Objective To study the conventional CT and HRCT manifestations of adult mycoplasma pneumoniae pneumonia. Methods Conventional CT and HRCT were performed in 16 adult patients with mycoplasma pneumoniae pneumonia proven by serology. The CT images were retrospectively analyzed. Results Areas of ground glass opacity(GGO)were found in 12 cases. GGO showed lobular or patchy distribution in 9 cases. Air space consolidation was observed in 8 cases,"tree in bud" sign in 9,thickening of the interlobular septa in 3,and thickening of bronchovascular bundle in 1. 15 cases had two or more findings simultaneously. Conclusion Mycoplasma pneumoniae pneumonia has some characteristic CT findings, which can help to distinguish it from bacterial pneumonia.

Objective To investigate the normal position and configuration of anterior mediastinum.Methods Chest CT scanning was performed in 100 healthy volunteers. Various parameters of the anterior mediastinum were measured, including position (shift distance from medial line of the body),frontal and retral width, and anterioposterior dimension.Results The normal range (with the limit of 95%) of the anterior mediastinum included: the position was shifted 5 mm to right and 15 mm to left, the frontal width was under 30 mm in both man and woman, the posterior width was under 40 mm in woman, and under 50 mm in man, the anterioposterior diameter was under 30 mm in woman and under 35 mm in man.Conclusion The normal region about position and configuration of the anterior mediastinum is established in this study. These data will helpful in detecting the subtle mediastinal shift or other abnormal situation affected the mediastinum.

Objective To investigate the image characteristics and clinical application of 18F-FDG PET/CT in autoimmune pancreatitis (ALP).Methods The PET/CT images from six male patients (age ranging from 51 to 78(average 69) years) with AIP from 2005 to 2012 were studied retrospectively.Of the six patients,two had follow-up PET/CT images after steroid therapy.The morphologic abnormality was visually analyzed and SUV was calculated.Scores were obtained according to the SUV of pancreas compared with that of the liver (3 =SUV higher than liver,2=SUV similar to liver,1 =SUV lower than liver).The difference between the regular and delayed SUV was compared by paired t test using SPSS 17.0.Results All of the 6 patients showed diffuse FDG uptake in the entire pancreas with SUVmax of 3.2-6.0(5.2± 1.1).Five patients had score 3 and one had score 2.Five patients had delayed scan,of which 4 had increased uptake (SUVmax5.3-7.2),but the SUVmax was not significantly different compared to that before delay scan (4.8-6.0,t =-2.424,P＞0.05).Five patients showed extrapancreatic uptake,especially in the salivary glands.After the steroid therapy,the enlarged pancreas reduced and the intense uptake of the pancreas disappeared.The extrapancreatic uptake showed coinstantaneous remission.Conclusions Increasing FDG uptake at entire pancreas was observed in patients with AIP.18F-FDG PET/CT may be useful for detecting AIP and the associated extrapancreatic uptake,and monitoring the change after therapy,yet it needs further evaluation.

The MRI data of 13 patients with autoimmune pancreatitis (AIP) were retrospectively analyzed. The results showed that the pancreas diffusely enlarged in 10 of 13 cases, and focally enlarged in 3cases. There were 13 cases with decreased signals on T1WI and mildly hyperintense on T2WI in the area with pancreatic lesions, 11 cases with thickened capsule-like structure showing moderate-low signal T1WI and low signal T2WI,and delayed enhancement in dynamic contrast-enhanced MRI, and 10 cases with stenotic common bile duct at the level of pancreas with proximal cholangiectasis. The findings in 9 cases were remarkably improved in followup MRI after glucocorticord treatment.

ObjectiveTo evaluate the effects caused by different doses of N-nitrosodiethylamine (DENA) on establishment of a multistep carcinogenesis model of liver cirrhosis in SD rats.MethodsFifty male SD rats were randomly divided into control group (n =5 ) and experimental group (n =45 ).Experimental group consisted of 3subgroups(high,median and low dosegroup ),which were intragastrically induced DENA once a week for 10 weeks,by using 70,50,35 mg/kg DENA solution,respectively.MRI was performed for inspecting pathological changes of rat livers in the following weeks.The mortality rates of different groups were calculated.The differences of the incidence of dysplastic nodule (DN)found in three groups were analyzed with Pearson Chi-square test.ResultsThe multistep carcinogenesis development from regenerative nodule (RN) to DN to hepatocellular carcinoma (HCC) was showed in the SD rat model.Two rats in median dose group and 4 rats in high dose group died.The incidence of DNs found in 3 different groups was 20.7％ ( 6/29 ),30.6％ ( 19/62 ),14.3％ (9/63),respectively,which showed no significant difference among three groups(x2 =4.901,P ＞ 0.05).However,significant difference existed between median and high dose group( x2 =4.811,P ＜ 0.05 ).Combined with the MRI presentation,the intragastric dose of 50 mg/kg could be more appropriate among three different doses.ConclusionsThe median dose DENA could induce an ideal multistep carcinogenesis model of HCC which is suitable for investigating DN on MRI.

