Objective To discuss the appearances of focal nodular hyperplasia(FNH) of the liver on the muhiphase helical CT scanning, and to improve its diagnostic accuracy with CT. Methods Helical CT scanning of pre- and post- contrast arterial phase,portal venous phase and delayed phase was performed in 10 cases with surgically and pathologically proved FNH. Results On pre- contrast scans,9 of 11 FNH lesions were hypodense(either homo-geneous or non-homogeneous), the other two lesions were isodense. On the arterial phase scans, all lesions were markedly and homogeneously enhanced,except for the central scar area. Tortuous and dilated arteries were seen at the center or peripheral area in 3 out of 11 lesions. On the portal phase and delayed phase scans ,4 of 11 lesions turned to isedanse of slightly hypodense,7 lesions remained slightly hyperdense. Central scar was found in 8 FNH lesions ,2 of them showed no enhancement while the other six demonstrated late enhancement. Conclusion Mulfiphase helical CT scanning can fully reflect the blood supplying and pathologic features of FNH, and it is of great value in diagnosing and differentiating FNH.

Objective To analyze CT features of extra-gastrointestinal stromal tumom(EGIST).Methods The CT data of 9 pa-tients with EGIST proved by operation and pathology were analysed retrospectively.Results Of 9 cases with EGIST,7 cases were malignant and 2 cases were benign.2 cases were origina-ted from liver.2 cases from mesocolon,2 cases from Small mesentericin,2 case showed widely diffuse nodules scattered in peritoneum,omentum,small intestine,mesangial and colon serosa.In those nodules, some nodules from pelvic cavity wereinosculated into larger mass.1 case came from right kidney week gap.The biggestdiameter of tumomrs of each case was ranged from 5.0 cm to 14.0 cm (mean 9.6 cm).5 cases showed lobulated shape,4 cases showed round or oval.All cases showed non-homogeneous density in plain CT,with cystic change and necrotic foci in 7cases,calcification in 2 cases.In arterial phase,all cases appeared significantly abnormal thickening or multiply tumor blood vessels in edge and center of those tumors.Conclusion EGIST has unique imaging performance.

Objective To characterize the MRI features of demyelinating pseudotumors(DPTs).Methods MR data of 10 cases clinically proved with DPTs were retrospectively analyzed .All cases were underwent MRI scan ,9 of 10 cases were performed with enhanced MRI,7 cases were underwent diffusion weight imaging(DWI),2 cases were performed with single voxel short echo 1 H-MRS.Results 8 cases showed lesions with mild to moderate edema,5 cases showed multiple lesions,3 cases were solitary nodular lesions,2 cases were solitary flaky lesions.On enhanced MRI,4 cases presented with open ring like enhancement,3 cases presented ring like enhancement,1 case with nodular enhancement,and 1 case showed patchy enhancement.All lesions showed high signal in DWI.In 1 H-MRS,2 cases demonstrated varying decrease in peaks heights of Nacetylaspartate(NAA),elevation of the choline(Cho),the lactate(Lac)and lipids(1ip).1 case demonstrated evident elevation in peaks height of glutamate/glutamine(Glx).Conclusion DPTs has some characteristics on MRI, especially as open ring like enhancement.It is helpful to identified DPTs from other lesions when together with DWI and 1 H-MRS.

Objective To investigate the clinical value of diffusion weighted imaging (DWI) in diagnosis of atypical cancerization nodules (CNs) of liver cirrhosis. Methods Totally 34 patients with atypical CNs of liver cirrhosis confirmed pathologically underwent routine MR, dynamic enhancement, and DWI (b=0, 500, 1000 s/mm~2). The detection rate of CNs of liver cirrhosis between routine MR and DWI was compared. Results Totally 21 patients with 28 cancerization nodules were diagnosed with routine and dynamic enhancement MR, while 27 patients with 37 cancerization nodules were detected with DWI. Significant difference was found in the detection rate between routine scan and DWI (P=0.025). Conclusion DWI shows more advantage than routine and dynamic enhancement MR for detection of liver cirrhosis with atypical CNs.

Objective To analyze the CT findings of pulmonary cryptococcosis (PC)in patients without HIV infection.Methods CT data of 26 patients with PC proved by pathology were analyzed retrospectively.All cases underwent plain CT scan,8 of whom underwent contrast-enhanced CT scan.Results 26 patients (17 male and 9 female),single lesion on CT was found in 11 cases,multiple nodules or masses in 10 cases,and mixed-type lesions in 5 cases.The lesion was located in left lung in 1 1 cases,in right lung in 7 cases and bilateral lungs in 8 cases.The lesions with burr sign were found in 1 9 cases,with cavities or vacuoles in 10 cases,and with halo sign in 8 cases.Enhanced CT showed marked heterogeneity in 1 case,moderate heterogeneity in 2 cases,slight enhancement in 3 cases and nonenhancement in 2 cases.Conclusion Lesions of PC with various CT findings are easy to be misdiagnosed as lung carcinoma or other lesions.CT-guided percutaneous lung biopsy is an effective method for diagnosis.

Objective To investigate the X-ray,CT and MRI features of peripheral primitive neuroectodermal tumors (pPNETs).Methods 14 patients were pathologically diagnosed with pPNETs.The imaging of X-ray (twelve image),Computed Tomography(eleven image) and Magnetic Resonance Imaging(five image) were retrospectively analyzed.Results Of 14 patients,there were two sites of tumour:soft tissue( eight patients) and bones( six patients).For tumoura of the soft tissue region,the appearance of X-ray and CT imaging showed equal or lower density soft mass without dear boundary.In some cases,tumours invaded adjacent bones.The appearance of MRI imaging showed large heterogeneous masses inside soft tissue without clear boundary.Tumours displaced adjacent cortical bone and cavitas medullaris.All masses were heterogeneous enhancement on contrast images.For tumours of bone region,X-ray and CT scan showed large scale osteolysis osteoclasia in bone surrounding with soft tissue masses of various size.The lesions were equal or lower signal on T1 WI.All masses were intermediate or hyperintense signal with heterogeneous midrange or obvious enhancement on T2WI.Conclusion Imaging characteristics of pPNETs were described.X-ray,CT and MRI were useful in understanding the property,extent and staging of tumor and very useful in the diagnosis.