Sreyankar Nandy

Post-Doctoral Fellow (Translational Biomedical Optics) at Massachusetts General Hospital / Harvard Medical School

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Division of Pulmonary and Critical Care Medicine / Department of Pathology Employer: Massachusetts General Hospital / Harvard Medical School The Hariri Optical Imaging Laboratory is a multidisciplinary research group at Massachusetts General Hospital and Harvard Medical School. The focus of the laboratory is on the design, development and clinical translation of endoscopic optical coherence tomography (OCT)-based imaging devices for microscopic detection, diagnosis and monitoring of pulmonary diseases, including lung fibrosis, smoking and vaping-related lung diseases, post-COVID lung disease and interstitial lung abnormalities. A highly motivated, independent, innovative, and organized individual with an interest in translational optical/diagnostic imaging and biomedicine is sought for a Post-Doctoral Research Fellow position. The appropriate candidate will work in a highly collaborative multidisciplinary research environment consisting of engineers, physicians and technici...

Reply to: Endobronchial Optical Coherence Tomography: Shining New Light on Diagnosing UIP?

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From the Authors: We thank Kalverda and colleagues for their letter regarding our recently published paper [1], and appreciate the opportunity to provide additional clarity on the points that they raise about the work. Below we address the questions asked by Kalverda and colleagues: Enrollment criteria Our primary objective was to conduct a blinded, prospective study to evaluate the diagnostic accuracy of endobronchial OCT (EB-OCT) for microscopic ILD diagnosis as compared to concurrent surgical lung biopsy (SLB) and clinical follow-up diagnosis. Our inclusion criteria were: a) age >21 years, b) fibrotic ILD based on high-resolution computed tomography (HRCT) with unclear diagnosis, c) SLB required for ILD diagnosis based on the clinical decision of the treating pulmonologist, and d) ability to give informed consent. Therefore, in our patient cohort, there was no high-confidence clinical-radiologic diagnosis prior to SLB. Our institution does not routinely use bronchoalveolar lav...

Rapid non-destructive volumetric tumor yield assessment in fresh lung core needle biopsies using polarization sensitive optical coherence tomography

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Adequate tumor yield in core-needle biopsy (CNB) specimens is essential in lung cancer for accurate histological diagnosis, molecular testing for therapeutic decision-making, and tumor biobanking for research. Insufficient tumor sampling in CNB is common, primarily due to inadvertent sampling of tumor-associated fibrosis or atelectatic lung, leading to repeat procedures and delayed diagnosis. Currently, there is no method for rapid, non-destructive intraprocedural assessment of CNBs. Polarization-sensitive optical coherence tomography (PS-OCT) is a high-resolution, volumetric imaging technique that has the potential to meet this clinical need. PS-OCT detects endogenous tissue properties, including birefringence from collagen, and degree of polarization uniformity (DOPU) indicative of tissue depolarization. Here, PS-OCT birefringence and DOPU measurements were used to quantify the amount of tumor, fibrosis, and normal lung parenchyma in 42 fresh, intact lung CNB specimens. PS-OCT res...

Diagnostic Accuracy of Endobronchial Optical Coherence Tomography for the Microscopic Diagnosis of Usual Interstitial Pneumonia

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Rationale: Early, accurate diagnosis of interstitial lung disease (ILD) informs prognosis and therapy, especially in idiopathic pulmonary fibrosis (IPF). Current diagnostic methods are imperfect. HRCT resolution is limited while surgical lung biopsy (SLB) carries risks of morbidity/mortality. Endobronchial optical coherence tomography (EB-OCT) is a low-risk, bronchoscope-compatible modality that images large lung volumes in vivo with microscopic resolution, including subpleural lung, and has the potential to improve the diagnostic accuracy of bronchoscopy for ILD diagnosis. Objectives: We performed a prospective diagnostic accuracy study of EB-OCT in ILD patients with a low-confidence diagnosis undergoing SLB. Primary endpoints were EB-OCT sensitivity/specificity for diagnosis of the histopathologic pattern of usual interstitial pneumonia (UIP) and clinical IPF. The secondary endpoint was agreement between EB-OCT and SLB for diagnosis of the ILD fibrosis pattern. Methods: EB-OCT was...

