Objective To probe the value of 3.0T MRI in the preoperative assessment of rectal carcinoma.Methods The study recruited 41 patients who were confirmed by biopsy of rectal carcinoma and underwent conventional MRI, high-resolution MRI and diffusion weighted imaging(DWI), the distance from the inferior part of tumor to transitional skin and the percentage of circumferential invasion were measured, the tumor's T staging, N staging,and the status of circumferential resection margin(CRM) and extramural vascular invasion(EMVI) were assessed.MRI findings were compared with endoscope and postoperative pathological results.Results MRI could accurately show the distance from the inferior part of tumor to transitional skin(P>0.05);The mean percentage of circumferential invasion for the tumor with T1-T2 and T3 were 61%,83% respectively (P>0.05);The total accuracy of T,N staging diagnose were 80.5%,75.6% respectively, which had a better consistent with pathological T,N staging(Kappa=0.564,0.634);The total accuracy of CRM and EMVI diagnose were 90.2%,73.2% respectively,which had a better or moderate consistent with pathological diagnose(Kappa=0.765,0.461).Conclusion 3.0T MRI has the unique application in the preoperative assessment of rectal carcinoma, which can provide more comprehensive information for clinic.

Objective To investigate the value of dynamic contrast-enhanced quantitative parameters of pancreatic cancer at 3.0T MR.Methods 27 patients with pathologically proved pancreatic cancers were underwent DCE-MR at a 3.0 T scanner.AToft with Vp model was used to quantify K trans ,k ep ,Ve and Vp in the pancreatic cancer and normal pancreatic tissues.All parameters among different tissues were analyzed and compared by SPSS1 7.0.Results The K trans 、k ep 、Ve 、Vp values of pancreatic cancer were(0.303± 0.321)min,(1.387±1.486)min,(25.07±10.98)%and(3.420±4.692)% respectively ,while those values of normal pancreatic tis-sue were (1.235±0.777)min,(9.277 ± 7.996 )min,(1 7.89 ± 8.882 )%,and(7.1 96 ± 6.704)%,respectively.The differences be-tween the four parameters of pancreatic cancer and normal pancreatic tissue were statistically significant(F =33.188,25.414,6.984, 5.78,P <0.05).Conclusion Quantitative parameters of DCE-MRI accurately reflect changes in tumor blood perfusion and microcir-culation,they may be helpful to differentiate the atypical lesion.

Objective To study the imaging manifestations and clinical significance of simple cochlear nerve canal(CNC)stenosis. Methods The HRCT findings of 14 patients(1 7 ears)with simple CNC stenosis diagnosed sensorineural hearing loss(SNHL)were retrospectively analyzed.The width of CNC and internal auditory canal was measured and compared with the normal ears,the data were statisti-cally analyzed by SPSS1 6.0.Thin-sliced MRI of internal auditory canal (axial and oblique sagittal position)was performed in 8 cases. Results HRCT displayed obvious CNC stenosis in all 14 patients(1 7 ears),2 ears with cochlear nerve canal atresia.Width of CNC and internal auditory canal was (0.5±0.3)mm and (4.6±1.0)mm,it was (2.1±0.2)mm and (5.1 ±1.3)mm in normal ears (1 1 ears),the width of CNC was of significant difference between normal ears and ears with SNHL,and there was no statistical sig-nificant difference in width of internal auditory canal.12 ears(from 1 7 ears with simple CNC stenosis)were lacking of fissure in the cribriform area,1 1 ears(normal ear)were existence of fissure in the cribriform area;cochlear nerves were not shown in 8 patients with MRI examination.Conclusion CNC stenosis can be isolated from internal auditory canal stenosis,MRI could display cochlear nerve dysplasia(CND).

Objective To investigate perfusion imaging and parameters of normal pancreas by dual-source CT and to evaluate the appropriate perfusion imaging scan.Methods Sixty-six subjects with normal pancreas underwent low-dose pancreatic perfusion and plain scan.CT images were sent to a separate workstation via a network.The blood flow (BF)and blood volume (BV)of pancreas head,body and tail were measured using the VPCT Body software and analyzed by one-way ANOVA.Then the time-density curve of pancreas was drawn,and the enhancement peak time and the corresponding CT value were also measured.Results The average BF values of pancreas head,body and tail were (1 1 6.09 ± 31.83)mL·100 g-1 ·min-1 ,(1 1 9.72±32.50)mL·100 g-1 ·min-1 , (1 14.65±31.42)mL·100 g-1 ·min-1 ,and the mean BV values were (29.83 ±1 9.07)mL/100 g,(30.39 ± 1 9.38)mL/100 g, (28.82±1 9.22)mL/100 g,respectively.The perfusion parameters in different pancreatic parts were not statistically different.The mean enhancement peak time was (27.92 s±4.52)s,(28.02±5.34)s in pancreas head,(27.40±4.36)s in pancreas body,(27.34±4.57)s in pancreas tail.On plain image,the average CT value of pancreas was (41.43±5.88)HU.However,on enhanced image,the mean CT value was (95.96±18.44)HU in normal pancreas [(96.73±19.71)HU in pancreas head,(98.45±17.52)HU in body,(92.69±18.1 7)HU in tail].Conclusion The perfusion parameters including blood flow and blood volume in pancreatic head,body and tail are identical. The mean enhancement peak time is (27.92±4.52)s,and the corresponding enhancement CT value is (95.96±18.44)HU.

