Value Of Susceptibility Weighted Imaging In Preoperative Grading Of Brain Gliomas And Its Differential Diagnosis From Solitary Brain Metastasis

This study is composed of two parts: Part One aims to investigate the clinical value ofsusceptibility weighted imaging (SWI), in contrast with dynamic susceptibility contrastperfusion weighted imaging (DSC-PWI), in the preoperative grading of brain gliomasusing the clinical and pathological results as the gold standard; Part Two aims tocomparatively study the values of intratumoral susceptibility signal intensity (ITSS) onSWI and relative cerebral blood volume (rCBV) on DSC-PWI in the differential diagnosisof high-grade brain gliomas and solitary brain metastasis.Part One: The value of SWI in the preoperative grading of brain gliomasObjective：To investigate the clinical value of SWI, in the preoperative grading ofbrain gliomas using the clinical and pathological results as the gold standard, and tocomparatively study the diagnostic accuracies of ITSS on SWI and rCBV on DSC-PWI inthe preoperative grading of brain gliomas.Materials and methodsSubjects of study: Clinical image data of forty-one patients with pathologicallyconfirmed brain gliomas who were admitted to our hospital were collected. The numbersof grades I, II, III, and IV cases were2,13,16, and10, respectively.Method of examination: All patients received examination by using GE Signa HDx3.0T MR with a eight channel head coil. Routine MR scans were performed; SWIadopted entirely speed compensated3D GRE sequence; DSC-PWI adopted GRE-EPIsequence. Finally, conventional contrast-enhanced sequence was used with Gd-DTPA asthe contrast medium.Image analysis: The raw data of SWI were transferred to the AW4.4workstation afterscanning and were post-processed by Functool software to obtain the magnitude map, phase maps and MIP maps. According to the susceptibility effect of the magnitude mapand analysis of phase maps, the ITSS grade was determined. The cerebral blood volume(CBV) maps were obtained by reconstruction after PWI scanning, and on this basis, theCBV of local tissue was measured in the region with the most marked tumor parenchymaperfusion and the contralateral normal brain tissue, and the rCBV value was calculated.The ITSS grade and rCBV value at the same level were analyzed.Statistical analysis: All data were subjected to analysis using SPSS19.0softwarepackage. The homogeneity of variance and normal distribution were tested before statistics.The ITSS grade and rCBV value were compared with pathological grades separately. Andthe correlation between ITSS grade, rCBV value, and pathological grades were determinedby Spearman correlation analysis for ranked data. Analysis was performed to evaluate thediagnostic accuracy of the two methods.Results The Kruskal-wallis test showed significant difference in ITSS grade betweenthe brain gliomas of different pathological grades (P <0.001); the Spearman correlationanalysis showed a positive correlation between ITSS grade and pathological grade (r=0.816, P <0.001); the ANOVA test showed significant differences in rCBV value betweenthe brain gliomas of different pathological grades (P <0.001). There was a positivecorrelation between rCBV value and pathological grade (r=0.676, P <0.001); there was apositive correlation between ITSS grade and rCBV value (r=0.557, P <0.001). Thereceiver operating characteristic curve showed that ITSS grade and rCBV value had a highdiagnostic accuracy for brain gliomas before operation, with areas under the curve wererespectively0.932and0.859, the specificities and sensitivities for high-grade gliomas wererespectively92.3%vs86.67%and88.46%vs80%; the positive predictive values andnegative predictive values were respectively88.9%vs85.7%and88.5%vs80%.Conclusion (1) ITSS grade the rCBV value are correlated with pathological grade.(2) SWI can be used for preoperative grading of brain gliomas; both SWI and DSC-PWIhave a high diagnostic accuracy, but ITSS grade of SWI have a higher diagnostic accuracy. Part Two: Value of ITSS and rCBV in the differentiation of high-gradebrain gliomas and solitary brain metastasisObjective：To investigate the clinical value of ITSS and rCBV in the differentialdiagnosis of high-grade brain gliomas and solitary brain metastasis.Materials and methodsSubjects of study: The MRI data of41patients with pathologically confirmed braintumors were retrospectively analyzed. Of the41patients,26had high-grade gliomas(WHOIII, IV), and15had solitary brain metastasis.Method of examination: All patients underwent examination using GE Signa HDx3.0T MR with a eight channel head coil and underwent conventional MRI, SWI, andDSC-PWI preoperatively, with both scans at the same level. Finally, conventionalcontrast-enhanced sequence was used with Gd-DTPA as the contrast medium.Image analysis: The raw data of SWI were transferred to the AW4.4workstation afterscanning and were post-processed by Functool software. The ITSS grade was determinedaccording to the susceptibility effect of brain tumor. The raw data of PWI werereconstructed to obtain CBV maps, and the rCBV values of maximum perfusion regions inbrain tumor parenchyma and peritumoral edema region were measured. The ITSS gradeand rCBV value at the same level were analyzed.Statistical analysis: Statistical analysis: All data were subjected to analysis usingSPSS19.0software package. The homogeneity of variance and normal distribution weretested before statistics. The high-grade gliomas and solitary brain metastasis werecompared with respect to the ITSS grade, and the rCBV values of brain tumor parenchymaand peritumoral edema region were compared.Results There was no significant difference in the ITSS grade between high-gradegliomas and solitary brain metastasis (P>0.05). The rCBV values (compared with thenormal cerebral white matter) of maximum perfusion regions in the brain tumorparenchyma of high-grade gliomas and solitary brain metastasis were4.658±1.889and3.522±1.680, respectively, without significant difference between them (P=0.045). Themaximum rCBV values in the edema regions of high-grade gliomas and solitary brainmetastasis were1.905±0.583and0.823±0.315, respectively, with a significant differencebetween them (P=0.002). Conclusion (1)There was no significant difference in the ITSS grade betweenhigh-grade gliomas and solitary brain metastasis, suggesting that ITSS grading has a lowdiagnostic accuracy in the differentiation of high-grade brain gliomas and solitary brainmetastasis.(2)The rCBV value in peritumoral edema region is of clinical significance in thedifferential diagnosis of high-grade brain gliomas and solitary brain metastasis.