1. Articles from Geoffrey Hohert

    1-11 of 11
    1. Airway luminal area and the resistive work of breathing during exercise in healthy young females and males

      Airway luminal area and the resistive work of breathing during exercise in healthy young females and males

      We examined the relationship between the work of breathing (W b ) during exercise and in vivo measures of airway size in healthy females and males. We hypothesized that sex-differences in airway luminal area (Ai) would explain the larger resistive W b during exercise in females. Healthy participants (n=11 females and n=11 males; 19-30 y) completed a cycle exercise test to exhaustion where W b was assessed using an esophageal balloon catheter. On a separate day, participants underwent a bronchoscopy procedure for optical coherence tomography measures of airways in the left (n=3) and right (n=4) lung. In ...

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    2. Small airway dilation measured by endoscopic optical coherence tomography correlates with chronic lung allograft dysfunction

      Small airway dilation measured by endoscopic optical coherence tomography correlates with chronic lung allograft dysfunction

      Significance: Chronic lung allograft dysfunction (CLAD) is the leading cause of death in transplant patients who survive past the first year post-transplant. Current diagnosis is based on sustained decline in lung function; there is a need for tools that can identify CLAD onset. Aim: Endoscopic optical coherence tomography (OCT) can visualize structural changes in the small airways, which are of interest in CLAD progression. We aim to identify OCT features in the small airways of lung allografts that correlate with CLAD status. Approach: Imaging was conducted with an endoscopic rotary pullback OCT catheter during routine bronchoscopy procedures (n = 54), collecting ...

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    3. Higher-Order Core-Like Modes in Double-Clad Fiber Contribute to Multipath Artifacts in Optical Coherence Tomography

      Higher-Order Core-Like Modes in Double-Clad Fiber Contribute to Multipath Artifacts in Optical Coherence Tomography

      Double-clad fiber (DCF) has enabled the combination of endoscopic optical coherence tomography (OCT) with secondary optical modalities. While DCF offers an additional optical channel, it is widely understood that its use reduces the quality of OCT owing to the introduction of multipath artifacts. We show here that an unexpected higher-order mode (HOM) with its energy confined to the DCF core can contribute to these artifacts. The existence of this HOM is confirmed using the spatially and spectrally (S2) resolved imaging method. The group delay difference of the HOM is shown to be consistent with the delay of the diffuse ghost ...

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    4. Feasibility of combined optical coherence tomography and autofluorescence imaging for visualization of needle biopsy placement

      Feasibility of combined optical coherence tomography and autofluorescence imaging for visualization of needle biopsy placement

      Significance: Diagnosis of suspicious lung nodules requires precise collection of relevant biopsies for histopathological analysis. Using optical coherence tomography and autofluorescence imaging (OCT-AFI) to improve diagnostic yield in parts of the lung inaccessible to larger imaging methods may allow for reducing complications related to the alternative of computed tomography-guided biopsy. Aim: Feasibility of OCT-AFI combined with a commercially available lung biopsy needle was demonstrated for visualization of needle puncture sites in airways with diameters as small as 1.9 mm. Approach: A miniaturized OCT-AFI imaging stylet was developed to be inserted through an 18G biopsy needle. We present design considerations ...

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    5. Small airway dilation visualized by optical coherence tomography (OCT) correlates with the diagnosis of chronic lung allograft dysfunction (CLAD)

      Small airway dilation visualized by optical coherence tomography (OCT) correlates with the diagnosis of chronic lung allograft dysfunction (CLAD)

      Background: Small airways and the surrounding tissue of the lung allograft are often affected by pathological processes including acute cellular rejection (ACR), infections and different phenotypes of CLAD. OCT with superior resolution but shallow penetration, allows the visualization of these structures in contrast to routine radiographic imaging. Methods: We studied 54 lung transplant (LTx) recipients with OCT imaging during surveillance (n=36) or event (n=19) bronchoscopies. Volumetric images of 3 segmental airways were collected from each patient. OCT features were scored by 4 raters blinded to the clinical status of LTx recipients. Pearson correlation coefficients (R) were used to ...

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    6. Submillimeter diameter rotary-pullback fiber-optic endoscope for narrowband red-green-blue reflectance, optical coherence tomography, and autofluorescence in vivo imaging

      Submillimeter diameter rotary-pullback fiber-optic endoscope for narrowband red-green-blue reflectance, optical coherence tomography, and autofluorescence in vivo imaging

      A fiber-based endoscopic imaging system combining narrowband red-green-blue (RGB) reflectance with optical coherence tomography (OCT) and autofluorescence imaging (AFI) has been developed. The system uses a submillimeter diameter rotary-pullback double-clad fiber imaging catheter for sample illumination and detection. The imaging capabilities of each modality are presented and demonstrated with images of a multicolored card, fingerprints, and tongue mucosa. Broadband imaging, which was done to compare with narrowband sources, revealed better contrast but worse color consistency compared with narrowband RGB reflectance. The measured resolution of the endoscopic system is 25  μm in both the rotary direction and the pullback direction. OCT ...