Objective To assess the value of apparent diffusion coefficient (ADC)in clinic ,pathology and prognosis of rectal cancer. Methods The MRI and DWI findings of 109 patients with pathological proved rectal adenocarcinoma were retrospectively analyzed. DWI with b=0 s/mm2 and b= 1 000 s/mm2 were acquired.Mean tumor ADCs were measured and compared between subgroups stratified by histologic differentiation grades,T-stage,N-stage,mesorectal fascia status and presence of lymphangiovascular or peri-neral invasion.Results Mean tumor ADCs were significantly different when comparing groups stratified by histologic differentiation grades,T-stage,mesorectal fascia status and presence of lymphangiovascular invasion.Tukey’s post hoc test showed that the differences of mean ADCs between good-moderate differentiated group and moderate differentiated group(P =0.996),moderate-poor differentiated group and poor differentiated group(P =0.957)were not significant.The differences among other groups of differentia-tion grades differed significantly(P <0.05).In the T-stage groups,the mean ADCs of T1 stage tumor was significantly higher than that of T3 stage tumor(P <0.05).There were no significant differences among other T-stage groups(P >0.05).There were no sig-nificant differences among N0,N1 and N2 in N-stage groups(P >0.05).Conclusion ADC values can reflect pathologic and prognos-tic features of rectal cancer.

Objective To explore the application value of monoexponential, biexponential models multiple b values diffusion weighted imaging(DWI) in distinguishing pancreatic cancer from non-tumorous pancreas.Methods Subjects comprised 37 pancreatic cancers confirmed by clinical or surgery.Pancreas multiple b values DWI was performed using 3.0T scanner.Standard apparent diffusion coefficient (ADCstandard) was calculated using monoexponential diffusion model.Pure diffusion coefficient (ADCslow), pseudodiffusion coefficient (ADCfast) and perfusion fraction (f) were calculated using intravoxel incoherent motion(IVIM) diffusion model.Parameters of pancreatic cancers and non-tumorous pancreas were compared using independent samples t test.Results Mean ADCslow value of pancreatic cancer was higher than that of non-tumorous pancreas (0.611×10-3 mm2/s vs 0.521×10-3 mm2/s,P=0.037).Mean ADCfast and f values of pancreatic cancer were lower than that of non-tumorous pancreas (5.066×10-3 mm2/s vs 7.188×10-3 mm2/s,P=0.035;55.8% vs 64.0%,P=0.016;respectively).ADCslow of pancreatic cancer was positively correlated to ADCstandard (r=0.824,P=0.000).ADCfast of pancreatic cancer was negatively correlated to f(r=-0.558,P=0.000).Conclusion ADCslow, ADCfast and f derived from IVIM-DWI model can distinguish pancreatic cancer from non-tumorous pancreas.IVIM-DWI may be a promising and non-invasive tool for early diagnosing and differentiating pancreatic carcinoma from non-tumorous pancreas.

Objective To evaluate the value of DWI and ADC value in monitoring the chemotherapy response of advanced gastric carcinoma dynamically.Methods 42 advanced gastric carcinoma patients who were confirmed by histopathology underwent T2 WI and DWI examinations at pre-chemotherapy,post-chemotherapy 3 d,7 d,30 d and 60 d respectively.The longest diameters of tumor pre-chemotherapy and post-chemotherapy 60 d were measured on axial T2 WI,meanwhile the ADC values at different time points were calculated.The mean ADC value among pre-and post-chemotherapy of each group (PR and SD)was compared.Results The ADC value of PR group increased gradually.The mean ADC value before therapy was statistically lower than those at differ-ent time points post-chemotherapy (P < 0.05).The ADC value of SD group increased gradually from pre-chemotherapy to post-chemotherapy 30 d,and then the ADC value decreased at post-chemotherapy 60 d.The differences of the mean ADC values in differ-ent time points were statistically significant (P < 0.05).Conclusion DWI and ADC value can dynamically,quantitatively and early detect and monitor the chemotherapy response of advanced gastric carcinoma.