Objective To identify the spatial distribution of stray radiation from mobile CT head scanning for the purpose of radiation protection.Methods The head series of CareTom mobile CT were scanned and the radiation dose was measured using TLD (LiF:Mg,Cu,P).The isodose maps of radiation dose field were plotted using Matlab software.Results Radiation dose in the front of the mobile CT was slightly higher than that in the back.The maximum value of 0.255 mGy was found to be at 0.5 m from the scanning hole center.Conclusions The stray radiation dose from mobile CT head scanning was relatively low.However in order to avoid the damage to the operators and other medical workers from long-term low dose exposure,it should keep 2 m away from mobile CT,beside or behind,when in operation.

Objective To evaluate the feasibility and its clinical application of 3.0 T MRI in the assessment of the late gadolinium enhancement in patients with cardiac arrhythmias with phase-sensitive inversion recovery (PSIR) single-shot true fast imaging with steady-state precession (True FISP) sequence.Methods Fifty-six patients with arrhythmia confirmed by electrocardiogram underwent MRI in this prospective study.Late gadolinium enhancement were performed with both PSIR single-shot True FISP (sequence 1) and conventional segmented PSIR Turbo FLASH sequences (sequence 2).The overall image quality (4 scales) was assessed and recorded independently by two experienced radiologists.Statistical analysis was performed with Chi-square test and weighted Kappa test.Results Late gadolinium enhancement of all the 56 patients were successfully examined with the sequence 1 and 2.All the image qualities of sequence 1 reached 3 scales or more and met the requirements of clinical diagnosis,and late gadolinium enhancement lesions were detection in 19 patients.All the sequence 2 images were improperly used for clinical diagnosis of the different degrees of artifacts,especially in patients with severe arrhythmia and those who breath-hold with difficulty.Sequence 1 images were classified as scale 4 in 50 cases and scale 3 in 6 cases by Doctor 1,while scale 4 in 48 cases and scale 3 in 8 cases by Doctor 2,respectively.However,sequence 2 images were classified as scale 2 in 15 cases and scale 1 in 41 cases by Doctor 1,as well as scale 2 in 13 cases and scale 1 in 43 cases by Doctor 2,respectively.Sequence 1 image qualities were significantly higher than those of the segmented sequence 2 (x2 values were 141.329 and 141.177,P＜0.01).Excellent agreements between two observers of the 2 sequences (Kappa values were 0.837 and 0.905,P＜ 0.01) were found.Conclusion PSIR single-shot True FISP sequence provides higher reliability for image quality of late gadolinium enhancement in patients with cardiac arrhythmia,which may be useful for clinical application.

Objective To investigate the feasibility and clinical value of anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV in chest CT scan.Methods A total of 60 patients of clinical diagnosis with lung tumor were enrolled.Those patients were randomly divided into test group and control group.Control group underwent a scan protocol with lateral scout scan combined with Care Dose 4D and Care kV,while anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV were performed in test group.The signal-to-noise ration (SNR),contrast-to-noise ratio (CNR),and overall image quality of two groups of images and diseased tissues were analyzed and evaluated by two high-grade radiologists using double-blind method.Effective doses (E) were also calculated.Results All the 60 patients had successfully completed the chest CT scans.Test group overall image quality (4.57 ± 0.45) and control group overall image quality (4.73 ± 0.45) had no statistically significant difference (P ＞ 0.05).The control group image SNR,CNR and diseased tissue SNR,CNR compared with test group had no statistical significance difference (P ＞ 0.05).The difference of the volume CT dose index (CTDIvol),dose-length product (DLP) and effective dose (E) of test group and control group was statistically significant (t =8.514,8.464,8.464,P ＜ 0.001).Compared with control group,the effective dose of test group decreased by 33.3％.Conclusions Compared with lateral scout scan,the technology of anteroposterior and lateral scout scan combined with Care Dose 4D and Care kV can decrease radiation dose without reducing the image quality.This technology can therefore be considered as a regular imaging modality for chest CT scan.

The Department of Radiology of West China Hospital of Sichuan University provides us a teaching model that image-reading combined with problem-based learning (PBL) for radiographer once a month. Based on the problem images and typical cases, after careful image-reading, radiographer is guided to think positively and propose specific solutions to the problems. Then designated personnel gives a detail lecture on related diseases, imaging performance, diagnostic requirements, conventional scanning schemes, operating specifications, common problems and image post-processing, etc., which aims at taking continuing education for radiographers.

