Investigation of tissue cellularity at the tip of the core biopsy needle with optical coherence tomography

Core Needle Biopsy Guidance Based on Tissue Morphology Assessment with AI-OCT Imaging

This paper presents a combined optical imaging/artificial intelligence (OI/AI) technique for the real-time analysis of tissue morphology at the tip of the biopsy needle, prior to collecting a biopsy specimen. This is an important clinical problem as up to 40% of collected biopsy cores provide low diagnostic value due to high adipose or necrotic content. Micron-scale-resolution optical coherence tomography (OCT) images can be collected with a minimally invasive needle probe and automatically analyzed using a computer neural network (CNN)-based AI software. The results can be conveyed to the clinician in real time and used to select the biopsy location more adequately. This technology was evaluated on a rabbit model of cancer. OCT images were collected with a hand-held custom-made OCT probe. Annotated OCT images were used as ground truth for AI algorithm training. The overall performance of the AI model was very close to that of the humans performing the same classification tasks. Specifically, tissue segmentation was excellent (~99% accuracy) and provided segmentation that closely mimicked the ground truth provided by the human annotations, while over 84% correlation accuracy was obtained for tumor and non-tumor classification.

Label-free multimodal nonlinear optical imaging of needle biopsy cores for intraoperative cancer diagnosis

SIGNIFICANCE

Needle biopsy (NB) procedures are important for the initial diagnosis of many types of cancer. However, the possibility of NB specimens being unable to provide diagnostic information, (i.e., non-diagnostic sampling) and the time-consuming histological evaluation process can cause delays in diagnoses that affect patient care.

AIM

We aim to demonstrate the advantages of this label-free multimodal nonlinear optical imaging (NLOI) technique as a non-destructive point-of-procedure evaluation method for NB tissue cores, for the visualization and characterization of the tissue microenvironment.

APPROACH

A portable, label-free, multimodal NLOI system combined second-harmonic generation (SHG) and third-harmonic generation and two- and three-photon autofluorescence (2PF, 3PF) microscopy. It was used for intraoperative imaging of fresh NB tissue cores acquired during canine cancer surgeries, which involved liver, lung, and mammary tumors as well as soft-tissue sarcoma; in total, eight canine patients were recruited. An added tissue culture chamber enabled the use of this NLOI system for longitudinal imaging of fresh NB tissue cores taken from an induced rat mammary tumor and healthy mouse livers.

RESULTS

The intraoperative NLOI system was used to assess fresh canine NB specimens during veterinary cancer surgeries. Histology-like morphological features were visualized by the combination of four NLOI modalities at the point-of-procedure. The NLOI results provided quantitative information on the tissue microenvironment such as the collagen fiber orientation using Fourier-domain SHG analysis and metabolic profiling by optical redox ratio (ORR) defined by 2PF/(2PF + 3PF). The analyses showed that the canine mammary tumor had more randomly oriented collagen fibers compared to the tumor margin, and hepatocarcinoma had a wider distribution of ORR with a lower mean value compared to the liver fibrosis and the normal-appearing liver. Moreover, the loss of metabolic information during tissue degradation of fresh murine NB specimens was shown by overall intensity decreases in all channels and an increase of mean ORR from 0.94 (standard deviation 0.099) to 0.97 (standard deviation 0.077) during 1-h longitudinal imaging of a rat mammary tumor NB specimen. The tissue response to staurosporine (STS), an apoptotic inducer, from fresh murine liver NB specimens was also observed. The mean ORR decreased from 0.86 to 0.74 in the first 40 min and then increased to 0.8 during the rest of the hour of imaging, compared to the imaging results without the addition of STS, which showed a continuous increase of ORR from 0.72 to 0.75.

CONCLUSIONS

A label-free, multimodal NLOI platform reveals microstructural and metabolic information of the fresh NB cores during intraoperative cancer imaging. This system has been demonstrated on animal models to show its potential to provide a more comprehensive histological assessment and a better understanding of the unperturbed tumor microenvironment. Considering tissue degradation, or loss of viability upon fixation, this intraoperative NLOI system has the advantage of immediate assessment of freshly excised tissue specimens at the point of procedure.

Compression optical coherence elastography versus strain ultrasound elastography for breast cancer detection and differentiation: pilot study

The aims of this study are (i) to compare ultrasound strain elastography (US-SE) and compression optical coherence elastography (C-OCE) in characterization of elastically linear phantoms, (ii) to evaluate factors that can cause discrepancy between the results of the two elastographic techniques in application to real tissues, and (iii) to compare the results of US-SE and C-OCE in the differentiation of benign and malignant breast lesions. On 22 patients, we first used standard US-SE for in vivo assessment of breast cancer before and then after the lesion excision C-OCE was applied for intraoperative visualization of margins of the tumors and assessment of their type/grade using fresh lumpectomy specimens. For verification, the tumor grades and subtypes were determined histologically. We show that in comparison to US-SE, quantitative C-OCE has novel capabilities due to its ability to locally control stress applied to the tissue and obtain local stress-strain curves. For US-SE, we demonstrate examples of malignant tumors that were erroneously classified as benign and vice versa. For C-OCE, all lesions are correctly classified in agreement with the histology. The revealed discrepancies between the strain ratio given by US-SE and ratio of tangent Young's moduli obtained for the same samples by C-OCE are explained. Overall, C-OCE enables significantly improved specificity in breast lesion differentiation and ability to precisely visualize margins of malignant tumors compared. Such results confirm high potential of C-OCE as a high-speed and accurate method for intraoperative assessment of breast tumors and detection of their margins.

