Digital facial models created from 3D scans could give doctors a new diagnostic tool for identifying children with fetal alcohol spectrum disorders, according to a study published in the October issue of Alcoholism: Clinical & Experimental Research.
“There’s really a need to make the diagnosis more objectified,” said Elizabeth Moore, PhD, a research scientist at St. Vincent Hospital in Indianapolis and lead author of the study.
Moore said that dysmorphologists look for a signature combination of features that include small eye openings, a thin upper lip, and a smooth area between the lips and nose that, together, indicate an abnormality—an approach that doesn’t work well for all patients.
To improve diagnosis, Moore and her colleagues recruited a total of 276 subjects from Cape Town, South Africa; Helsinki, Finland; Buffalo, N.Y.; and San Diego, Calif., and completed a detailed dysmorphology evaluation to classify subjects as either fetal alcohol syndrome (FAS) (43 percent) or control (57 percent). Computerized anthropometry was employed to identify facial features that could distinguish FAS patients from controls across a wide age range and across ethnically disparate study populations.
Using a portable, commercial 3D laser scanner, researchers took six images of each child, two from the front, and two from each side. The scanner captured depth data accurate to less than a millimeter by scanning a low-intensity laser line over the face while simultaneously capturing a low-resolution color picture. A camera in the scanner measured the time it takes the laser pulses to reflect back from the face. By combining this information with the known distance between the laser source and the camera, the software calculated the 3D coordinates for each point on the face and then overlaid the color data. Moore and her team combined three of these 3D perspectives together to form one complete model.
Moore then examined each model and marked the location of 20 facial landmarks, such as the corners of the eyes. Customized software then measured 16 different distances between the various landmarks and found that the best indicators of alcohol exposure varied by ethnicity.
According to the results, researchers were able to identify “a unique set of variables which provided excellent discrimination between the two groups (FAS, control). In each study group, at least one ocular-related measurement, shortened palpebral fissure, reduced outer canthal width, or reduced inner canthal width, was included in the final classification model.”
Moore said that she found measurements that reflected reduced size of the orbit are a consistent feature discriminating FAS and controls across each study population. However, each population had a unique, though often overlapping, set of variables which discriminated the two groups, suggesting important ethnic differences in the presentation of FAS. “It is possible that these differences were accentuated by the wide age distribution of the study subjects,” Moore said.
Moore said her team plans to use the scanner on infants next, an important step in catching the disorder early.