Full-field optical coherence tomography for the analysis of fresh unstained human lobectomy specimens

High-resolution full-field optical coherence tomography microscope for the evaluation of freshly excised skin specimens during Mohs surgery: A feasibility study

Histopathology for tumor margin assessment is time-consuming and expensive. High-resolution full-field optical coherence tomography (FF-OCT) images fresh tissues rapidly at cellular resolution and potentially facilitates evaluation. Here, we define FF-OCT features of normal and neoplastic skin lesions in fresh ex vivo tissues and assess its diagnostic accuracy for malignancies. For this, normal and neoplastic tissues were obtained from Mohs surgery, imaged using FF-OCT, and their features were described. Two expert OCT readers conducted a blinded analysis to evaluate their diagnostic accuracies, using histopathology as the ground truth. A convolutional neural network was built to distinguish and outline normal structures and tumors. Of the 113 tissues imaged, 95 (84%) had a tumor (75 basal cell carcinomas [BCCs] and 17 squamous cell carcinomas [SCCs]). The average reader diagnostic accuracy was 88.1%, with a sensitivity of 93.7%, and a specificity of 58.3%. The artificial intelligence (AI) model achieved a diagnostic accuracy of 87.6 ± 5.9%, sensitivity of 93.2 ± 2.1%, and specificity of 81.2 ± 9.2%. A mean intersection-over-union of 60.3 ± 10.1% was achieved when delineating the nodular BCC from normal structures. Limitation of the study was the small sample size for all tumors, especially SCCs. However, based on our preliminary results, we envision FF-OCT to rapidly image fresh tissues, facilitating surgical margin assessment. AI algorithms can aid in automated tumor detection, enabling widespread adoption of this technique.

Value of high-resolution full-field optical coherence tomography and dynamic cell imaging for one-stop rapid diagnosis breast clinic

BACKGROUND

Full-field optical coherence tomography combined with dynamic cell imaging (D-FFOCT) is a new, simple-to-use, nondestructive, quick technique that can provide sufficient spatial resolution to mimic histopathological analysis. The objective of this study was to evaluate diagnostic performance of D-FFOCT for one-stop rapid diagnosis breast clinic.

METHODS

Dynamic full-field optical coherence tomography was applied to fresh, untreated breast and nodes biopsies. Four different readers (senior and junior radiologist, surgeon, and pathologist) analyzed the samples without knowing final histological diagnosis or American College of Radiology classification. The results were compared to conventional processing and staining (hematoxylin-eosin).

RESULTS

A total of 217 biopsies were performed on 152 patients. There were 144 breast biopsies and 61 lymph nodes with 101 infiltrative cancers (49.27%), 99 benign lesions (48.29%), 3 ductal in situ carcinoma (1.46%), and 2 atypias (0.98%). The diagnostic performance results were as follow: sensitivity: 77% [0.7;0.82], specificity: 64% [0.58;0.71], PPV: 74% [0.68;0.78], and NPV: 75% [0.72;0.78]. A large image atlas was created as well as a diagnosis algorithm from the readers' experience.

CONCLUSION

With 74% PPV and 75% NPV, D-FFOCT is not yet ready to be used in clinical practice to identify breast cancer. This is mainly explained by the lack of experience and knowledge of this new technic by the four lectors. By training with the diagnosis algorithm and the image atlas, radiologists could have better outcomes allowing quick detection of breast cancer and lymph node involvement. Deep learning could also be used, and further investigation will follow.

Diagnostic accuracy of optical coherence tomography for margin assessment in breast-conserving surgery: A systematic review and meta-analysis

BACKGROUND

Breast cancer is the most common malignant tumor among women, and its incidence is increasing annually. At present, the results of the study on whether optical coherence tomography (OCT) can be used as an intraoperative margin assessment method for breast-conserving surgery (BCS) are inconsistent. We herein conducted this systematic review and meta-analysis to assess the diagnostic value of OCT in BCS.

METHODS

PubMed, Web of Science, Cochrane Library, and Embase were used to search relevant studies published up to September 15, 2022. We used Review Manager 5.4, Meta-Disc 1.4, and STATA 16.0 for statistical analysis.

