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Objective To investigate the effect of different noise index (NI) combined with iterative recombination on the image quality and radiation dose of CT scan in patients with different body mass index (BMI). Method One hundred and sixty patients who had a liver CT enhanced scan were divided into group A (18 kg/m2≤BMI<24 kg/m2 ) and group B (24 kg/m2≤BMI<31 kg/m2) according to BMI, and each group had 80 patients. The two groups were randomly divided into 4 subgroups which NI value was 11, 13, 15 and 17 respectively. All images were restructured with 50% adaptive statistical iterative reconstruction. Subjective evaluation, objective evaluation [signal noise ratio (SNR) and contrast noise ratio (CNR)] and the effective dose of each group were recorded and calculated after the scan. ANOVA and Kruskal-Wallis test were used to evaluated the difference of imaging quality and radiation dose. Results In group A, the SNR, CNR and the subjective score of the later arterial phase images showed a statistical difference between NI=17 group and other subgroups (P<0.05), while there was no statistical differences among the other three subgroups during three CT enhanced phase. The average ED of NI=15, 17 group were decreased by 57.56%(2.17/3.77) and 61.54% (2.32/3.77) compared with NI=11 group, respectively. In group B, the SNR, CNR and the subjective image scores of the later arterial phase showed a significant difference between NI=15 and NI=11, 13 group (P<0.05). There was a statistically difference of image quality in group NI=17 compared with the other three subgroups in the later arterial phase, portal venous phase and equilibrium phase (P<0.05). The average ED of NI= 13, 15 group was decreased by 26.41% (1.69/6.40) and 45.31%(2.90/6.40) compared with NI=11 group, respectively. Conclusion Upon maintaining diagnostic imaging quality, setting different NI according to BMI and applying the iterative reconstruction algorithm can effectively reduce the radiation dose of liver CT enhanced scanning.
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BACKGROUND:Endothelial progenitor cel s have been shown to play an important role in the pathogenesis of traumatic diseases in recent years. OBJECTIVE:To explore the effect of magnetic labeled endothelial progenitor cel transplantation on renal function of diabetic rats through a MRI imaging study.METHODS:Sixty Wistar rats were randomly divided into normal (no treatment), control and experimental groups. Intraperitoneal injection of 40 mg/kg streptozotocin was performed to make a rat model of type 1 diabetes in the control and experimental groups. Four weeks after modeling, rats in the experimental group were given intravenous injection of magnetic labeled endothelial progenitor cel s (0.15 mL, 1×109/L). Fasting blood glucose, serum insulin, serum creatinine, urea nitrogen and 24-hour urinary protein levels in rats were measured at 8 weeks after cel transplantation. MRI was used to trace transplanted cel s in vivo in comparison with renal biopsy findings, and rat body mass and kidney weight were measured to calculate kidney weight index. RESULTS AND CONCLUSION:After modeling, fasting blood glucose, serum creatinine, urea nitrogen and 24-hour urinary protein levels as wel as kidney weight index were increased significantly (P<0.05), while the insulin level decreased (P<0.05). Compared with the model group, the endothelial progenitor cel transplantation reversed these indices (P<0.05). Additional y, in the experimental group, there was slightly longer T1 and shorter T2 signals as wel as marked lesion edge, and the FLASH sequence became more remarkable compared with the T2-weighted RARE sequence. The other groups showed no significant low signal changes. Magnetic-labeled positive cel s in the experimental group showed by the MRI were consistent with the tissue biopsy results, while no positive cel s were found in the model and normal groups. To conclude, the magnetic labeled endothelial progenitor cel transplantation can improve renal dysfunction in diabetic rats to a certain extent.
