Objective To evaluate the tumor targeting characteristic by observing signal varying of human gastric cancer transplanted nude mice (SGC-7901) using Folate-Receptor MR contrast agent. Methods As a Folate-Receptor MR contrast agent, Gd-DTPA-Folate was obtained by conjugation of DTPA-Folate and GdCl3 under specific conditions. Nude mice of subcutaneously transplanted human gastric cancer (SGC-7901) were used as animal models, 12 mice were divided into experimental group(n=6) and control group(n=6) randomly. Both were injected with Gd-DTPA-Folate and Gd-DTPA (contained same gadolinium) via abdominal cavity respectively. Tumor signal varying was observed by T1WI after injection of contrast agent immediately,1,2,3,4,6,12 and 24 h, and tumor signal changing of experimental group was compared with that of control group. CNR (contrast noise ratio) was regarded as evaluating mark. Results Tumor signal intensity of experimental group was increased evidently between 1-2 hours after injecting Gd-DTPA-Folate. Comparison with pre-injection, there was a significant difference(evaluating mark is CNR: q1=5.80, q2=4.64; P0.05). Conclusion Gd-DTPA-Folate shows definite characteristic of tumor targeting effect to nude mice of subcutaneously transplanted human gastric cancer (SGC-7901).

Background and purpose:A pre-surgery diagnosis of cervical invasion in endometrial cancer was usually determined by dilatations and curettage(D&C),so it could help in optimizing surgery,but the reliability of D&C still was controversial.This study was to compare MRI with D&C to estimate their accuracy for the diagnosis of cervical invasion in endometrial carcinoma respectively.Methods:34 endometrial cancer patients had been proved to have cervical invasion in endometrial cancer through examinations of either fractional dilatations and curettages(D&C),magnetic resonance imaging(MRI)before surgery or postoperative histopathologic examination.The results of D&C and MRI were compared with postoperative histopathologic examination,and the sensitivity,specificity were estimated for accuracy of cervical involvement in endometrial cancer.Results:21 of 34 patients were identified as having cervical invasion in endometrial cancer by histopathology after operation.D&C test matches 26.5% of them and MRI test matches 80%.The sensitivity was 35% vs.76.5% and the specificity 7.7% vs.100% for D&C and MRI methods respectively.All of them had significant statistical differences.Conclusions:MRI test is much better than D&C method for preoperative diagnosis of cervical invasion in endometrial carcinoma.

Objective To analyze the variable appearances of hepatic angiomyolipomas on CT and MRI, and to improve the diagnostic accuracy with CT and MRI. Methods All 13 cases were proved by surgical pathology. Helical CT scanning of pre- and post-contrast arterial phase, portal venous phase were performed in 12 cases, delayed phase scanning was performed in 5 of 12 cases. Magnetic resonance imaging with SE T 1WI, FSE T 2WI, and FMPSPGR axial dynamic multi-phase contrast scanning were performed in 7 cases. Results On pre-contrast CT scans, 11 of 12 lesions appeared as hypodensity, the other one appeared as slight hyperdensity. On the arterial phase scans, all lesions were markedly enhanced, the central vascular structure could be seen in 8 lesions. On the portal venous phase, 8 lesions remained enhanced and the central vascular structure could also be seen in 6 lesions. 5 of 7 lesions showed inhomogeneous hypointensity on SE T 1WI, and all of 7 lesions showed hyperintensity (from slight hyperintensity to strong hyperintensity) on FSE T 2WI. 6 lesions showed enhancement on the MR arterial phase scans, the other one showed no marked enhancement because the most parts of the lesion were fat. 4 lesions showed prolonged enhancement on the portal venous phase, and the other 3 lesions showed hypointensity. The central vascular structure could also be seen in 4 of 7 lesions on MR contrast dynamic scanning. Conclusion Both CT and MR could demonstrate the characterization of hepatic angiomyolipomas, especially the central vascular structure in the lesions strongly hint the diagnosis of angiomyolipomas. MR SE sequence with fat suppression is more sensitive than CT in the demonstration of the fat. CT and MR dynamic multi-phase contrast scanning can fully reflect the characterization of hepatic angiomyolipomas and can be helpful to improve the diagnostic accuracy.

Objective To explore the effect on image quality and scanning time by changing parameters and using different scan-ning technique for the clinical application of axial FLAIR pulse sequence.Methods Seven different sets of parameters of T2-FLAIR Pulse Sequences were performed on thirty patients at a 3.0 T MR scanner.Group A was scanned with a routine sequence for refer-ence.Group B,reducing the matrix to 128.Group C,increasing the turbo factor parameter to 24.Group D,setting the contatena-tion to 1.Group E setting the Accel.factor PE to 4.Group F,using a BLADE-FLAIR sequence.Group G,using a HASTE-FLAIR sequence.The SNRs of all images were statistically analyzed by ANOVA among 7 sequences.The image quality of all images was statistically analyzed by Kruskal-Wallis test among 7 sequences.Results The SNR of seven groups of images were 54.69 ±8.12, 1 57.57±25.61,44.56±7.37,38.48 ± 9.32,44.1 9 ±8.79,45.60 ± 6.92,105.20 ± 18.25,respectively(F = 266.368,P =0.000). The scores of image quality were 3.87±0.09,2.50±0.12,3.72±0.1 6,3.10±0.10,1.88±0.10,3.92±0.07,2.08±0.10,re-spectively and the differences among groups were statistically significant(χ2 =1 93.361,P =0.000).Conclusion Suitable turto factor and BLADE technique can be the best option for FLAIR sequence in the head.HASTE-FLAIR sequence can act as the secondary op-tion for the uncooperative patients.