RESULTS

The results displayed 18 studies with 782 patients included according to the inclusion and exclusion criteria. Meta-analysis showed the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and the area under the curve (AUC) of OCT in the margin assessment of BCS were 0.91 (95% CI 0.88-0.93), 0.88 (95% CI 0.83-0.92), 7.53 (95% CI 5.19-10.93), 0.11(95% CI 0.08-0.14), 70.37 (95% CI 39.78-124.47), and 0.94 (95% CI 0.92-0.96), respectively.

CONCLUSIONS

OCT is a promising technique in intraoperative margin assessment of breast cancer patients.

EB-OCT: a potential strategy on early diagnosis and treatment for lung cancer

Lung cancer is the leading cause of cancer-related death in China and the world, mainly attributed to delayed diagnosis, given that currently available early screening strategies exhibit limited value. Endobronchial optical coherence tomography (EB-OCT) has the characteristics of non-invasiveness, accuracy, and repeatability. Importantly, the combination of EB-OCT with existing technologies represents a potential approach for early screening and diagnosis. In this review, we introduce the structure and strengths of EB-OCT. Furthermore, we provide a comprehensive overview of the application of EB-OCT on early screening and diagnosis of lung cancer from in vivo experiments to clinical studies, including differential diagnosis of airway lesions, early screening for lung cancer, lung nodules, lymph node biopsy and localization and palliative treatment of lung cancer. Moreover, the bottlenecks and difficulties in developing and popularizing EB-OCT for diagnosis and treatment during clinical practice are analyzed. The characteristics of OCT images of normal and cancerous lung tissues were in good agreement with the results of pathology, which could be used to judge the nature of lung lesions in real time. In addition, EB-OCT can be used as an assistant to biopsy of pulmonary nodules and improve the success rate of biopsy. EB-OCT also plays an auxiliary role in the treatment of lung cancer. In conclusion, EB-OCT is non-invasive, safe and accurate in real-time. It is of great significance in the diagnosis of lung cancer and suitable for clinical application and is expected to become an important diagnostic method for lung cancer in the future.

Slide Over: Advances in Slide-Free Optical Microscopy as Drivers of Diagnostic Pathology

Conventional analysis using clinical histopathology is based on bright-field microscopy of thinly sliced tissue specimens. Although bright-field microscopy is a simple and robust method of examining microscope slides, the preparation of the slides needed is a lengthy and labor-intensive process. Slide-free histopathology, however, uses direct imaging of intact, minimally processed tissue samples using advanced optical-imaging systems, bypassing the extended workflow now required for the preparation of tissue sections. This article explains the technical basis of slide-free microscopy, reviews common slide-free optical microscopy techniques, and discusses the opportunities and challenges involved in clinical implementation.

Rapid pseudo-H&E imaging using a fluorescence-inbuilt optical coherence microscopic imaging system

A technique using Linnik-based optical coherence microscopy (OCM), with built-in fluorescence microscopy (FM), is demonstrated here to describe cellular-level morphology for fresh porcine and biobank tissue specimens. The proposed method utilizes color-coding to generate digital pseudo-H&E (p-H&E) images. Using the same camera, colocalized FM images are merged with corresponding morphological OCM images using a 24-bit RGB composition process to generate position-matched p-H&E images. From receipt of dissected fresh tissue piece to generation of stitched images, the total processing time is <15 min for a 1-cm² specimen, which is on average two times faster than frozen-section H&E process for fatty or water-rich fresh tissue specimens. This technique was successfully used to scan human and animal fresh tissue pieces, demonstrating its applicability for both biobank and veterinary purposes. We provide an in-depth comparison between p-H&E and human frozen-section H&E images acquired from the same metastatic sentinel lymph node slice (∼10 µm thick), and show the differences, like elastic fibers of a tiny blood vessel and cytoplasm of tumor cells. This optical sectioning technique provides histopathologists with a convenient assessment method that outputs large-field H&E-like images of fresh tissue pieces without requiring any physical embedment.

