Background: Enteritis is one of the most frequently reported symptoms in piglets infected with porcine circovirus type 2 (PCV2), but the immunopathogenesis has not been reported. Objectives: This study examined the effect of a PCV2 infection on the intestinal mucosal immune function through morphological observations and immune-related molecular detection. Methods: Morphological changes within the ileum of piglets during a PCV2 infection were observed. The expression of the related-molecules was analyzed using a gene chip. The immunocyte subsets were analyzed by flow cytometry. The secretory immunoglobulin A (SIgA) content was analyzed by enzyme-linked immunosorbent assay. Results: The PCV2 infection caused ileal villus damage, intestinal epithelial cells exfoliation, and an increase in lymphocytes in the lamina propria at 21 days post-infection.Differentially expressed genes occurred in the defense response, inflammatory response, and the complement and coagulation cascade reactions. Most of them were downregulated significantly at the induction site and upregulated at the effector site. The genes associated with SIgA production were downregulated significantly at the induction site. In contrast, the expression of the Toll-like receptor-related genes was upregulated significantly at the effector site. The frequencies of dendritic cells, B cells, and CD8 + T cells were upregulated at the 2 sites. The SIgA content decreased significantly in the ileal mucosa. Conclusions PCV2 infections can cause damage to the ileum that is associated with changes in immune-related gene expression, immune-related cell subsets, and SIgA production.These findings elucidated the molecular changes in the ileum after a PCV2 infection from the perspective of intestinal mucosal immunity, which provides insights into a further study for PCV2-induced enteritis.

Objective Cardiac MRI is the "gold standard" for non-invasively assessing the structure and function of the heart.Compared with conventional cine imaging,MR strain technique can identify the abnormalities of segmental myocardial motion of heart diseases in the early stage by quantifying the displacement of myocardial tissue,which is of great value in evaluating the disease condition as well as guiding treatment and assessing prognosis.Myocardial strain can quantify the segmental wall motion,which is less impacted by other factors.The application of MR strain imaging in cardiac diseases were reviewed in this paper.

Objective To analyze the impact of dual energy monochromatic reconstructions (50-160 keV) on coronary calcified plaque stenosis quantification in a cardiac phantom with the real stenosis as standard of reference.Methods Signal-to-noise(SNR)and contrast-to-noise ratios(CNR)were calculated. In conventional 120 kV coronary CT angiography (CCTA) images as well as 12 monochromatic series(50-160 keV),luminal narrowing of calcified plaque was measured and compared to the real stenosis. Bland-Altman plots were performed to analyze the correlation of reference standard with conventional 120 kV and 12 monochromatic series (50-160 keV). The sensitivity, specificity, and accuracy of CCTA for detection of≥50% stenosis were calculated and receiver operating characteristic(ROC)curve was analyzed with the real stenosis as reference standard.Results The SNR and CNR were decreased with the increase of keV from 70 keV.The SNR and CNR of monochromatic imaging were lower compared with conventional 120 kV images(SNR:76.4±16.1;CNR:274.7±54.1)(P<0.05).The Bland-Altman plots presented a smaller measurement bias towards 90-160 keV than conventional 120 kV, and smallest measurement bias was revealed in 100-130 keV imaging(100-130 keV:bias 17.2% vs 120 kV:21.4%).Using the stenosis≥50% as cut-off value, the specificity were higher in the monochromatic series (70-160 keV) than conventional 120 kV CCTA.The specificity(75.0%)were the highest in the 120 keV and 130 keV images.The area under the ROC curve(AUC)of 90-130 keV(0.991-0.995)was higher than that in conventional 120 kV imaging (0.990). Conclusions The use of monochromatic imaging improves the overall accuracy of stenosis evaluation in coronary calcified plaques. Reconstructions at 100-130 keV for calcified lesions yielded the optimal results.