Objective To explore the clinical application value of second-generation dual-source CT combined with intelligent modulation and iterative reconstruction in emergency aortic dissection imaging.Methods A total of 40 emergency patients with clinical suspected aortic dissection were included in this study.Conventional scanning was performed in the control group,and large-pitch intelligent modulation and iterative reconstruction were performed in the test group.The mean CT value,mean noise,signal noise ratio(SNR),contrast noise ratio(CNR),effective dose,image quality and aortic root image quality were evaluated and analyzed.Results Totally 40 patients successfully completed CT aortic dissection imaging.There was no difference in image quality between the two groups (P＞ 0.05).The quality of aortic root images in the test group was better than that in the control group,and the difference was statistically significant(x2=22.556,P＜0.05).The mean CT value and mean noise of aorta in the control group were slightly higher than those in the test group.However,SNR and CNR in the test group were higher than those in the control group,and the difference was statistically significant (t =-21.042,-15.924,8.530,11.495,P＜0.05).The effective dose of the control group [(10.59±3.89)mSv] was significantly higher than that [(6.39±0.81) mSv] of the test group,the difference was statistically significant (t =-12.327,P＜0.05).Conclusions The combined intelligent modulation technique and iterative reconstruction technique with dual-source CT large pitch scanning can meet the requirements of image quality and reduce the effective dose,and can be used as a conventional imaging method for emergency CT of aortic dissection.

OBJECTIVE: To compare the image quality of three-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) with sparse undersampling and iterative reconstruction (sparse TOF) with that of conventional TOF MRA. MATERIALS AND METHODS: This study included 56 patients who had undergone sparse TOF MRA for intracranial artery evaluation on a 3T MR scanner. Conventional TOF MRA scans were also acquired from 29 patients with matched acquisition times and another 27 patients with matched scanning parameters. The image quality was scored using a five-point scale based on the delineation of arterial vessel segments, artifacts, overall vessel visualization, and overall image quality by two radiologists independently, and the data were analyzed using the non-parametric Wilcoxon signed-rank test. Contrast ratios (CRs) of vessels were compared using the paired t test. Interobserver agreement was calculated using the kappa test. RESULTS: Compared with conventional TOF at the same spatial resolution, sparse TOF with an acceleration factor of 3.5 could reduce acquisition time by 40% and showed comparable image quality. In addition, when compared with conventional TOF with the same acquisition time, sparse TOF with an acceleration factor of 5 could also achieve higher spatial resolution, better delineation of vessel segments, fewer artifacts, higher image quality, and a higher CR (p < 0.05). Good-to-excellent interobserver agreement (κ: 0.65–1.00) was obtained between the two radiologists. CONCLUSION: Compared with conventional TOF, sparse TOF can achieve equivalent image quality in a reduced duration. Furthermore, using the same acquisition time, sparse TOF could improve the delineation of vessels and decrease image artifacts.
Acceleration ; Arteries ; Artifacts ; Humans ; Magnetic Resonance Angiography

Objective To assess the value of cardiac magnetic resonance (CMR) imaging in left ventricular structure and function in patients with end stage renal disease (ESRD).Methods Twenty-five patients with ESRD and 10 healthy subjects underwent CMR.Left ventricular end diastolic volume(EDV),end-diastolic diameter(EDD),end-systolic volume(ESV),end-systolic diameter(ESD),stroke volume(SV),ejection fraction(EF),LVM and interventricular septum (IVS) thickness were measured and compared.The parameters from CMR and 2DTTE were compared.Results The EF in patients with ESRD was significantly lower than that in controls (P＜0.001),while ESV,ESD,IVS and LVM were respectively higher than these in controls (P＜0.05).There was no significant difference (P＞0.05) in ESV between CMR and 2DTTE,but EF of CMR was significantly higher than this of 2DTTE (P＜0.05).There was no significant difference (P =0.296) in left ventricular systolic functional category.Bland-Altman plots showed a good agreement between the two methods.Conclusion CMR is a helpful tool to assess left ventricular structure and function in patients with ESRD.

