Management and Reconfiguration of a Radiology Department under the Threat of Coronavirus Disease 2019:Experience from Wuhan

Summary:The corona virus disease 2019(COVID-19)is an emerging respiratory infectious disease caused by SARS-CoV-2,which first occurred in December 2019 in Wuhan,China.These days,in China,chest CT is used for diagnosis of COVID-19,as an important complement to the reverse-transcription polymerase chain reaction(RT-PCR)test.Because of contacting with a large number of suspected or probable cases closely during chest CT examination,radiographers are easily infected with COVID-19.This article included the rearrangement of CT examination room in fever clinic,the rearrangement of human resources in radiology department,and the drafting of new operating procedures for radiologists who carry out CT examination on COVID-19 patients.This article also introduced the emergency management procedures of the department of radiology during the outbreak,and the experience of infection prevention for the staff of the department of radiology.

Therapeutic Effectiveness of Leukocyte-and Platelet-rich Fibrin for Diabetic Foot Ulcers:A Retrospective Study

Objective Diabetic foot ulcer(DFU)is one of the most serious complications of diabetes.Leukocyte-and platelet-rich fibrin(L-PRF)is a second-generation autologous platelet-rich plasma.This study aims to investigate the clinical effects of L-PRF in patients with diabetes in real clinical practice.Methods Patients with DFU who received L-PRF treatment and standard of care(SOC)from 2018 to 2019 in Tongji Hospital were enrolled.The clinical information including patient characteristics,wound evaluation(area,severity,infection,blood supply),SOC of DFU,and images of ulcers was retrospectively extracted and analyzed.L-PRF treatment was performed every 7±2 days until the ulcer exhibited complete epithelialization or an overall percent volume reduction(PVR)greater than 80%.Therapeutic effectiveness,including overall PVR and the overall and weekly healing rates,was evaluated.Results Totally,26 patients with DFU were enrolled,and they had an ulcer duration of 47.0(35.0,72.3)days.The severity and infection of ulcers varied,as indicated by the Site,Ischemia,Neuropathy,Bacterial Infection,and Depth(SINBAD)scores of 2–6,Wagner grades of 1–4,and the Perfusion,Extent,Depth,Infection and Sensation(PEDIS)scores of 2–4.The initial ulcer volume before L-PRF treatment was 4.94(1.50,13.83)cm3,and the final ulcer volume was 0.35(0.03,1.76)cm3.The median number of L-PRF doses was 3(2,5).A total of 11 patients achieved complete epithelialization after the fifth week of treatment,and 19 patients achieved at least an 80%volume reduction after the seventh week.The overall wound-healing rate was 1.47(0.63,3.29)cm3/week,and the healing rate was faster in the first 2 weeks than in the remaining weeks.Concurrent treatment did not change the percentage of complete epithelialization or healing rate.Conclusion Adding L-PRF to SOC significantly improved wound healing in patients with DFU independent of the ankle brachial index,SINBAD score,or Wagner grade,indicating that this method is appropriate for DFU treatment under different clinical conditions.

A Prediction Model for Detecting Dysthyroid Optic Neuropathy Based on Clinical Factors and Imaging Markers of the Optic Nerve and Cerebrospinal Fluid in the Optic Nerve Sheath

Objective This study aimed to develop and test a model for predicting dysthyroid optic neuropathy(DON)based on clinical factors and imaging markers of the optic nerve and cerebrospinal fluid(CSF)in the optic nerve sheath.Methods This retrospective study included patients with thyroid-associated ophthalmopathy(TAO)without DON and patients with TAO accompanied by DON at our hospital.The imaging markers of the optic nerve and CSF in the optic nerve sheath were measured on the water-fat images of each patient and,together with clinical factors,were screened by Least absolute shrinkage and selection operator.Subsequently,we constructed a prediction model using multivariate logistic regression.The accuracy of the model was verified using receiver operating characteristic curve analysis.Results In total,80 orbits from 44 DON patients and 90 orbits from 45 TAO patients were included in our study.Two variables(optic nerve subarachnoid space and the volume of the CSF in the optic nerve sheath)were found to be independent predictive factors and were included in the prediction model.In the development cohort,the mean area under the curve(AUC)was 0.994,with a sensitivity of 0.944,specificity of 0.967,and accuracy of 0.901.Moreover,in the validation cohort,the AUC was 0.960,the sensitivity was 0.889,the specificity was 0.893,and the accuracy was 0.890.Conclusions A combined model was developed using imaging data of the optic nerve and CSF in the optic nerve sheath,serving as a noninvasive potential tool to predict DON.

