Objective To evaluate the effect of MRI in reflecting the pathological changes of VX2 carcinoma in rabbits after radiofrequency ablation (RFA) . Methods RFA was performed in the livers of 24 rabbits with planted VX2 carcinoma. The rabbits were divided into 4 groups. After RFA, the rabbits were killed after MR imaging on 0, 1, 2, and 4 weeks, respectively. The correlation between MRI and pathological findings was analyzed. Results In the acute phase, coagulative necrosis of the ablated tumors and inflammatory reaction with hyperemia around were detected at microscopic examination. The ablated tumor showed as hypointensity on T1WI and hyperintensity on T2WI, while rim of high signal intensity on T1WI and low signal intensity on T2WI was found. Gadolinium-enhanced MRI showed a thin high signal rim surrounding the central coagulative necrosis. In the subacute phase, extensive coagulative necrosis and marked infiltration by neutrophils, lymphocytes, macrophages and a peripheral fibrous generation rim were observed microscopically on the ablated tumor. The ablated tumor showed iso-or hyperintensity on T1WI and hypointensity on T2WI, while the periphery of ablated lesions was hypointensity on T1WI and hyperintensity on T2WI. There was prominent rim enhancement along the ablated margin. In the chronic phase, peripheral fibrous rim became obvious, more regular and thicker than at subacute phase as hypointensity on T1WI and T2WI, and unenhancement was observed. Residual or recurrence of tumor was found in 17 rabbits as hypointensity on T1WI and hyperintensity on T2WI, and irregular, thicker rim or nodular enhancing abnormalities. Conclusion MRI can effectively show the histopathological tissue changes of rabbit VX2 carcinoma after ablation and demonstrate the residual or recurrence of tumor.

Objective Retrospectively evaluate the effect of Z-axis tube-current modulation technique with desired noise level to improve image quality (image noise level) and decrease radiation doses of MSCT (16-slice CT) in chest scanning. Methods Consecutive two hundred patients whose CT scan projection radiographs showed no significant abnormal were randomly divided into two groups by the examination order: Z-axis tube-current modulation (ZTCM) group (odd number, test group) and constant tube-current (CTC) group (even number, contrast group). The desired noise level of ZTCM group was 10HU and the machine automatically set the dynamic tube-current in scanning according to attenuated information of chest acquired in scan projection radiographs, the tubo-current of CTC group was set at 200mA, while the other scan parameters remained totally the same. The maximum tube-current value,CTDIvol, DLP and the tube-current of the slice at the maximum breast level of female patients were recorded respectively. The noise of image at upper lung, aorta arch, left atrium and bottom lung level were measured and compared. The qualities of Images were classified in three levels (excellent, good, poor) with double blind method. Results The mean value of maximum mA, CTDIvol, DLP and mA of the slice at the maximum breast level of ZTCM group were (178.5±125.6) mA, (10.5±3.8) mGy, (231.6±24.3)mGy/cm and (116.0±22.5) mA, those of CTC were 200.0 mA, 12.8 mGy, (274.7±18.4)mGy/cm and 200.0 mA, ZTCM group decreased by 10.8%, 19.9%, 15.7% and 42.0%,respectively, as compared with CTC group. The image quality at upper lung and bottom lung level in ZTCM group was improved significantly (P < 0.05) and the cases of excellent images in ZTCM group was significantly higher than that of CTC group (P < 0.05). Conclusion ZTCM technique not only contributes to more rational distribution of radiation doses but also realizes individuation, decreases the total radiation doses and improves image quality in chest CT scanning. It is valuable and promising in chest CT scan.

