Objective To evaluate MR appearances of normal and injured anterior cruciate ligament(ACL).Methods The MR findings of normal ACL in 16 cases and ACL tear in 15 cases were reviewed retrospectively.Results Normal ACL appeared as a flat band with low signal intensity on T1 and T2-weighted imaging. The injured ACL can appeared as interruption in continuation(n=5), irregular shape(n=1),abnormal direction(n=2) and increased in signal intensity(n=7).Conclusion MRI is a accurate and noninvasive diagnostic method for ACL tear.

Objective To translate Parents' Perception of Uncertainty Scale (PPUS) into Chinese,analyze and selected items,and then test the reliability and validity of the Chinese version of PPUS initially.Methods 210 parents of hospitalized children were recruited for the investigation.Frequency analysis,dispersion degree analysis,correlation analysis and so on were applied to analyze and select items.Internal consistency test,Pearson correlation analysis and exploratory factor analysis etc.were applied to test reliability and validity of the scale.Results The final Chinese version of PPUS contained 28 items.The Cronbach α and parity split-half reliability coefficients were 0.844 and 0.835; The Cronbach α coefficient of 4 dimensions ranged from 0.537 to 0.770.The item-total scale correlation coefficient ranged from 0.300 to 0.737.Item-dimension correlation coefficients ranged from 0.376 to 0.762.Item-other dimension correlation coefficients ranged from 0.028 to 0.514.Dimension-total scale correlation coefficients ranged from 0.480 to 0.863 and those between dimensions ranged from 0.226 to 0.536.In the content validity assessed by experts,I-CVI ranged from 0.75 to 1.00,S-CVI/Ave was 0.928.Four-factor model was performed in the principal component analysis and they explained for 41.401％ variances.The maximum factor loading of all items were higher than 0.3,and most of items had adequate loadings in related dimensions.Conclusions Chinese version of PPUS had appropriate reliability and validity as an assessment tool for parental uncertainty in illness of hospitalized children' parents.

Objective To observe the value of electron density map(EDM)from spectral CT combined with CT features in differentiating acute and chronic osteoporotic vertebral fractures(OVF).Methods Thoracic and/or lumbar spectral CT data of 48 patients with acute complicated chronic OVF were retrospectively analyzed.Totally 110 fractured vertebrae were enrolled,including 53 vertebrae with acute fractures(acute group)and 57 with chronic fractures(chronic group).The quantitative parameters of spectral CT,including CT values of conventional 120 kVp polyenergetic image(PI,i.e.routine CT images)and 40,70,100 keV virtual monoenergetic images(VMI),effective atomic number(Z-eff)and electron density(ED),as well as routine CT finding were compared between groups,and those being significantly different were included in multivariate logistic regression to screen the independent risk factors for acute OVF and construct a combined model.Receiver operating characteristic(ROC)curves were drawn to evaluate the efficacy of each single independent risk factor and the combination for differentiating acute and chronic OVF.Results Significant differences of all spectral CT quantitative parameters,also of routine CT findings including interruption of vertebral endplate,cortical folds,increased vertebral density,gas within vertebral body and vertebral compression degree were found between groups(all P＜0.05).Logistic regression analysis showed that CTPI(OR=0.855,P=0.005),ED(OR=16.432,P=0.005),cortical folds(OR=0.038,P=0.034)and increased vertebral density(OR=0.025,P=0.013)were all independent risk factors for acute OVF.The area under the curve(AUC)of the above single parameters for identifying acute and chronic OVF was 0.870,0.889,0.879 and 0.866,respectively,all lower than that of the combined model(0.977)(Z=3.47,3.73,2.95,2.71,all P＜0.05).Conclusion Spectral CT EDM combined with CT findings could effectively differentiate acute and chronic OVF.

Objective To investigate the relationship between the ratio of signal intensity of fluid-attenuated inversion recovery (FLAIR)sequence lesion side／contralateral side and the onset time of acute ischemic stroke. Methods Forty-three consecutive patients with acute ischemic stroke admitted to the Department of Neurology,Dongguan Hospital of Traditional Chinese Medicine from November 2016 to January 2018 were enrolled retrospectively. They were all first onset and were diagnosed by MRI,and the onset time was 0. 5 to 6. 0 h. According to the time window of effective rescue of the penumbra,43 patients were divided into a ≤4. 5 h group (n＝19)and a ＞4. 5-6. 0 h group (n＝24). The signal intensity values of FLAIR, diffusion-weighted imaging,signal intensity of apparent diffusion coefficient sequence on the lesion side and contralateral brain tissue in the two groups of patients were measured respectively,and the relative signal intensity (RSI)was calculated and compared between the two groups. Taking RSI as the dependent variable and onset time as the independent variable,a general linear regression analysis was performed. Results (1)In FLAIR sequence,the signal intensity value and RSI value of patients in the≤4. 5 h group were lower than those in the ＞4. 5-6. 0 h group. There were significant differences between the 2 groups (disease side signal intensity value:531 ± 109 vs. 681 ± 306,t ＝2. 04;RSI value:1. 19 ± 0. 13 vs. 1. 45 ± 0. 18,t＝5. 29,all P＜0. 05). There was no significant difference in the signal intensity values on the contralateral sides between the two groups (P＞0. 05). (2)In diffusion weighted imaging and apparent diffusion coefficient sequence,there were no significant differences in the signal intensity value and RSI value on the disease side and the contralateral side between the the≤4. 5 hours group and the ＞4. 5-6. 0 h group (all P＞0. 05). (3)In the FLAIR sequence,with the prolongation of the time of the disease,RSI gradually increased,and was positively correlated (r＝0. 756,P＜0. 01). Conclusions The quantitative measurement of the disease side／contralateral side of FLAIR sequence might reflect the onset time of acute ischemic stroke. Its RSI value increased with the prolonged onset time.