Machine-learning-based models assist the prediction of pulmonary embolism in autoimmune diseases:A retrospective,multicenter study

Background:Pulmonary embolism(PE)is a severe and acute cardiovascular syndrome with high mortality among patients with autoimmune inflammatory rheumatic diseases(AIIRDs).Accurate prediction and timely intervention play a pivotal role in enhancing survival rates.However,there is a notable scarcity of practical early prediction and risk assessment systems of PE in patients with AIIRD.Methods:In the training cohort,60 AIIRD with PE cases and 180 age-,gender-,and disease-matched AIIRD non-PE cases were identified from 7254 AIIRD cases in Tongji Hospital from 2014 to 2022.Univariable logistic regression(LR)and least absolute shrinkage and selection operator(LASSO)were used to select the clinical features for further training with machine learning(ML)methods,including random forest(RF),support vector machines(SVM),neural network(NN),logistic regression(LR),gradient boosted decision tree(GBDT),classification and regression trees(CART),and C5.0 models.The performances of these models were subsequently validated using a multicenter validation cohort.Results:In the training cohort,24 and 13 clinical features were selected by univariable LR and LASSO strategies,respectively.The five ML models(RF,SVM,NN,LR,and GBDT)showed promising performances,with an area under the receiver operating characteristic(ROC)curve(AUC)of 0.962-1.000 in the training cohort and 0.969-0.999 in the validation cohort.CART and C5.0 models achieved AUCs of 0.850 and 0.932,respectively,in the training cohort.Using D-dimer as a pre-screening index,the refined C5.0 model achieved an AUC exceeding 0.948 in the training cohort and an AUC above 0.925 in the validation cohort.These results markedly outperformed the use of D-dimer levels alone.Conclusion:ML-based models are proven to be precise for predicting the onset of PE in patients with AIIRD exhibiting clinical suspicion of PE.Trial Registration:Chictr.org.cn:ChiCTR2200059599.

Left inferior phrenic arterial malformation mimicking gastric varices: A case report and review of literature

BACKGROUND Gastric submucosal arterial dilation resulting from splenic artery occlusion represents an exceedingly rare etiology of acute upper gastrointestinal bleeding(UGIB).Although endoscopy is a widely utilized diagnostic and therapeutic modality for gastrointestinal bleeding,it has limitations in detecting arterial abnormalities.CASE SUMMARY This report presents a rare case of massive UGIB in a 57-year-old male with a tortuous left inferior phrenic artery accompanied by splenic artery occlusion.“Gastric varices”was identified during the patient's endoscopy one year before hemorrhage.Despite initial hemostasis by endoscopic clipping,the patient experienced massive rebleeding after one month,requiring intervention with transcatheter arterial embolization(TAE)to achieve hemostasis.CONCLUSION This is the first case to report UGIB due to a tortuous left inferior phrenic artery.This case highlights the limitations of endoscopy in identifying arterial abnormalities and emphasizes the potential of TAE as a viable alternative for the management of arterial bleeding in the gastrointestinal tract.

Noninvasive Characterization of Metabolic Changes in Ischemic Stroke Using Z-spectrum-fitted Multiparametric Chemical Exchange Saturation Transfer-weighted Magnetic Resonance Imaging