Objective To assess the value of susceptibility-weighted imaging (SWI) in staging hepatic fibrosis (HF) in rabbits. Methods Sixty healthy rabbits were randomly divided into HF group (n=44), control group (n=16). Rabbits in the HF group and supplementary group were injected subcutaneously with 50%CCl4 oily solution to establish hepatic fibrosis model. On the basis of preliminary test, 8 rabbits in the HF group and 4 rabbits in the control group were selected randomly at the 4th, 5th, 6th, 10th week after CCL4 injection ,respectively , to undergo liver MR scan,including conventional axial T1WI, T2WI and axial SWI, DWI scan. All rabbits were sacrificed after MR scan and the tissue of liver were sampled for pathological test and hepatic fibrosis staging. Rabbits were classified into group F0, F1-2 and F3-4 based on pathological results. Liver signal intensity (SI), and liver-to-muscle SI ratio were measured on SWI images and ADC values were measured on DWI images correspondently. One-way ANOVA analysis was performed to compare difference in liver SI, liver-to-muscle SI ratio and ADC values among group F0 (no fibrosis), F1-2 (mild-moderate fibrosis) and F3-4 (severe fibrosis) . Spearman correlation analysis was performed to correlate pathological staging and liver SI, liver-to-muscle SI ratio and ADC values. Receiver operating characteristic (ROC) curve analysis was performed to compare the diagnostic performance of SWI and DWI for staging HF. Results Two and 5 rabbits in the HF group died at the 5th and the 6th week after CCL4 injection , respectively due to acute hepatic necrosis, hepatorrhexis and systemic failure. Seven rabbits in supplementary group were used as supplement. Of the 16 rabbits in the control group, 1 was excluded from the study due to liver fibrosis. Fifteen rabbits in group F0, sixteen rabbits in group F1-2 and sixteen rabbits in group F3-4 underwent MRI and were included into this study. Liver-to-muscle SI ratio in group F0, F1-2 and F3-4 were 0.973 ± 0.020, 0.880 ± 0.090 and 0.649 ± 0.140, respectively. Liver SI were 378 ± 45, 374 ± 19 and 317 ± 34. ADC values were (1.473 ± 0.320) × 10-3, (1.311 ± 0.310) × 10-3 and (0.942 ± 0.180) × 10-3mm2/s. There were statistically significant differences in liver SI, liver-to-muscle SI ratio and ADC values among group F0, F1-2 and F3-4 (F=46.571,15.803 and 15.317, P< 0.01). Liver-to-muscle SI ratio was highly negatively correlated with HF staging (r=-0.818,P<0.01), while liver SI and ADC values were moderately correlated with HF staging (r=-0.565,-0.630;P<0.01). Area under ROC curve (AUC) of liver-to-muscle SI ratio, liver SI and ADC value for differentiating hepatic fibrosis stage F0 and stage F1-4 were 0.916, 0.695 and 0.768, while the AUC for differentiating hepatic fibrosis stage F0-2 and stage F3-4 were 0.951, 0.904 and 0.900. Conclusion Liver-to-muscle SI ratio on SWI provide added diagnostic value and could be an useful parameter for staging hepatic fibrosis.

Objective To compare the diagnostic values of magnetic resonance elastography (MRE) and T1ρ imaging in staging hepatic fibrosis (HF) in a rabbit model.Methods The institutional animal care and use committee approved all experiments.Sixty healthy rabbits were divided into HF group (n=44) and control group (n=16).Each eight rabbits in the HF group and 4 rabbits in the control group were randomly selected at the 4th,5th,6th week and the remaining rabbits at the 10th week after subcutaneous injection with 0.1 ml 50％ CCl4 oily solution per kilogram of body respectively,to undergo liver MR scan including axial liver MRE and T1ρ imaging.The values of liver stiffness (LS) and T1ρ were measured.Masson trichrome staining of liver tissue was used.According to the Scheuer scoring system,rabbits were classified into F0 to F4 group based on the percentage of hepatic fibrosis.The difference of LS values and Tip values among stage F0 to F4 were compared by the one-way ANOVA analysis.The correlations between pathological staging and LS,T1ρ values were performed by the Spearman correlation analysis.ROC curve analysis was performed to compare the value of MRE with T1ρ imaging.Results Forty three rabbits were included,there were 10,8,8,8,9 rabbits in F0,F1,F2,F3 and F4 stage,respectively.LS values were (1.051±0.155),(1.335±0.235),(1.401±0.163),(2.001±0.499) and (2.981±0.714) kPa in F0,F1,F2,F3 and F4,respectively,while T1 p values were (23.20±4.02),(24.28±2.93),(25.40± 1.82),(24.69± 1.85) and (31.54±3.39) ms (all P＜0.05).The correlation of LS values with hepatic fibrosis staging measured on MRE was stronger than T19 values (r values were 0.916 and 0.608,all P＜0.01).Area under ROC curve of LS value for differentiating hepatic fibrosis stage were 0.938 to 0.989,while the areas of T1ρ were 0.771 to 0.954.Conclusion MR elastography is an accurate technique for quantitatively staging hepatic fibrosis and superior to T1ρ imaging.