Use of high-resolution full-field optical coherence tomography and dynamic cell imaging for rapid intraoperative diagnosis during breast cancer surgery

BACKGROUND

Although traditional intraoperative assessments (ie, frozen sections) may lower reoperation rates in patients with breast cancer, time/tissue limitations and accuracy concerns have discouraged their routine clinical use. Full-field optical coherence tomography (FFOCT) and dynamic cell imaging (DCI) are novel optical imaging techniques offering rapid histologic approximations that are unfettered by requisite handling steps. This study was conducted to determine the feasibility and diagnostic utility of FFOCT and DCI in examining breast and lymph node specimens during breast cancer surgery.

METHODS

FFOCT and DCI were applied to normal and cancerous breast tissue, benign breast lesions, and resected axillary lymph nodes. The tissues were then subjected to conventional processing and staining (hematoxylin-eosin) for purposes of comparison.

RESULTS

A total of 314 specimens, including 173 breast biopsies (malignant, 132; benign/normal, 41) and 141 resected lymph nodes (tumor-positive, 48; tumor-negative, 93), were obtained from 158 patients during breast surgery for prospective imaging evaluations. In breast cancer diagnosis, the minimum sensitivities (FFOCT, 85.6%; DCI, 88.6%) and specificities of optical imaging (FFOCT, 85.4%; DCI, 95.1%) were high, although they diverged somewhat in nodal assessments (FFOCT sensitivity, 66.7%; FFOCT specificity, 79.6%; DCI sensitivity, 83.3%; DCI specificity, 98.9%).

CONCLUSIONS

These timely and tissue-sparing optical imaging techniques proved highly accurate in diagnosing breast cancer and nodal metastasis. They compare favorably with routine histologic sections and demonstrate their promise in this setting.

Value of Full-Field Optical Coherence Tomography Imaging for the Histological Assessment of Head and Neck Cancer

BACKGROUND AND OBJECTIVES

In head and neck surgery, intraoperative and postoperative evaluation of tumor margins is achieved by histopathological assessment, which is a multistep process. Intraoperative analysis of tumor margins to obtain a preliminary diagnosis is usually carried out on frozen sections. Analysis of frozen sections is challenging due to technical difficulties in processing. Full-field optical coherence tomography (FFOCT) provides ex vivo images of fresh tissue samples at a microscopic scale without tissue processing. The objectives of our study were to define the diagnostic criteria required to interpret head and neck FFOCT images and to evaluate the reliability of a histological diagnosis made on an "optical biopsy" produced by head and neck FFOCT imaging compared with conventional histology.

STUDY DESIGN/MATERIALS AND METHODS

First, we established an atlas of comparative images (FFOCT/standard histology) and defined the diagnostic criteria based on FFOCT images. Two pathologists subsequently performed a blinded review on 57 FFOCT images (32 patients). Specificity and sensitivity were measured by comparison with the standard histological diagnosis. The primary endpoint was major concordance, defined as two classifications leading to the same therapeutic decision (treatment/no treatment).

RESULTS

Pathologists identified four main criteria for tissue diagnosis on FFOCT images: heterogeneous cell distribution, stromal reaction, coiling, and keratinization abnormalities. The correlation study showed good results, with sensitivity from 88% to 90% and specificity from 81% to 87%, regardless of whether the FFOCT image review was performed by a pathologist with or without previous experience in optical imaging.

CONCLUSIONS

Our results demonstrate that FFOCT images can be used by pathologists for differential diagnosis, and that high-resolution FFOCT imaging can provide an assessment of microscopic architecture in head and neck tissues without tissue processing requirements. Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

Advances in Optical Coherence Tomography and Confocal Laser Endomicroscopy in Pulmonary Diseases