Objective This study aimed to noninvasively characterize the metabolic alterations in ischemic brain tissues using Z-spectrum-fitted multiparametric chemical exchange saturation transfer-weighted magnetic resonance imaging(CEST-MRI).Methods Three sets of Z-spectrum data with saturation power(B_(1))values of 1.5,2.5,and 3.5µT,respectively,were acquired from 17 patients with ischemic stroke.Multiple contrasts contributing to the Z-spectrum,including fitted amide proton transfer(APT_(fitted)),+2 ppm peak(CEST@2ppm),concomitantly fitted APT_(fitted) and CEST@2ppm(APT&CEST@2ppm),semisolid magnetization transfer contrast(MT),aliphatic nuclear Overhauser effect(NOE),and direct saturation of water(DSW),were fitted with 4 and 5 Lorentzian functions,respectively.The CEST metrics were compared between ischemic lesions and contralateral normal white matter(CNWM),and the correlation between the CEST metrics and the apparent diffusion coefficient(ADC)was assessed.The differences in the Z-spectrum metrics under varied B1 values were also investigated.Results Ischemic lesions showed increased APTfitted,CEST@2ppm,APT&CEST@2ppm,NOE,and DSW as well as decreased MT.APT&CEST@2ppm,MT,and DSW showed a significant correlation with ADC[APT&CEST@2ppm at the 3 B_(1) values:R=0.584/0.467/0.551;MT at the 3 B_(1) values:R=−0.717/−0.695/−0.762(4-parameter fitting),R=−0.734/−0.711/−0.785(5-parameter fitting);DSW of 4-/5-parameter fitting:R=0.794/0.811(2.5µT),R=0.800/0.790(3.5µT)].However,the asymmetric analysis of amide proton transfer(APT_(asym))could not differentiate the lesions from CNWM and showed no correlation with ADC.Furthermore,the Z-spectrum contrasts varied with B_(1).Conclusion The Z-spectrum-fitted multiparametric CEST-MRI can comprehensively detect metabolic alterations in ischemic brain tissues.

IN VIVO ~1 H MAGNETIC RESONANCE SPECTROSCOPY IN EVALUATION OF HEPATOCELLULAR CARCINOMA AND ITS EARLY RESPONSE TO TRANSCATHETER ARTERIAL CHEMOEMBOLIZATION

Objective To investigate the value of in vivo proton magnetic resonance spectroscopy （MRS） in the assessment of hepatocelhilar carcinoma （HCC） and monitor its metabolic change shortly after transcatheter arterial chemoembolization （TACE）. Mothoda In this prospective study, 28 consecutive patients with large HCC （ ≥3 cm in diameter） confirmed by fine needle aspiration biopsy were recruited. The ^1H MRS of all hepatic lesions and some uninvolved liver parenchyma were performed with 1.5T whole body MR scanner. Among them, 15 cases were evaluated again about one week after TACE. The main metabolites such as choline and lipid before and after interventional therapy were measured to assess the early response of the tumor. The technical success rate of IH MRS in liver was high （33/41, 80% ）, closely related to breath motion, location of lesion, and size of voxeL In spectra, the choline compound peak of HCC elevated compared with uninvolved liver parenchyma. After TACE, both the amplitude and the area of choline resonance peak significantly descended （ choline-to-lipid ratios from 0.352±0. 080 to 0. 167±0. 030, P = 0. 026; from 0. 205±0. 060 to 0. 070±0. 020, P = 0. 042, respectively ） ; yet lipid resonance peak ascended. Conclusions In vivo tH MRS is technically feasible for the evaluation of large focal hepatic lesions, however, the reproducibility and stability are not as good as routine MR scan. IH MRS can monitor the early stage metabolic changes of HCC after TACE but limitation like quantification still exists.

Quantitative diffusion-weighted magnetic resonance enterography in ileal Crohn’s disease: A systematic analysis of intra and interobserver reproducibility

