Objective To study the feasibility of DCE-MRI application in the orthotopic transplantation model of gastric cancer in nude mice.Methods Orthotopic transplantation model of gastric cancer in nude mice was established, and 15 models underwent DCE-MRI using the contrast agent of gadopentetate.Subsequently, the tumor was dissected in order to detect the MVD.The MVD was compared between orthotopic transplantation tumor model of gastric cancer and normal gastric mucosa.Results Fifteen nude mice with orthotopic transplantation of gastric cancer successfully underwent DCE-MRI examination.As for the cancer, the values of Ktrans, Kep and Ve were (2.11±0.44) min-1, (4.59±0.93) min-1, and 0.46±0.06, respectively.The MVD in gastric cancer tissues was significantly higher than that in normal gastric mucosa (χ2=16.205, P<0.001).Conclusion DCE-MRI can be used for noninvasively quantitative evaluation of vascular parameters of gastric carcinoma.

Objective To investigate the effect of gastric filling degree on the thickness of advanced gastric carcinoma and the clinical value of the thickness measured by CT.Methods Totally 38 patients with advanced gastric carcinoma were enrolled and 21 patients were newly diagnosed,17 patients were reexamination after non surgical treatments.The stomach cavity was filled with oral gas-producing powder.The plain scanning (before filling) and enhanced scanning in venous phase (after filling) were performed.The thickness of the normal gastric wall and gastric carcinoma before and after filling were measured on axial images,and the differences were compared.The patients were measured again one month later by the same investigator,and the consistency between the twice measurements was evaluated.Results Before and after filling,the normal gastric wall thickness of each regions was significantly different (all P＜0.001),and the change was greatest at the region of greater curvature.Carcinoma thickness was similar in newly diagnosed patients (P＜0.05),but significantly different in patients for reexamination (P＜0.05).The twice measurements had a good consistency.Conclusion The thickness of gastric carcinoma can be considered as a baseline measurement indicator in newly diagnosed patients.It is critical to maintaining a similar gastric filling degree during reexamination,which is helpful to evaluate the efficacy of treatment accurately.

Objective To evaluate the CT features and differential value of gastric leiomyomas(GLs)and gastric stromal tumors(GSTs)after propensity score matching.Methods Twenty-six GLs were 1∶1 propensity score matched to GSTs based on sex,age,tumor site and size.Tumor shape and contour,mucosal ulcer,tumor growth patterns,enhancement pattern and degree,the lon-gest diameter(LD)of the tumor,and the ratio of the LD to the vertical diameter(VD)were analyzed.CT signs included hemor-rhage,calcification,peripheral invasion,and distant metastasis,etc.Regression analysis was used to determine the best quantitative evaluation for differentiation of them.Results The presence of mucosal ulcer was significantly more frequent in GSTs than in GLs(P=0.032).Both tumors showed progressive enhancement;however,the enhancement degree of GSTs was significantly higher than GLs in the arterial and portal venous phases(P=0.004,P=0.002,respectively).The above influential factors were included in a regression analysis using enhancement degree of 18 HU and 23 HU in the arterial and portal venous phases as cutoff values respectively.An enhancement degree≤18 HU in the arterial phase was identified as an independent influential factor in the diagnosis of GLs[odds ratio(OR)=12.776,95％confidence interval(CI)1.270-128.535].No significant difference was found in other morphological characteristics(P＞0.05).Conclusion Less ulceration on the tumor surface and mild enhancement in arterial phase are characteristic features of GLs compared with GSTs.

Objective To evaluate the application value of golden angle radial sparse parallel(Grasp)sequence in contrast-enhanced MRI of liver.Methods The imaging data of 30 patients who underwent gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid contrast-enhanced MRI of liver were collected.With the same equipment,images were collected by Grasp sequence and breath-hold sequence separately,with an interval of less than 3 months.The subjective and objective scores of the late arterial phase and portal venous phase images were evaluated.Results There were no significant differences in all subjective scores of the late arterial phase and portal venous phase images between the two sequences(P＞0.05).The signal-to-noise ratio(SNR)of the late arterial phase images in the Grasp sequence was lower than that in the breath-hold sequence(148.4±52.8 vs 195.6±68.4),and the difference was statistically significant(P＜0.01).Although the SNR of the portal venous phase in the Grasp sequence was lower than that in the breath-hold sequence,the difference was not statistically significant(P＞0.05).There was no statistical difference in the other objective scores between the two sequences(P＞0.05).Conclusion The image quality of Grasp sequence in contrast-enhanced MRI of liver can meet the diagnositic requirements,and it is suitable for patients with poor breath-hold capacity,which has important application value.

Objective To analyze the clinical and MR characteristics of fibroadenoma(FA)and phyllodes tumor(PT)with maxi-mum diameter≥5 cm.Methods A total of 33 cases with FA and 34 cases with PT were selected,and all lesions with maximum diameter≥5 cm were confirmed by surgical pathology.The clinical and MR characteristics were analyzed retrospectively.Results PT and FA with tumor maximum diameter≥5 cm were more common in perimenopausal women[(47.35±11.36)years old vs(49.42±11.73)years old,P>0.05],while the FA patient was with the wider age range(19-79 years old).There was statistically significant difference in tumor maximum diameter between PT group and FA group(P<0.001),and tumor maximum diameter of PT group(median 7.06 cm,tumor maximum diameter 17.3 cm)was significantly larger than that of FA group.Coarse calcification was more common in the FA group compared to the PT group(5 vs 0,P=0.011).High signal on T1WI was more common in PT group rela-tive to FA group(50%vs 9.1%,P<0.001).There were no significant differences between the two groups in four characteristics,including tumor margin lobulation(97.1%vs 81.8%),T2WI low signal separation(32.4%vs 30.3%),fibroglandular tissue(FGT),and background parenchymal enhancement(BPE)(P>0.05).Time-signal intensity curve(TIC)of FA group showed typeⅠ and Ⅱ curves,while 4 cases(11.8%)in PT group showed type Ⅲ curves,and there was statistically significant difference in TIC between the two groups(P=0.008).The apparent diffusion coefficient(ADC)values of PT group[(1.48±0.17)×10-3mm2/s]was slightly lower than that of FA group[(1.55±0.20)×10-3 mm2/s],and there was no significant difference in ADC between the two groups(P>0.05).The receiver operating characteristic(ROC)curve showed that the best diagnostic cut-off value for distinguishing between PT and FA with maximum diameter≥5 cm was 6.36 cm,the area under the curve(AUC)was 0.927[95%confidence in-terval(CI)0.860-0.994;P<0.001].The AUC of the T1 WI high signal was 0.705,and the standard error was 0.065(95%CI 0.578-0.831;P=0.004).Conclusion Among FA and PT with tumor maximum diameter≥5 cm,PT appear to be more larger lesion and prone to higher signal intensity on T1WI compared to FA,while coarse calcification is more common in FA.