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    7. Correction of motion artifacts in endoscopic optical coherence tomography and autofluorescence images based on azimuthal en face image registration

      Correction of motion artifacts in endoscopic optical coherence tomography and autofluorescence images based on azimuthal en face image registration

      We present a method for the correction of motion artifacts present in two- and three-dimensional in vivoendoscopic images produced by rotary-pullback catheters. This method can correct for cardiac/breathing-based motion artifacts and catheter-based motion artifacts such as nonuniform rotational distortion (NURD). This method assumes that en face tissue imaging contains slowly varying structures that are roughly parallel to the pullback axis. The method reduces motion artifacts using a dynamic time warping solution through a cost matrix that measures similarities between adjacent frames in en face images. We optimize and demonstrate the suitability of this method using a real and ...

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    8. Dual-beam manually-actuated distortion-corrected imaging (DMDI) with micromotor catheters

      Dual-beam manually-actuated distortion-corrected imaging (DMDI) with micromotor catheters

      e present a new paradigm for performing two-dimensional scanning called dual-beam manually-actuated distortion-corrected imaging (DMDI). DMDI operates by imaging the same object with two spatially-separated beams that are being mechanically scanned rapidly in one dimension with slower manual actuation along a second dimension. Registration of common features between the two imaging channels allows remapping of the images to correct for distortions due to manual actuation. We demonstrate DMDI using a 4.7 mm OD rotationally scanning dual-beam micromotor catheter (DBMC). The DBMC requires a simple, one-time calibration of the beam paths by imaging a patterned phantom. DMDI allows for distortion ...

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    9. Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature

      Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature

      We present the first endoscopic Doppler optical coherence tomography and co-registered autofluorescence imaging (DOCT-AFI) of peripheral pulmonary nodules and vascular networks in vivo using a small 0.9 mm diameter catheter. Using exemplary images from volumetric data sets collected from 31 patients during flexible bronchoscopy, we demonstrate how DOCT and AFI offer complementary information that may increase the ability to locate and characterize pulmonary nodules. AFI offers a sensitive visual presentation for the rapid identification of suspicious airway sites, while co-registered OCT provides detailed structural information to assess the airway morphology. We demonstrate the ability of AFI to visualize vascular ...

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    10. Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer

      Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer

      Diagnosis of peripheral lung nodules is challenging because they are rarely visualized endobronchially. Imaging techniques such as endobronchial ultrasound (EBUS) are employed to improve tumor localization. The current EBUS probe provides limited nodule characterization and has an outer diameter of 1.4 mm that restricts access to small peripheral airways. We report a novel co-registered autofluoresence Doppler optical coherence tomography (AF/DOCT) system with a 0.9 mm diameter probe to characterize peripheral lung nodules prior to biopsy in vivo. Method: Patients referred for evaluation of peripheral lung nodules underwent bronchoscopy with examination of standard EBUS and the novel AF ...

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    11. A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

      A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography

      We present a power-efficient fiber-based imaging system capable of co-registered autofluorescence imaging and optical coherence tomography (AF/OCT). The system employs a custom fiber optic rotary joint (FORJ) with an embedded dichroic mirror to efficiently combine the OCT and AF pathways. This three-port wavelength multiplexing FORJ setup has a throughput of more than 83% for collected AF emission, significantly more efficient compared to previously reported fiber-based methods. A custom 900 µm diameter catheter ‒ consisting of a rotating lens assembly, double-clad fiber (DCF), and torque cable in a stationary plastic tube ‒ was fabricated to allow AF/OCT imaging of small airways ...

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    1-11 of 11
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    1. (9 articles) British Columbia Cancer Agency
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    A high-efficiency fiber-based imaging system for co-registered autofluorescence and optical coherence tomography Doppler optical coherence tomography and co-registered autofluorescence imaging of peripheral lung cancer Endoscopic Doppler optical coherence tomography and autofluorescence imaging of peripheral pulmonary nodules and vasculature Dual-beam manually-actuated distortion-corrected imaging (DMDI) with micromotor catheters Correction of motion artifacts in endoscopic optical coherence tomography and autofluorescence images based on azimuthal en face image registration Submillimeter diameter rotary-pullback fiber-optic endoscope for narrowband red-green-blue reflectance, optical coherence tomography, and autofluorescence in vivo imaging Small airway dilation visualized by optical coherence tomography (OCT) correlates with the diagnosis of chronic lung allograft dysfunction (CLAD) Feasibility of combined optical coherence tomography and autofluorescence imaging for visualization of needle biopsy placement Higher-Order Core-Like Modes in Double-Clad Fiber Contribute to Multipath Artifacts in Optical Coherence Tomography Airway luminal area and the resistive work of breathing during exercise in healthy young females and males Comparison of Anterior Segment Measurements with a New Multifunctional Unit and Five Other Devices Efficacy of Notal Vision Home OCT demonstrated by a series of scientific and clinical work