Objective To investigate the reliability of cast measurements by comparing Photoshop and conventional hand-held method. Methods Maxillary standard plaster models from 10 orthodontic cases with crowding were enrolled in this study. The space available and the space required of anterior region were measured by using Photoshop in the digital pictures or conventional method used by 5 observers respectively.The measurement results of the same sample among every observer were analyzed with ANOVA, and the difference between the 2 methods was calculated and paired t test was used to analyze the data. Results The repeatability of measurement results was not good when the space available was measured with conven-tional method by different observer( M1 ～ M5 ), and the measurement results of M1 were significantly different from that of M3 and M5 respectively( P ＜ 0.05 ). The repeatability of measurement results was relatively good when the space available was measured by using Photoshop, and the measurement results of M5 were significantly different from other observers ( P ＜ 0.05 ). The measurement results of space required measured by different observer were very close, and the reproducibility was excellent when they were measured by means of Photoshop or conventional methods. Conclusion There were no much difference between Photoshop and conventional method to measure the required space. Photoshop had significant advantage over conventional method when available sRace was measured.

Objective:To explore the value of nomogram based on arterial spin labeling (ASL) MRI perfusion parameters and clinicopathological features in predicting the response to chemoradiotherapy (CRT) in advanced nasopharyngeal carcinoma (ANPC, stage Ⅲ and Ⅳ).Methods:From June 2018 to January 2021, 70 patients with ANPC confirmed by pathology were prospectively enrolled in Affiliated Hospital of Jiangnan University. Nasopharyngeal MRI plain scan, ASL and contrast-enhanced scan were performed before CRT, and routine MRI re-examination was performed within 1 week after the end of CRT. The pre-CRT perfusion parameter tumor blood flow (TBF) from ASL and clinicopathological features were recorded, and the maximum diameter (MD) of the tumor on T 1WI images was measured. The patients were divided into CRT effective group (48 cases) and ineffective group (22 cases) according to the response evaluation criteria in solid tumors. The independent sample t test was used to compare the differences of TBF, age and MD between effective group and ineffective group. The χ 2 test was used to compare the differences of gender, clinical stage and pathological type between the 2 groups. Using binary logistic regression analysis, clinicopathological model and TBF combined clinicopathological model were constructed, and the nomogram of combined model was constructed. The diagnostic efficacy of the models was obtained by receiver operating characteristic (ROC) curve analysis, and the area under the ROC curves (AUC) of the 3 models were compared by DeLong method. The calibration curve for the nomogram was generated, and the concordance index (C index) was acquired. Results:The TBF of the effective group and the ineffective group were (113±9) and (97±14) ml·100 g -1·min -1, with a statistical difference ( t=5.17, P<0.001). The MD value of the effective group was smaller than that of the ineffective group, with a statistical difference ( t=-2.24, P=0.028). There were statistical differences in clinical stage and pathological type between the 2 groups (χ 2 values were 12.21 and 12.95, respectively, both P<0.001). Three independent predictors, including TBF (OR=7.749), clinical stage (OR=0.129) and pathological type (OR=5.228), were included in logistic regression analysis. The AUC, sensitivity and specificity of TBF model in predicting the response to CRT were 0.843, 87.5% and 72.7%, of clinicopathological model were 0.822, 80.2% and 59.1%, of the nomogram model were 0.893, 81.2% and 90.9%. There was no statistical difference of AUC between the nomogram model and TBF model ( Z=1.23, P=0.215). However, the AUC of the nomogram model was greater than that of the clinicopathological model ( Z=2.47, P=0.031). The calibration curve showed that there was a good concordance index (C index=0.892) between the predicted value of nomogram and the actual clinical observation value. Conclusion:TBF, clinical stage and pathological type are independent predictors of the response to CRT in ANPC patients, and the nomogram based on these three factors has a good ability in predicting the response to CRT.