Quantitative Evaluation Of Rejuvenation Treatment Of Nasolabial Fold Wrinkles By Regression Model And 3D Photography

Background and objectives:Nasolabial fold wrinkles are remarkable signs of facial skin aging.The qualitative evaluation of nasolabial wrinkle is now very prevalent but is subject to subjective and environmental factors.The evaluation of nasolabial rejuvenation is mainly performed by an improvement of wrinkle grading or an decrease of a quantitative parameter,but there doesn't exist a method which evaluates the wrinkle improvement in terms of age.With the help of 3D photography,this experiment aims at quantifying parameters of static nasolabial wrinkles and at establishing a mathematic regression model between wrinkle parameters and age,in order to evaluate quantitatively the wrinkle improvement after rejuvenation treatment in terms of age.ObjectsDuring the establishment of the nasolabial fold wrinkle-age model,433 Chinese female volunteers,aged between 25 and 60 years,were recruited at the Peking Union Medical College Hospital from October 2016 to May 2018;at the application stage of the model,the study included 10 patients,recruited at Peking Union Medical College Hospital from December 2017 to February 2018 and aged 32 to 59 years,who accepted to receive bilateral nasolabial polylactic acid injection.Methods1.At the establishment stage of the model,eight parameters of static nasolabial wrinkles on the left and right sides of the volunteers were collected using Antera 3D camera:overall size,average depth(mm),average width(mm),maximum depth(mm),average concentration of hemoglobin its relative variation,average concentration of melanin and its relative variation.The data were plotted to see if there was a linear relationship with age.For those which presented a linear relationship with age,one-dimensional linear regression fitting was performed with the help of SPSS 24(for MAC)and Excel,followed by residual analysis,goodness-of-fit test,and significance test.Then we used the recursive cycle method in RStudio 3.3.3 to perform a segment fitting,in order to find age interval or age cutoff point with the fastest parameter change.For data presenting no linear correlation with age,we tried to explore a meaningful average or extremum,and we used an independent sample t-test to compare the difference between the left and right nasolabial folds.The test level was 0.05,and P<0.05 was considered statistically significant.2.At the application stage of the model,three injections of poly-lactic acid nasolabial folds were performed on each volunteer on the first,3rd,and 6th week.The eight parameters were measured using an Antera 3D camera before and one hour after the first week injection and at the 16th week.The data of the same volunteers before and after rejuvenation treatment were paired samples.Data were processed using SPSS 24(for MAC),Excel.Paired t-test was used to compare data before and after rejuvenation treatment.The significance test level remained the same as mentioned above.Then,the nasolabial wrinkle data before and after the rejuvenation treatment were brought into the established fitting equations,and the mearsurement of the rejuvenation level should be performed in terms of age change.Results1.There is a clear linear relationship between the maximum depth y,(mm),average depth y2(mm),overall size y3 of nasolabial fold wrinkles and age(age).The regression equations are:y1=?0+?1x,with ?0=-0.0668±0.0271,?1=0,00636±0.00062,R2 = 0.926 y2=?0+?1x,with ?0=-0.0421±0.0194,?1= 0.00366±0.00044,R2 = 0.889 y3=?0+?1x,with ?0=-23.803±12.115,?1=2.17810.977,R2=0.879The significance test of regression coefficients is less than 0.0001.2.In the 46 to 50-year-old age range,the increase of maximum depth of nasolabial fold wrinkles is the fastest,and significantly higher than other age ranges.3.There is no linear relationship between the following nasolabial wrinkle parameters and the age:the average concentration of hemoglobin and its relative variation,the average concentration of melanin and its relative variation.4.In the nasolabial wrinkle area,The average concentration of hemoglobin is 1.021±0.0065,and the average concentration of melanin is 0.624±0.0842.5.There is a significant difference in the relative variation of hemoglobin concentration in the nasolabial wrinkles area of the left and right sides(P = 0.012);the degree of variation in the left side was 15%higher than that in the right side;there was no significant difference in the relative variation of the melanin concentration in the wrinkles of the left and right nasolabial folds,and the variation is 5.625±1.551%.6.According to the regression model,after 1 hour of polylactic acid filling treatment at the first week,the nasolabial fold wrinkles are 11.4 years younger;at the 16th week,the nasolabial fold wrinkle are 6.2 years years.Conclusions1.Among the three parameters of nasolabial fold wrinkles,the maximum depth of wrinkle has the best fitting relationship with age.Then comes the average depth followed by the overall size.2.From 46 to 50 years old,women's facial aging rate is accelerated,thus a rejuvenation treatment intervention is necessary.3.The average concentrations and relative variation of hemoglobin and melanin in nasolabial wrinkles can not directly reflect the degree of facial aging,nor can they be directly used for the evaluation of facial rejuvenation treatment effect.4.The polylactic acid filling treatment has a certain effect on improving the maximum depth,average depth and overall size of nasolabial wrinkles.However,future studies will need to further explore the treatment curse and duration of effective time.5.With the regression model between nasolabial fold wrinkle and age,the effect of rejuvenation treatment can be quantitatively evaluated in terms of age,which has certain reference and promotion value.Future research can establish models for different groups of people,further reducing errors,increasing sample homogeneity in order to obtain better predictions and assessments.