Objective To investigate the correlation between b value and image quality of diffusion weighted imaging(DWI).Methods DWI was performed in 20 healthy volunteers and 60 patients with liver lesions.Signal to noise ratio ( SNR ) and contrast to noise ratio ( CNR ) were calculated . Results The mean SNR was larger than 5 when b value was 100 s/mm2 or 300 s/mm2, while b value was 600 s/mm2 or 1100 s/mm2, SNR was less than 5. With b value increased, the influence of blood supply on ADC decreased, but the artifacts increased and CNR decreased, CNR of cystic lesions decrease more than that of solid lesions.Conclusion The gradient factor(b)between 300 s/mm2 and 600 s/mm2 is the most suitable in DWI.

Objective To evaluate blood oxygen level-dependent (BOLD) MRI on assessing renal damage after injection of iodine contrast medium with a 3.0 T system. Methods Routine MRI examination,including T1WI and T2WI, and BOLD MRI were performed in 29 SD rats with a 3.0 T system before the injection of iodine contrast agent and 20 min, 24 h, 48 h, 72 h after the injection, respectively. T2 * and R2 * ( = 1/T2 * ) measurements were obtained in the cortex, inner and outer medulla of kidney,respectively. The results obtained before contrast agent administration were considered as the self-controls.AVONA test were used for the comparison of R2 * values in different parts of both kidneys before contrast agent administration. Two-sample t test was used to compare R2 * values before and at each time point after contrast agent administration, and R2 * values in different parts of the kidneys. Results Before contrast agentadministration, R2 * values in outer medulla in both sides of kidney [R2 *left oM = (31.76 ± 2.73 ) / s,R2 * right OM = (32.77±3.07) /s] were higher than those in cortex [R2 * left c=(30.20±3.48) /s,R2 * right c = (28.84 ±3.11 )/s] and in inner medulla [ R2 * letf IM = (29.54 ± 2.42) /s, R2 * right IM =(28.37±2.80) /s ] ( F = 3.357 and 14.961, P＜ 0.05 ). There was no statistical significance in R2 *values in the three parts between left and right kidney, including cortex, outer and inner medulla (P＞0.05). After contrast agent administration, R2* values in outer medulla changed obviously, which reached to the peak values at 20 minutes after contrast agent administration [R2* left OM = ( 43.57 ± 3.84 )/s,R2*right OM= (44.58±3.13) /s] and dropped from 24 hours [R2*left OM = (42.07 ±4.82) /s,R2* right OM = (42.89±3.40) /s]. R2* values in inner medulla and cortex only presented slight changes.Conclusion R2* values reflected the changes of oxygen content in renal cortex and medulla quantitatively,which helped for detecting medullar ischemia and hypoxia. BOLD MR imaging could offer a feasible method for evaluating oxygen metabolism and renal injury in cortex and medulla.

Objective To investigate the qualitative diagnostic value of MRCP in patients with benign obstructive jaundice.Methods MRCP and conventional MR images were performed in 128 patients with benign obstructive jaundice on a superconductive MR scanner (Plilips medical systems Inc. Eclipse. 1.5T) . Final diagnosis was confirmed by surgical and histopathological findings in 123 patients and other 5 patients by follow-up.Results The accuracy of location diagnosis of MRCP was 100%; the qualitative diagnosis was 95.3%. The specificity, accuracy, sensitivity of the deadwood-sign for diagnosis of benign obstructive jaundice were 100%, 95.3%, 85.7% respectively. Conclusion The deadwood-sign was a specific indicator in MRCP of benign obstructive jaundice.

Aim To assay the mutagenicity of Enphorbia lunulata(EL) decoction and to modify the Ames test for evaluation the mutagenicity of herbal medicine samples.Method The mutagenicity of EL decoction was assayed by standard Ames test; the teratogenicity was done by mammalian bone marrow chromosomal aberration test. In modified Ames test system,the influence of histidine EL decoction was excluded by additional negative control, in which the test media was supplied with histidine (histidine amount equaled to the histidine in different concentration of EL decoction).Result The mutagenicity of EL decoction was positive in the standard Ames test. The teratogenicity of EL decoction was negative in mammalian bone marrow chromosomal aberration test. By the modified Ames tests,the mutagenicity of EL decoction was negative.Conclusion The standard Ames test is not suitable for evaluating the mutagenicity of EL decoction, but the modified Ames test is. The mutagenicity in vitro and the teratogenicity in vivo of EL decoction are all negative.