Objective To compare the diagnostic accuracy of clinically significant prostate cancer by general radiologist and uroradiology specialist based on the Prostate Imaging Reporting and Data System (PI-RADS).Methods A total of 45 men from Beijing United Family Hospital and Clinics undergoing prostate mpMRI examination and subsequent MRI-targeted biopsy were included in the study.The age of patients was (60.0 ± 8.0) years,the median PSA level was 7.2 ng/ml (1.2-95.8 ng/ml) and the median prostate volume was 45.0 ml (18.3-127.0 ml).The general radiologists from Beijing United Family Hospital and Clinics made the diagnosis according to PI-RADS 2.0.One uroradiology specialist from Beijing Anzhen hospital reviewed all the mpMRIs retrospectively and marked new PI-RADS score based on PI-RADS 2.0.The PI-RADS ≥ 3 lesion was recognized as suspicious of clinically significant prostate cancer.The distribution of PI-RADS score from different doctors and the diagnostic accuracy of clinically significant prostate cancer was compared.Results All the 45 patients underwent MRI-targeted cognitive biopsy and 14 cases of prostate cancer were detected,including 9 cases of clinically significant prostate cancer.There was no significant difference in the distribution of PI-RADS by general radiologist and uroradiology specialist (P =0.064).82.8％ (37/45) and 37.8％ (17/45) patients were diagnosed with PI-RADS ≥ 3 by general radiologist and uroradiology specialist respectively.The interobserver agreement was only 17.8％ (8/45).The positive predictive value of PI-RADS≥3 was 35.1％ (13/37) and 76.5％ (13/17) for prostate cancer by general radiologist and uroradiology specialist respectively,and for clinically significant prostate cancer,the positive predictive value of PI-RADS ≥ 3 was 21.6％ (8/37) and 52.9％ (9/17) respectively.Conclusions Uroradiology specialist achieved significantly superior in predictive value of PI-RADS for clinically significant prostate cancer compared with general radiologist.In the experienced centers,MRI-targeted biopsy could be performed only on high PI-RADS score lesions,thus to reduce unnecessary biopsies and to avoid over diagnosis and over treatment of prostate cancer.

Objective To evaluate the diffuse myocardial fibrosis of the left ventricle (LV) in patients with atrial fibrillation (AF) by cardiac MR (CMR) T1 mapping methods.Methods Totally 60 subjects (30 paroxysmal AF patients and 30 persistent AF patients) and 59 normal control underwent MR cardiac cine,late gadolinium enhancement,and LV T1 mapping.For T1 mapping,modified Look-Locker inversion recovery sequence was used.Compared with control,pre-contrast ventricular T1 times were quantified and extracellular volume (ECV) was calculated.Results All subjects completed the CMR exam,no myocardial delay enhanced lesion was found.Pre-contrast ventricular T1 time in healthy controls was lower than that in patients with persistent and paroxysmal AF,and the pre-comrast ventricular T1 time in persistent AF patients was higher than that of paroxysmal AF patients (all P＜0.05).The mean LV myocardial ECV had no statistical difference between healthy controls and paroxysmal AF patients (P＞ 0.05),while lower than persistent AF patients (P ＜ 0.05).The mean LV myocardial ECV in patients with persistent AF was larger than that in patients with paroxysmal AF (P＜0.05).LV functional indexes were positive correlated with pre-contrast ventricular T1 time and ECV in patients with AF (all P＜0.05).Conclusion There is LV myocardial fibrosis in patients with AF,and the degree in patients with persistent AF is more severe than that in patients with paroxysmal AF.

