrocytoma were graded as low or high based on histopathologic grading.Metabolite ratios (Cho/NAA and Cho/Cr) were measured from the core of tumor and peritumoral regions at PRESS(TE=144ms) respectively.The ADC and ADCR measurements were obtained from the core of tumor and the peritumoral regions respectively.Astrocytoma grade determined with the three methods was then compared with that from histopathologic grading.Receiver operating characteristic analyses were performed to determine optimum thresholds for tumor grading.Sensitivity and specificity for identifying high-grade astrocytoma were also calculated. The Mann-Whitney test was used to compared histologically verified low-and high-grade astrocytoma in term of Cho/NAA ,Cho/Cr ,Lac/Cr,ADC and ADCR from the core of tumor and the peritumoral regions respectively.Results:①Sensitivity and specificity for determining the high-grade astrocytoma with conventional MR were 70.5% and 68.8%.②Significant statistical differeces were found in the Cho/NAA, Cho/Cr,Lac/Cr,ADC and ADCR between low-and high-grade astrocytoma respectively(p<0.01).③The Youden index was chosen to determine the optimum thresholds of all the parameters in ROC analyses.Statistical analysis demonstrated a threshold value of 2.35 for Cho/NAA of the core of tumor to provide sensitivity 82.0% and specificity 81.0% to differentiate the high-grade astrocytoma from the low-grade ones;in the same way,a threshold value of 0.97 for Cho/NAA of peritumoral regions to provide sensitivity 77.0% and specificity 81.0%;a threshold value of 0.3 for LAC/Cr of the core of tumor to provide sensitivity 82.0% and specificity 88.0% and a threshold value of 0.1 for Lac/Cr of peritumoral regions to provide sensitivity 91.0% and specificity 69.1%; a threshold value of 1.08 for ADCR of the core of tumor to provide sensitivity 77.0% and specificity 81.0% and a threshold value of 1.61 for ADCR of peritumoral regions to provide sensitivity 70.0 % and specificity 81.0%。④The combination of Cho/NAA and ADCR of the core of tumor resulted in sensitivity and specificity of 93.2%,75.0% respectively.Conclusion:①When compared with conventional MR imaging alone,the metabolite ratios of 3D multi-voxel 1H- MR spectroscopy (MRS) and the measurements of ADC respectively can increase the sensitivity in grading astrocytoma.②The combination of Cho/NAA and ADCR of the core of tumor can remarkable increase the sensitivity and decrease the false negative rate in grading astrocytoma.