Objective To quantitative evaluate the myocardial microcirculation dysfunction in patients with end-stage renal disease (ESRD),and to provide the imaging characteristic for early detection myocardial dysfunction and microcirculation damage in the ESRD patients after dialysis therapy.Methods Sixty-seven patients with ESRD and 1 9 healthy subj ects were enrolled in our study, and the ESRD patients were divided into two groups including patients with preserved systolic function (n=51,EF≥50%)and patients with impaired systolic function (n=16,EF＜50%).The LV regional myocardial perfusion parameters were analyzed including upslope, time to maximum signal intensity (TTM)and max signal intensity (Max SI).Those continuous variables were compared using one-way analysis of variance (A N OVA )in all three groups.Results Compared with the controls and the ESRD patients with preserved EF,the ESRD patients with impaired EF had a significantly lower SV and markedly increased LV mass (all P＜0.001).For the fist-pass perfusion analysis,first-pass perfusion Max SI of all segments were significantly reduced in the ESRD patients with preserved/impaired EF compared with the normal subjects (all P＜0.05).Compared with the ESRD patients with preserved EF and controls,the ESRD patients with impaired EF had lower upslope in the basal segment (P＜0.05).And the ESRD patients with preserved/impaired EF had shorter TTM in the apical segment than that in normal controls (P＜0.01).Conclusion The CMR first-pass perfusion can detect the myocardial deformation and dysfunction in ESRD patients,the Max SI may be more valuable to early detect myocardial microcirculation dysfunction.

Objective To investigate the feasibility of chemical exchange saturation transfer (CEST) imaging in the measurement of myocardial creatine (Cr) metabolites in phantom model using 3.0 T MR. Methods Five phantoms were made according to the volume percentage of Cr ranging from 10 to 50 mmol/L with an interval of 10 mmol/L. 3.0 T MR examinations with base protocol sequence,sequence with and without ECG were performed. Signal to noise,CrEST effect and Z spectra were analyzed. Comparison of signal noise ratio (SNR) among the three methods was performed using an analysis of variance. Bivariate correlations were obtained through Pearson analysis. Results Phantom studies demonstrated that different concentrations of Cr exhibited significant CEST effect with the three sequences. The SNR obtained by sequences with and without ECG were both higher than that of base sequence (both P<0.05). Moreover,no significance of SNR was found between sequences with and without ECG (P>0.05). There were positive correlation of MTR between sequences with ECG,sequences without ECG and base protocol sequence (r2= 0.974 and 0.997, both P<0.05). Conclusion Compared with base protocol sequence, the optimized sequence with ECG can acquire higher SNR CrEST images,indicating that myocardial CrEST imaging could be performed in clinical practice.

Objective:To preliminarily assess the clinical value of sirolimus combined with prednisone in the treatment of Kaposiform hemangioendothelioma (KHE) complicated by Kasabach-Merritt phenomenon (KMP) .Methods:A retrospective study was conducted. General clinical data and relevant data on efficacy and adverse reactions were collected from 36 patients with KHE complicated by KMP, who received oral sirolimus combined with prednisone in Department of Pediatric Surgery, West China Hospital, Sichuan University from January 2011 to January 2018.Results:Among the 36 patients with KHE complicated by KMP, the male-to-female ratio was 1∶0.8; their average age was 15.0 months (range, 4.0 - 60.0 months) , and the average age of onset was 6.3 months (range, 0.8 - 48.0 months) ; 32 (88.9%) patients were diagnosed with mixed KHE, and 4 (11.1%) with deep KHE; the tumor size ranged from 2.5 cm × 4.0 cm to 20.0 cm × 24.0 cm. During the combined treatment, the average duration of prednisone administration was 6.4 weeks (range, 5.0 - 9.0 weeks) , and that of sirolimus administration was 19.3 months (range, 13.0 - 27.0 months) . After 1-5 weeks of combined treatment, platelet counts and fibrinogen levels of the 36 patients gradually returned to normal. After short-term prednisone combined with long-term sirolimus treatment, the average disease severity score decreased from 4.0 before treatment to 2.4 at 6 months and 1.6 at 12 months. After 12 months of the combined treatment, tumors mostly regressed in 32 (88.9%) patients, partially regressed in 3 (8.3%) , showed no obvious change in 1 (2.8%) . During the treatment, common adverse reactions included gastrointestinal discomfort and oral ulcers, no patient discontinued the treatment due to severe adverse reactions, and no drug toxicity-related death occurred.Conclusion:Sirolimus combined with prednisone is effective and safe for the treatment of KHE complicated by KMP.