Objective To analyze retrospectively the MR features of MELAS patients,in order to improve the early diagnosis of MELAS.Methods MR data of 1 6 MELAS patients confirmed by clinical diagnose and muscle biopsy were retrospectively analyzed. MR features of plain scan(n=1 6),ASL(n=3),MRA(n=1 5),DWI(n=14)and MRS(n=3)were analyzed.Results MRI data demonstrated brain lesions mainly distributed in posterior cerebral hemisphere extending to subcortical area,which was not consistent with the vascular supply territories.The lesions were observed as low signal on Spin-echo sequence of T1 WI,while high signal on T2 WI, FLAIR and DWI.The focal lesions showed increasing Lac peak on MRS.Fifteen of 16 patients underwent MRA and one showed increased arterial branches in lesion zones.Three patients had ASL scanning demonstrating high irrigation in lesion zones which would wander once relapsed.Meanwhile,old lesions showed encephalatrophy and cerebromalacia.All patients’muscle biopsy pathology showed ragged red muscle fibers.Under electron-microscopic,bioblasts were bigger and more than average level and muscle fibers atrophied.Mitochondrial DNA sequence of 3 patients showed mtDNA A3243G transgenation.Conclusion The DWI,MRS and ASL sequences show good ability in MELAS diagnosis and differential diagnosis.

Objective To explore the feasibility of high-frequency electric welding systemin cholecyste-ctomy when compared with ultrasound scalpel , Ligasure and traditional scalpel. Methods Ninety-six rabbits were enrolled in the study and divided into high-frequency electric welding system group , ultrasound scalpel group , Ligasure group and traditional scalpel group. The working temperature was recorded. Eight rabbits of each group were killed to observe the occlusion at 1st, 4th, 7th day postoperatively. Tissues were collected for observation under HE staining. Results High-frequency electric welding system group excelled in operative time , bleeding, working temperature, granulation tissue and inflammatory reaction. No significant difference was found in preope-rative and postoperative liver function test. Conclusion High-frequency electric welding system in cholecyste-ctomy has similar effect as ultrasound scalpel and Ligasure.

Objective To investigate the application value of CT perfusion imaging in patient with traumatic brain injury(TBI).Methods Thirty-seven patients with TBI were included retrospectively and divided into mild,moderate,and severe groups according to Glasgow coma scale(GCS)score.Perfusion parameters of the cerebral hemispheres on the injured side and the contralateral side of the level of basal ganglia were compared.After three months,the correlations between perfusion parameters and GCS score at baseline and Glasgow outcome scale-extended(GOSE)score at follow-up were further analyzed,respectively.Results The injured side of TBI patients showed hypo-perfusion compared with that of the contralateral side.The abnormal perfusion volumes of time to maximum of the residual function(Tmax)>10 s was significantly negatively correlated with GOSE score(ρ=-0.55,P=0.01),and could distinguish the good prognosis group from the poor prognosis group with GOSE score[area under the curve(AUC)=0.82,P= 0.01].In the group of patients undergoing decompressive craniectomy,the abnormal perfusion volumes of Tmax>4 s and Tmax>6 s were significantly associated with GCS score(ρ=0.61,P=0.01;ρ=0.53,P=0.03).Conclusion CT perfusion imaging may be useful in assessing the hemodynamics and severity of TBI,and in predicting the clinical prognosis.