Diagnosing and monitoring pulmonary diseases is highly dependent on imaging, physiological function tests and tissue sampling. Optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE) are novel imaging techniques with near-microscopic resolution that can be easily and safely combined with conventional bronchoscopy. Disease-related pulmonary anatomical compartments can be visualized, real time, using these techniques. In obstructive lung diseases, airway wall layers and related structural remodelling can be identified and quantified. In malignant lung disease, normal and malignant areas of the central airways, lung parenchyma, lymph nodes and pleura can be discriminated. A growing number of interstitial lung diseases (ILDs) have been visualized using OCT or CLE. Several ILD-associated structural changes can be imaged: fibrosis, cellular infiltration, bronchi(ol)ectasis, cysts and microscopic honeycombing. Although not yet implemented in clinical practice, OCT and CLE have the potential to improve detection and monitoring pulmonary diseases and can contribute in unravelling the pathophysiology of disease and mechanism of action of novel treatments. Indeed, assessment of the airway wall layers with OCT might be helpful when evaluating treatments targeting airway remodelling. By visualizing individual malignant cells, CLE has the potential as a real-time lung cancer detection tool. In the future, both techniques could be combined with laser-enhanced fluorescent-labelled tracer detection. This review discusses the value of OCT and CLE in pulmonary medicine by summarizing the current evidence and elaborating on future perspectives.

Ex Vivo Microscopy: A Promising Next-Generation Digital Microscopy Tool for Surgical Pathology Practice

CONTEXT.—

The rapid evolution of optical imaging modalities in recent years has opened the opportunity for ex vivo tissue imaging, which has significant implications for surgical pathology practice. These modalities have promising potential to be used as next-generation digital microscopy tools for examination of fresh tissue, with or without labeling with contrast agents.

OBJECTIVE.—

To review the literature regarding various types of ex vivo optical imaging platforms that can generate digital images for tissue recognition with potential for utilization in anatomic pathology clinical practices.

DATA SOURCES.—

Literature relevant to ex vivo tissue imaging obtained from the PubMed database.

CONCLUSIONS.—

Ex vivo imaging of tissues can be performed by using various types of optical imaging techniques. These next-generation digital microscopy tools have a promising potential for utilization in surgical pathology practice.

Confocal Fluorescence Microscopy Platform Suitable for Rapid Evaluation of Small Fragments of Tissue in Surgical Pathology Practice

CONTEXT.—

Rapid advances in the fields of biophotonics, computer science, and instrumentation have allowed for high-resolution imaging of biologic tissues.

OBJECTIVE.—

To evaluate the quality of images from an optimized confocal fluorescence microscopy (CFM) platform for rapid evaluation of small fragments of tissue, compared with hematoxylin-eosin staining.

DESIGN.—

Tissue fragments (up to 1.0 × 0.3 cm) were stained with 0.6 mM acridine orange for 60 seconds and imaged using a CFM platform at 488-nm and 785-nm wavelength. The imaged tissues were then fixed in formalin and processed to generate hematoxylin-eosin-stained tissue sections. The quality of CFM images was scored on a scale of 0 to 3 on the basis of the percentage of the CFM images with recognizable tissue architecture (0, 0%; 1, <20%; 2, 20%-50%; 3, >50%). The diagnoses made using CFM images were compared with those made using histopathologic analysis of the hematoxylin-eosin-stained tissue sections.

RESULTS.—

We imaged 118 tissue fragments obtained from 40 breast, 23 lung, 39 kidney, and 16 liver surgical excision specimens. We acquired CFM images in 2 to 3 minutes; 95.8% (113 of 118) of images showed a quality score of 3, and 4.2% (5 of 118) had a score of 2. We achieved a sensitivity of 95.5%, specificity of 97.3%, positive predictive value of 95.5%, and negative predictive value of 97.3%.

CONCLUSIONS.—

Our results demonstrate the suitability of the CFM platform for rapid and accurate evaluation of small tissue fragments in surgical pathology practice.

The clinical usefulness of optical coherence tomography during cancer interventions

INTRODUCTION

Tumor detection and visualization plays a key role in the clinical workflow of a patient with suspected cancer, both in the diagnosis and treatment. Several optical imaging techniques have been evaluated for guidance during oncological interventions. Optical coherence tomography (OCT) is a technique which has been widely evaluated during the past decades. This review aims to determine the clinical usefulness of OCT during cancer interventions focussing on qualitative features, quantitative features and the diagnostic value of OCT.

METHODS

A systematic literature search was performed for articles published before May 2018 using OCT in the field of surgical oncology. Based on these articles, an overview of the clinical usefulness of OCT was provided per tumor type.

