Objective To analyse the CT,MRI features of pleomorphic xanthoastrocytoma and improve the diagnosis.Methods Imaging feature of pleomorphic xanthoastrocytoma of 26 cases confirmed by surgery and pathology were analyzed retrospectively.Distribution,size,shape,signal,dense,peritumor edema and invasion of adjacent structures of lesion were summarized.Results The locations of lesions included:temporosphenoid lobe (19 cases),frontal lobe (2 cases),the lateral and three ventricles in 1 case,occipital lobe (1 case),medulla oblongata (1 case),and cervical cord (1 case).The tumor size:maximum:82 mm × 40 mm × 70 mm,minimum:16 mm × 13 mm × 14 mm.Solid lesions (3 cases),solid lesions with necrosis (7 cases),solid and cystic lesions (16 cases),lesion with calcification (4 cases).The solid lesions of the tumors showed equal signal intensity or slightly low signal intensity on T1WI,and equal signal intensity or slightly high signal intensity on T2WI.The equidensite and high density on CT,peritumor edema degree:mild (2 cases),moderate (5 cases),severe (1 case).Conclusion The characteristic imaging features can help in the understanding and diagnosis of pleomorphic xanthoastrocytoma.

Objective To investigate the correlation of extent and pattern of computed tomography ( CT) enhancement of tumor lesions and histological types in advanced gastric carcinoma .Methods A total of 121 ca-ses of advanced gastric carcinoma were included in this study .Tri-phase enchanced 64-slice spiral CT scan-ning was performed before operation for every patient .We judged the extent lesions′of and pattern of enhance-ment using axial images combined with reconstruction of VR ,MPR and MIP.Then the radiographic result of every subject was compared with its corresponding postoperative histological type after operation .Results In the pres-ent study,the correlation of extent of CT enhancement of tumor lesions and histological types were as follows :ade-nocarcinoma patients were mostly with moderate enhancement ( n=57,61.3%),mucinous adenocarcinoma pa-tients were mostly with mild enhancement (n=7,46.7%).While obvious enhancement were mostly observed in patients with signet ring cell carcinoma(n=8,61.5%).The correlation of pattern of CT enhancement of tumor lesions and histological types were as follows:adenocarcinoma patients were mostly with well -distributed en-hancement(n=58,62.4%),while endothecium obvious enhancement were mostly seen in patients with mucinous adenocarcinoma(n=13,86.7%)and signet ring cell carcinoma (n=7,58.3%).Conclusions There are signif-icant correlation between advanced gastric carcinoma′s tri-phases enhancement characteristics with 64-slice spiral CT and its histological types .Judging histological type using 64-slice spiral CT before operation is useful for formulating and optimizing the therapeutic regimen for gastric cancer patients ,and it is significant for observing the tumors′biological behavior and judging the curative effect .