Measuring facial symmetry in cleft lip kids and everyday people.

How the heck did Dr. Coe manage to visualize the tangle of my oral tissue and muscle when he sewed me—Humpty Dumpty— back together?  As I wrote in my memoir, Cleft Heart: chasing normal,
 
           “With final form and functionality in mind, Dr. Coe set about joining the two sides of my face. The union had to be exactly right so that when the scars contracted, they would   not notch the red vermillion of my lip or distort the area between my lip and nose. …All this had to be figured out fast, as tissues begin to swell and discolor the moment they are cut.” (p.24)

 Well, Dr. Coe had some 30 years of surgical experience under his belt. He’d learned through trial and error, but he also had keen powers of observation. 

Facial measured the hi-tech way.

[According to a National Institutes of Health report], the use of 3D surface imaging technology is becoming increasingly common in craniofacial clinics and research centers into genetics and dysmorphology.*

Due to fast capture speeds and ease of use, 3D digital stereophotogrammetry is quickly becoming the preferred facial surface imaging modality. These systems can serve as an unparalleled tool for craniofacial surgeons, proving an objective digital archive of the patient’s face without exposure to radiation.

3 bust shots of young black man, an example of 3-D scans of facial symmetry,

Example of 3-D scan images of .

Methods that allow for the objective assessment of facial form are becoming increasingly important for research in dysmorphology, genetics, orthodontics and surgical disciplines among others. As will be noted below, such methods also have the potential to enhance clinical care by facilitating surgical planning, improving outcome assessment, and aiding in syndrome delineation.

Stereophotogrammetry (fancy word for 3D imaging).

As you may’ve noticed if you’ve had a tooth crowned or replaced lately, non-contact 3D surface imaging systems are rapidly replacing traditional “hands-on” anthropometry as the preferred method for capturing quantitative information about the facial soft-tissues . These systems offer a number of distinct advantages: minimal invasiveness, quick capture speeds (tho my last bridge took :20 to capture), and the ability to archive images for subsequent analyses

Infants and young kids with cleft lip.

The safety, speed and reliability of data acquisition that these systems offer are particularly helpful when working with infants and young children, for whom quantification of facial features can be challenging. Regarding kids (infants can be held), it is essential to provide them and their parents with a safe route to the seating area so that they do not disrupt the many wires to the scanning pod. It is best to ask the parents to hold kids till they are securely placed in the pod chair.

Figure 7
 Smiles and other facial expressions may alter the position of landmarks and affect the reliability of facial measurements. Older children can follow instructions to keep neutral, relaxed face, with the mouth shut and lips gently touching. It may also help to ask them to swallow and relax. Younger children often require distraction devices to focus their attention in the preferred direction.

Future challenges for repair.

A recent study in the Cleft Palate Craniofacial Journal suggests there’s still a role for human discernment in cleft lip repair. Newbie reconstructive surgeons shouldn’t rely too much on 3D imaging. I’ve summarized the the article below. 
 
Objective:

Quantitative measures of facial form to evaluate treatment outcomes for cleft lip (cl) are currently limited. Computer-based analysis of three-dimensional (3D) images provides an opportunity for efficient and objective analysis. The purpose of this study was to define a computer-based standard of identifying the 3D mid-facial reference plane of the face in children with unrepaired cleft lip for measurement of facial symmetry.

 

Participants:

The 3D images of 50 subjects (35 with unilateral cl, 10 with bilateral cl, five controls) were included in this study.

 

Interventions:

Five methods of defining a mid-facial plane were applied to each image, including two human-based (direct placement, manual landmark) and three computer-based (mirror, Deformation, learning) methods.

 

Main outcome measure:

Six blinded raters (threes cleft surgeons, two craniofacial pediatricians, and one craniofacial researcher) independently ranked and rated the accuracy of the defined planes.

 

Results: 

Among computer-based methods, the Deformation method performed significantly better than the others. Although human-based methods performed best, there was no significant difference compared with the Deformation method.

The average correlation coefficient among raters was .4; however, it was .7 and .9 when the angular difference between planes was greater than 6° and 8°, respectively.

Raters can agree on the 3D mid-facial reference plane in children with unrepaired CL using digital surface mesh. The Deformation method performed best among computer-based methods evaluated and can be considered a useful tool to carry out automated measurements of facial symmetry in children with unrepaired cleft lip.

3 pics of an infant's facial symmetry. An Example of a 2D screen capture of a 3D facial surface  image.

Example of a 2D screen capture of a 3D facial symmetry image.

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* The study of human congenital malformations (birth defects), particularly those affecting the anatomy (morphology) of an individual.