Rapid histopathological examination of surgical specimen margins using fluorescence microscopy during breast conservation therapy has the potential to reduce the rate of positive margins on postoperative histopathology and the need for repeat surgeries. To assess the suitability of imaging modalities, we perform a direct comparison between confocal fluorescence microscopy and multiphoton microscopy for imaging unfixed tissue and compare to paraffin-embedded histology. An imaging protocol including dual channel detection of two contrast agents to implement virtual hematoxylin and eosin images is introduced that provides high quality imaging under both one and two photon excitation. Corresponding images of unfixed human breast tissue show that both confocal and multiphoton microscopy can reproduce the appearance of conventional histology without the need for physical sectioning. We further compare normal breast tissue and invasive cancer specimens imaged at multiple magnifications, and assess the effects of photobleaching for both modalities using the staining protocol. The results demonstrate that confocal fluorescence microscopy is a promising and cost-effective alternative to multiphoton microscopy for rapid histopathological evaluation of ex vivo breast tissue.
Optical Coherence Tomography (OCT) can discriminate morphological tissue features important for oral cancer detection such as the presence or absence of basement membrane and epithelial thickness. We previously reported an OCT system employing a rotary-pullback catheter capable of in vivo, rapid, wide-field (up to 90 x 2.5mm2) imaging in the oral cavity. Due to the size and complexity of these OCT data sets, rapid automated image processing software that immediately displays important tissue features is required to facilitate prompt bed-side clinical decisions.
We present an automated segmentation algorithm capable of detecting the epithelial surface and basement membrane in 3D OCT images of the oral cavity. The algorithm was trained using volumetric OCT data acquired in vivo from a variety of tissue types and histology-confirmed pathologies spanning normal through cancer (8 sites, 21 patients). The algorithm was validated using a second dataset of similar size and tissue diversity. We demonstrate application of the algorithm to an entire OCT volume to map epithelial thickness, and detection of the basement membrane, over the tissue surface. These maps may be clinically useful for delineating pre-surgical tumor margins, or for biopsy site guidance.
We present a portable multiphoton system designed for evaluating centimeter-scale surgical margins on surgical breast specimens in a clinical setting. The system is designed to produce large field of view images at a high frame rate, while using GPU processing to render low latency, video-rate virtual H&E images for real-time assessment. The imaging system and virtual H&E rendering algorithm are demonstrated by imaging unfixed human breast tissue in a clinical setting.
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/DOCT system. The lesion of interest was first identified with EBUS and then imaged
with the AF/DOCT system. The abnormal area was biopsied. AF/DOCT images of pathology proved lung malignancies
were reviewed by a panel of a pathologist, respirologists, and AF/DOCT experts.
Results: Eleven patients with biopsy proven lung cancer underwent examination with AF/DOCT. The majority of the
cancers were adenocarcinoma. AF/DOCT images were obtained in all patients. There were no complications to the
procedures. Lung abnormalities visualized in AF/ OCT images were observed in 11 cases. In one case large blood
vessels were identified and biopsy was avoided.
Conclusion: In this pilot study, AF/DOCT obtained high quality images of peripheral pulmonary nodules. The present
study supports the safety and feasibility of AF/DOCT for the evaluation of lung cancer. The addition of Doppler
information may improve biopsy site selection and reduce hemorrhage.
Polarization Sensitive Optical Coherence Tomography (PSOCT) is a functional extension of Optical Coherence
Tomography (OCT) that is sensitive to well-structured, birefringent tissue such as scars, smooth muscle and cartilage. In
this work, we present a novel completely fiber based swept source PSOCT system using a fiber-optic rotary pullback
catheter. This PSOCT implementation uses only passive optical components and requires no calibration while adding
minimal additional cost to a standard structural OCT imaging system. Due to its complete fiber construction, the system
can be made compact and robust, while the fiber-optic catheter allows access to most endoscopic imaging sites. The
1.5mm diameter endoscopic probe can capture 100 frames per second at pullback speeds up to 15 mm/s allowing rapid
traversal of large imaging fields. We validate the PSOCT system with known birefringent tissues and demonstrate in vivo
PSOCT imaging of human oral scar tissue.
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