PurposeTo investigate the role of diffusion weighted imaging (DWI) in the detection of focal liver lesions (FLL).Materials and Methods T2WI, dynamic contrast enhancement (DCE) and DWI (b=100 s/mm2 and 600 s/mm2 respectively) were performed in 205 patients with 310 FLLs. All images were read by two reviewers to determine the detection of FLLs and score the confidence. The consistency of the results given by the two reviewers was evaluated. The confidence scores between different sequences and the detection rate of different sequences were also compared.Results The consistency of the two reviewers was excellent or good in T2WI, high b value DWI, low b value DWI, and DCE (Kappa=0.71, 0.85, 0.82 and 0.64,P<0.05). As to the confidence score of lesion detection, high b value DWI and low b value DWI were both significantly higher than T2WI (P<0.01), but both were lower than DCE (P<0.01). DWI yielded higher score and detection rate for detecting FLLs than T2WI (86.5%vs. 70.3%,P<0.01), but lower than DCE (91.6%,P<0.05). For small malignant lesions (≤2 cm in diameter), DWI showed similar detection rate with DCE (P>0.05), but higher than T2WI (P<0.01). The combination of DWI and DCE detected more small malignant lesions than DWI or DCE alone (P<0.01).Conclusion DWI can detect more FLLs than T2WI, and can help DCE detect small malignant FLLs. Therefore DWI is suggested to be included in the routine protocol of liver MRI examination.

Objective To test the central frequency (CF) and transmitter gain(TG) of MRI scanners,and set up their action limits.Methods Three different MRI devices (GE 3.0T HD,GE 1.5T HDi and GE 3.0T 750W) were tested by scanning American College of Radiology (ACR) phantom with the axial T1WI series.In the pre-scanning of T1WI series for the ACR phantom,the CF and TG were recorded.It was tested for eight times when MRI scanners were in good condition.The action limits of CF and TG were calculated based on mean values and standard deviations.Results The mean values of CF for three devices were (127 725 772.38±39.68)Hz,(63 875 740.13± 34.15)Hz,and (127 771 958.38±12.19)Hz,respectively.Their action limits were ≤119.04 Hz,≤68.30 Hz,and ≤36.57 Hz,respectively.The mean values of TG for three devices were (125.25±1.28)dB,(101.75±1.98)dB,and (113.25±0.89)dB,respectively.Their action limits were (125.25±2.56)dB,(101.75±3.96)dB,and (113.25±1.78)dB,respectively.Conclusion The CF and TG for three MRI scanners are all consistent with the action limits in this study.The CF and TG action limits will provide criterions for the clinical quality control.

Objective To investigate CT characteristics of ganglioneuroma.Methods CT findings in 12 patients with ganglioneuroma proved histopathologically were retrospectively analyzed.Results The lesions localized in the adrenal gland in 8,the retroperitoneum in 3,the posterior mediastinum in 1.eleven lesions appeared as homogeneous hypo-or isodense oval masses with well delineated margins and 1 was cysto-solid on plain CT scans.The calcifications were seen inside one tumor.On enhanced CT scans,the lesions were mild enhancement in 4,moderate enhancement in 3,significant enhancement in 3 and no enhancement in 2.Mild delayed enhancement in 5 cases,moderate delayed enhancement in 4 cases and no delayed enhancement in 3 cases were showed.Conclusion Typical ganglioneuroma shows low intensity,mild or moderate enhancement and delayed enhancement.