BACKGROUND Magnetic resonance enterography(MRE) is increasingly attractive as a noninvasive and radiation-free tool for assessing Crohn’s disease(CD). Diffusionweighted imaging(DWI) is recommended as an optional MRE sequence for CD by the European Society of Gastrointestinal and Abdominal Radiology, and has shown a superb potential as a quantitative modality for bowel inflammation evaluation. However, the measurement reproducibility of quantitative DWI analysis in MRE has not been ascertained so far. To facilitate the application of quantitative diffusion-weighted MRE in the clinical routine, systematic investigations of the intra and interobserver reproducibility of DWI quantitative parameters should be performed.AIM To evaluate the intra and interobserver reproducibility of quantitative analysis for diffusion-weighted MRE(DW-MRE) in ileal CD.METHODS Forty-four subjects(21 with CD and 23 control subjects) who underwent ileocolonoscopy and DW-MRE(b = 800 s/mm2) within one week were included.Two radiologists independently measured apparent diffusion coefficients(ADC)of the terminal ileum and signal intensity ratio(SR) of the terminal ileum to ipsilateral psoas muscle on DWI images(b = 800 s/mm2). Between-and withinreader agreements were assessed using intraclass correlation coefficients(ICC),coefficients of variation(CoV), and 95% limits of agreement of Bland-Altman plots(BA-LA LoA). Diagnostic performances of ADC and SR for identifying inflamed terminal ileum from the normal were evaluated by receiver operating characteristic(ROC) curve analysis.RESULTS There were no significant differences in ADC or SR values between the two sessions or between the two radiologists either in the CD or control group(paired t-test, P > 0.05). The intra and interobserver reproducibility of ADC(ICC: 0.952-0.984;CoV: 3.73-6.28%;BA-LA LoA: ±11.27% to ±15.88%) and SR(ICC: 0.969-0.989;CoV: 3.51%-4.64%;BA-LA LoA: ±10.62% to ±15.45%) was excellent for CD.Agreement of ADC measurements was slightly less in control subjects(ICC:0.641-0.736;CoV: 10.47%-11.43%;BA-LA LoA: ± 26.59% to ± 30.83%). SR of normal terminal ileum demonstrated high intra and interobserver reproducibility(ICC: 0.944-0.974;CoV: 3.73%-6.28%;BA-LA LoA: ± 18.58% to ± 24.43%). ADC and SR of two readers had outstanding diagnostic efficiencies(area under the ROC curve: 0.923-0.988).CONCLUSION Quantitative parameters derived from DW-MRE have good to excellent intra and interobserver agreements with high diagnostic accuracy, and can serve as robust and efficient quantitative biomarkers for CD evaluation.

Application of Low Tube Voltage, Low-concentration Contrast Agent Using a 320-row CT in Coronary CT Angiography: Evaluation of Image Quality, Radiation Dose and Iodine Intake

The effect of low voltage and low concentration contrast agent on image quality of coronary CT angiography,radiation dose and iodine intake was evaluated.A total of 121 patients with body mass index(BMI)<26 kg/m2 and heart rate(HR)<70 beats/min were randomly divided into four groups:group A(n=31,80 kVp,270 mgl/mL);group B(n=33,100 kVp,270 mgl/mL);group C(h=30,100 kVp,320 mgl/mL);group D(w=27,100 kVp,400 mgl/mL).The automatic current modulation system and the iterative algorithm for reconstruction were adopted in each group.The CT values and SD values of the aortic root(AR),subcutaneous fat,left coronary artery opening(LCA),and right coronary artery opening(RCA)were measured in all groups,the signalto-noise ratio(SNR)and contrast noise ratio(CNR)were calculated,and effective radiation dose and iodine intake were recorded.The subjective assessment for image quality was performed by two physicians using a 4-point scale.The results were compared using the one-way ANOVA and rank sum tests.The image quality of the four groups met the clinical diagnostic requirements.The CT values of AR in groups A,B,C,and D were 537.6±71.4,447.2±81.9,445.2±64.9 and 518.5±94.9 Hu,respectively,with no significant difference between group A and group D,or between group B and group C,while CT values in groups B and C were significantly lower than those in groups A and D(P<0.05).In groups A,B,C,and D,the LCA SNR values were 22.7±9.1,23.3±9.1,23.3±7.7 and 26.6±8.9,and the RCA CNR values were 26.9±9.&28.5±11.4,27.7土&8 and 32」±10.6,respectively.The AR visual scores in groups A,B,C and D were 3.8±0.2,3.9±0.3,3.9±0.3 and 4.0±0.3,respectively.There were no significant differences in SNR,CNR and visual score among the four groups(P>0.05).The radiation doses in groups A,B,C and D were 2.6±1.4,3.6±1.&4.9±3.5 and 4.9±2.8 mSv,respectively.The radiation dose in group A was significantly less than that in the rest three groups(P<0.05).The iodine intakes in groups A,B,C and D were 14.9±1.5,15.0±1.5,17.7±2.0 and 18.1±2.5 g,respectively.There was no significant difference in the intake of iodine between groups C and D,or between groups A and B,while iodine intake in groups A and B were significantly reduced as compared with that in groups C and D(P<0.05).It was concluded that for patients with low BMI and controlled HR,compared to 100 kVp tube voltage combined with multiple concentration contrast agents,80 kVp combined with 270 mgl/mL contrast agent is enough to ensure the quality of the images,and can reduce the radiation dose significantly,while reducing the amount of iodine intake notably,thus reducing the incidence of adverse reaction.