Objective To investigate the clinical applications of coronary CT angiography in patients with suspected coronary artery disease and identify factors that affect CT findings. Methods Medical records of patients suspected of coronary artery disease over a period of 12 months from a tertiary teaching hospital were retrospectively reviewed. Patient age, sex (male/female), duration of symptoms and abnormal rates of coronary CT angiography scans were analysed to investigate the relationship among these parameters. The patients by age were duration of symptoms was also classified into five groups: less than one week, one week to one month, one to three months, three to six months and more than six months. Results Of the 880 patient records reviewed, 800 met the above study criteria. Five hundred and forty nine patients demonstrated abnormal CT findings (68.6%). There was no significant difference in the percentage of abnormal CT findings based on patient sex and the duration of symptoms (P = 0.14). The abnormal rates of coronary CT angiography, however, increased significantly with increasing age (P < 0.001); with patients over 65 years of age 2.5 times more likely to have an abnormal CT scan relative to a patient under 45 years. A significant difference was found between abnormal coronary CT angiography and the duration of symptoms (P = 0.012). Conclusions Our results indicate coronary CT angiography findings are significantly related to the patient age group and duration of symptoms. Clinical referral for coronary CT angiography of patients with suspected coronary artery disease needs to be justified with regard to the judicious use of this imaging modality.

Objective To study the value of diffusion tensor imaging(DTI) in early assessment of prognosis of hypoxic-ischemicencephalopathy(HIE) in new infants. Methods 96 cases of full term infants with HIE underwent DTI examinations at 0～12 days and 6～36 months. Based on clinical diagnostic criteria, 96 cases were divided into three groups: mild, moderate and severe HIE groups. Fractional anisotropy(FA) values in the corpus callosum splenium and the posterior limb of internal capsules were measured. Results (1) Varying degrees of FA groups was significantly different from the same site, increased linearly with time,but the magni-tude of change was different;(2)When FA value of corpus callosum splenium in the cut-off point was ≥0.437,the sensitivity(SE) was 83.8% , the specificity(SP) was 18.6% , ROC area under the curve was 0.903 , 95% confidence interval was from 0.846 to 0.961,standard error was 0.029;when FA value of posterior limb of internal capsule in the cut-off point ≥0.391,SE was 86.5%, SP was 11.9% ,ROC area under the curve was 0.940,95% confidence interval was from 0.898 to 0.984,standard error was 0.022. Conclusion MR DTI examination is of significant value in evaluating early the prognosis of HIE in infants.

Objective:To study the value of ultrasound-guided endoscopic retrograde appendicitis therapy in children with uncomplicated appendicitis.Methods:This study was a single center, retrospective study, including all electronic cases of appendicitis diagnosed clinically in Department of Pediatrics, the Second Affiliated Hospital of Air Force Military Medical University from October 2018 to October 2020 and received ultrasound-guided endoscopic retrograde appendicitis therapy.The clinical features, treatment and prognosis of the children were retrospectively analyzed.Results:A total of 152 electronic cases were included, there were 77 males and 75 females, aged(6.84±3.09) years.All the 152 children were treated with ultrasound-guided endoscopic retrograde appendicitis therapy.Intubation success rate and clinical success rate was 98.03%(149/152 cases)and 97.99%(146/149 cases), respectively.The median time of endoscopic therapy was 42.50 (31.00, 56.00) minutes.Mean postoperative hospital stay was (2.81 ±1.41) days, and the mean total hospital stay was (4.19 ±1.71) days.A total of 139 patients were followed up with a median follow-up time of 5 (1, 26) months.During the follow-up, the recurrence rate was 7.19%(10/139 cases), and the median time of recurrence was 2 (1, 3) months.Conclusions:Ultrasound-guided endoscopic retrograde appendicitis therapy had high effective rate and low recurrence rate in children with uncomplicated appendicitis, preserved the physiological function of appendix and avoided radiation damage.It can be used as a safe and effective treatment for acute and chronic uncomplicated appendicitis in children.