Objective To investigate the clinical value of MR elastography in the diagnosis of prostate cancer at 3.0 T, and to assess the elasticity and viscosity of prostate cancer and benign prostatic diseases. Methods Eight patients (63±7years old) with 12 foci of prostate cancer and 10 patients(59±3 years old) with 14 foci of prostatitis in the peripheral zone were evaluated by MR elastography.MR elastography was performed by transmitting low-frequency longitudinal mechanical waves of 100 Hz into prostate with a transducer placed above the pubic bones. The phase images were reconstructed to acquire viscoelastic mapping. T test was used to compare the mean elasticity and viscosity of prostate cancer and prostatitis. The correlation of elasticity and Gleason scores between prostate cancer and prostatitis were also retrospectively analyzed with Pearson Correlation. Results The mean elasticity and viscosity were significantly higher in prostate cancer[(6.55±0.47)kPa,(6.56±0.99)Pa·s,respectively]than in prostatitis[(1.99±0.66)kPa,(2.13±0.21)Pa·s,respectively],and the difference was statistically significant (t=19.392,16. 372; P ＜ 0.01). In 8 patients with prostate cancer, the Gleason scores were 5 (2 cases), 6 (3 cases), 7 (2 cases) and 8 (1 case), respectively. The mean elasticity for the cases with different Gleason scores was 5.83,6.02,7.45 and 8.05 kPa, respectively. There was a positive correlation between Gleason scores and elasticity of the prostate cancer( r = 0. 913, P ＜ 0. 01 ) in this study.Conclusion MR elastography can be used to visualize the difference in stiffness between prostate cancer and benign prostatic disease, it is a new imaging method with great potential in grading of prostate cancer.

Objective To evaluate the reproducibility of ADC measurements at 1.5 vs 3.0 T and at 1.5 T of different scanners in liver,spleen and pancreas of healthy volunteers.Methods Abdominal DWI were performed on 33 healthy volunteers by using GE 1.5 T,Siemens 1.5 T and Philips 3.0 T MR scanners.The mean ADC values of liver,spleen,pancreatic head,body,and tail were calculated.The ADC data were analyzed by using paired-sample t tests.Results The mean ADC of liver at GE 1.5 T,Siemens 1.5T and Philips 3.0 T were (1.56 ±0.10) ×10-3,(1.67 ±0.15) ×10-3 and(1.35 ±0.12) ×10-3 mm2/s,spleen were (0.96±0.10) × 10 3,(0.98 ±0.11) ×10-3and(0.81 ±0.14) × 10-3 mm2/s,pancreatic head were (2.09 ± 0.27) × 10-3,(2.20 ± 0.21) × 10-3 and (2.05 ± 0.27) × 10-3 mm2/s,pancreatic body were (2.03 ± 0.27) × 10-3,(2.09 ± 0.30) × 10-3 and (1.76 ± 0.25) × 10-3 mm2/s,pancreatic tail were (1.88 ± 0.28) × 10-3,(1.88 ± 0.27) × 10-3 and (1.56 ± 0.27) × 10-3 mm2/s,respectively.From the aspect of different field strength MR scanners,there were significant differences in mean ADC of liver (t =11.073,P ＜0.01 in GE 1.5 T vs Philips 3.0 T; t =12.795,P ＜0.01 in Siemens 1.5 T vs Philips 3.0 T),spleen (t =4.143,P ＜ 0.01 in GE 1.5 T vs Philips 3.0 T; t =5.376,P ＜ 0.01 in Siemens 1.5 T vs Philips 3.0 T),pancreatic body (t =4.677,P ＜ 0.01 in GE 1.5 T vs Philips 3.0 T; t =5.174,P ＜0.01 in Siemens 1.5 T vs Philips 3.0 T) and tail (t =5.356,P ＜0.01 in GE 1.5 T vs Philips 3.0 T; t =4.648,P ＜0.01 in Siemens 1.5 T vs Philips 3.0 T),but there were no significant differences in mean ADC of pancreatic head (t =0.340,P ＞ 0.05 in GE 1.5 T vs Philips 3.0 T; t =1.349,P ＞ 0.05 in Siemens 1.5 T vs Philips3.0 T).From the aspect of different 1.5 T MR scanners,there were significant differences in mean ADC of liver (t =-4.563,P ＜ 0.01),but there were no significant differences in mean ADC of spleen (t =-0.732,P ＞ 0.05),pancreatic head (t =-0.879,P ＞ 0.05),body (t =-1.020,P ＞0.05) and tail (t =0.054,P ＞ 0.05).Conclusion Between 1.5 T and 3.0 T MR scanners,there were significant differences in mean ADC of liver,spleen,pancreatic body and tail,but there were no significant differences in mean ADC of pancreatic head.At different 1.5 T MR scanners,there were significant differences in mean ADC of liver,but there were no significant differences in mean ADC of spleen,pancreatic head,body and tail.