Objective To investigate the assessment value of diffusion-weighted magnetic resonance imaging (DWI)and apparent diffusion coefficient (ADC)in the differential diagnosis of common cerebellar tumors of children.Methods 45 patients with cerebel-lar tumors were retrospectively analyzed,including 23 medulloblastomas,14 astrocytomas,and 8 ependymomas .The ADCmin of parenchyma of different tumors were measured and Receiver operating characteristic (ROC)curve were delineated.The optimum ADC value for differential diagnosis of common cerebellar tumors of children was analyzed and determined.Results The mean ADC-min of medulloblastoma (0.497 ± 0.023 )× 10 -3 mm2/s was lowest,the mean ADCmin of astrocytoma (1.572 ± 0.145 )× 10 -3 mm2/s was highest,while that of ependymoma was (0.784 ± 0.037 )× 10 -3 mm2/s.The optimum ADC to distinguish ependymomas from medulloblastomas was 0.61 1 × 10 -3 mm2/s (100% sensitivity and 95.7% specificity).The optimum ADC to distinguish low-grade astrocytomas from ependymomas was 1.064×10 -3 mm2/s (92.9% sensitivity and 100% specificity).Conclu-sion ADC is very helpful with differential diagnosis of common cerebellar tumors of children.

Objective To improve the recognition to synovial sarcoma in spine by discussing the imaging features of the disease.Methods The clinical and imaging data of 4 cases (2 cases of male,2 cases of female) with synovial sarcoma in spine were analyzed retrospectively, which were confirmed by surgery and pathology,the imaging features and surgical pathology were mainly analyzed.Results All the 4 patients underwent conventional CT and MRI examination,3 of which underwent CT and MRI contrast enhancement examination.On CT plain scan,2 cases showed equal density,2 showed slightly high density.After enhancement,3 cases showed inhomogeneous enhancement.On T1WI,2 cases showed low signal intensity,2 showed iso-signal intensity.On T2WI,1 case showed high signal intensity,1 showed slightly high signal intensity,and 2 showed mixed high signal intensity.On Fat suppression sequence image,2 cases showed hyperintensity,1 had mixed hyperintensity,and 1 had slightly hyperintensity.On DWI,4 cases showed obviously hyperintensity.On T1WI enhancement,1 case had significant enhancement,2 showed inhomogeneous enhancement.Conclusion The CT and MRI manifestation of synovial sarcoma in spine has certain characteristics.Combined with clinical manifestations, CT and MRI are significantly helpful to improve the cognition and diagnosis of synovial sarcoma in spine.

Objective To analyze magnetic resonance images of medulloblastomas and ependymomas by texture analysis method, and evaluate the texture characteristics of two tumors by support vector machine (SVM).Methods 58 tumors were analyzed retro-spectively,including 31 medulloblastomas and 27 ependymomas,which had been confirmed with operation and pathology.Texture analysis was performed onthese tumors.Results The 5 texture parameters extracted from the gray level co-occurrence matrix and at least 3 parameters which had statistical significance between the two different classes of data sets(P<0.05).For all data sets,the variance parameters of gray value of ROI region have statistical significance.The accuracy of SVM test was (86.15±4.16)%,which had remarkable significance between the ependymomas and medulloblastomas.Conclusion The analysis of texture features can pro-vide a lot of quantitative information,and can be a potential method for the differential diagnosis of medulloblastomas and ependy-momas.

Objective To improve the diagnosis of oligodendroglioma(OD)in cerebellar hemispheres and discuss MRI features. Methods Clinical and imaging data of 7 cases with OD in cerebellar hemispheres were analyzed retrospectively,which were confirmed by surgery and pathology.Results In 7 patients,4 patients were OD,and 3 patients were anaplastic oligodendroglioma(AOD).MRI showed hypointense on T1WI and vividly hyperintense or mixed hyperintense on T2WI.The time intensity curve(TIC)manifested rise slowly;DWI(b=1 000 s/mm2) showed homogeneously hypointense or iso-hypointense.The ratios of OD and AOD were 1.753±0.784,1.660±0.551 respectively;Magnetic resonance spectroscopy(MRS)of oligodendrogliomas revealed a increased choline(Cho)and reduced N-acetylaspartate(NAA)without lactate(Lac)peak.Conclusion MRI manifestation of OD in cerebellar hemispheres has certain characteristics:the boundary of lesion is unclear, irregular in shape,easy to cystic and necrotic,with or without peripheral edema of the tumor,delayed enhancement,higher in Cho peak,lower in NAA peak and lacking in Lac peak.