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 describe the characteristic CT imaging of adenomyomatosis of gallbladder and to improve the diagnostic knowledge of the disease. Methods Eleven (5 males and 6 females, mean age = 43 years) patients with adenomyomatosis of gallbladder (4 diffuse, 2 segmental, and 5 fundal) confirmed by histopathology and performed by CT examination including plain, dynamic or multiphase enhancement and / or oral cholegraphic agent were reviewed. Results Correct diagnosis was made in 7 of 11 patients(3 diffuse, 1 segmental, and 3 fundal). CT findings included segmental or diffuse gallbladder wall thickening in the involved area, associated with well defined and regular borders at both of the inner and outer layers. Significant CT findings of this entity were marked enhancement of wall layers during triphase contrast CT scanning, especially at delayed scans. Rokitansky Aschoff sinuses were clearly shown by CT, presenting as characteristic "aureola " sign, when performed with application of a cholegraphic agent. Conclusion Understanding the CT findings and using the optimal methods, we can use CT scan as a valuable method to help make the diagnosis in most cases of adenomyomatosis.

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.

Objective To investigate the value of syngo WARP technology for spine MR imaging in patients with metallic prosthesis.Methods Twenty-five patients with metallic prosthesis in cervical spine or lumbar spine were prospectively included in this study.Both conventional MR sequences and optimized sequences with syngo WARP were applied in all patients.Acquisition time and image quality of two sequences were compared using a paired t test.Results All patients were examined successfully.Scanning time of cervical spine was 8 min 16 s vs.12 min 45 s for conventional sequences and syngo WARP optimized sequences respectively,with a significant difference (t =7.963,P ＜ 0.01).Scanning time of lumbar spine was longer by syngo WARP optimized sequences compared with conventional sequences (11 min 53 s vs.9 min 16 s),with a significant difference (t =4.904,P ＜ 0.01).However,image quality was better for syngo WARP optimized sequences compared with conventional sequences (4.22 ± 0.67 vs.3.56 ± 0.53 ;t =3.364,P =0.002).STIR with syngo WARP could optimize the signal loss of metallic prosthesis surrounding tissues,and significantly improve image distortion and blurring compared to the conventional sequence.Conclusion Syngo WARP technique could effectively reduce metal artifacts and better display metal implant surrounding tissue and anatomical structure with potential clinical value.

Objective To investigate the diagnostic value of ADC for breast lesions with different enhancement shape or mass size. Methods One hundred and thirty-six breast lesions confirmed by histopathology were included in this study. According to enhancement shape and size of the lesion, all lesions were divided into 3 groups: non-masslike enhancement ( G1 ), masslike enhancement with the largest diameter ＜ 2. 0 cm (G2a) and masslike enhancement with the largest diameter ＞ 2. 0 cm (G2b). Echo planar imaging DWI was performed and three b-values (0,500 and 1000 s/mm2) were applied. The t-test was used for testing the difference of ADC between malignant and non-malignant breast lesions in each group. ROC curve was deduced to test the diagnostic efficiency of ADC. The sensitivity, specificity, negative predictive value( NPV), positive predictive value(PPV) and accuracy of ADC for the diagnosis of breast lesions were calculated under the different threshold. Appropriate b value and threshold were determined with the combination of morphologic evaluation. Results There were no significant differences for the mean ADC values between malignant [b =800 mm2/s: ADC value = ( 1.13 ±0. 23) × 10-3 mm2/s,b=1000 mm2/s: ADC value = (1.05 ±0.20) × 10-3 mm2/s] and non-malignant breast lesions [b =800 mm2/s: ADC value = ( 1.28 ±0. 27) × 10-3 mm2/s, t = 1. 636, P =0. 112,b = 1000 mm2/s: ADC value=(1.20 ±0.23) × 10-3 mm2/s, t = 1.720, P =0. 109] in Group 1. The mean ADC values of malignant breast lesion [b =800 mm2/s: ADC value = (1.07 ±0. 15) × 10-3 mm2/s,b = 1000 mm2/s:ADC value = (0. 99 ±0. 14) × 10-3 mm2/s] were significantly lower than that of non-malignant lesion [b =800 mm2/s: ADC value = ( 1.37 ± 0. 37 ) × 10-3 mm2/s, t = 4. 803, P = 0. 000; b = 1000 mm2/s: ADC value= (1.30 ±0.34) × 10-3 mm2/s, t =4.227, P =0.000] in Group 2a. The mean ADC values of malignant breast lesion [b =800 mm2/s: ADC value = (0. 97 ±0. 14) × 10-3 mm2/s; b = 1000 mm2/s:ADC value = (0. 93 ±0. 14) × 10-3 mm2/s] were significantly lower than that of non-malignant lesion [b =800 mm2/s: ADC value = ( 1.40 ± 0. 39) × 10 -3 mm2/s, t = 4. 227, P = 0. 000; b = 1000 mm2/s: ADC value = ( 1.35 ±0. 36) × 10-3 mm2/s, t =4. 329, P =0. 000] in Group 2b. The diagnostic efficiency was equal( x2 =0. 36,P =0. 5460) whenever b value of 800 or 1000 s/mm2 was selected. The highest sensitivity (97.7%) and NPV (97. 1%) were obtained with b value of 1000 s/mm2 and threshold of 1.25 ×10 -3 s/mm2. Conclusion MR DWI is useful for the differential diagnosis of breast lesions with masslike enhancement rather than nonmasslike enhancement.