Objective To observe the value of MSCT in diagnosis of gastrointestinal foreign bodies and the resulting gastrointestinal perforations.Methods MSCT and clinical data of 30 patients with gastrointestinal foreign bodies,including 17 with gastrointestinal perforations were reviewed retrospectively.The location,morphology,density of foreign bodies,and the performances of gastrointestinal perforations were observed.Results All gastrointestinal foreign bodies could be displayed by MSCT in 30 patients.Toothpicks were the most common type of foreign bodies (12/30,40.00％),followed by fish bones (5/30,16.67％),jujube nuclei (3/30,10.00％),chicken bones (2/30,6.67％) and so on.Foreign bodies were found in small intestine in 15 patients (15/30,50.00％),in stomach in 7 (7/30,23.33％),in colon in 6 (6/30,20.00％) and in ileocecus in 2 patients (2/30,6.67％).High density foreign bodies were demonstrated on abdominal X-ray films in 11 patients (11/30,36.7 ％).Gastrointestinal perforations caused by toothpicks,fishbones and other sharp objects were observed in 14 patients (14/17,82.35 ％).Intestinal wall edema,peripheral exudation,foreign bodies "cross through the intestinal wall" and the surrounding small bubbles were found in perforation site or nearby.Conclusion MSCT can comprehensively display the location,shape and associated changes of gastrointestinal foreign bodies,with important diagnostic value for gastrointestinal perforations.

Objective To explore the value of prostate specific antigen density (PSAD) in clinical decision making for patients with prostate imaging reporting and data system version 2 (PI-RADS v2) category 3 lesions.Methods Totally 54 patients with PI-RADS v2 category 3 lesions who underwent prostate biopsy before MRI were enrolled and divided into prostate cancer (PCa) group (n=11) and benign group (n=43) according to biopsy results.Then clinical data and imaging features,including total prostate specific antigen (TPSA),free prostate specific antigen (FPSA),FPSA/TPSA ratio (F/T),PSAD,prostate volume and the volume of index lesion were collected and statistically analyzed between the two groups.ROC curve was used to evaluate the diagnostic efficacy of PSAD in predicting malignant and benign lesions in patients with PI RADS v2 category 3 lesions.Results PSAD had statistical difference (P=0.006),whereas TPSA,FPSA,F/T,prostate volume and the volume of index lesion showed no statistical differences between PCa group and benign group (all P＞0.05).ROC curves showed that area under the curve was 0.771(P＜0.05).Using the optimal threshold of PSAD-0.25 ng/ml2,the sensitivity and specificity of PSAD in predicting PCa and benign lesions was 72.73 ％ (8/11) and 74.42％(32/43),respectively.Conclusion PSAD is an effective index to predict the risk of PCa in patients with PI-RADS v2 category 3 lesions.Using the threshold of PSAD=0.25 ng/ml2 to screen high risk patients for prostate biopsy,the positive rate could be improved and unnecessary biopsies could be avoided.

To investigate the efficacy and safety of modified endoscopic retrograde appendicitis therapy (ERAT) in children with acute uncomplicated appendicitis complicated with intussusception. Data of 6 patients with acute uncomplicated appendicitis complicated with intussusception who received modified ERAT were collected from October 2018 to February 2020 in Pediatrics Department of Tangdu Hospital. The reduction rate of intussusception, the success rate of ERAT appendiceal intubation and endoscopic treatment, the remission time of clinical symptoms, the time of white blood cells return to normal, the length of hospital stay, complications and recurrence were summarized. All the 6 patients were confirmed to be acute uncomplicated appendicitis combined with ileocecal intussusceptions under colonoscopy. Endoscopic intussusception reduction and ERAT were performed successfully. The mean time of disappearance of abdominal tenderness was 1.3 days after the therapy, and the time of white blood cells return to normal was 1 day after surgery. The endoscopic treatment were all successful and the length of hospital stay was 3-6 days. No complications or recurrence of intussusception and appendicitis occurred during the follow-up period of 6-12 months. Modified ERAT can effectively, safely and minimally invitingly treat acute uncomplicated appendicitis with intussusception in children on the basis of definite diagnosis.