Objective To investigate balanced steady-state free precession with flow-sensitive dephasing magnetization preparation (FSD-bSSFP) in the assessment of arteries of foot in diabetic patients.Methods The lower-extremity peripheral arteries of 43 diabetic patients were evaluated by FSD-bSSFP no contrast MRA and contrast-enhanced MRA (CE-MRA)in. Two experienced observers assessed the image quality, degree of venous contaminated and visibility of pedal artery branches by FSD-bSSFP and CE-MRA respectively in consensus. The signal intensity( SI), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the source images of both groups were measured and Wilcoxon and t tests were performed. Results The image score of FSD-bSSFP group was 2.7 ± 1.1 and CE-MRA was 2.6 ± 0.8, there was no statistical difference ( Z = 0. 134, P ＞ 0. 05 ). The image score of demonstration of the pedal artery branches and degree of venous contamination on FSD-bSSFP were 3.2 ± 0. 9 and 1.8 ± 0. 4 respectively which were superior to that of CE-MRA (2.5 ± 0.9 and 2.1 ± 0.8 respectively). Significant statistical difference existed between the two groups in demonstration of pedal artery branches ( Z = 5.246, P ＜ 0.05 ) and degree of venous contamination (Z =2.541 ,P ＜0.05). SNR of FSD-bSSFP was 148.6 ±26.7, CNR was 88.3 ± 19.0. SNR of CE-MRA was 148.5 ± 45.6, CNR was 121.0 ± 41.0. No statistical difference existed between SNR between two methods (t = 0.013, P ＞ 0.05 ). But CNR of CE-MRA was superior to that of FSD-bSSFP and significant statistical difference existed between these two methods ( t = 5.113, P ＜ 0.01 ). Conclusion FSD-bSSFP without contrast could be used in the evaluation of foot arteries in patients of renal dysfunction and diabetes.

OBJECTIVETo analyze the cause of atypical manifestation of hepatocellular carcinoma (HCC) in triple-phase spiral CT enhanced scan.

METHODSTriple-phase spiral CT scan was performed in 75 patients with HCC. The hepatic arterial phase (HAP), portal venous phase (PVP) and delayed phase (DP) images were started at 25 to 30 s, 65 to 70 s and 3 tp 5 min after injection of contrast medium. The contrast enhanced patterns of lesion were observed and analyzed.

RESULTSNinety-two lesions were found in 75 patients. Typical enhanced findings such as hyperdense in HAP and hypodense in PVP and DP was found in 60 of 92 lesions. Atypical enhanced findings were observed in the other 32 lesions. Fourteen of 32 atypical enhanced lesions were hyperdense in HAP and isodense in PVP, of which 8 were seen in liver cirrhosis and 3 in fatty liver. In DP, 10 were hypodense and 4 still isodense. Eight of the 32 lesions were hyperdense both in HAP and PVP, of which 6 were seen in fatty liver. In DP, 3 were isodense and 5 were hypodense. Six of 32 lesions were isodense in HAP which became hypodense in PVP and DP. Four of 32 lesions were all hypodense in HAP, PVP and DP.

CONCLUSIONMultiple atypical enhanced manifestations are present by triple-phase spiral CT scan in HCC. Pattern of blood supply, scanning technique and pathophysiologic status are usually the cause of these findings.

Adult ; Aged ; Carcinoma, Hepatocellular ; diagnostic imaging ; Contrast Media ; Humans ; Liver Neoplasms ; diagnostic imaging ; Male ; Middle Aged ; Tomography, X-Ray Computed

Objective To assess diagnostic performance of multi?parametric MRI including MR elastography (MRE), susceptibility?weighted imaging (SWI) and T1ρ imaging in detecting the early stage of liver fibrosis (LF). Methods Eighty healthy rabbits were randomly divided into LF group (n=60) and control group (n=20). The LF group (n=12) and control group (n=5) were randomly selected at the end of the 4th, 5th, 6th, 15th week after injection of 50% CCl4 oil solution, respectively. All rabbits underwent 3.0 T MRI scans and histopathological Scheuer staging. Differences between groups were examined using one?way analysis of variance with Dunnett's T3 test. Spearman correlation was used to analyze the correlation between liver stiffness (LS), liver?to?muscle SI ratio (SIR), T1ρ value in different LF stages. ROC curve analysis was used to assess the diagnostic performance. Results Fifty?five rabbits were included in our study, which covered F0 (n=14), F1 (n=11), F2 (n=10), F3 (n=9) and F4 (n=11). Significant differences of all characteristic values were found among different LF stages (P<0.05).There were significant differences in LS values between F0 and F2, F3, F4, respectively; F1 and F3, F4, respectively; F2 and F4; F3 and F4 (P<0.05). There were significant differences in SIR between F0 and F2, F3, F4, respectively; F1 and F2, F3, F4, respectively; F2 and F4 (P<0.05). T1ρ value showed significant differences between F0, F1, F2, F3 and F4, respectively (P<0.05). LS, SIR, and T1ρ values were correlated with LF stage (r=0.910, -0.808, 0.512, respectively, P<0.01). The area under curve (AUC) for LS value were greater than those for the other two methods (0.953 for≥F1, 0.949 for≥F2, 0.986 for≥F3, 0.979 for F4). The AUCs of the combination of MRE and SWI for detecting≥F1 was 0.965, for≥F2 was 0.983, for≥F3 was 0.991, and for F4 was 0.950. Combining all three MR methods showed the highest diagnostic performance for staging LF with AUCs of 0.969, 0.985, 0.996 and 1.000.Conclusion MRE is the most prominent MRI method, and combination of MRE and SWI show higher diagnostic performance than the others for staging LF; however, combining all three MR methods exhibits the most excellent diagnostic efficacy.