Posterior segment findings by spectral-domain optical coherence tomography and clinical associations in active toxoplasmic retinochoroiditis

Toxoplasmic retinochoroiditis is a common, potentially blinding parasitic infection. We sought to define the spectrum and frequency of signs of active toxoplasmic retinochoroiditis by spectral domain optical coherence tomography (SD-OCT), and to identify clinical associations. Ninety eyes of 90 individuals presenting consecutively to a tertiary referral uveitis service with active toxoplasmic retinochoroiditis and gradable SD-OCT scans were evaluated prospectively. SD-OCT features were collated, and associations with lesion location, primary versus recurrent episode, serological status, human immunodeficiency virus infection and best-corrected Snellen visual acuity were explored. Active toxoplasmic retinochoroiditis presented with thickened (65%) and hyperreflective (61%) retina, choroidal thickening (55%) and hyporeflectivity (61%), hyperreflective vitreous dots (80%) and deposits (36%), and posterior hyaloid thickening (35%) on SD-OCT. Most signs occurred with similar frequency across clinical groups. Retinal hyporeflectivity (17%) was significantly associated with a visual acuity of 20/200 or worse at resolution. Our observations demonstrate that active toxoplasmic retinochoroiditis has diverse SD-OCT signs and that none are universally present. Retinal hyporeflectivity—suggesting liquefactive necrosis—predicts poor visual outcome.

In vivo optical imaging-guided targeted sampling for precise diagnosis and molecular pathology

Conventional tissue sampling can lead to misdiagnoses and repeated biopsies. Additionally, tissue processed for histopathology suffers from poor nucleic acid quality and/or quantity for downstream molecular profiling. Targeted micro-sampling of tissue can ensure accurate diagnosis and molecular profiling in the presence of spatial heterogeneity, especially in tumors, and facilitate acquisition of fresh tissue for molecular analysis. In this study, we explored the feasibility of performing 1–2 mm precision biopsies guided by high-resolution reflectance confocal microscopy (RCM) and optical coherence tomography (OCT), and reflective metallic grids for accurate spatial targeting. Accurate sampling was confirmed with either histopathology or molecular profiling through next generation sequencing (NGS) in 9 skin cancers in 7 patients. Imaging-guided 1–2 mm biopsies enabled spatial targeting for in vivo diagnosis, feature correlation and depth assessment, which were confirmed with histopathology. In vivo 1-mm targeted biopsies achieved adequate quantity and high quality of DNA for next-generation sequencing. Subsequent mutational profiling was confirmed on 1 melanoma in situ and 2 invasive melanomas, using a 505-gene mutational panel called Memorial Sloan Kettering-Integrated mutational profiling of actionable cancer targets (MSK-IMPACT). Differential mutational landscapes, in terms of number and types of mutations, were found between invasive and in situ melanomas in a single patient. Our findings demonstrate feasibility of accurate sampling of regions of interest for downstream histopathological diagnoses and molecular pathology in both in vivo and ex vivo settings with broad diagnostic, therapeutic and research potential in cutaneous diseases accessible by RCM-OCT imaging.

Tumor radiosensitization by photobiomodulation

PURPOSE

To investigate the safety of photobiomodulation therapy (PBM) in tumors and its potential as a radiosensitizer when combined with radiotherapy.

METHODS

We have performed in vitro experiments in A431 cells to assess proliferation and cell cycle after PBM, as well as clonogenic assay and H2AX-gamma immunolabeling to quantify double strand breaks after the combination of PBM and radiation. In vivo experiments in xenografts included Kaplan-Meier survival analysis, optical coherence tomography (OCT) and histological analysis.

RESULTS

PBM did not induce proliferation in vitro, but increased the G2/M fraction by 27% 24h after illumination, resulting in an enhancement of 30% in radiation effect in the clonogenic assay. The median survival of the PBM-RT group increased by 4 days and the hazard ratio was 0.417 (CI 95%: 0.173-1.006) when compared to radiation alone. OCT analysis over time demonstrated that PBM increases tumor necrosis due to radiation, and histological analysis showed that illumination increased cell differentiation and angiogenesis, which may play a role in the synergetic effect of PBM and radiation.

CONCLUSION

PBM technique may be one of the most appropriate approaches for radiosensitizing tumors while protecting normal tissue because of its low cost and low training requirements for staff.

Intraoperative Label-Free Multimodal Nonlinear Optical Imaging for Point-of-Procedure Cancer Diagnostics

Intraoperative imaging in surgical oncology can provide information about the tumor microenvironment as well as information about the tumor margin. Visualizing microstructural features and molecular and functional dynamics may provide important diagnostic and prognostic information, especially when obtained in real-time at the point-of-procedure. A majority of current intraoperative optical techniques are based on the use of the labels, such as fluorescent dyes. However, these exogenous agents disrupt the natural microenvironment, perturb biological processes, and alter the endogenous optical signatures that cells and the microenvironment can provide. Portable nonlinear imaging systems have enabled intraoperative imaging for real-time detection and diagnosis of tissue. We review the development of a label-free multimodal nonlinear optical imaging technique that was adapted into a portable imaging system for intraoperative optical assessment of resected human breast tissue. New developments have applied this technology to assessing needle-biopsy specimens. Needle-biopsy procedures most always precede surgical resection and serve as the first sampling of suspicious masses for diagnosis. We demonstrate the diagnostic feasibility of imaging core needle-biopsy specimens during veterinary cancer surgeries. This intraoperative label-free multimodal nonlinear optical imaging technique can potentially provide a powerful tool to assist in cancer diagnosis at the point-of-procedure.