title: In vivo optical imaging of human vaginal gel thickness distributions with a probe-based, dual-modality instrument.
abstract: ABSTRACT. We used a probe-based dual-modality optical imaging instrument to measure in vivo coating thickness distributions of a gel distributed along the vaginal lumen, in a clinical study. The gel was a surrogate for one delivering an anti-HIV topical microbicide. Imaging data from Fourier-domain multiplexed low-coherence interferometry (mLCI) and fluorimetric measurements were compared to assess the feasibility and accuracy of mLCI in measuring in vivo gel coating thickness distributions. In each study session, 3.5 mL of Replens gel was inserted to the vaginal fornix while the participant was supine. The participant either: 1. remained supine (10 or 60 min); or 2. sat up (1 min), stood up (1 min), sat down (1 min) and returned to the supine position; net elapsed time was 10 or 60 min after which the gel distribution was imaged. Local coating thickness distributions were qualitatively and quantitatively similar. Here mLCI did not accurately measure thicker gel coatings (&gt;0.8  mm), a limitation not seen with fluorimetry. However, mLCI is capable of measuring in vivo microbicide gel distributions with resolution on the order of 10 μm, without the need for exogenous contrast agents, and can accurately capture relevant summary coating measures in good agreement with fluorimetry.
authors.affiliation: Duke University, Department of Biomedical Engineering, Durham, North Carolina 27708, USA.
authors.forename: Tyler K
authors.initials: TK
authors.lastname: Drake
authors.forename: Michael G
authors.initials: MG
authors.lastname: DeSoto
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Peters
authors.forename: Marcus H
authors.initials: MH
authors.lastname: Henderson
authors.forename: Bonnie
authors.initials: B
authors.lastname: Thiele
authors.forename: Tammy Sinclair
authors.initials: TS
authors.lastname: Bishop
authors.forename: Amy P
authors.initials: AP
authors.lastname: Murtha
authors.forename: David F
authors.initials: DF
authors.lastname: Katz
authors.forename: Adam
authors.initials: A
authors.lastname: Wax
mesh_terms: D000293:Adolescent; D000328:Adult; D000891:Anti-Infective Agents, Local / Q000008:administration & dosage / Q000032:analysis; D004867:Equipment Design; D005260:Female; D019793:Fluorescein / Q000008:administration & dosage / Q000032:analysis; D005470:Fluorometry / Q000295:instrumentation*; D005782:Gels; D006801:Humans; D007368:Interferometry / Q000295:instrumentation*; D008055:Lipids / Q000008:administration & dosage / Q000032:analysis; D008875:Middle Aged; D055620:Optical Phenomena; D016683:Supine Position; D014622:Vaginal Creams, Foams, and Jellies / Q000008:administration & dosage* / Q000032:analysis*; D055815:Young Adult
chemical_list: D000891:Anti-Infective Agents, Local; D005782:Gels; D008055:Lipids; C085472:Replens; D014622:Vaginal Creams, Foams, and Jellies; D019793:Fluorescein