• 3D facial analysis shows biologic basis

    From ScienceDaily@1:317/3 to All on Friday, April 01, 2022 22:30:38
    3D facial analysis shows biologic basis for gender-affirming surgery
    Data-driven study improves guidance for adult craniofacial surgery

    Date:
    April 1, 2022
    Source:
    University of California San Francisco Medical Center
    Summary:
    Gender-affirming facial surgery (GFS) is pursued by transgender
    individuals who desire facial features that better reflect their
    gender identity. Until now, there have been few objective guidelines
    to justify and facilitate effective surgical decision-making for
    gender-affirming facial surgery. In order to validate surgical
    decisions for GFS, researchers set out to quantify the effect
    of sex on adult facial size and shape through an analysis of
    three-dimensional (3D) facial surface images.



    FULL STORY ========================================================================== Gender-affirming facial surgery (GFS) is pursued by transgender
    individuals who desire facial features that better reflect their gender identity. Until now, there have been few objective guidelines to justify
    and facilitate effective surgical decision-making for gender-affirming
    facial surgery.


    ==========================================================================
    In order to validate surgical decisions for GFS, researchers from the
    UC San Francisco and the University of Calgary set out to quantify the
    effect of sex on adult facial size and shape through an analysis of three-dimensional (3D) facial surface images.

    In a study published online Thursday afternoon in Facial Plastic Surgery
    & Aesthetic Medicine, the investigators undertook a surgically oriented analysis of 3D facial size and shape to quantify and visualize facial
    sex differences.

    Their findings reveal significant differences in both shape and size of
    male and female craniofacial features and provide data-driven anatomic
    guidance and justification for GFS, particularly for forehead contouring cranioplasty, mandible and chin alterations, rhinoplasty, and cheek modifications.

    "Our purpose was to establish an important, definitive, and
    biologically-based relationship of facial features to sex. This
    empowers the patient to navigate towards a facial appearance that
    matches with their gender identity, and thereby reduces mis-gendering
    and gender dysphoria while improving self- perception," said senior
    author Rahul Seth, MD, Associate Professor in the Facial Plastic and
    Aesthetic Surgery in the UCSF Department of Otolaryngology- Head and
    Neck Surgery. "We feel that this data provides surgeons, patients, and insurance payors with a life-like and surgically-oriented analysis of
    3D facial size and shape to guide patients and surgeons in performing
    these complex and life-altering surgeries." Brow, jaw, nose, cheek
    show biggest differences by sex The researchers were able to determine
    that, on average, male faces are 7.3% larger than female faces. Sex
    was associated with significant facial shape differences in the entire
    face as well as in each sub-region considered in the study. The facial
    regions in which sex has the largest effect on shape are the brow, jaw,
    nose, and cheek. The authors, therefore, provide supportive evidence and guidelines for the appropriate alterations of these facial areas for GFS, although each individual patient's goals and face is unique.



    ==========================================================================
    To yield these results, the researchers obtained facial measurements by applying an atlas facial surface to 3D surface scans of 545 males and
    1028 females older than 20 years of age. The differences between male
    and female faces were analyzed and visualized for a set of predefined surgically relevant facial regions.

    Each scan used a 3D surface mesh composed of 3D vertices connected
    by triangles. The triangular meshes were used to digitally represent
    surface data.

    While the exact number per face differed slightly in the raw data, each
    mesh contained 27,903 vertices to provide consistent, high-resolution
    facial data.

    Concepts central to rigorous geometric morphometrics were applied to
    the surface data to provide detailed results.

    To analyze the effects of sex on facial size and shape, a variety of
    facial sub-regions were first specified based on the potential for
    surgical application and relevance to surgical decision making and
    planning. The regions included both large area sections of the face
    (cheeks, nose) as well as axial or sagittal curves. Dense surface-based measurements and comparisons of form, size, and shape were performed
    for the whole face and facial subregions.

    The researchers represented their findings in a "heat map" to show the
    mean difference between male and female facial shape differences. Using
    this information, these changes were applied to an example face to
    demonstrate their validity to "surgically" alter the face along an axis
    of masculinity and femininity.

    While the study provides important differentiators for male and female
    facial size and shape differences, the results also suggest that in some
    cases, effective gender modification may be achieved by over-correcting
    either size or shape. For example, if functional concerns prevent a
    surgeon from reducing jaw size, it may be most ideal to contour the area
    to be less square, emphasizing a more feminine shape.

    The findings of this study provide anatomic rationale and guidance
    that may enable optimal GFS results for transgender and gender diverse individuals.

    Authors: First author is Jordan Bannister, BASc, University of Calgary, Biomedical Engineering Graduate Program. Co-Authors are Hailey
    M. Juszczak, BA, and P. Daniel Knott, MD, UCSF, Division of Facial
    Plastic and Reconstructive Surgery, Department of Otolaryngology-Head
    and Neck Surgery; J. David Aponte, MSc, David C. Katz, PhD, and Benedikt Hallgrimsson, PhD, Department of Cell Biology and Anatomy, Alberta
    Children's Hospital Research Institute, University of Calgary; Seth
    Weinberg, University of Pittsburgh, Department of Oral and Craniofacial Sciences, School of Dental Medicine; Nils D. Forkert, PhD, University of Calgary, Department of Radiology, Alberta Children's Hospital Research Institute and Hotchkiss Brain Institute, Cumming School of Medicine.

    Funding: This research was funded by the of and the National Institutes
    of Health (U01-DE024440) and the Canada Research Chairs program.

    Disclosures: Authors J.J.B., J.D.A, D.C.K., B.H., N.D.F., and R.S. are affiliated with Deep Surface AI, Inc., a company specializing in 3D
    facial analytics and morphing.


    ========================================================================== Story Source: Materials provided by University_of_California_San_Francisco_Medical_Center.

    Original written by Melinda Krigel. Note: Content may be edited for
    style and length.


    ========================================================================== Journal Reference:
    1. Jordan J. Bannister, Hailey Juszczak, Jose David Aponte, David
    C. Katz,
    P. Daniel Knott, Seth M. Weinberg, Benedikt Hallgri'msson, Nils D.

    Forkert, Rahul Seth. Sex Differences in Adult Facial
    Three-Dimensional Morphology: Application to Gender-Affirming
    Facial Surgery. Facial Plastic Surgery & Aesthetic Medicine, 2022;
    DOI: 10.1089/fpsam.2021.0301 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220401094900.htm

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