Three-dimensional facial scanner in the hands of patients: validation of a novel application on iPad/iPhone for three-dimensional imaging

Abstract

Background: Three-dimensional (3D) photography plays an important role in surgical planning and postoperative evaluation. Commercial 3D facial scanners are expensive, and they require patients to come to the clinics for 3D photography. To solve this problem, we developed an iPad/iPhone application to enable patients to capture 3D images of themselves on their own. This study aimed to evaluate the validity and reproducibility of this novel imaging system. Methods: 3D images were taken on 20 volunteers using the novel imaging system. Twenty-one anthropometric parameters were measured using calipers (direct measurement) and 3D photographs (3D photogrammetry). The results were compared to assess the accuracy and bias of 3D photogrammetry. The reproducibility was evaluated by testing intra-and interobserver reliabilities. Furthermore, 3D virtual models obtained by the novel imaging system and Vectra H1 camera were compared by performing heat map analysis. Results: The 3D photogrammetric results showed excellent correlations with direct measurements. Most anthropometric parameters did not show statistically significant differences between the two methods. The 95% limits of agreement exceeded 2 mm in some parameters, especially those with large numbers, although their relative error measurements were very small. Intra-and interobserver reliabilities were high enough to ensure good reproducibility. The comparison of 3D models obtained by the novel imaging system and Vectra H1 camera showed that the mean distance and the mean RMS were 0.08 and 0.67 mm, respectively. Conclusions: The novel 3D facial scanning system is validated to enable patients to take 3D images on their own. The imaging quality of the subnasale region needs further improvement. Future clinical applications include surgical planning, postoperative evaluation, and early diagnosis of diseases that affect facial appearance.

Facial Scanning Accuracy with Stereophotogrammetry and Smartphone Technology in Children: A Systematic Review

“…Table 2 shows the risk of bias and application concerns according to the QUADAS-2 guidelines. Among 23 articles [ 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ], 14 papers showed an overall low risk of bias [ 40 , 41 , 43 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 53 , 56 , 59 , 60 , 61 ], 3 articles had unclear risk of bias [ 39 , 44 , 52 , 57 ] and 4 articles displayed a high risk of bias [ 42 , 54 , 55 , 58 ]. Concerning applicability concerns, all articles showed an overall low level of concern, however, the domain “index test” showed more frequently an unclear concern because some papers did not sufficiently describe the scanning procedures and the used devices [ 40 ,…”

The iPad/iPhone 3D photography app—a promising device, but how about its accuracy?

“…Thirdly, the anthropometric landmarks in this study involved the entire facial region, including the periorbital, the nasal, and the orolabial region (1). Except for some landmarks in the periorbital and nasal regions, most landmarks did not differ significantly between iPad/ iPhone 3D photography app and calipers used in this study.…”

“…With great interest, we read the article entitled "Threedimensional facial scanner in the hands of patients: validation of a novel application on iPad/iPhone for three-dimensional imaging" by our highly appreciated colleagues Yuming Chong, Xinyu Liu, Mai Shi, Jiuzuo Huang, Nanze Yu, and Xiao Long (1).…”

Reply to letter to the editor: “The iPad/iPhone 3D photography app—a promising device, but how about its accuracy?”

“…We are happy to find your readers showed interest in our previous work entitled "Three-dimensional facial scanner in the hands of patients: validation of a novel application on iPad/iPhone for three-dimensional imaging" and left some valuable comments about it in a letter (1,2). By writing this response letter, the authors would like to thank them for their interest and discuss some important points they raised in their letter.…”

“…Thirdly, the validation study aimed to test the accuracy of this novel imaging system in the entire face (1). There were two standards in choosing parameters.…”