RESULTS

A total of 785 articles were revealed by our search, of which a total of 136 original articles were available for analysis, which formed the basis of this review. OCT is currently utilised for both preoperative diagnosis and intraoperative detection of skin, oral, lung, breast, hepatobiliary, gastrointestinal, urological, and gynaecological malignancies. It showed promising results in tumor detection on a microscopic level, especially using higher resolution imaging techniques, such as high-definition OCT and full-field OCT.

CONCLUSION

In the near future, OCT could be used as an additional tool during bronchoscopic or endoscopic interventions and could also be implemented in margin assessment during (laparoscopic) cancer surgery if a laparoscopic or handheld OCT device will be further developed to make routine clinical use possible.

Ex Vivo Confocal Fluorescence Microscopy for Rapid Evaluation of Tissues in Surgical Pathology Practice

CONTEXT

- Optical imaging techniques are currently available for imaging tissues without the need for any type of extensive tissue preparation. There are several applications for their potential use in surgical pathology practice.

OBJECTIVE

- To evaluate the feasibility of using a confocal fluorescence microscopy (CFM) platform for ex vivo examination of tissues obtained from surgical resections of breast, lung, kidney, and liver.

DESIGN

- Tissue fragments (0.5-1.0 cm) were immersed in 0.6 mM acridine orange for 6 seconds and imaged using a CFM platform at a 488-nm wavelength. The imaged tissues were subsequently fixed in formalin and processed routinely to generate hematoxylin-eosin-stained tissue sections. Mosaics of the grayscale CFM images were studied at different magnifications for recognition of the tissue and were compared with conventional histopathologic examination of hematoxylin-eosin tissue sections.

RESULTS

- We imaged 55 tissue fragments obtained from 16 breast (29%), 18 lung (33%), 14 kidney (25%), and 7 liver (13%) surgical excision specimens. Acridine orange labeled the nuclei, creating the contrast between nucleus and cytoplasm and thereby recapitulating the tissue architecture. We could obtain CFM images of good quality within 5 to 10 minutes that allowed recognition of the cytomorphologic details for categorization of the imaged tissue and were similar to histologic examination of hematoxylin-eosin tissue sections.

CONCLUSIONS

- The ease and speed of acquisition of CFM images together with the resolution and resemblance of the CFM images to hematoxylin-eosin sections suggest that the CFM platform has excellent potential for use in surgical pathology practice.

Review of optical coherence tomography in oncology

The application of optical coherence tomography (OCT) in the field of oncology has been prospering over the past decade. OCT imaging has been used to image a broad spectrum of malignancies, including those arising in the breast, brain, bladder, the gastrointestinal, respiratory, and reproductive tracts, the skin, and oral cavity, among others. OCT imaging has initially been applied for guiding biopsies, for intraoperatively evaluating tumor margins and lymph nodes, and for the early detection of small lesions that would often not be visible on gross examination, tasks that align well with the clinical emphasis on early detection and intervention. Recently, OCT imaging has been explored for imaging tumor cells and their dynamics, and for the monitoring of tumor responses to treatments. This paper reviews the evolution of OCT technologies for the clinical application of OCT in surgical and noninvasive interventional oncology procedures and concludes with a discussion of the future directions for OCT technologies, with particular emphasis on their applications in oncology.

Classification and analysis of human ovarian tissue using full field optical coherence tomography

In this study, a full field optical coherence tomography (FFOCT) system was used to analyze and classify normal and malignant human ovarian tissue. 14 ovarian tissue samples (7 normal, 7 malignant) were imaged with the FFOCT system and five features were extracted by analyzing the normalized image histogram from 56 FFOCT images, based on the differences in the morphology of the normal and malignant tissue samples. A generalized linear model (GLM) classifier was trained using 36 images, and sensitivity of 95.3% and specificity of 91.1% was obtained. 20 images were used to test the model, and a sensitivity of 91.6% and specificity of 87.7% was obtained.

Advanced Imaging Techniques for the Pathologist

Advanced imaging refers to direct microscopic imaging of tissue, without the need for traditional hematoxylin-eosin (H&E) microscopy, including microscope slides or whole-slide images. A detailed example is presented of optical coherence tomography (OCT), an imaging technique based on reflected light. Experience and example images are discussed in the larger context of the evolving relationship of surgical pathology to clinical patient care providers. Although these techniques are diagnostically promising, it is unlikely that they will directly supplant H&E histopathology. It is likely that OCT and related technologies will provide narrow, targeted diagnosis in a variety of in vivo (patient) and ex vivo (specimen) applications.

