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OBJECTIVE@#To evaluate the changes in renal oxygenation in rats with acute aristolochic acid nephropathy using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) at 7.0T.@*METHODS@#Wistar rats were randomly divided into AAN group (=18) and control group (=6) for intraperitoneal injections of AAI at 40 mg/kg and PEG400, respectively, on a daily basis for 6 consecutive days. All the control rats and 6 rats from AAN group underwent BOLD MRI scan before and at 2, 4, and 6 days after the initial injection for measuring renal cortical and medullary R2 values. At each of the 4 time points, 3 rats in AAN group were sacrificed for histological evaluation; the control rats were examined at 6 days after the initial injection.@*RESULTS@#The cortical and medullary R2 values of the rats in AAN group on days 4 and 6 were significantly higher than those in the control group ( < 0.05). In AAN group, the cortical R2 values showed no obvious changes on day 2 as compared with the baseline values, but increased significantly on day 4 ( < 0.05) and day 6 ( < 0.01); the medullary R2 values increased progressively and were significantly higher than the baseline values on day 4 ( < 0.01) and day 6 ( < 0.01). In the control group, no significant changes were detected in either cortical or medullary R2 values throughout the experiment.@*CONCLUSIONS@#BOLD MRI allows non-invasive measurement of renal oxygenation levels in rats with AAN. The increase of renal cortical and medullary R2 values, and particularly the latter, indicates a lowered renal oxygenation level, which provides potentially useful information for clinical decisions.
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Animals , Rats , Aristolochic Acids , Kidney , Kidney Diseases , Metabolism , Magnetic Resonance Imaging , Oxygen , Random Allocation , Rats, WistarABSTRACT
Objective To explore the efficacy of quantitative susceptibility mapping (QSM) in the assessment of osteoporosis and the impact factors on the QSM values.Methods A total of 105 volunteers (35 males and 70 females) were recruited in this study.The height,weight,waistline and hipline were measured,and the body mass index was calculated.All the subjects underwent MRI-based QSM and quantitative computed tomography (QCT).The measurement of QSM and QCT values was performed on L3 vertebrae body.According to QCT value,the subjects were divided into three groups (normal,osteopenia and osteoporosis).According to age,the subjects were divided into group I (21-30 years old),group 2 (31-40 years old),group 3 (41-50 years old),group 4 (51-60 years old),and group 5 (＞60 years old).Differences among all groups were compared using one-way ANOVA or Kruskal-Wallis.Results According to QCT value,54 subjects were normal,22 osteopenic and 29 osteoporotic.The QSM value for the subjects with osteoporosis [148.60(109.42,188.81)ppb] was significantly higher than that of normal (P＜0.001)and the osteopenia (P＜0.001).The QSM value for the subjects with osteopenia was significantly higher than the normal (P＜0.001).The coefficient of QSM and BMD was-0.749 (P＜0.001).Multiple linear regression showed age was the independent influence factor for QSM value (r=0.72,P＜0.001),whereas the gender,BMI,waistline and hipline showed no significant difference (P＞0.05).With the increasing of age,the QSM value showed a gradual increasing trend.And there were significant differences of QSM values among the different age groups (P＜0.001).The QSM value of 138.98 (100.37,183.84)ppb for group 5 (＞60 years old) was significantly higher than that of group 1,group 2,and group 3 (P＜0.001).There is no difference between group 5 and group 4 (P＞0.05).The QSM value of 96.62(28.62,143.99)ppb for group 4 (51-60 years old) was significantly higher than that of group 1 and group 2 (P＜0.001).And there was no difference between group 4 and group 3 (P＞0.05).The QSM value of group 1,group 2,and group 3 showed no significant difference (P＞0.05).Conclusions The QSM of bone is feasible in the assessment of osteoporosis and has the potential to be a biomarker providing new insights into osteoporosis.And age is the critical factor affecting QSM value.
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Objective To compare the value of assessment with DWI and contrast-enhanced MRI (CE-MRI) in activity of sacroiliitis of patients with ankylosing spondylitis(AS).Methods Ninety-six patients conforming to modified New York criteria were prospectively collectedas the AS group, and twenty-one healthy volunteers were enrolled into the control group. According to the Bath AS disease activity index (BASDAI), erythrocyte sedimentation rate and C-reaction protein, AS patients were divided into the active AS group (n=60) and the chronic AS group (n=36) . All subjects were performed with conventional MRI, DWI and CE-MRI of bilateral sacroiliac joints. The MRI manifestations were reviewed and the ADC values and signal intensity enhancement rate (ΔSI) were measured.ANOVA was performed for the comparison ofΔSI and ADC values among active AS group, chronic AS group and control group with BASDAI and lab test results as the gold standards. ROC was analyzed with ΔSI and ADC values for activity of AS and paired samples t test was obtained to comparethe areas under the ROC ofΔSI and ADC values.Results Among 96 cases of AS patients, MRI of sacroiliac jointsshowed that 62 cases had subchondral bone edema (57 cases of active group, 5 cases of chronic group), that 11 cases had bone surface erosion(4 cases of active group, 7 cases of chronic group), that 15 cases had bone sclerosis(6 cases of active group, 9 cases of chronic group) and that 58 cases had fat deposition on the sacroiliac joints (27 cases of active group, 31 cases of chronic group). The ΔSI values of the active group, the chronic group and control group were respectively (2.51 ± 1.69)%,(1.19 ± 0.67)%and(0.75 ± 0.21)%, and the ADCvalues were(1.33 ± 0.33)× 10-3,(1.00 ± 0.43)× 10-3 and(0.38±0.13)×10-3mm2/s. There were significant differences forΔSI and ADC values among three groups (F=18.375, 16.366. P<0.01), and statistical significance ofΔSI and ADC values were found between every two groups of three(P< 0.05).The area under the ROC between ΔSI and ADC to determine activity of AS patients were respectively 0.814 and 0.730, which had nostatistical significance(t=1.632, P=0.103). The sensitivity and specificity to determine activity of AS patients byΔSI=1.44%were 81.67%and 80.00%.The sensitivity and specificity to determine activity of AS patients by ADC=1.15 × 10-3/mm2 were 76.67% and 71.43%.Conclusion DWI and CE-MRI performed equally in detecting activity of AS patients.
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The long-period CT perfusion imaging leads to an excess amount of radiation dose to the patient. However, the radiation dose could be significantly reduced if a previous normal-dose image is acquired before a set of low-dose scans of perfusion, and a filtering processing is performed on the differences between the current low-dose images and the previous normal-dose image, then the results are added to the previous image. But the selection of plenty of parameters makes the algorithm complicated. This paper proposes an innovative approach performed in sinogram domain instead of in image domain. First a normal-dose image and a set of low-dose projection data are acquired before the perfusion. Second the perfusion information is commendably reconstructed with sparsity constraints of the differences between current low-dose perfusion sinograms and previous low-dose sinogram. Finally, the reconstructed perfusion information is added to the previous normal-dose image. The proposed method was validated by simulated experiments with a set of brain CT perfusion images, which showed that the new method provided more accurate perfusion information; the time-attenuation curve was more close to that for normal-dose scan and the mean transit time more repeatable.