Objective To evaluate the value of multi-slice CT(MSCT)classification in the assessment of the hilar cholangiocarcinoma resectahility.Methods Thirty patients with surgically and histopathologically proved hilar cholangiocarcinomas who underwent preoperative MSCT and were diagnosed correctly were included in present study.Transverse images and reconstructed MPR images were reviewed for Bismuth-Corlette classification and morphological classification of hilar cholangiocarcinoma.Thcn MSCT classification was compared with findings of surgery and histopathology.Curative resectabilty of different types according to Bismuth-Corlette classification and morphological classification were analyzed with chi-square test.Results In 30 cases,the numbers of Type Ⅰ,Ⅱ,Ⅲa,Ⅲb and Ⅳ according to BismuthCorlette classification were 1,3,4,5 and 17.Seventeen patients underwent curative resections,among which 1,2,1,4 and 9 belonged to Type Ⅰ,Ⅱ,Ⅲa,Ⅲb and Ⅳ respectively.However,there was no significant difference in curative resectability among different types of Bismuth-Corlette classification(X2=0.9875.P＞0.05).In present study,the accuracy of MSCT in Bismuth-Corlette classification reached 86.7%(26/30).The numbers of periducatal infiltrating,mass forming and intraductal growing type were 13,13 and 4,while 6,8 and 3 cases of each type underwent curative resections.There was no significant difference in curative resectability among different types of morphological classification(X2=1.2583,P＞0.05).The accuracy of MSCT in morphological classification was 100%(30/30)in this study group.Conclusion MSCT can make accurate diagnosis of Bismuth-Corlette classification and morphological classification.which is helpful in preoperative respectability assessment of hilar cholangiocarcinoma.

Objective To describe the characteristic MR appearances in hepatocellular carcinoma after radiofrequency ablation (RFA) during follow-up studies. Methods MR images of 110 patients with hepatocellular carcinoma after RFA ,which were categorized into 3 MR examination intervals ( ≤48 h, 1-6 m, ＞6 m), were analyzed retrospectively. The sequential changes of MR images were assessed and compared using Chi-square test. Results All RFA areas of 110 patients typically exhibited hyperintensity on GRE-T1 WI and hypointensity on TSE-T2 WI with fat suppression within 48 h after ablation. Subsequently,the signal intensities of the RFA areas decreased on GRE-T1 WI which showed significant differences after 6 months( P ＜0. 015 ). On GRE-T1 WI , RFA lesions were hyperintense in 72, iso-or hypo-intense in 4 at 1-6 months and hyperintense in 60, iso-or hypo-intense in 17 after 6 months. On TSE-T2 WI, 65 RFA lesions were hypointense, 11 isointense at 1-6 months and 47 were hypointense, 30 isointense after 6 months. The increased intensity on TSE-T2 WI showed significant differences after 6 months( P ＜ 0. 015 ).On contrast-enhanced MR images, RFA lesions showed peripheral rim of enhancement within 48 h and exhibited a tendency to show no enhancement ( n = 37 at 16 months and n = 63 after 6 months ) with significant differences between MR examination intervals( P ＜ 0. 015 ). In 6 patients with residual tumor or local tumor progression, nodular lesions were found at the periphery of the RFA. These nodular lesions showed moderate to marked enhancement as well as hypointense signal on GRE-T1WI, and moderate hyperintense signal on TSE-T2WI. Conclusion MR imaging could depict the characteristics of coagulative necrosis of tumor, residual tumor or local tumor progression in patients with hepatocellular carcinoma after RFA therapy.

Objective To analyze the value of CT in diagnosing and following-up gastrointestinal stromal tumors(GIST).Methods 117patients with CT examination and histological diagnosis of GIST were retrospectively reviewed.Results 117 patients had 118 GIST.Thelocations of primary tumor were as follows: stomach(n=56),small intestine(n=40),esophagus(n=6),colorectum(n=6),mesentery(n=3),retroperitoneum(n=2) and indefinite origin(n=5).Size of tumor was 1.7~18 cm.Tumors(5 cm) often demonstrated lobulated shape with central low attenuation area and heterogeneous enhancement.There were 17 tumors with bubble,13 with scattered calcifications,12 with metastases of liver.With following-up,23 of 37 were developed local recurrence or hepatic metastases.Conclusion CT is aneffective and useful imaging modality in the diagnosis and follow-up gastrointestinal stromal tumors.