Rapid and high-resolution imaging of human liver specimens by full-field optical coherence tomography

We report rapid and high-resolution tomographic en face imaging of human liver specimens by full-field optical coherence tomography (FF-OCT). First, the arrangement of the FF-OCT system was described and the performance of the system was measured. The measured axial and lateral resolutions of the system are 0.8 and 0.9 μm, respectively. The system has a sensitivity of ∼60 dB and can achieve an imaging rate of 7 fps and a penetration depth of ∼80 μm. The histological structures of normal liver can be seen clearly in the en face tomographic images, including central veins, cords of hepatocytes separated by sinusoidal spaces, and portal area (portal vein, the hepatic arteriole, and the bile duct). A wide variety of histological subtypes of hepatocellular carcinoma was observed in en face tomographic images, revealing notable cancerous features, including the nuclear atypia (enlarged convoluted nuclei), the polygonal tumor cells with obvious resemblance to hepatocytes with enlarged nuclei. In addition, thicker fibrous bands, which make the cytoplasmic plump vesicular nuclei indistinct, were also seen in the images. Finally, comparison between the portal vein in a normal specimen versus that seen in the rare type of cholangiocarcinoma was made. The results show that the cholangiocarcinoma presents with a blurred pattern of portal vein in the lateral direction and an aggregated distribution in the axial direction; the surrounding sinusoidal spaces and nuclei of cholangiocarcinoma are absent. The findings in this work may be used as additional signs of liver cancer or cholangiocarcinoma, demonstrating capacity of FFOCT device for early cancer diagnosis and many other tumor-related studies in biopsy.

Rapid evaluation of fresh ex vivo kidney tissue with full-field optical coherence tomography

BACKGROUND

Full-field optical coherence tomography (FFOCT) is a real-time imaging technique that rapidly generates images reminiscent of histology without any tissue processing, warranting its exploration for evaluation of ex vivo kidney tissue.

METHODS

Fresh tissue sections from tumor and adjacent nonneoplastic kidney (n = 25 nephrectomy specimens; clear cell renal cell carcinoma (CCRCC) = 12, papillary RCC (PRCC) = 4, chromophobe RCC (ChRCC) = 4, papillary urothelial carcinoma (PUC) = 1, angiomyolipoma (AML) = 2 and cystic nephroma = 2) were imaged with a commercial FFOCT device. Sections were submitted for routine histopathological diagnosis.

RESULTS

Glomeruli, tubules, interstitium, and blood vessels were identified in nonneoplastic tissue. In tumor sections, the normal architecture was completely replaced by either sheets of cells/trabeculae or papillary structures. The former pattern was seen predominantly in CCRCC/ChRCC and the latter in PRCC/PUC (as confirmed on H&E). Although the cellular details were not very prominent at this resolution, we could identify unique cytoplasmic signatures in some kidney tumors. For example, the hyper-intense punctate signal in the cytoplasm of CRCC represents glycogen/lipid, large cells with abundant hyper-intense cytoplasm representing histiocytes in PRCC, and signal-void large polygonal cell representing adipocytes in AML. According to a blinded analysis was performed by an uropathologist, all nonneoplastic tissues were differentiated from neoplastic tissues. Further, all benign tumors were called benign and malignant were called malignant. A diagnostic accuracy of 80% was obtained in subtyping the tumors.

CONCLUSION

The ability of FFOCT to reliably differentiate nonneoplastic from neoplastic tissue and identify some tumor types makes it a valuable tool for rapid evaluation of ex vivo kidney tissue e.g. for intraoperative margin assessment and kidney biopsy adequacy. Recently, higher resolution images were achieved using an experimental FFOCT setup. This setup has the potential to further increase the diagnostic accuracy of FFOCT.

Validation of human small airway measurements using endobronchial optical coherence tomography

BACKGROUND

Small airway remodeling is the cardinal feature underlying chronic airway diseases. There is no modality which identifies small airway pathological changes, which is crucial for early diagnosis, efficacy and prognostic assessment.

