Study Of Diffusion, Dynamic T2～* Perfusion And 2D-CSI ～1H-MRS Imaging In Evaluation Of Cerebral Astrocytomas In Human

Study of Diffusion, Dynamic T2* Perfusion and 2D-CSI MRSpectroscopy Imaging in Evaluation of Astrocytomas in HumanPartâ… : Analysis of Values of ADC and rCBV in Astrocytomas at 3．0T MRPurpose: To determine the values of ADC and rCBV in astrocytomas under 3．0T MR and to investigate their relations. Materials and Methods: 32 cases with neurohistologically verified astrocytomas were performed diffusion (DWI), dynamic T2^* perfusion (PWI) and routine MRI scans before operations. For each imaging case, the mean minimum ADC, mean maximum rCBV at the solid and the peritumoral parts on all tumoral slices were recorded and analyzed. Pearson correlation between the two was also investigated. Results: the mean minimum ADC(×10^-3 mm²/s), mean maximum rCBV at solid part in gradeâ…¡,â…¢andâ…£astrocytomas were 1．21±0．16, 1．4±0．3; 1．16±0．22, 2．3±1．2 and 1．03±0．21, 5．1±3．8, respectively. Significant differences of ADC between gradeâ…¡andâ…£, and rCBV between gradeâ…¡andâ…¢, between gradeâ…¢andâ…£was revealed (P<0．05) . Overlap of values of ADC and rCBV between different grades of astrocytomas were also showed. Significant positive correlations (Spearman correlation=0．661, P<0．01 and 0．579, P<0．01, respectively) were found between ADC, rCBV values and grading. No significant correlation was demonstrated in solid part of astrocytomas between the mean minimum ADC and mean maximum rCBV (Pearson correlation=-0．112, P=0．39) . Conclusions: High-grade astrocytomas tended to be of lower ADC and higher rCBV values than that in low-grade ones. Increased values of rCBV in peritumoral region might indicat tumor infiltration, and this should be further studied under intro-operative MRI guidance. No significant correlation was showed between restricted diffusion and increased blood volume.Partâ…¡: Dynamic Contrast Enhanced CT and T2^*MR Perfusion Imaging inAstrocytoma: a Comparative StudyPurpose: To investigate the differences and similarities between dynamic enhanced CT and MRI perfusion in astrocytoma imaging. Materials and Methods: Two cases of brain tumors (one was glioblastoma, the other was central neurocytoma) were performed dynamic enhanced CT and DSC-T2^* MR perfusion imaging before operations. The results of rCBV and CBF of CT perfusion (CTP) were compared with corresponding MR perfusion (MRP) outcomes. Both the perfusion results and perfusion techniques were analyzed in detail. Results: Results of rCBV and CBF in CTP and MRP were slightly different, yet no statistic significance was revealed (P>0．05) . There also existed the differences in location of the maximal rCBV and regions with abnormal increased blood flow besides the solid part of tumor between the two methods.Conclusions: Both CTP and MRP can reflect haemodynamic changes of brain tumors, each with advantages and disadvantages, and they may partly complementary to each other. CTP possesses the advantages of low cost, easier examination and more accurate result. Limited spacial coverage, radiation and side effect of contrast media comprise its main disadvantages. CTP was not always consistent with MRP. Micro vessels quantification of CTP may replace MRP, but it does not likely to replace MRP as a whole to invasively assess biological behavior of brain tumors.Partâ…¢: Study of Effects of Gd-DTPA on Metabolites Peak Areas onT2-Weighted ¹H-MRSI in Cerebral AstrocytomaPurpose: To determine whether Gd-DTPA has influences on the metabolites peak areas on T2-weighted ¹H-MRSI in astrocytomas. Materials and Methods: The pre-and-post administration of Gd-DTPA T2WI (TR/TE 1000/144ms, PRESS) CSI-MRS scans were performed in each group of patients with low-grade astrocytomas, high-grade astrocytomas, meningiomas and normal subjects, each with four cases. The Cho, Cr and NAA peak areas in tumoral solid and peritumoral parts, and in normal-appearing parenchyma were recorded and analyzed (643 valid voxels in total). Results: Less than 10% decrease of Cho peak area in group of meningioma was showed on MRSI 5 to 10 minutes after Gd-DTPA administration (TE=144ms, PRESS), and significant difference was showed in comparison with normal control (P<0．05) . No significant differences were found between the other groups. In general, no obvious changes of the Cho, Cr and NAA peak areas were showed. Conclusion: Slightly decreased Cho peak areas was seen in meningioma after Gd-DTPA administration, and this change could be attributed to T2* susceptibility effect. In general, Gd-DTPA had no obvious influences on metabolites peak areas. It was applicable using Gd-DTPA contrast enhanced MRSI, and was more reliable to adopt ratio of Cho/Cr to indicate Cho level in astrocytomas. Partâ…£: Study of Diffusion, Dynamic T2* Perfusion and 2D-MRS Imaging inPresurgically Evaluation of AstrocytomasPurpose: To determine the role of diffusion, DSC T2* perfusion and 2D-CSI MRS imaging in presurgically astrocytomas grading in comparison with conventional MRI, and to provide quantitative data on the clinical utility of these techniques in distinguishing low-grade from high-grade astrocytomas. Changes in