Objective To explore the clinical application value of left atrial function with feature tracking cardiac magnetic resonance imaging (FT-CMR) by evaluating preliminarily left atrial strain and strain rate in patients with atrial fibrillation. Methods Thirty patients with paroxysmal atrial fibrillation, thirty patients with persistent atrial fibrillation and twenty-two healthy subjects were enrolled. All the subjects underwent cardiac magnetic resonance imaging with the real steady-state free precession(SSFP) sequence. FT-CMR parameters included left atrial strain and strain rate parameters, left atrial volume and function parameters were detected by using offline cardiovascular analysis software, respectively. Left atrial strain and strain rate parameters included left atrial total strain(Εs), passive strain(Εe), active strain(Εa), peak positive strain rate(SRs), peak early negative strain rate(SRe)and peak late negative strain rate(SRa). Volume and function parameters included maximum of left atrial volume(LAVmax), minimum of left atrial volume(LAVmin), total left atrial emptying fraction(LATEF), passive left atrial emptying fraction(LAPEF)and active left atrial emptying fraction(LAAEF). The differences in the general data among the paroxysmal atrial fibrillation group, the persistent atrial fibrillation group and the control group were compared by usingχ2 test or ANOVA analysis. The differences in all parameters between the atrial fibrillation group and the control group, the paroxysmal atrial fibrillation group and the persistent atrial fibrillation group were compared by using independent t test. Left atrial strain and strain rate parameters on an intra-observer and inter-observer were determined by intraclass correlation coefficient(ICC)analyses. Results Compared to control group, LAVmax and LAVmin in atrial fibrillation group were significantly increased(t=9.737,7.889,P<0.001);The LATEF and LAPEF had no significant difference, the LAAEF in two groups had statistically significant difference(t=-4.762,P<0.001).The absolute value of Es, Ee, Ea, SRs, SRe, SRa in atrial fibrillation group were significantly reduced than in control group(t=-7.732,-6.610,-6.493,-7.546, 6.864, 5.917,P<0.001). Compared with paroxysmal atrial fibrillation group, LAVmax and LAVmin in persistent atrial fibrillation group were increased obviously, LATEF and LAPEF were significantly decreased, and the differences were statistically significant(t=-4.575,-5.524, 4.002, 4.028,P<0.001).The LAAEF in two groups had no statistically significant difference. Compared with strain and strain rate in two groups, absolute value of Es, Ee, Ea, SRs, SRe, SRa in persistent atrial fibrillation group significantly decreased than in paroxysmal atrial fibrillation(t=4.310, 3.128, 4.465, 5.496,-3.290,-3.863,P<0.001). The intra-group and inter-group had well correlation coefficients between the observers in the left atrial strain and strain rate parameters of the subjects(ICC=0.85—0.94,0.81—0.90). Conclusions FT-CMR technique can be used to assess the left atrial strain and strain rate in patients with atrial fibrillation;Left atrial reservoir, conduit and booster-pump functions in patients with atrial fibrillation were impaired. Patients with persistent atrial fibrillation had worse left atrial function throughout the entire cardiac cycle compared with those with paroxysmal atrial fibrillation.

Objective To investigate the diagnostic performance of stress cardiac magnetic resonance(CMR) for evaluating low-risk patients with suspected acute coronary syndrome(ACS).Methods Twenty-two patients with low risk of suspected ACS were prospectively and consecutively enrolled in this study.Diagnostic performance of stress CMR was compared with single-photon emission computed tomography(SPECT) for diagnosis of myocardial ischemia with coronary angiography (CAG) as the reference method.Results On the patient-based level analysis,the diagnostic performance of CMR for detection of ACS was sensitivity 93% and specificity 75%.The corresponding value of SPECT was 79%,63%.The area under the ROC (AUC) of CMR was 0.897, which was slightly superior to that of SPECT at 0.723 (P=0.19).On the per-vessel assessment, the diagnostic value of CMR was sensitivity 89%,specificity 87%, while the corresponding value of SPECT was 68%,83%.The AUC of CMR was 0.923,which was significantly higher than that of SPECT at 0.774 (P<0.05).Furthermore, the AUC of CMR was significantly superior to that of SPECT with AUC being 0.900 and 0.553 in the left anterior descending (LAD) vessels (P=0.009 6).Conclusion Stress perfusion CMR has excellent diagnostic performance in low risk ACS patients.Compared with SPECT,stress perfusion CMR performed better in the low-risk ACS populations.