Objective:To compare the diagnostic efficacy of MR elastography (MRE), Gd-EOB-DTPA dynamic contrast-enhanced MRI (DCE-MRI) in early quantitative evaluation of liver fibrosis (LF) staging of experimental rabbits.Methods:From April to December 2019, 200 healthy rabbits were randomly divided into LF group ( n=160) and control group ( n=40). LF group were injected subcutaneously with 50% CCl 4 oil solution, while control group were injected with normal saline solution. The LF group ( n=40) and control group ( n=10) were randomly selected at the end of the 4th, 8th, 12th and 16th weeks respectively to undergo axial MRI scan including MRE and Gd-EOB-DTPA DCE-MRI. The quantitative parameter values were obtained, including liver stiffness (LS), volume transfer constant (K trans), reflux rate constant (K ep), volume fraction of extravascular extracellular space (V e) and volume fraction of plasma (V p). Histopathological LF staging was based on Scheuer staging. One-way ANOVA analysis was used to evaluate the differences of LS, K trans, K ep, V e and V p among different LF stages. The Spearman correlation analysis was used to evaluate the correlations between pathological LF staging and quantitative parameter values. The ROC curve was used to compare the diagnositic performance of all quantitative parameter values. Results:Among the final qualified 150 rabbits, there were 32 in F0, 32 in F1, 35 in F2, 30 in F3, 21 in F4. Significant differences of LS, K trans, K ep, V e and V p were found among different LF stages. There was correlation between LS, K trans, K ep and LF stages ( r=0.832, 0.730, -0.617, all P<0.001), respectively. However, no statistically correlation was found between V e, V p and LF stages ( r=-0.074, P=0.367; r=-0.078, P=0.342). The area under the ROC curve (AUCs) of LS were the greatest (0.920 for F0 vs F1-F4, 0.900 for F0 vs F1-F2, 0.945 for F0 vs F3-F4, 0.926 for F1-F2 vs F3-F4), while the AUCs of K trans were 0.897, 0.863, 0.942, 0.809, respectively. Conclusion:The early quantitative diagnostic efficacy for LF staging by MRE was superior to Gd-EOB-DTPA DCE-MRI in rabbits.

Objective:To explore the value of MR elastography (MRE) and shear wave elastography (SWE) for staging liver fibrosis in a rabbit model.Methods:From March to November 2020, 200 healthy New Zealand white rabbits were randomly divided into control group ( n=40) and liver fibrosis group ( n=160) by random number table method. The volume ratio of CCl 4 and olive oil was 1∶1 to prepare 50% CCl 4 oil solution, and the experimental rabbits in the liver fibrosis group were subcutaneously injected with 50% CCl 4 olive oil solution. It was injected once a week at the dose of 0.1 ml/kg in the first to third weeks, once a week at the dose of 0.2 ml/kg in the 4th to 6th weeks. The dose of 0.1 ml/kg was injected twice a week from week 7 to 16. The control group were subcutaneously injected with an equal dose of normal saline. At the end of the 4th, 8th, 12th, and 16th week, 40 and 10 animals in the liver fibrosis group and the control group were randomly selected by random number table method for MRE and SWE, respectively, to obtain the liver elastic stiffness (LS), which were recorded as LS MRE and LS SWE. After the examination, the experimental rabbits were sacrificed and liver tissue of rabbits were taken for histopathological Scheuer staging, and they were divided into F0-F4 groups. One-way ANOVA was used to evaluate the differences of LS MRE and LS SWE in different stages of liver fibrosis. Spearman correlation was used to analyze the correlation between LS and pathological stages. The receiver operating characteristic curve was used to evaluate the efficacy of LS MRE and LS SWE in diagnosing liver fibrosis staging, and the area under the curve (AUC) was compared using the Z test. Results:Totally 162 rabbits were included, which covered F0 ( n=38), F1 ( n=33), F2 ( n=35), F3 ( n=31) and F4 ( n=25). Significant differences of LS MRE and LS SWE values were found among different stages of liver fibrosis ( F=295.29, 102.40, both P<0.001). LS MRE, LS SWE were both positively correlated with liver fibrosis stage ( r=0.93, 0.81, both P<0.001). The AUC of LS MRE for diagnosing liver fibrosis stages ≥F1, ≥F2, ≥F3, and ≥F4 were 0.955, 0.967, 0.996, and 0.980, respectively; the AUC of LS SWE were 0.856, 0.880, 0.974, and 0.953, respectively. The AUC of liver fibrosis stage ≥ F1, ≥ F2 for LS MRE value were greater than LS SWE value ( Z=2.93, 3.29, P=0.003, 0.001), and the AUC of ≥F3, ≥F4 had no significant differences ( Z=1.58, 1.68, P=0.115, 0.093). Conclusion:Both MRE and SWE can accurately predict the stage of liver fibrosis in experimental rabbits, and MRE is better than SWE in diagnosing early liver fibrosis.