peritumoral region and correlations between these techniques were also investigated. Materials andMethods: Thirty-two histologically verified cases with astrocytoma were prospectively studied before operations with routine MRI, adding multivoxel proton MR spectroscopy (2D-CSI MRS), echo planar diffusion (DWI) and DSC T2* perfusion (PWI) MRI. For each imaging case, the solid part, immediate and distant peritumoral regions on the same slice with the maximum relative cerebral blood volume (rCBV), minimum apparent diffusion coefficient (ADC) and multiple metabolites peak area ratios were calculated and analyzed. Correlations between the maximum Cho level, maximum rCBV and the minimum ADC was sought. The sensitivities, specificities and the best cut-off values of the maximum rCBV, the minimum ADC and the maximum Cho/Cr ratio in grading were analyzed with ROC curve. Results: High-grade astrocytomas tended to be of higher rCBV, higher Cho level and lower ADC value in comparison with low-grade ones. In solid part of tumors, significant differences (P<0．05) were found between the two groups in maximum rCBV (1．75±0．42 Vs 3．50±2．22) , minimum ADC (1．27±0．13 Vs 1．04±0．26×10^-3 mm² /s), maximum Cho/NAA (1．48±0．29 Vs 2．32±1．16) and maximum Cho/cr (1．33±0．31 Vs 1．90±0．66) . In immediate peritumoral region, the minimum ADC (1．22±0．13 Vs 1．42±0．27×10^-3 mm²/s, P<0．05) and maximum Cho/cr (1．15±0．31 Vs 1．90±0．92) also showed significant difference. The minimum NAA/cr in the distant peritumoral region was found significant difference between the low-grade and high-grade tumors (1．64±0．14 Vs 0．95±0．30, P<0．05) . Good positive correlations were demonstrated in solid part of tumor only between the maximum Cho/Cr and the maximum Cho/Cr-n (P=0．001) . 30 of 32 cases were correctedly graded based on the conventional MRI with accuracy, sensitivities and specificities of 93．8%,90．9% and 100%, respectively. The best cut-offs of the minimum ADC, maximum rCBV, and maximum Cho/cr in the solid part of astrocytomas to differentiate the high-grade from low-grade tumors were 1．09× 10^-3 mm²/s, 2．55, and 1．80, with sensitivities and specificities of 63．6%, 100%; 59．1%, 100% and 54．5%, 100%, respectively. Conclusions: Diffusion, DSC T2* perfusion and multi-voxel proton MRSI can offer complementary diagnostic information in presurgically grading of astrocytomas. Abnormalities in peripheral region of astrocytomas can be indicated well with these techniques, and they may be complementary to each other. Howerer, the sensitivities and specificities of these new techniques may not exceed conventional MRI, which might suggest considerable biological variability between individuals. To delineate the tumor infiltration zone is still challengeable, and it is required to be further studied with refined techniques under intra-operative MRI guidance.Partâ…¤: Diffusion, Dynamic T2*Perfusion and ¹H-MRS Imaging in DifferentiatingRing-like Enhanced Cerebral Lesions: an Initial StudyPurpose: To determine the role of DWI, T2* PWI and 2D-MRSI in differenting some ring-like enhanced cerebral lesions. Materials and Methods: 29 cases of ring-like enhanced cerebral lesions (12 cases with glioblastoma, 8 cases with solitary metastasis, 5 cases with radition therapy induced necrosis of brain, and 4 cases with inflammatory/demylinating disease) proved by neurohistological examination or follow-up were prospectively studied. Each case was performed DWI, T2* PWI and 2D-MRSI before operations or treatment. Values of ADC, rCBV and metabolite peak ratios both in tumoral ring-like enhanced part and peritumoral region were calculated and analyzed. Results: ADC in content of lesion in high-grade glioma and inflammatory/demylinating lesion were significantly different from the other two diseases (P<0．05) . ADC between each group in mural enhanced part, and values in peritumoral edematous part between high-grade glioma and solitary metastasis revealed significant differences (P<0．01) . rCBV in mural enhanced part in high-grade glioma and solitary metastasis, and values between these two and radition therapy induced necrosis of brain, and inflammatory/demylinating diseases showed significant difference (P<0．01) . rCBV in peritumoral edematous part in high-grade glioma were much higher than that in the other groups (P<0．01) . No significant differences were found in Cho/Cr, Cho/NAA and NAA/Cr in mural enhanced part between each group. In peritumoral edematous part, Cho/Cr in high-grade glioma and radition therapy induced necrosis of brain showed significant differences compared with the other groups (P<0．001) . Cho/NAA between high-grade glioma and radition therapy induced necrosis of brain and other groups were significant (P<0．001) . Conclusions: rCBV and Cho in peripheral edematous part of ring-like enhanced brain lesions faciliated to differentiating high-grade glioma from solitary metastasis and radio-induced necrosis. Changes of perfusion and metabolite ratios in inflammatory or demylinating lesions were different from oncologic diseases. DWI, T2* PWI and MRSI play an important part in differentiating some ring-like enhanced brain lesions. More studies should be further summarized.