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Objective To investigate the feasibility of automatic spectral imaging protocol selection (ASIS) and adaptive statiatical iterative reconstruction (ASiR) technique to reduce radiation dose and dose of contrast agent.Methods Sixtyfour patients underwent routine abdominal examination were randomly divided into two groups.The test group used ASIS technique,with 30％ ASiR and 50％ ASiR reconstruction algorithm.The control group used 120 kVp tube voltage,FBP reconstruction method.The noise of liver,pancreas,sacrospinal muscle,CNR of liver and pancreas,subjective image score in arterial phase and portal venous phase were compared between the image of 70 keV+30％ ASIR and control group.CNR of abdominal aorta and its branchs,CNR of portal vein,and subjective image score were statistically analyzed between im age 55 keV+50％ ASiR and control group in the arterial phase and portal venous phase.Results Compared with control group,CT dose index volume for arterial phase and portal venous phase in test group decreased by 23.68％,23.57％ and dose length product decreased by 25.61％,18.45 ％,total contrast injection decreased 16.86 ％,the noise of liver,pancreas and sacrospinal muscle in 70 keV+30％ ASiR were lower than those of control group in abdominal arterial and portal phase (all P＜0.05).CNR of abdominal aorta,superior mesenteric artery,celiac axis and score in 55 keV+50％ ASiR were higher than those of control group in abdominal arterial phase (all P＜0.05),CNR of portal vein and score in portal phase had no statistically difference (all P＞ 0.05).Conclusion Combining of ASIS and ASiR including 70 keV + 30％ ASiR and 55 keV+50％ ASiR,images are superior to that of the conventional 120 kVp+FBP scan mode for abdominal CT image and vessel image quality,which can reduce the radiation dose and the dose of contrast agent.
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Objective To study the difference of image quality and radiation dose between different exposure modes with full-field digital mammography (FFDM).Methods The Fluke18-220mammographic phantom was exposed by FFDM system with different exposure modes at automatic exposure control ( AEC ) ,including contrast mode,standard mode and dose mode,and the exposure factors and radiation dose were recorded.The images on monitor with the best window width and window level were read by four independent radiologists.The images of specks groups,nylon fibers and masses was assessed by the four experienced readers at the criterion of American College of Radiology.Results The detection of specks groups,nylon fibers and masses were statistically different at the contrast mode and standard mode (F =41.321,P ＜ 0.05),further at the contrast mode and dose mode.The detection of specks groups、nylon fibers and masses were not statistically different( P ＞ 0.05 ) at standard mode and dose mode,but the radiation doses were different.The ESD at standard mode and dose mode was 4.5 and 3.15 mGy,respectively.The AGD of standard mode and dose mode was 1.18 mGy and 0.78 mGy,respectively.Conclusions The standard mode and dose mode of FFDM might be fit for most patients,especially at the dose mode.Contrast mode of FFDM should be strictly controled in use.
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Objective To assess the value of a fibrin-targeted contrast agent (EP-2104R) for MR detection of thrombus, and to compare this modality with non-contrast-enhanced (NCE) MRI and Gd-DTPA injection at acute period after thrombus generation. Methods Thrombus was induced with external injury and stasis in 5 rabbits. MRI was performed before and after contrast agent injection at 6.0 h after injury, and the MRI findings were compared with that of histopathologically examinations. Results EP-2104R enhanced MRI accurately detected thrombus, which was superior to both NCE and Gd-DTPA injection (P<0.001). Gd-DTPA injection was not associated with improvement of thrombus detection. Conclusion Being a fibrin-targeted MR contrast agent for in vivo detection of acute thrombus, EP-2104R is superior to NCE MRI and Gd-DTPA injection.