OBJECTIVE

To evaluate the usefulness of endobronchial optical coherence tomography (EB-OCT) in assessing small airways morphology in vivo.

METHODS

Twelve patients with pulmonary nodules scheduled for lung resection underwent spirometry, multi-detector computed tomography (MDCT) and EB-OCT. We measured D(mean) (mean luminal diameter), Ai (inner luminal area), Aw (airway wall area) and Aw% [Aw/(Ai + Aw) × 100%] from the 3rd to 5th generation bronchi of RB9 segment by MDCT. D(mean), Ai, Aw and Aw% from the 3rd to 9th generation bronchi of RB9 segment were measured by EB-OCT and histology. Correlations of these parameters, measured by three different methods, were evaluated. We recruited 4 COPD patients to determine if EB-OCT could identify peripheral airway remodeling.

RESULTS

The 4 parameters, measured by CT and EB-OCT, correlated significantly [D(mean) (r = 0.991), Ai (r = 0.997), Aw (r = 0.997), Aw% (r = 0.991), all P < 0.01]. Significant correlation were found for these parameters, measured by histology and EB-OCT, from the 3rd to 5th generation bronchi [D(mean) (r = 0.989), Ai (r = 0.997), Aw (r = 0.999), Aw% (r = 0.988), all P < 0.01], and from the 6th to 9th generation bronchi [D(mean) (r = 0.979), Ai (r = 0.997), Aw (r = 0.994) and Aw% (r = 0.988), all P < 0.01]. Significant small airways morphological abnormalities were observed in COPD patients.

CONCLUSIONS

EB-OCT, a minimally invasive imaging modality with high-resolution, is useful and clinically practical for assessing proximal and distal airways of human compared with CT and histology.

Fourier spectrum analysis of full-field optical coherence tomography for tissue imaging

We propose a model of the full-field optical coherence tomography (FFOCT) technique for tissue imaging, in which the fractal model of the spatial correlation function of the refractive index of tissue is employed to approximate tissue structure. The results may be helpful for correctly interpreting en face tomographic images obtained with FFOCT.

Advanced Imaging Techniques for the Pathologist

Advanced imaging refers to direct microscopic imaging of tissue, without the need for traditional hematoxylin-eosin (H&E) microscopy, including microscope slides or whole-slide images. A detailed example is presented of optical coherence tomography (OCT), an imaging technique based on reflected light. Experience and example images are discussed in the larger context of the evolving relationship of surgical pathology to clinical patient care providers. Although these techniques are diagnostically promising, it is unlikely that they will directly supplant H&E histopathology. It is likely that OCT and related technologies will provide narrow, targeted diagnosis in a variety of in vivo (patient) and ex vivo (specimen) applications.

Assessment of Sentinel Node Biopsies With Full-Field Optical Coherence Tomography

Current techniques for the intraoperative analysis of sentinel lymph nodes during breast cancer surgery present drawbacks such as time and tissue consumption. Full-field optical coherence tomography is a novel noninvasive, high-resolution, fast imaging technique. This study investigated the use of full-field optical coherence tomography as an alternative technique for the intraoperative analysis of sentinel lymph nodes. Seventy-one axillary lymph nodes from 38 patients at Tenon Hospital were imaged minutes after excision with full-field optical coherence tomography in the pathology laboratory, before being handled for histological analysis. A pathologist performed a blind diagnosis (benign/malignant), based on the full-field optical coherence tomography images alone, which resulted in a sensitivity of 92% and a specificity of 83% (n = 65 samples). Regular feedback was given during the blind diagnosis, with thorough analysis of the images, such that features of normal and suspect nodes were identified in the images and compared with histology. A nonmedically trained imaging expert also performed a blind diagnosis aided by the reading criteria defined by the pathologist, which resulted in 85% sensitivity and 90% specificity (n = 71 samples). The number of false positives of the pathologist was reduced by 3 in a second blind reading a few months later. These results indicate that following adequate training, full-field optical coherence tomography can be an effective noninvasive diagnostic tool for extemporaneous sentinel node biopsy qualification.