The Study Of Detecting Blood Products With Susceptibility-Weighted Imaging In Evaluation The Histopathologic Grade Of Cerebral Gliomas

PurposeTo know the imaging features of cerebral gliomas on susceptibility-weighted imaging(SWI), detect the blood products within the tumors with SWI sequence and analyze the relationship between the amount of the blood products and the histopathologic grade of cerebral gliomas, so that to evaluate the diagnostic value of SWI for grading the malignancy degree of cerebral gliomas.Materials and Methods1. Research object30 patients (17 males and 13 females, 13～66 years old, mean age = 46.5 years) with cerebral gliomas were prospectively examined with routine MR sequences and SWI. Of all the tumors, 4 evaluated as WHO grade I, 11 evaluated as WHO grade II, 8 evaluated as WHO grade III and 7 as WHO grade IV. The cerebral gliomas were divided into low potential malignancy (grade I and II) and high potential malignancy (grade III and IV) groups according to their biological behavior.2. Instrument and methodAll examinations were performed on GE Signa 1.5T Excite HDMR scanner using an eight aisle head coil. All patients underwent T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), fluid-attenuated inversion recovery (FLAIR), susceptibility-weighted imaging (SWI) and contrast enhanced T1-weighted imaging (CE T1WI). We got the corrected phase images and magnitude images by using the SWI postprocessing software of the MR system and created a minimum-intensity projection settings (MinPs) by applying a minimum intensity projection to several adjacent magnitude images. All SWI images were reviewed independently by two radiologists who did not know the pathologic findings. Observing the susceptibility effects on the magnitude images, combing with the phase images to analyse, using MinP images to view venous vasculature. The susceptibility effects are hypointense foci on the magnitude images, when the calcium was excluded by computed tomography (CT), the venous vasculature was excluded by MinP images, the hypointense foci on the magnitude images were regarded as blood products. We measured the area of the blood products detected by SWI slice by slice using a measurement software, calculated the total area of the blood products in the tumor of every patient (mm2) .3. Statistics analysis:To deal the data with SPSS 13.0 software .Calculate the Sensitivity, Specificity, Accuracy, Positive predictive value (PV+) and Negative predictive value (PV—) of using the blood products detected by SWI to grade the cerebral gliomas; The incidence of detected blood products on SWI between low potential malignancy and high potential malignancy groups were compared using Fisher exact test. Mann-Whitney U Test was used to determine the statistical difference of the amount of blood products within the tumor between low potential malignancy and high potential malignancy groups,α=0.05.ResultsSWI can show 29 cases of all the 30 gliomas. The imaging features of the gliomas on magnitude images were like what they were on FLAIR images, the parenchyma and edema region were hyperintense signal ,cyst and necrosis region were hypointense signal on the magnitude images though it is not as clear as what they were on FLAIR images. However SWI displayed imaging features of the tumor different from what they were on routine MR sequences.22 cases were detected susceptibility effects within the tumor on magnitude images of SWI which were caused by calcium, blood products and venous vasculature. It appeared significant hypointense signal on magnitude images and mixed signal on phase images. After we excluded calciums with CT and excluded venous vasculature with MinP images, susceptibility effects within 19 tumors can viewed as blood products. They were 2 gliomas of grade I, 5 gliomas of grade II ,6 gliomas of grade III and 6 gliomas of grade IV. The Sensitivity, Specificity, Accuracy, Positive predictive value and Negative predictive value of using the blood products detected on SWI to grade the cerebral gliomas were 80% (12/15) ,53.3% (8/15) ,66.7% (20/30) , 63.2% (12/19) ,72.7% (8/11) respectively; There was no statistical significance in the incidence of detected blood products on SWI (P=0.064) though it was higher in high potential malignancy groups than that in low potential malignancy groups ,and there was statistical significance in the area of blood products detected on SWI between low potential malignancy and high potential malignancy groups(Z=-2.275 ,P=0.026).ConclusionSWI sequence not only shows the general imaging features of cerebral gliomas but also detect blood products, calcium and venous vasculature within the tumor with superlative contrast, this demonstrates that the information presented by SWI is complementary in nature to that available from conventional MR sequences. There was no statistical significance in the incidence of blood products detected on SWI between low potential malignancy and high potential malignancy groups; The area of blood products within the tumor of high potential malignancy groups detected on SWI was significant higher than that of low potential malignancy groups, it is valuable in the preoperative evaluation of cerebral gliomas.