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.

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.

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.

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 explore the feasibility of coronary magnetic resonance angiography(CMRA) with a T2-prepared turbo field echo(T2-TFE) sequence at 3.0T MR scanner.Methods 33 objects underwent CMRA at 3.0T MR imaging unit.The CMRA was performed with a 3D T2-TFE sequence.Electrocardiographically gating combined with real-time respiratory navigator gating and tracking was used to suppress the cardiac motion and correct for respiratory-induced coronary artery motion.The original images were reconstructed with MIP and Soap Bubble software.The quality of CMRA was evaluated and the lengths of the main coronary arterial branches were measured.Results 115 of 128 coronary arteries were scored higher than 3 with the standard of image quality.The lengths of LM,LAD,LCX and RCA were(12.0?3.8) mm,(79.4?18.9) mm,(60.0?12.7) mm and(110.7?27.2) mm,respectively.Conclusion CMRA with T2-TFE sequence is feasible at 3.0T.

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 radiation dose and image quality of spectral and conventional CT scan in neck.Methods Sixty patients with enhanced neck CT scan were analyzed retrospectively.The 30 patients with spectral CT scan were included in spectral CT group,and the 30 patients with conventional CT scan were included in conventional CT group.The tube voltage,tube current and rotation speed of the spectral CT group were fast switching with 80 and 140 kVp,630 mA and 0.5 s,respectively.The scanning parameters of conventional CT group were 120 kVp,auto tube current (100 to 600 mA),and 0.6 s,respectively.The objective evaluation [noise and (contrast to noise ratio) CNR] and subjective scores in the upper,middle and lower neck were evaluated.The radiation dose was also evaluated in the two groups.The independent-samples t test was used in comparison of the radiation dose.The independent-samples t test and the rank sum test were used to compare the objective and subjective image quality.Results The CT dose index of spectral and conventional scan in the neck were 17.77 mGy and (17.26±2.18) mGy,respectively without significant difference (t=-1.26,P=0.218).The noises of 65 keV images in upper,middle and lower neck were (4.5 ± 0.8),(4.5 ± 0.9),(5.2 ± 1.0) HU,and the noises of conventional CT images in above-mentioned regions were (4.5± 1.1),(4.1± 1.0),(5.0± 1.7) HU.There was no significant differences (t=0.102,-1.362,-0.621;P＞0.05).The subjective scores of 65 keV images in upper,middle and lower neck were (4.1 ± 0.3),(4.7 ± 0.5),(3.8 ± 0.7),while the subjective scores of conventional CT images in associated region were (4.1±0.4),(4.6 ±0.5),(3.5 ±0.6),wihtout significant differences (Z=-0.286,-0.531,-1.568;P＞0.05).The noises of 55 keV images in upper,middle and lower neck were (5.4±0.9),(5.6± 1.1),(6.6± 1.6) HU,which were significantly higher than noise of conventional images (t=-3.614,-5.560,-3.784;P＜0.05).The subjective scores of 55 keV images in upper and middle neck were (3.7±0.5),(4.2±0.4),which were significantly lower than those of conventional images (Z=-2.541,-3.136;P＜0.05).The subjective score of 55 keV images in lower neck was (3.3±0.8),which was no significant difference in comparison with conventional image (Z=-1.318,P＞0.05).There was no significant difference between the CNR of conventional images and CNR of spectral images with 65 keV and 55 keV in upper,middle and lower neck (P＞0.05).Conclusion The radiation dose and the image quality of spectral CT scan are same to the conventional CT scan in the neck,the 65 keV monochromatic images can be used routinely.