Comparative Study of DSC-PWI and 3D-ASL in Ischemic Stroke Patients

Summary： The purpose of this study was to quantitatively analyze the relationship between three di- mensional arterial spin labeling （3D-ASL） and dynamic susceptibility contrast-enhanced perfusion weighted imaging （DSC-PWI） in ischemic stroke patients. Thirty patients with ischemic stroke were in- cluded in this study. All subjects underwent routine magnetic resonance imaging scanning, diffusion weighted imaging （DWI）, magnetic resonance angiography （MRA）, 3D-ASL and DSC-PWI on a 3.0T MR scanner. Regions of interest （ROIs） were drawn on the cerebral blood flow （CBF） maps （derived from ASL） and multi-parametric DSC perfusion maps, and then, the absolute and relative values of ASL-CBF, DSC-derived CBF, and DSC-derived mean transit time （MTT） were calculated. The rela- tionships between ASL and DSC parameters were analyzed using Pearson＇s correlation analysis. Re- ceiver operative characteristic （ROC） curves were performed to define the thresholds of relative value of ASL-CBF （rASL） that could best predict DSC-CBF reduction and MTT prolongation. Relative ASL better correlated with CBF and MTT in the anterior circulation with the Pearson correlation coefficients （R） values being 0.611 （P〈0.001） and-0.610 （P〈0.001） respectively. ROC curves demonstrated that when rASL 〈0.585, the sensitivity, specificity and accuracy for predicting ROIs with rCBF〈0.9 were 92.3%, 63.6% and 76.6% respectively. When rASL 〈0.952, the sensitivity, specificity and accuracy for predicting ROIs rMTT〉I.0 were 75.7%, 89.2% and 87.8% respectively. ASL-CBF map has better linear correlations with DSC-derived parameters （DSC-CBF and MTT） in anterior circulation in ischemic stroke patients. Additionally, when rASL is lower than 0.585, it could predict DSC-CBF decrease with moderate accuracy. IfrASL values range from 0.585 to 0.952, we just speculate the prolonged MTT.

Apparent diffusion coefficient-based histogram analysis differentiates histological subtypes of periampullary adenocarcinoma

BACKGROUND For periampullary adenocarcinoma,the histological subtype is a better prognostic predictor than the site of tumor origin.Intestinal-type periampullary adenocarcinoma(IPAC)is reported to have a better prognosis than the pancreatobiliary-type periampullary adenocarcinoma(PPAC).However,the classification of histological subtypes is difficult to determine before surgery.Apparent diffusion coefficient(ADC)histogram analysis is a noninvasive,nonenhanced method with high reproducibility that could help differentiate the two subtypes.AIM To investigate whether volumetric ADC histogram analysis is helpful for distinguishing IPAC from PPAC.METHODS Between January 2015 and October 2018,476 consecutive patients who were suspected of having a periampullary tumor and underwent magnetic resonance imaging(MRI)were reviewed in this retrospective study.Only patients who underwent MRI at 3.0 T with different diffusion-weighted images(b-values=800 and 1000 s/mm^2)and who were confirmed with a periampullary adenocarcinoma were further analyzed.Then,the mean,5th,10th,25th,50th,75th,90th,and 95th percentiles of ADC values and ADCmin,ADCmax,kurtosis,skewness,and entropy were obtained from the volumetric histogram analysis.Comparisons were made by an independent Student's t-test or Mann-Whitney U test.Multiple-class receiver operating characteristic curve analysis was performed to determine and compare the diagnostic value of each significant parameter.RESULTS In total,40 patients with histopathologically confirmed IPAC(n=17)or PPAC(n=23)were enrolled.The mean,5th,25th,50th,75th,90th,and 95th percentiles and ADCmax derived from ADC1000 were significantly lower in the PPAC group than in the IPAC group(P<0.05).However,values derived from ADC800 showed no significant difference between the two groups.The 75th percentile of ADC1000 values achieved the highest area under the curve(AUC)for differentiating IPAC from PPAC(AUC=0.781;sensitivity,91%;specificity,59%;cut-off value,1.50×10^-3 mm^2/s).CONCLUSION Volumetric ADC histogram analysis at a b-value of 1000 s/mm2 might be helpful for differentiating the histological subtypes of periampullary adenocarcinoma before surgery.

