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Objective To compare the diagnostic value of 3.0T and 1.5T magnetic resonance diffusion weighted imaging (DWI) in lymph node metastasis of gastric cancer. Methods Preoperative magnetic resonance examination was performed on 50 patients with gastric cancer by using Siemens 1.5T and 3.0T superconducting magnetic resonance imaging system, and the outcomes were compared with postoperative pathological results. The sensitivity, specificity and accuracy of the diagnosis in lymph node metastasis of gastric cancer were analyzed statistically. The apparent diffusion coefficient (ADC) values of lymph nodes were also evaluated for 1.5T and 3.0T magnetic resonance DWI. Results The sensitivity, specificity and accuracy of the diagnosis on lymph node metastasis of gastric cancer by 1.5T magnetic resonance DWI were 79.4 %, 81.4%and 80.0%, respectively, and the corresponding percentages of 3.0T magnetic resonance DWI were 84.6%, 79.7%and 83.1%. The accuracy rate of 3.0T magnetic resonance DWI was slightly higher than that of 1.5T in the diagnosis of lymph node metastasis of gastric cancer (χ2=5.451, P=0.020), but there were no significant differences in the sensitivity and specificity between the two groups (both P> 0.05). The accuracy rate of 1.5T magnetic resonance DWI in the diagnosis of lymph node metastasis of gastric cancer was less effective than that of the pathological diagnosis (χ2=7.410, P=0.007), but there was no significant difference between 3.0T magnetic resonance DWI and pathological diagnosis (χ2=2.450, P=0.120). The mean ADC values of metastatic and non-metastatic lymph nodes detected by 1.5T magnetic resonance DWI were (1.036 ±0.203) × 10-3 mm2/s and (1.476 ± 0.215) × 10-3 mm2/s (t= 6.813, P< 0.001), meanwhile, the corresponding values detected by 3.0T magnetic resonance DWI were (1.154 ± 0.183) × 10-3 mm2/s and (1.502 ± 0.264) × 10-3 mm2/s (t= 5.991, P< 0.001). The coincidence of the two methods for ADC value was favorable. Conclusions The diagnostic effect of 3.0T magnetic resonance DWI on lymph node metastasis of gastric cancer is better than that of 1.5T. ADC value provides a reliable imaging quantitative indicator for the determination of metastatic lymph nodes in gastric cancer, which plays a significant role in the clinical treatment options and prognosis of patients.
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Objective To investigate MR findings and dynamic changes of the brain after gas explosion,and to evaluate the relationship between MR findings and post-traumatic stress disorder (PTSD).Methods Forty-nine survivors of a gas explosion (group A) were examined with brain MRI within 1 to 3 days,and serial MR follow-up examinations were also performed.Forty miners not under the ground that day were assigned as group B,and 40 staff working on the ground as group C.The signal intensity values of hippocampus and globus pallidus on T2WI were measured in the three groups and F test was performed by using SPSS 13.0.The relationship between signal intensity values of hippocampus/globns pallidus and PTSD was explored,and the relationship between ADC values of hippocampus and PTSD was also investigated.Results In group A,slight low signal on T1WI and high signal on T2WI were detected on initial MRI in hippocampus (33 cases),globus pallidus (12 cases),cortex (10 cases),and midbrain (2 cases),respectively.On follow-up MRI at 2 months,lesions in hippocampus disappeared (25 cases) or remained slight high signal on T2WI (8 cases),lesions in globus pallidus disappeared (3 cases,5 sides) or showed shrinkage and encephalomalacia (9 cases),cortical lesions resulted in encephalomalacia in 2 cases and returned normal in the others,and lesions in the midbrain showed encephalomatacia.For comparison of T2 signal intensity values in hippocampus and globus pallidus,there was significant difference between group A and group B(P <0.01),and also between group A and group C(P <0.01),but no difference was detected between group B and group C (P>0.05).In group A,the T2 signal intensities of PTSD and non-PTSD were 455±37 and 462±53 in the left hippocarnpus,and 458±36 and 460±43 in the right hippoeampus on 1 to 3 days,and the T2 signal intensities of PTSD and non-PTSD were 438±29 and 424±37 in the left hippocampns,and 442±31 and 430±32 in the right hippocampus at 2 months.The T2 signal intensities of PTSD and non-PTSD were 361 ±35 and 366±63 in the left globus pallidus,and 363 ±41 and 375±62 in the right globus pallidus on 1 to 3 days,and the T2 signal intensities of PTSD and non-PTSD were 341±24 and 337±39 in the left globns pallidus,340±26 and 332±35 in the tight glohus pallidns at 2 months.There was no difference of T2 signal intensity values in hippocampus and globus pallidus between PTSD and non-PTSD( t=0.350,0.826,0.503,0.907,P>0.05).In group A,ADC values of PTSD and nun-PTSD were (8.1±1.1)×10-4 and(8.1 ±0.9)×10-4mm2/s in the left hippocampus,and (8.2±1.0)×10-4 and(8.2±0.8)×10-4mm2/s in the tight hippocampus on 1 to 3 days,ADC values were (8.8±0.7)×10-4 and (9.0±1.0)×10-4mm2/s in the left hippocampus,and (8.5±0.9)×10-4 and (9.3±1.1)×10-4mm2/s in the tight hippocampus at 2 months.ADC values in hippocampns showed no difference between PTSD and non-PTSD(t=0.016,0.081,P>0.05)on initial MRI,but showed significant difference between PTSD and non-PTSD in tight hippocampus (t=7.407,P < 0.05) on follow-up MRI at 2 months,while no difference in left hippocampus (t =0.333,P>0.05) was observed at 2 months.Conclusion Hippocampns and globus pallidus are the most vulnerable structures in gas explosion.The occurrence of PTSD may be related to the injury of fight hippocampus,but not related to the injury of globns pallidus.