Objective:To explore the value of proton density fat fraction(PDFF) based on histogram analysis for quantification hepatic steatosis and fibrosis in rabbit model and the interference of hepatic fibrosis to the evaluation of hepatic steatosis with PDFF.Methods:From March to November 2020, 135 New Zealand white rabbits were randomly divided into control group ( n=30) and experimental group ( n=105) using a random number table. The volume ratio of CCl 4 and olive oil was 1∶1 to prepare 50% CCl 4 oil solution, and experimental rabbits were subcutaneously injected with the oil solution. An equal dose of normal saline was subcutaneously injected for control group rabbits. At the end of the 4 th, 8 th, and 12 th week, 35 in the experimental group and 10 rabbits in the control group were randomly selected to conduct the mDixon-Quant scanning, and histogram analysis of PDFF was analyzed including volume, mean, median, standard deviation, 25 th, 50 th, 75 th, 90 th quantile, skewness, kurtosis, entropy and inhomogeneity. After the examination, the rabbits were sacrificed and the liver percentage of steatosis (PSH) and fibrosis (POF) were recorded by semi-quantitative analysis. Spearman correlation analysis was used to correlate PDFF with PSH and POF. Multiple linear regression analysis was used to determine independent PDFF histogram parameters for evaluating PSH and POF. A receiver operator characteristic (ROC) curve was used to assess the diagnostic accuracy of PDFF for discriminating mild from moderate-severe hepatic steatosis and mild from moderate-severe hepatic fibrosis with median of PSH or POF for dichotomy, and DeLong test was used to compare the area under the curve (AUC). With the correction of hepatic fibrosis, correlation coefficient and AUC were compared of PDFF for discrimination mild from moderate-severe hepatic steatosis. Results:The PDFF mean, median, standard deviation, 75 th, 90 th showed correlation with PSH ( r=0.558, 0.522, 0.319, 0.723, 0.646, -0.589, all P<0.05). The entropy and 75 th were independent parameters for evaluating PSH (β=2.347, -5.960, P=0.018, 0.001). The PDFF 75 th was the optimal parameter for discriminating mild from moderate-severe hepatic steatosis with AUC=0.915 ( P=0.001). The PDFF volume, mean, median, standard deviation, 75 th, 90 th, entropy showed correlation with POF ( r=0.355, 0.393, 0.376, 0.298, 0.485, 0.426, -0.681, all P<0.05). The entropy, standard deviation and volume (β=-11.041, 1.356, 0.190, P=0.001, 0.026, 0.016) were independent parameters for evaluation of hepatic fibrosis, and the entropy was the optimal parameter for hepatic fibrosis (AUC=0.771, P=0.001). The correlation between PSH and PDFF 75 th was less pronounced when fibrosis was present ( r=0.512, P=0.001) than when fibrosis was absent ( r=0.751, P=0.002). The PDFF 75 th showed a significant difference in discriminating mild hepatic steatosis from moderate-severe hepatic steatosis after correction of POF (AUC=0.895, 0.950, Z=2.970, P=0.025). Conclusions:PDFF based on histogram analysis provided a noninvasive, accurate estimation of quantification for hepatic steatosis and fibrosis. Hepatic fibrosis reduced the correlation between hepatic steatosis and PDFF and the presence of hepatic fibrosis can confound the quantification of hepatic steatosis with PDFF.