title: Non-invasive terahertz imaging of tissue water content for flap viability assessment.
abstract: Accurate and early prediction of tissue viability is the most significant determinant of tissue flap survival in reconstructive surgery. Perturbation in tissue water content (TWC) is a generic component of the tissue response to such surgeries, and, therefore, may be an important diagnostic target for assessing the extent of flap viabilityin vivo. We have previously shown that reflective terahertz (THz) imaging, a non-ionizing technique, can generate spatially resolved maps of TWC in superficial soft tissues, such as cornea and wounds, on the order of minutes. Herein, we report the firstin vivopilot study to investigate the utility of reflective THz TWC imaging for early assessment of skin flap viability. We obtained longitudinal visible and reflective THz imagery comparing 3 bipedicled flaps (i.e. survival model) and 3 fully excised flaps (i.e. failure model) in the dorsal skin of rats over a postoperative period of 7 days. While visual differences between both models manifested 48 hr after surgery, statistically significant (p <0.05, independentt-test) local differences in TWC contrast were evident in THz flap image sets as early as 24 hr. Excised flaps, histologically confirmed as necrotic, demonstrated a significant, yet localized, reduction in TWC in the flap region compared to non-traumatized skin. In contrast, bipedicled flaps, histologically verified as viable, displayed mostly uniform, unperturbed TWC across the flap tissue. These results indicate the practical potential of THz TWC sensing to accurately predict flap failure 24 hours earlier than clinical examination.
authors.affiliation: Department of Bioengineering, University of Los Angeles, California (UCLA), 410 Westwood Plaza, Los Angeles, CA 90025, USA.
authors.forename: Neha
authors.initials: N
authors.lastname: Bajwa
authors.affiliation: Department of Head and Neck Surgery, UCLA, 200 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Au
authors.affiliation: Department of Plastic Surgery, UCLA, California, 200 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Jarrahy
authors.affiliation: Department of Electrical Engineering, UCLA, 410 Westwood Plaza, Los Angeles, CA 90025, USA.
authors.forename: Shijun
authors.initials: S
authors.lastname: Sung
authors.affiliation: Department of Pathology and Laboratory Medicine, UCLA, 200 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Fishbein
authors.affiliation: Department of Bioengineering, University of Los Angeles, California (UCLA), 410 Westwood Plaza, Los Angeles, CA 90025, USA.
authors.forename: David
authors.initials: D
authors.lastname: Riopelle
authors.affiliation: Department of Bioengineering, University of Los Angeles, California (UCLA), 410 Westwood Plaza, Los Angeles, CA 90025, USA; Department of Radiological Sciences, UCLA, 300 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Ennis
authors.affiliation: Department of Head and Neck Surgery, UCLA, 200 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Tara
authors.initials: T
authors.lastname: Aghaloo
authors.affiliation: Department of Head and Neck Surgery, UCLA, 200 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Maie A
authors.initials: MA
authors.lastname: St John
authors.affiliation: Department of Bioengineering, University of Los Angeles, California (UCLA), 410 Westwood Plaza, Los Angeles, CA 90025, USA; Department of Electrical Engineering, UCLA, 410 Westwood Plaza, Los Angeles, CA 90025, USA; Department of Surgery, UCLA, California, 200 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Warren S
authors.initials: WS
authors.lastname: Grundfest
authors.affiliation: Department of Electrical Engineering, UCLA, 410 Westwood Plaza, Los Angeles, CA 90025, USA; Department of Surgery, UCLA, California, 200 Medical Plaza, Los Angeles, CA 90025, USA.
authors.forename: Zachary D
authors.initials: ZD
authors.lastname: Taylor
keywords: (110.0110) Imaging systems; (170.0170) Medical optics and biotechnology; (170.6795) Terahertz imaging