Objective To analyze quantitatively intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI)of normal adult kidney and to evaluate the effects of the location of the kidney,gender and age on IVIM-DWI parameters.Methods Thirty healthy adult volunteers were recruited to undergo IVIM-DWI examination.Two radiologists measured the D ,D? and f values of renal parenchyma in both the upper pole,middle part and lower pole of the kidneys separately.Results The D ,D? and f values of the middle part of kidneys in healthy adult were(1.61±0.1 6)×10 -3 mm2/s,(1 7.45 ±3.78)×10 -3 mm2/s and (26.88 ±5.1 9)%, respectively.The D values of right kidney were higher than that of left kidney (P <0.05).The f values of normal kidney in male volunteers were higher than that of female (t = 3.321,P =0.001).The D values of normal kidney in > 50 years group were lower than that of ≤50 years group (t = 3.548,P=0.001).D value of the kidney and age was negatively correlated (r=-0.406).Intraclass correlation coefficient of D,D? and f values between two observers were 0.881,0.56 and 0.741,respectively.The consistency of two observers in measurement of IVIM-DWI parameters in the middle part of kidneys was higher than that of the upper pole and lower pole of the kidneys.Conclusion The IVIM-DWI parameters of adult normal kidneys are influenced by different parts of the kidney,gender and age.

Objective To analyze the computed tomography(CT)and magnetic resonance imaging (MRI)appearances of primary clear cell carcinoma of the liver (PCCCL)and evaluate the value in the diagnosis of the disease.Methods CT and MR images of 38 patients of pathologically confirmed PCCCL were evaluated retrospectively.Twenty-six patients underwent CT,23 underwent MRI, and 1 1 underwent both CT and MRI.Results In pre-contrast CT scanning,24 PCCCLs appeared hypodense and 2 hyperdense.As for MRI 1 9 of the 23 PCCCLs were hypointense and 4 were iso-hypointense on T1 WI.While on T2 WI,22 cases were heterogeneously hyperintense,and 1was iso-hypointense.On the arterial phase of CT/MRI,all cases presented intense enhancement,and on the portal venous phase,35 cases(35/38,92.1%)were relatively hypodense/hypointense and 3 were slightly hyperdense/hyperintense.Among the tumors larger than 3 cm(n=22),nodular enhancement pattern was found in 14 cases(63.6%,14/22).The capsular rim en-hancement was demonstrated in 26 cases.Conclusion PCCCL showed similar dynamic enhancement pattern as common hepatocellu-lar carcinoma,but also depicted specific imaging features.

Objective To investigate the imaging features of focal nodular hyperplasia and hepatocellular carcinoma on DWI. Methods The data of patients with histopathologically confirmed FNHs and HCCs between August 2008 and November 2010 were collected. A total of 24 patients with 26 FNH lesions and 36 patients with 39 HCC lesions were included in our study. All patients underwent breath-hold DWI with b = 500 s/mm2 and dynamic contrasted-enhanced (DCE) MRI. The imaging findings of FNHs and HCCs were retrospectively analyzed and compared. The signal intensity (SI) of the lesions on DWI were classified as iso-, slightly high, high SI and the distribution of SI between FNHs and HCCs was compared with Fisher exact test. ADC value and lesion-to-liver ADC ratio of FNHs and HCCs were measured and compared by using independent sample t test. ROC was performed to assess the diagnostic value of ADC value and lesion-liver ADC ratio in the characterization FNHs versus HCCs. Results Of 26 FNHs,23 manifested as isointensity or slightly high SI on DWI, but most 25 out of 39 HCCs showed high SI. The distribution of SI between FNHs and HCCs had significant difference ( P = 0. 000). The mean ADC value and lesion-liver ADC ratio for FNHs [ (1.76 ± 0. 62 ) × 10-3 mm2/s and 1.06 ± 0. 18, respectively ] were significantly higher ( P = 0. 001, P = 0. 000, respectively ) than those for HCCs [ ( 1.26 ± 0. 46 ) × 10-3mm2/s and 0. 79 ±0. 12, respectively]. The area (Az) under the ROC for the ADC value and lesionliver ADC ratio for the differentiation of FNHs versus HCCs were 0. 79 ± 0. 05 and 0. 85 ± 0. 05,respectively, with no significant difference (P =0. 270). The specificity of the two measures was 69. 23% and 97.44%, respectively, with significant difference (P = 0. 001 ). Conclusion FNH shows isointensity or slightly high SI with relatively higher ADC value and lesion-liver ADC ratio than those of HCCs on DWI,which is characteristic for its diagnosis and differentiation.