Objective: To retrospectively analyze the potential correlation between cardiac magnetic resonance (CMR) imaging and clinical features and idiopathic arrhythmia in patients with straight back syndrome (SBS). Methods: Patients receiving CMR imaging examination from April 2015 to March 2016 at our department (n=1 432) were screened, 76 patients met the diagnosis criteria of flat chest (anteroposterior diameter/transthoracic diameter (APD/TTD) ratio<0.37 at the T8 vertebra). After excluding 33 patients with structural heart disease, 43 SBS patients were divided into two groups: SBS without obvious morphological change in the heart (group A, n=19) and SBS with morphological change of the heart (group B, n=24). CMR images were analyzed, focusing the heart morphological changes induced by SBS. The clinical data were collected to comprehensively analyze the medical history, electrocardiogram and electrophysiological examination in order to observe the relationship between SBS induced heart morphological change and the arrhythmia type and origin. Results: There were 21 male patients in this cohort, mean age was (28.5±11.5) years (13-58 years). APD/TTD ratio was similar between the two groups (0.30±0.03 vs. 0.29±0.04, P>0.05). LVEF tended to be lower in group B than in group A ((47.48±12.77)%vs. (59.31±9.04)%, P>0.05) . In group B, there were 15 patients with left ventricular enlargement, 2 with left ventricular wall thickening, 5 with uncoordinated ventricular wall motion, 5 with tricuspid regurgitation, 3 with mitral regurgitation, 2 with myocardial fibrosis, 5 with increased trabecular and 16 with decreased left ventricular function. Direct compression sign of right ventricle (disappeared precordial fat tissue space, secondary right atria enlargement and tricuspid regurgitation) and left atria (with or without secondary left ventricular enlargement and mitral regurgitation) were evidenced in patients of group B. CMR revealed that the arrhythmia origin corresponded the compression site of the heart in 8 cases (42.1%) in group A and 13 cases (54.2%) in group B, not corresponded to the compression site in 6 patients (31.6%) in group A and in 7 patients (29.2%) in group B, not attributable in 5 patients (26.3%) in group A and 4 patients (16.7%) in group B. The percent of arrhythmia origin corresponded the compression site of the heart tended to be higher in group B as compared to group A (P>0.05). Conclusion SBS can induce changes of cardiac morphology and cardiac function. SBS induced cardiac compression is linked with the development of arrhythmias and might be one of the reasons of arrhythmias in these patients.

Objective To investigate the value of contrast enhancement T1 mapping in detection of diffuse myocardial fibrosis in cardiomyopathy, and the relationship between myocardial fibrosis and cardiac function. Methods From September 2013 to September 2014, 76 cases of cardiomyopathy patients (including myocarditis) and 33 cases of healthy controls were enrolled in our study. All the subjects underwent cardiac MR (CMR) examination. Scan sequences included cine MR, pre-contrast and post-contrast T1 mapping and late gadolinium enhancement (LGE) imaging. The pre-/post-contrast left ventricle average T1 value and cardiac function of patients and controls were measured and compared by using independent-samples t test. According to the LGE imaging, all the subjects were subsequently divided into LGE positive group, LGE negative group and control group. The myocardial average T1 value and cardiac function among the three sub-groups were compared by using one-way ANOVA, and the relationship among them were analyzed by using Pearson correlation. Results Among the 76 cases of non-ischemia cardiomyopathy patients, 51 cases (67.1%) had LGE. Compared with controls, cardiomyopathy patients presented with higher pre-contrast T1 value [(1 306.4 ± 84.6)ms vs. (1 266.6 ± 57.3)ms, t=2.10, P<0.05] and lower post-contrast T1 value [(483.6 ± 112.0)ms vs. (534.1 ± 92.7)ms,t=-0.27, P<0.05]. Pre-contrast and post-contrast average T1 value of LGE positive patients were (1 322.2 ± 85.8) and (459.7 ± 132.2)ms respectively;pre-contrast and post-contrast average T1 value of LGE negative patients were (1 267.0 ± 68.5) ms and (521.0±95.2)ms, there were statistical significant differences of T1 value between LGE positive and LGE negative patients (P<0.01), however, there were no statistical significant differences of T1 value between LGE negative patients and controls (P>0.05). There were correlation between pre-/post-contrast left ventricle T1 value and ejection fraction (EF) in cardiomyopathy patients (r=-0.252,-0.217, P<0.01), however no statistical correlation with other cardiac function parameters (P>0.05). Conclusions The average pre-/post-contrast T1 value in left ventricle myocardium are helpful for detection of diffuse fibrosis in cardiomyopathy patients. The LGE positive is a sign that can greatly change the T1 value of the myocardial tissue, meanwhile, myocardial fibrosis is negative correlated with ejection fraction in cardiomyopathy patients.

Objective:To study the feasible training model of graduate students with professional degree. Methods:According to the purpose of training-clinical skills of graduate students with professional degree in department of radiology, we have made several ways to ensure the procedural and standardization of the training from course setting, multiple level clinical operation training, the ability of study and evaluation system. Results:To introduce the mode by using evaluation system and to standardize the steps. Conclusion:The model which includes proper course setting, multiple level clinical operation training, the ability of study and evaluation system can enhance the clinical skill training and advance the professionalism of the students.