Objective To evaluate the feasibility of low dose CT perfusion imaging of brain using the tube voltage of 70 kV.Methods Twenty New Zealand white rabbits underwent cerebral CT perfusion imaging with tube voltage 70 and 80 kV separately,and the interval between two scans was 24 h.The effective dosage (E),cerebral perfusion parameters (CBF,CBV,MTT) and image quality indicator (SNR) of middle cerebral artery of each protocol were acquired and compared statistically.Results The effective dosage of70 kV group was 1.91 mSv,34.8％ lower than that of 80 kV group with the dose of 2.93 mSv.There were no significant differences between the cerebral perfusion parameters acquired at different corresponding ROI.SNR of 70 kV group and 80 kV group were (23.15 ± 5.98) and (21.23 ±9.18) with no significantly statistical difference.Conclusions The effective dosage of 70 kV cerebral CT perfusion imaging could be dramatically reduced with no significant influence on the results of perfusion parameters and image quality.

Objective To investigate the imaging features of primary hepatic neuroendocrine carcinoma.Methods The imaging features of primary hepatic neuroendocrine carcinoma confirmed by pathology in 5 patients were reviewed retrospectively.Among the patients,plain and contrast enhanced CT in 4 and plain and contrast enhanced MRI in 1 were performed.Results CT showed a single lesion in 2 patients and multiple lesions in other 2 with the maximum diameter of 5.5 cm-10 cm.On plain CT,all lesions were hy-podensity with clear boundary and lower area in the center.The enhanced CT showed the lesions with obvious enhancement in arteri-al phase and gradually increasing enhanced area in portal vein and delayed phases but without enhancement in the lesion center.MRI showed the only one lesion in 1 patient with heterogenerous hypointensity on T1 WI,hyperintersity on T2 WI and DWI,and with mild to moderate delayed enhancement.The maximum diameter of the lesion was 5.0 cm,accompanied by a small round cystic structure at the periphery.The compression and displacement of peripheral blood vessels by the lesion without thrombus,and no lymphade-nopathy were also identified.Conclusion CT and MRI may show the imaging characteristics of the primary hepatic neuroendocrine carcinoma,which is helpful for the diagnosis of the tumor.

Objective To assess the image quality of coronary CT angiography(CCTA) by using high-pitch spiral CT under 80 kV in patients with a normal body mass index(BMI), and to investigate the feasibility of low radiation dose.Methods 60 patients,who suspicious coronary artery diseases and BMI between 18.6-25.0 kg/m2 underwent CCTA in our hospital.All patients were randomly divided into group A and group B(each with 30).Patients in group A were given 100 kV CCTA and filter back-projection algorithm (FBP), and patients in group B were given 80 kV CCTA and iterative reconstruction(IR).CT values of aortic root, right coronary artery (RCA), left anterior descending artery (LAD), left circumflex (LCX) and standard deviation (SD) were measured.Then signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.All images were given quality subjective scoring by using 3-score method.The CT dose index was recorded and effective radiation dose (ED) was calculated.Results ED of group A and group B was 0.8 mSv and 0.41 mSv, respectively.Statistically significant difference was found between these two groups.In the study, SD was (28±6) HU in group A and (46±9) HU in group B, and the difference was statistically significant between the two groups.The CT values of aortic root, RCA, LAD and LCX under 80 kV were significantly increased, and the difference was statistically significant between the two groups.There was no statistically significant difference between two groups in RCA-SNR, LAD-SNR and RCA-CNR.But in LCX-SNR, LAD-CNR, LCX-CNR, there was statistically significant difference between two groups.There was no significant difference between the two groups in coronary artery segments which could be used for diagnosis.Conclusion For patients with a normal BMI, CCTA using Flash spiral CT under 80 kV could diagnose coronary artery disease and significantly reduce the radiation dose.

Objective To evaluate the feasibility of high-pitch spiral coronary CT angiography (CCTA) under low tube voltage and low contrast agent concentration for the patients with normal body mass index (BMI).Methods Ninety patients suspected with coronary artery diseases and with BMI of 18.6-25 kg/m2 underwent high-pitch CCTA and were randomly divided into three groups (each=30).Group A used iohexol (350 mg I/mL) 60 mL;Group B used iopromide (300 mg I/mL) 60 mL;Group C used iopromide (300 mg I/mL) 45 mL.All of them were scanned under Flash spiral pattern with 80 kV tube voltage,and the original data was calculated with sinogram affirmed iterative reconstruction algorithm(SAFIR).CT values and noises of the aorta root,right coronary artery (RCA),left anterior descending artery (LAD),and left circumflex (LCX) were measured,then signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.All of images were subjectively assessed by using 3-score method.The effective radiation dose (ED) and total iodine were recorded.Results ED of the three groups were all about 0.4 mSv,and there was no statistically significant.Compared with group A,the total iodine in group C decreased by 35.6 ％ and there was significant difference.There were no significant differences in image noise,SNR and CNR between group A and group B.Between group B and group C,there were significant differences in CT values of coronary,LCX-SNR and LCX-CNR,but there were no significant differences in image noise,SNR and CNR of RCA and LAD.There was no significant difference in the number of coronary artery segments for diagnosis among the three groups.Conclusion For the patients with normal BMI,application of high-pitch spiral CCTA with iopromide (300 mg I/mL)45 mL under 80 kV tube voltage could meet the requirement for clinical diagnosis,and the radiation dose and total iodine were significantly decreased.

Objective To measure the abdominal muscle composition of maintenance dialysis patients using quantitative computed tomography(QCT)and to analyze its relationship with abdominal aortic calcification(AAC).Methods The abdominal CT data of 193 maintenance dialysis patients were analyzed retrospectively and their clinical data were collected.The abdominal muscle composi-tion,including muscle area and muscle fat area,was measured at the middle level of L3 vertebral by QCT.The abdominal aortic calcifica-tion scores(AACs)were calculated using the Agatston method.The groups were grouped according to the quartiles of AACs,and differences in muscle area,muscle fat area and their associated variables were compared between the four groups.The relationship between abdominal muscle composition and AAC was assessed using Spearman rank correlation analysis and partial correlation analysis.Results AACs were positively correlated with age,male,dialysis age,diabetes,hypertension,and abdominal muscle fat area(r=0.555,0.172,0.192,0.348,0.335,0.358,all P<0.05),while no significant correlation was found with abdominal muscle area.A partial correlation analysis controlling for age,sex,dialysis age,hypertension and diabetes showed that AACs were still positively correlated with abdominal muscle fat area(r=0.183,P=0.012).Conclusion Abdominal muscle fat area in maintenance dialysis patients is positively associ-ated with the degree of AAC,and high abdominal muscle fat area is a risk factor for AAC.Enhanced muscle exercise may prevent the risk of vascular calcification in dialysis patients.