RESUMO
Objective:To assess the value of the parotid fat fraction (FF) and T 2 relaxation time (T 2 value) in the evaluation of early parotid involvment in patients with primary Sj?gren′s syndrome (pSS) using multi-echo Dixon technique and T 2 mapping imaging. Methods:From December 2018 to December 2019, 26 early pSS patients (pSS group) and 20 healthy controls (control group), matched to age and gender, were enrolled at the First Affiliated Hospital of Zhengzhou University in this prospectively study. All subjects underwent conventional MRI, DWI, multi-echo Dixon and T 2 mapping sequences before treatment. The ADC, FF and T 2 value of bilateral parotid parenchyma in pSS group and control group were measured respectively. Paired sample t test was used to compare the differences of ADC, FF and T 2 values between left and right parotid glands for pSS group and control group, while independent sample t test was used to compare the differences of ADC, FF and T 2 values between pSS group and control group. The ROC curves were drawn to evaluate diagnostic performance of ADC, FF and T 2 values to distinguish early pSS, and the difference of diagnostic efficacy of each parameter was compared by Delong test. Binary logistic regression analysis and ROC curve were used to evaluate the diagnostic performance of the combination of the 3 parameters in early pSS. Results:There were no significant differences of ADC, FF and T 2 values between left and right parotid glands for pSS group and control group (all P>0.05). The parotid ADC values were significantly lower in pSS group than control group ( t=4.641, P=0.006), while the FF and T 2 values of pSS group were significantly higher than those of control group ( t=-2.910, -6.411, both P<0.001). The areas under the ROC curve of ADC, FF and T 2 values to distinguish early pSS were 0.666, 0.750 and 0.862, respectively. The area under ROC curve of the combination of ADC, FF and T 2 values was 0.930, with a sensitivity of 73.1% and a specificity of 97.5%. T 2 values showed a better diagnostic efficacy than ADC values ( Z=2.626, P=0.009) and FF values ( Z=2.112, P=0.035) when distinguishing pSS group from control group. The area under ROC curve of the combination of ADC, FF and T 2 values showed a better diagnostic efficacy than each parameter alone ( Z=4.869, P<0.001, Z=3.628, P<0.001, Z=2.162, P=0.031). Conclusions:Multi-echo Dixon technique and T 2 mapping can quantitatively evaluate the parotid gland fat deposition and inflammatory response in the early stage of pSS. T 2 value has great potential in evaluating early parotid gland injury of pSS, and the combination of ADC, FF and T 2 values can further improve the diagnostic efficiency.
RESUMO
Objective To investigate the value of ADC histogram in the differential diagnosis of angiomatous meningioma (AM) and hemangiopericytoma (HPC)and to screen out the best diagnostic parameter.Methods The MRI data of 21 cases with AM and 22 cases with HPC confirmed by surgical pathology were analyzed retrospectively.The ROI were drawn on the maximum cross section of the tumor on ADC maps,and the ADC histogram analysis was performed using the software named Mazda.Then the histogram parameters were statistically analyzed to find out the statistically significant parameters between the two groups,and the ROC curve was drawn to evaluate their diagnostic efficacy.Results ADCvariance ,ADC1th and ADC10th had statistical significances between the two groups (P＝0.030,0.002 and 0.02 1 ). ADC1th had the best diagnostic efficacy among them,with the optimal cut-off value of 0.086×10－3 mm2/s,the AUC was 0.814(P＝0.003),and the sensitivity and specificity were 86.70%and 64.70%,respectively.ADCvariance took the second place,for the AUC was 0.725 (P＝0.030),and the sensitivity and specificity were 7 6.50%and 80.00%,respectively.Conclusion The ADC histogram is of great value in the differential diagnosis of AM and HPC,and the ADC1th is the most effective parameter.