The Value Of Susceptibility Weighted Imaging And Magnetic Resonance Spectroscopy In Grading Brain Astrocytoma

Objective: To evaluate the magnetic resonance spectroscopy (MRS) and susceptibility weighted imaging (SWI) in differentiation of high and low grade astrocytoma.Methods: 37 patients confirmed primary astrocytomas had undergone conventional MRI imaging, 2D multi-voxel 1H- MRI spectroscopy (MRS) and susceptibility -weighted imaging(SWI) examination on 3.0T scanner (SIEMENS Verio 3.0T ) pre-operatively from December 2009 to Januray 2011. 24 cases were low-level(WHOI,II) and 13 cases (WHOIII,IV) were high on histopathologic grading.â‘ 37 patients put out grade diagnosis after routine MRI examination and arrive sensitivity,specificity to compare to histopathologic diagnosis.â‘¡Bleeding index (C ) were obtained from the all areas of bleeding(A ) dividing the all areas of tumor(B ) by SWI images. We could depicture the ROC curve and arrive homologous threshold,sensitivity and specificity to compare to routine MRI examination.â‘¢Cho/NAA,Cho/Cr and NAA /Cr of the core of tumor were measured respectively . The ROC curve could be drawed and homologous threshold,sensitivity and specificity be acquired comparing to routine MRI examination.â‘£The sensitivity and specificity were obtained by combination SWI with MRS screening comparing to routine MRI examination.Results:â‘ Sensitivity,specificity and accuracy of routine MRI for the high-grade astrocytoma were 76.9%,75% and 75.7%.â‘¡Sensitivity,specificity ,accuracy,PPV and NPV of the C value for the high-grade astrocytoma were 38%,100%, 65%,100% and 56%. No significant statistical differeces were found in Ratio of hemorrhage between high and low grade astrocytoma with SWI, but significant statistical differeces were found in blood volume.â‘¢The optimum threshold was determined by the Sensitivity and specificity in ROC analyses.There were the threshold of 2.54 and AUC of 0.858 for Cho/NAA of the core of tumor to provide sensitivity 85.0%,specificity 83.0% and accuracy 84% to differentiate the high-grade astrocytoma; Likewise,there were the threshold of 2.56 and AUC of 0.794 for Cho/Cr to provide sensitivity 54.0%,specificity 92.0% and accuracy 78% .The threshold of 0.51 and AUC of 0.651for NAA/Cr to provide sensitivity 54.0%,specificity 79.0% and accuracy 70%. It was Significant different in statistics that the Cho/NAA, Cho/Cr and NAA /Cr determined high-grade astrocytoma respectively(p<0.05).â‘£Sensitivity and specificity for the C value and combination of Cho/NAA was 100% and 83.3%.Conclusion:â‘ SWI could increase the specificity and the metabolite ratios of MRS could increase accuracy in grading astrocytoma to comparing with routine MRI imaging.â‘¡It could increase the sensitivity in grading astrocytoma to combine the C value with the Cho/NAA.