ObjectivesTo explore the effect of diffuse glioma with precentral-gyrus invasion on fMRI activation maps by grasping T-fMRI. MethodsA total of 56 diffuse glioma patients were divided into precentral-gyrus invasion （PGI： n=21） and precentral-gyrus non-invasion （PGNI： n=35） groups. Three statistical thresholds （P value： 10^-4， P1； 10^-6， P2； 10^-8， P3） were set to obtain the activation maps accordingly （V1， V2 and V3）. The interhemispheric and bilateral precentral gyrus activation volumes ratios （IAVR and PAVR） were calculated， respectively. The activation volumes ［△V1=V1-V2； △V2=V2-V3； △Vn （ipsilateral）/△Vn’ （contralateral）， n=1， 2］ within two statistical thresholds and the corresponding interhemispheric ratio was further compared. In addition， the associations of tumor characteristics with IAVR and PAVR were analyzed. ResultsCompared with PGNI， PGI showed significantly decreased IAVR at p1， and the same trends of PAVR in PGI at P1 and P2 （P＜0.05）. However， neither IAVR nor PAVR showed significant differences at P3. PGI showed significantly lower ratios of △V1/△V1’ than PGNI （P=0.02）， except for △V2/△V2’. Additionally， within PGI， PAVR was negatively correlated with tumor volume （P=0.043）， and the distance from the tumor to the hand-knob was positively correlated with the IAVR and PAVR （P＜0.05）. ConclusionDiffuse glioma invading eloquent areas tended to affect interhemispheric asymmetry of activation at relatively lower statistical thresholds than diffuse glioma without invasion， rather than stricter statistical thresholds. Multiple ranges of statistical thresholds were recommended to analyze T-fMRI.

Objective To investigate the MRI features of primary retroperitoneal leiomyosarcoma(PRLS).Methods Thirty-three cases of pathologically confirmed PRLS were analyzed retrospectively,and their multi-parameter MRI features were analyzed qualitatively and quantitatively.Results Of the 33 PRLS,24 cases were located in the renal hilum,inferior vena cava,or the area around the bifurcation of the iliac vessels.Twenty-four cases had relatively intact capsule,25 cases had necrosis,and 15 cases had coagulated geographic necrosis.The mean diameter of the tumors was(9.9±5.1)cm,ranging from 3.0 to 20.7 cm,among which 27 cases with a diameter larger than 5 cm.The tumor parenchyma of the 33 PRLS all showed significantly high signal intensity on diffusion weighted imaging(DWI),and significantly low signal intensity on apparent diffusion coefficient(ADC)map.The tumor parenchyma showed moderate to obvious degree of progressive enhancement,and the signal intensity value of the tumor in each phase after contrast injection was higher than that of the psoas major muscle(P＜0.001).Conclusion PRLS are usually large but have a relatively intact capsule and are closely related to the major retroperitoneal veins.The coagulated geographic necrosis,significantly limited diffusion of water molecules,and progressive enhancement pattern all show certain MRI characteristics.