Generalized Image Reconstruction in Optical Coherence Tomography Using Redundant and Non-Uniformly-Spaced Samples

In this paper, we use Frame Theory to develop a generalized OCT image reconstruction method using redundant and non-uniformly spaced frequency domain samples that includes using non-redundant and uniformly spaced samples as special cases. We also correct an important theoretical error in the previously reported results related to OCT image reconstruction using the Non-uniform Discrete Fourier Transform (NDFT). Moreover, we describe an efficient method to compute our corrected reconstruction transform, i.e., a scaled NDFT, using the Fast Fourier Transform (FFT). Finally, we demonstrate different advantages of our generalized OCT image reconstruction method by achieving (1) theoretically corrected OCT image reconstruction directly from non-uniformly spaced frequency domain samples; (2) a novel OCT image reconstruction method with a higher signal-to-noise ratio (SNR) using redundant frequency domain samples. Our new image reconstruction method is an improvement of OCT technology, so it could benefit all OCT applications.

Novel Image Features of Optical Coherence Tomography for pathological classification of lung cancer: results from a prospective clinical trial

Background This study aimed to explore the characteristics of Optical coherence tomography (OCT) imaging for differentiating between benign and malignant lesions, and different pathological types of lung cancer in bronchial lesions, and to preliminarily evaluate the clinical value of OCT. Methods Patients who underwent bronchoscopy biopsy and OCT between February 2019 and December 2019 at the Chinese PLA General Hospital were enrolled in this study. White-light bronchoscopy (WLB), auto-fluorescence bronchoscopy (AFB) and OCT were performed at the lesion location. The main characteristics of OCT imaging for the differentiation between benign and malignant lesions and the prediction of the pathological classification of lung cancer in bronchial lesions were identified and their clinical value was evaluated. Results A total of 135 patients were included in this study. The accuracy of OCT imaging for differentiating between benign and malignant bronchial lesions was 94.1%, which was significantly higher than that of AFB (67.4%). For the OCT imaging of SCC, adenocarcinoma and small cell lung cancer the accuracies were 95.6%, 94.3% and 92%, respectively. The accuracy, sensitivity and specificity of OCT were higher than those of WLB. In addition, these main OCT image characteristics are independent influencing factors for predicting the corresponding diseases through Logistic regression analysis between the main OCT image characteristics in the study and the general clinical features of patients(p༜0.05). Conclusion As a non-biopsy technique, OCT can be used to improve the diagnosis rate of lung cancer and promote the development of non-invasive histological biopsy.

P–361 Endometrium optical coherence tomography (OCT) and histomorphometry in implantation window and their relationships with reproductive failure and implantation outcome

Study question How do endometrium OCT image characteristics during peri-implantation window correlate with histomorphometry and associate with implantation outcomes in women with reproductive failure? Summary answer Endometrium OCT intensity correlated with stromal cell density and gland size. Endometrium with recurrent implantation failure had low OCT intensity but reversed in successful implantation. What is known already OCT is a non-invasive imaging technique using low energy near-infrared light to capture micrometer-scale resolution images from optical scattering media. An image produced by OCT resembles tissue architecture observed in histology, so OCT imaging has been regarded as “optical biopsy”. Our previous findings demonstrated OCT is better than ultrasound to identify endometrial pathology. We also showed association of OCT signal with microvessel density in peri-implantation endometrium. However, other histomorphometry were not evaluated. It is still unclear whether endometrium OCT image characteristics are different in reproductive failure and can predict implantation outcomes. Study design, size, duration This was a prospective study conducted at teaching hospital of The Chinese University of Hong Kong from Jan 2018 to Dec 2019. 46 infertile women with or without recurrent miscarriage (RM) and implantation failure (RIF) were recruited in this study. Endometrium OCT imaging and subsequent biopsy were performed on the seventh day after luteal hormone surge (LH + 7) in natural cycle prior to the consecutive natural conception or embryo transfer (ET) cycle. Participants/materials, setting, methods At least 5 systematic random endometrium OCT images from uterine fundus, body and lower segment of each subject were included for intensity analysis by two independent observers. OCT intensity of each image was classified as low, moderate, high based on optical range and then average OCT intensity in each uterine region was calculated for group comparison. Endometrium glandular epithelial, stromal, endothelial, uNK cells were defined by standard H&E and specific immunostaining for histomorphometry and correlation. Main results and the role of chance OCT intensity significantly correlated with endometrial cell and gland parameters regardless classifications of reproductive failure and implantation outcome. Higher OCT intensity indicated higher stromal cell density, gland to stromal (G/S) ratio and average gland area, but fewer microvessel and uNK cells. None of the endometrium histomorphometry were significantly different among different reproductive failure types and implantation outcomes, suggesting it may not be sensitive enough to detect the abnormal histological features. However, OCT intensity was significantly lower in the uterine fundus and body of RIF group than in that of infertile and RM groups. There was no significant difference of OCT intensity in the lower part of the endometrium among three groups. It indicates that OCT intensity is a sensitive marker to differentiate endometrium with RIF from the endometrium with other conditions and also endometrium with RIF is characterized with less stromal cells and smaller glands. Compared with infertile group with unsuccessful implantation, OCT intensity was higher in all three parts of the uterus from the infertile group with successful implantation, but the results were not statistically different. The results further implied that endometrial cells and gland size may potentially contribute to the endometrium receptivity for implantation. Limitations, reasons for caution Current endometrium OCT imaging depth is within 3mm, change beyond this thickness is inaccessible but still the most important layer for implantation. This is a pilot and small study with lack of normal fertile control. Endometrium OCT imaging in the same natural conception or ET cycle will be more accurate. Wider implications of the findings: OCT imaging could be used as a potential noninvasive modality to evaluate peri-implantation window endometrium. It enables real-time and in-situ visualization of endometrium structure and pathology with no additional biopsy risk and examination delay. Larger clinical trials are needed to confirm its clinical applications and utilities. Trial registration number CREC 2016.160