Chronic hepatitis virus infection increases the risk of pancreatic cancer: a meta-analysis

BACKGROUND:Several reports have inconsistently demonstrated that there is an association between hepatitis B virus(HBV)or hepatitis C virus(HCV)infections and pancreatic cancer(PC).The aim of the present meta-analysis is to assess this possible relationship.DATA SOURCES:Studies were identified by searching available database from January 2000 to July 2012.Possible associations between PC risk and hepatitis B surface antigen(HBsAg)and its antibody(HBsAb),hepatitis B e antigen(HBeAg)and its antibody(HBeAb),anti-HBcAg antibody(HBcAb),and HCV antibody(anti-HCV)were evaluated.RESULTS:Eight case-control and two cohort studies were included,and their quality scores were assessed by the modified Newcastle-Ottawa Quality Assessment Scale(NOS).We found that HBsAg and anti-HCV seropositivity significantly increased risk of PC(OR=1.28,95%CI:1.11-1.48 and OR=1.21,95%CI:1.02-1.44).The presence of HBsAb was associated with a statistically significant decrease in the risk of PC(OR=0.40,95%CI:0.20-0.79)and HBeAb(OR=0.62,95%CI:0.39-0.99).HBsAg–/HBcAb+/HBsAb–or HBsAg–/HBcAb+/HBsAb+profile was not related to PC risk(OR=1.57,95%CI:0.83-2.98 and OR=1.24,95%CI:0.72-2.14).CONCLUSIONS:HBV/HCV infection increases the risk of PC.HBsAb and HBeAb seropositivity may be the protective factors against PC.It is still uncertain whether serological pattern of past exposure to HBV with or without natural immunity is associated with an enhanced probability of this malignancy.

Comparison of Various Parameters of DWI in Distinguishing Solitary Pulmonary Nodules

In order to prospectively assess various parameters of diffusion weighted imaging (DWI)in differential diagnosis of benign and malignant solitary pulmonary nodules (SPNs),58 patients (40 men and 18 women,and mean age of 48.1±10.4years old) with SPNs undergoing conventional MR,DWI using b=500s/mm^2 on a 1.5T MR scanner, were studied.Various DWI parameters [apparent diffusion coefficient (ADC),lesion-to-spinal cord signal intensity ratio (LSR),signal intensity (SI)score] were calculated and compared between malignant and benign SPNs groups.A receiver operating characteristic (ROC)curve analysis was employed to compare the diagnostic capabilities of all the parameters for discrimination between benign and malignant SPNs.The results showed that there were 42 malignant and 16 benign SPNs.The ADC was significantly,lower in malignant SPNs (1.40±0.44)×10^-3mm^2/s than in benign SPNs (1.81±0.58)×10^-3mm^2/ s.The LSR and SI scores were significantly increased in malignant SPNs (0.90±0.37 and 2.8±1.2)as compared with those in benign SPNs (0.68±0.39 and 2.2±1.2).The area under the ROC curves (AUC)of all parameters was not significantly different between malignant SPNs and benign SPNs.It was suggested that as three reported parameters for DWI,ADC,LSR and SI scores are all feasible for discrimination of malignant and benign SPNs.The three parameters have equal diagnostic performance.

Superparamagnetic Iron Oxide Labeling of Neural Stem Cells and 4.7T MRI Tracking in vivo and in vitro

Neural stem cells were labeled with superparamagnetic iron oxide （SPIO） and tracked by MRI in vitro and in vivo after implantation, Rat neural stem cells were labeled with SPIO combined with PLL by the means of receptor-mediated endocytosis. Prussian blue staining and electron microscopy were conducted to identify the iron particles in these neural stem cells. SPIO-labeled cells were tracked by 4.7T MRI in vivo and in vitro after implantation, The subjects were divided into 5 groups, including 5× 10^5 labeled cells cultured for one day after labeling, 5 × 10^5 same phase unlabeled cells, cell culture medium with 25μg Fe/mL SPIO, cell culture medium without SPIO and distilled water. MR/scanning sequences included TIWI, T2WI and T2＊WI. R2 and R2＊ of labeled cells were calculated. The results showed： （1） Neural stem cells could be labeled with SPIO and labeling efficiency was 100%. Prussian blue staining showed numerous blue-stained iron particles in the cytoplasm; （2） The average percentage change of signal intensity of labeled cells on TIWI in 4.7T MRI was 24.06%, T2WI 50.66% and T2＊WI 53.70% respectively; （3） T2 of labeled cells and unlabeled cells in 4.7T MRI was 516 ms and 77 ms respectively, R2 was 1.94 s^-1 and 12.98 s^-1 respectively, and T2＊ was 109 ms and 22.9 ms, R2＊ was 9.17 s^-1 and 43.67 s^-1 respectively; （4） Remarkable low signal area on T2WI and T2＊WI could exist for nearly 7 weeks and then disappeared gradually in the left brain transplanted with labeled cells, however no signal change in the right brain implanted with unlabeled cells. It was concluded that neural stem cells could be labeled effectively with SPIO. R2 and R2＊ of labeled cells were increased obviously. MRI can be used to track labeled cells in vitro and in vivo.