Objective To discuss the diagnostic value of CT and MRI for primary anorectal malignant melanoma(AMM).Methods 5 patients(2 males and 3 females)with AMM confirmed pathologically were analyzed retrospectively,which were examined by CT(n=4)and 1.5T MRI(n=1).Results AMM presented as bulky intraluminal fungating masses without intestinal obstruction(n=4)and irregular rectal wall thickening(n=1).2 cases had perirectal fat infiltration and extended to the presacral space in one case,4 cases had perirectal enlarged lymph nodes and larger than 3 cm in diameter in one case.Nonenhanced CT showed a hypodense lesion and contrast-enhanced CT showed slight enhancement(n=1)and mild enhancement(n=3).The tumor scanned by MRI depicted high intensity on T1WI and low intensity on T2WI,so did the enlarged lymph nodes and bone metastasis.Fat-saturation T1WI significantly improved the extention of tumor and detection of metastasis.Conclusion Bulky intraluminal fungating masses without intestinal obstruction,perirectal fat infiltration and enlarged lymph nodes may be helpful to diagnose AMM.MRI is especially useful in differentiating melanotic AMM from other rectal tumors.

Objectives To analyse the radiological features of dynamic MRI and diffusion weighted imaging for atypical small hepatic hemangiomas (≤2 cm).Methods The MR images of 14 patients with 14 pathologically-confirmed small atypical hepatic hemangiomas were retrospectively analyzed.All these patients underwent MR imaging including plain T1 weighted imaging,T2 weighted imaging,dynamic contrast enhanced scanning,and diffusion weighted imaging.The signal-to-noise ratios of hemangiomas,the portal vein and the aorta,lesion-to-liver contrast-to-noise ratios,ADCs of hemangiomas and the liver,lesion-to-liver signal ratios in DWI were assessed to generalize the MRI features and the key points in differential diagnosis of this type of hepatic hemangioma.Results In dynamic contrast enhanced scanning,the atypical hemangiomas were barely enhanced and they were hypointense most of the time.The lesions might show a faint enhancement in the delayed phase.There were significant differences in the changes in signal-to-noise ratio between hemangiomas and aorta as well as portal vein in all the three phases (P＜0.05).In DWI,the signal intensities and ADCs of the hemangiomas were higher than the liver parenchyma (P＜0.01).Conclusions MRI dynamic contrast enhanced scanning,diffusion weighted imaging and evaluation of the ADCs were important in the diagnosis and differential diagnosis of small atypical hepatic hemangiomas.

Objective To explore the value of time-resolved angiography with interleaved stochastic trajectories (TWIST)in providing hemodynamic indices and morphological imaging of calf arteries in patients with peripheral arterial occlusive disease(PAOD) with 3.0 T MR scanner. Methods Forty patients with confirmed or suspected PAOD underwent TWIST MRA for the calf arteries and conventional contrast-enhanced MRA(CE-MRA) for the whole lower peripheral arteries. TWIST MRA data were used to determine the bolus arriving time of the popliteal artery, the time difference of the bolus arrival in the popliteal artery between the two legs, calf artery transit time, and the mean peak enhancement time of calf arteries. The mean value of peak enhancement time of calf arteries was correlated with ankle-brachial index(ABI). The calf arteries were divided into 13 segments. The visible score of arterial segment was recorded, and the degree of arterial stenosis was graded too. In 16 patients, DSA was used as the gold standard to evaluate the sensitivity and specificity of TWIST MRA and CE-MRA. Results The bolus arriving time of the popliteal artery was (0.7±7.6) s the time difference of the bolus arrival in the popliteal artery between the two legs was (2.1±2.5) s, the calf artery transit time was (35.6±16.9) s, the mean value of peak enhancement time of calf arteries was (52.6±17.6) s. ABI was acquired from 24 patients and 48 legs, which correlated well with the mean value of peak enhancement time in calf arteries (r＝0.627,P＜0.01). The mean visible score was (2.83±0.48) of TWIST MRA images and (2.78±0.43) of CE-MRA images. There was no significant difference between them (P＞0.05). On CE-MRA, there were 38 legs with varying degrees of early venous enhancement; in contrast, there was no venous contamination on TWIST MRA. The sensitivity and specificity of TWIST MRA were 96.7% (118/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 94.1% (32/34) and 96.2% (154/160) in showing severe stenosis, and 94.7% (36/38) and 98.7% (154/156) in showing occlusion. The sensitivity and specificity of CE-MRA were 95.9% (117/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 91.2% (31/34) and 95.6% (153/160) in showing severe stenosis, and 94.7% (36/38) and 98.1% (153/156) in showing occlusion. Conclusion TWIST MRA is a preferable choice for calf arterial occlusive disease, which provided nice morphological images and useful hemodynamic indices with simple operation.