Assessment and Diagnosis of Human Ovarian and Colorectal Cancer using Optical and Photoacoustic Imaging (Thesis)

Optical imaging modalities have the advantage of high resolution, label free, rapid, low cost imaging for both in vivo and ex vivo diagnosis of biological tissues. Optical scattering, which is the main contrast of optical coherence tomography (OCT), is related to elastic scattering components, mainly stromal collagen. Tissue elasticity has recently emerged as an important diagnostic parameter associated with tumor development and progression and is also related to the distribution of structural components such as tissue collagen. We have used an optical coherence tomography elastography (OCTE) system for characterizing the differences in the micro-mechanical properties of benign and malignant human ovarian tissue and correlated with the corresponding tissue collagen content (chapter 1). Additionally, spatial heterogeneity has also been associated with diagnosis of normal and malignant tissue. Automated image recognition and analysis can be a useful tool for overcoming the limitation...

3D visualization of the ovarian tissue scattering coefficient with swept-source optical coherence tomography

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It is important to provide timely information to surgeons on diagnosis of a suspicious ovarian tissue before excision to avoid unnecessary surgery, especially for young women. In this report, we introduce a new 3-D surface mapping technique to map ovarian tissue scattering properties by fitting the swept-source optical coherence tomography (SS-OCT) signals to a scattering model. We observed that lower scattering coefficients and heterogeneous spatial distribution were associated with malignant ovarian tissues, and higher scattering coefficients and homogeneous spatial distribution indicated benign ovarian tissues. The initial results suggest that the 3-D scattering map has potential to be an effective tool to characterize normal and malignant ovarian tissues. ( Read Full Article )

Classification of human ovarian tissue using full field optical coherence tomography

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The feasibility of a full-field optical coherence tomography (FFOCT) system for rapid wide field optical analysis of normal and malignant human ovarian tissue pathologies was demonstrated. Five features were extracted from the normalized image histogram from 56 FFOCT images, based on the differences in the morphology of the normal and malignant tissue samples. ( Read Full Article )

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

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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. ( Read Full Article )

Correlating optical coherence elastography based strain measurements with collagen content of the human ovarian tissue

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In this manuscript, the initial feasibility of a catheter based phase stabilized swept source optical coherence tomography (OCT) system was studied for characterization of the strain inside different human ovarian tissue groups. The ovarian tissue samples were periodically compressed with 500 Hz square wave signal along the axial direction between the surface of an unfocused transducer and a glass cover slide. The displacement and corresponding strain were calculated during loading from different locations for each tissue sample. A total of 27 ex vivo ovaries from 16 patients were investigated. Statistically significant difference (p < 0.001) was observed between the average displacement and strain of the normal and malignant tissue groups. A sensitivity of 93.2% and a specificity of 83% were achieved using 25 microstrain (με) as the threshold. The collagen content of the tissues was quantified from the Sirius Red stained histological sections. The average collagen are...

Estimation of elastic parameters of ovarian tissue using phase stabilized swept source optical-coherence tomography

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We have estimated the micro-mechanical properties of ovarian tissue using phase-sensitive swept source optical coherence tomography. Ovary samples were mechanically excited by periodical vibration of an ultrasound transducer. The displacement and strain of the tissues were calculated during loading. Significant difference in strain was observed between the normal and malignant ovary groups, which indicates much softer and heterogeneous tissue structure for malignant ovaries. The initial results show that the phase sensitive swept source optical coherence elastography (OCE) can be an effective tool for characterization of stiffness and other micro-mechanical properties of normal and malignant ovarian tissue. ( Read Full Article )

High-resolution full-field spatial coherence gated optical tomography using monochromatic light source

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We demonstrate dispersion free, high-resolution full-field spatial coherence gated optical tomography using spatially incoherent monochromatic light source. Spatial coherence properties of light source were synthesized by means of combining a static diffuser and vibrating multi mode fiber bundle. Due to low spatial coherence of light source, the axial resolution of the system was achieved similar to that of conventional optical coherence tomography which utilizes low temporal coherence. Experimental results of fringe visibility versus optical path difference are presented for varying numerical apertures objective lenses. High resolution optically sectioned images of multilayer onion skin, and red blood cells are presented. ( Read Full Article )

High-resolution corneal topography and tomography of fish eye using wide-field white light interference microscopy

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Topography and tomography of fish cornea is reconstructed using high resolution white light interference microscopy. White light interferograms at different depths were recorded by moving the object axially. For each depth position, five phase shifted interferograms were recorded and analyzed. From the reconstructed phase maps, the corneal topography and hence the refractive index was determined and from amplitude images the cross-sectional image of fish cornea was reconstructed. In the present method, we utilize a nearly common-path interference microscope and wide field illumination and hence do not require any mechanical B-scan. Therefore, the phase stability of the recorded data is improved. ( Read Full Article )

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