Experimental Study of Cell Migration and Functional Differentiation of Transplanted Neural Stem Cells Co-labeled with Superparamagnetic Iron Oxide and Brdu in an Ischemic Rat Model

Objective To explore the migration of transplanted neural stem cells co-labeled with superparamagnetic iron oxide （SPIO） and bromodeoxyuridine （Brdu） using the 4.7T MR system and to study the cell differentiation with immuno-histochemical method in ischemic rats. Methods Rat neural stem cells （NSCs） co-labelled with SPIO mediated by poly-L-lysine and bromodeoxyuridine （BrdU） were transplanted into the unaffected side of rat brain with middle cerebral artery occlusion （MCAO）. At weeks 1, 2, 3, 4, 5, and 6 after MCAO, migration of the labelled cells was monitored by MRI. At week 6 the rats were killed and their brain tissue was cut according to the migration site of transplanted ceils indicated by MRI and subjected to Prussian blue staining and immunohistochemical staining to observe the migration and differentiation of the transplanted NSCs. Results Three weeks after transplantation, the linear hypointensity area derived from the migration of labelled NSCs was observed by MRI in the corpus callosum adjacent to the injection site. Six weeks after the transplantation, the linear hypointensity area was moved toward the midline along the corpus callosum. MRI findings were confirmed by Prussian blue staining and immunohistochemical staining of the specimen at week 6 after the transplantation. Flourescence co-labelled immunohistochemical methods demonstrated that the transplanted NSCs could differentiate into astrocytes and neurons. Conclusion MRI can monitor the migration of SPIO-labelled NSCs after transplantation in a dynamical and non-invasive manner. NSCs transplanted into ischemic rats can differentiate into astrocytes and neurons during the process of migration.

Experimental Study of Multi-slice Spiral CT Perfusion Imaging in VX_ 2 Soft-tissue Tumor of Rabbits

An experimental animal model of malignant soft-tissue tumor was established to investigate the applied value of multi-slice spiral CT perfusion imaging preliminarily. Ten New Zealand white rabbits which were implanted with VX2 tumor in either proximal thigh were subjected to CT plain scan and perfusion scan two weeks later respectively, then the original perfusion images were transmitted to AW4.0 Workstation. The functional maps and perfusion parameters including blood flow （BF）, blood volume （BV）, mean transit time （MTT） and permeability surface （PS） were computed and analyzed. All the values of BF, BV and PS in VX2 soft-tissue tumors were obviously higher while the MTT-values were lower than those in the normal muscular tissues significantly. It was suggested that multi-slice spiral CT perfusion imaging is an accurate, convenient and relatively safe functional imaging technique, and can give a quantitative assessment to angiogenesis and blood perfusion of soft-tissue tumors.

MR Cholangiography and Dynamic Examination of Duodenal Fluid inthe Differential Diagnosis between Extrahepatic Biliary Atresia and Infantile Hepatitis Syndrome

In order to evaluate the value of magnetic resonance cholangiography （MRC） and dynamic examination of duodenal fluid in the differential diagnosis between extrahepatic biliary atresia （EHBA） and infantile hepatitis syndrome （IHS）, 52 patients with infantile cholestatic jaundice were examined by MRC and duodenal fluid examination. Original interpretations were compared with clinical outcome. Calculated sensitivity of duodenal fluid examination in diagnosis of EHBA was 100 %, and specificity was 91.1%. Sensitivity of MRC in the diagnosis of EHBA was 94.4 % and specificity 88.24 %. The sensitivity of MRC and examination of duodenal fluid combined in diagnosis of EHBA was 94.4 % and specificity 97.06 %. We are led to conclude that MRC and dynamic examination of duodenal fluid are useful in the differential diagnosis between IHS and EHBA and the combined use of the two techniques yield better resutls.

