title: Validation of airway wall measurements by optical coherence tomography in porcine airways.
abstract: Examining and quantifying changes in airway morphology is critical for studying longitudinal pathogenesis and interventions in diseases such as chronic obstructive pulmonary disease and asthma. Here we present fiber-optic optical coherence tomography (OCT) as a nondestructive technique to precisely and accurately measure the 2-dimensional cross-sectional areas of airway wall substructure divided into the mucosa (WAmuc), submucosa (WAsub), cartilage (WAcart), and the airway total wall area (WAt). Porcine lung airway specimens were dissected from freshly resected lung lobes (N = 10). Three-dimensional OCT imaging using a fiber-optic rotary-pullback probe was performed immediately on airways greater than 0.9 mm in diameter on the fresh airway specimens and subsequently on the same specimens post-formalin-fixation. The fixed specimens were serially sectioned and stained with H&E. OCT images carefully matched to selected sections stained with Movat's pentachrome demonstrated that OCT effectively identifies airway epithelium, lamina propria, and cartilage. Selected H&E sections were digitally scanned and airway total wall areas were measured. Traced measurements of WAmuc, WAsub, WAcart, and WAt from OCT images of fresh specimens by two independent observers found there were no significant differences (p>0.05) between the observer's measurements. The same wall area measurements from OCT images of formalin-fixed specimens found no significant differences for WAsub, WAcart and WAt, and a small but significant difference for WAmuc. Bland-Altman analysis indicated there were negligible biases between the observers for OCT wall area measurements in both fresh and formalin-fixed specimens. Bland-Altman analysis also indicated there was negligible bias between histology and OCT wall area measurements for both fresh and formalin-fixed specimens. We believe this study sets the groundwork for quantitatively monitoring pathogenesis and interventions in the airways using OCT.
authors.affiliation: Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada.
authors.forename: Anthony M D
authors.initials: AM
authors.lastname: Lee
authors.affiliation: Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Miranda
authors.initials: M
authors.lastname: Kirby
authors.affiliation: Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada.
authors.forename: Keishi
authors.initials: K
authors.lastname: Ohtani
authors.affiliation: Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Tara
authors.initials: T
authors.lastname: Candido
authors.affiliation: Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Shalansky
authors.affiliation: Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada.
authors.forename: Calum
authors.initials: C
authors.lastname: MacAulay
authors.affiliation: Department of Pathology, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: John
authors.initials: J
authors.lastname: English
authors.affiliation: Department of Surgery, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Finley
authors.affiliation: Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Lam
authors.affiliation: Department of Radiology, Vancouver General Hospital, Vancouver, British Columbia, Canada.
authors.forename: Harvey O
authors.initials: HO
authors.lastname: Coxson
authors.affiliation: Department of Integrative Oncology - Imaging Unit, British Columbia Cancer Agency Research Centre, Vancouver, British Columbia, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Lane
mesh_terms: D000818:Animals; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000166:cytology*; D015588:Observer Variation; D055100:Optical Fibers; D013552:Swine; D013556:Swine, Miniature; D041623:Tomography, Optical Coherence / Q000295:instrumentation / Q000379:methods*