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Objective To explore the dynamic changes of diffusion tensor imaging(DTI) in spinal cord of goats with persistent compression injury. Methods Eighteen goats weighted 20--25 kg were divided into three groups with completely random design: A, B and C. A balloon catheter was inserted into the epidural space at C3-4 level via intervertabral foramen for each goat. The balloon was inflated by injection of variable volumes of saline in group A and B 10 days following operation. The volume of saline was 0. 3 ml in group A and 0. 2 ml in group B,respectively. The compression sustained for 40 days. Group C served as uncompressed control without injection of saline. The locomotor rating score was applied to each group. Conventional MRI and DTI were performed. The apparent diffusion coefficient (ADC)and fractional anisotropy (FA) values were measured. Histopathological assessments of the compressed spinal cord were performed 50 days following operation with light microscope and transmission electron microscopy. Results Before operation, the locomotor rating score was 5, the ADC value was ( 1.23 ± 0. 05 ) × 10-3 mm2/s and the FA value was (0. 72 ± 0. 05 ) each group. Of six goats in Group A, the locomotor rating score severely decreased and reached( 1.5±0. 4)on the 40 th day after compression. The ADC value at compression site decreased soon and reached the minimum (0. 75±0. 04) × 10-3mm2/s on the 5 th day after compression. Then the ADC value increased gradually, restored normal on the 10 th day or so, then became markedly higher than normal and reached( 1.61±0. 05) × 10-3mm2/s on the 40 th day. The FA value at compression site decreased soon, reached(0. 54±0. 04)on the 1st day, then decreased gradually and reached(0. 43 ± 0.05) on the 40 th day. It appeared high signal intensity on T2WI on the 10 th day. In Group B, the locomotor rating score was moderately decreased and reached(3.4±0. 5 )on the 40 th day. The ADC value at compression site decreased slightly firstly, reached( 1.08±0. 04) × 10-3mm2/s on the 1st day, restored normal on the 20 th day or so, then increased gradually, became higher than normal and reached ( 1.27 ± 0. 05) × 10-3mm2/s on the 40 th day. The FA value increased slightly firstly, reached (0. 78±0. 05 )on the 1st day, then decreased gradually, restored normal on the 15 th day or so, became lower than normal and reached(0. 67±0. 05) on the 40 th day. There was no abnormality on conventional MRI. In Group C, the locomotor rating score, ADC value and FA value remained unchanged. There was no abnormality on conventional MRI. There were dynamic changes over time of the ADC value and FA value in Group A and B, which was more marked in Group A than that in Group B ( repeated measurements analysis of variance, F=426. 7 for the ADC value and F =7895.2 for the FA value, P < 0. 01 ). Histopathologically, swelling and degeneration of axons and neurons as well as the disarrangement of myelin sheathes could be seen. The pathological changes were more marked in Group A than in Group B. In Group C, no abnormality could be seen. Conclusion There are dynamic changes of DTI in cervical spinal cord with compressive injury that correlated with the degree and duration of compression. The ADC value decreased firstly, restored normal and then increased. The FA value increased firstly, restored normal and then decreased in mild compression while solely decreased in serious compression.
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[Objective]To explore the therapeutic effect of the posterior-anterior approach surgical treatment for severe cervical spondylotic myelopathy.[Method]Totally 32 patients with severe cervical spondylotic myelopathy operated by posterior-anterior approach surgical treatment from September in 1998 to January in 2005 were retrospectively analyzed.In the 32 patients,20 males and 12 females.Their age averaged 53.8 years(ranged,41~78 years),invasional segments:C3、42 cases,C4、5 9 cases,C5、611 cases,C6、7 10 cases.Four cases with lesions involving one intervenebral space,the other 12 and 16 cases involving two and three intervertebral spaces respectively.All cases had the posterior cervical open-door laminoplasty decompression in first,and had the anterior cervical decompression and bone grafting or fusion with titanium Cage internal fixation after a week.To follow up all the postoperative cases,neural function was recorded.According to JOA score,preoperative score and postoperative follow-up score were compared,improvement rates were caleulated respectively.[Result]All cases were regularly followed up.The duration of follow-up averaged 13.6 months(ranged,12~18 months).The JOA of before operation was(6.51?1.10),the JOA of first period of time after operation was(9.47?0.5),and follow-up JOA was(12.42?0.79).T-test was used to compare pre-operative and follow-up JOA scores.The statistical results were significantly different(P