MiR-21 Mediates the Radiation Resistance of Glioblastoma Cells by Regulating PDCD4 and hMSH2

Summary： The purpose of this study was to investigate the molecular mechanism by which miR-21 and its target genes mediate radiation resistance of glioblastoma cells. Real-time PCR was employed to detect miR-21 expression in normal brain tissues, glioblastoma tissues and glioblastoma cell lines （A172, T98G and U87MG）. T98G cells were transfected with anti-miR-21 oligonucleotides, or plasmids con- taining PDCD4 or hMSH2 （PDCD4-pcDNA3 and hMSH2-pcDNA3）. The survival curve was obtained to investigate the sensitivity of T98G cells to radiation. Cell apoptosis was measured by using the Cas- pase-3/7 kit and cell cycle by flow cytometry. Western blotting was performed to detect the expression of hMSH2 and PDCD4 in miR-21-inhibiting T98G cells. The results showed that miR-21 expression in glioblastoma cells and tissues was conversely associated with the radiation sensitivity. Over-expression of miR-21 resulted in radiation resistance, while knockdown of miR-21 led to higher sensitivity of glioblastma cells to radiation. After miR-21 knockdown, the apoptosis of T98G cells was significantly increased and the G2 phase arrest was more significant. In addition, miR-21 knockdown increased the expression of endogenous PDCD4 and hMSH2, which contributed to the apoptosis and G2 arrest of T98G cells. The findings suggested that miR-21 may mediate the resistance of glioblastoma cells against radiation via its target genes PDCD4 and hMSH2. MiR-21 and its target genes may be used as potential molecular targets for clinical radiotherapy sensitization in the future.

Tuberous Sclerosis Complex:Imaging Characteristics in 11 Cases and Review of the Literature

Tuberous sclerosis complex（TSC） is an uncommon multiorgan disorder that may present many and different manifestations on imaging. Radiology plays an important role in diagnosis and management, and can substantially improve the clinical outcome of TSC. Therefore, a comprehensive understanding of this disease is essential for the radiologist. The manifestations of TSC on computer tomography（CT） and magnetic resonance（MR） images were analyzed. Eleven patients with a clinical diagnosis of TSC were retrospectively reviewed. Central nervous system lesions included subependymal nodules（SENs）（11/11）, subependymal giant cell astrocytomas（SEGAs）（2/11）, cortical and subcortical tuber lesions（5/11）, and white matter lesions（4/11）. Of the 6 patients with abdominal scans, there were 6 cases of renal angiomyolipomas（AMLs）, and one case of hepatic AMLs. Of the 4 patients undergoing chest CT, lung lymhangioleiomyomatosis（LAM）（2/4）, and multiple small sclerotic bone lesions（2/4） were observed. Different modalities show different sensitivity to the lesion. Analysis of images should be integrated with patients＇ history in order to diagnose TSC.

Early Reversible Ischemia of Femoral Head Epiphysis in Piglets on Gadolinium-enhanced MRI:An experimental study

Summary： The purpose of this study is to demonstrate if Gadolinium-enhanced MRI can detect early reversible ischemia of the femoral head epiphysis caused by hip hyper-abduction in piglets. Between 3 and 6 h consistent hyper-abduction, gadolinium-enhanced MRI was performed in 20 femoral heads of 10 piglets. After completion of MRI scan, the piglets were allowed to ambulate freely for 1 or 7 days and re-imaged. The enhanced-MRI results of epiphyseal and physeal cartilage and the secondary center of ossification were observed. MRI appearances and histological findings were compared. On Gadolinium-enhanced MRI, decreased or absent enhancement was seen in 14 cartilaginous epiphyses of all 20 femoral heads. Reperfusion was completed in 10 of 14 femoral heads after one day of ambulation and in the rest 4 after 7 days of ambulation. Gadolinium-enhanced MR/can identify early ischemia and its reversal of the capital femoral epiphysis induced by hip hyper-abduction.