arXiv subjects

Parsin Haji Reza

Publications and source records attributed to Parsin Haji Reza.

23 records · Page 2Linked to original sources

arXiv2021

Single Acquisition Label-free Histology-like Imaging with Dual Contrast Photoacoustic Remote Sensing Microscopy

Significance: Histopathological analysis of tissues is an essential tool for grading, staging, diagnosing and resecting cancers and other malignancies. Current histopathological techniques require substantial sample processing prior to staining with hematoxylin and eosin (H&E) dyes, to highlight nuclear and cellular morphology. Sample preparation and staining is resource-intensive and introduces potential for variability during sample preparation. Aim: We present a novel method for direct label-free histopathological assessment of formalin fixed paraffin embedded tissue blocks and thin tissue sections using a dual contrast photoacoustic remote sensing (PARS) microscopy system. Approach: To emulate the nuclear and cellular contrast of H&E staining, we leverage unique properties of the PARS system. Here the ultraviolet excitation of the PAARS microscope takes advantage of DNA's unique optical absorption to provide nuclear contrast analogous to hematoxylin staining of cell nucelli. Concurrently, the optical scattering contrast of the PARS detection system is leveraged to provide bulk tissue contrast analogous to eosin staining of cell membranes. Results: We demonstrate the efficacy of this technique by imaging human breast tissue and human skin tissues in formalin fixed paraffin embedded tissue blocks and frozen sections respectively. Salient nuclear and extra-nuclear features such as cancerous cells, glands and ducts, adipocytes, and stromal structures such as collagen. Conclusions. The presented dual contrast PARS microscope enables label-free visualizations of tissue with contrast and quality analogous to the current gold standard for histopathological analysis. Thus, the proposed system is well positioned to augment existing histopathological workflows, providing histological imaging directly on unstained tissue blocks and sections.

physics.med-ph↗

arXiv2020

Histopathology for Mohs Micrographic Surgery with Photoacoustic Remote Sensing Microscopy

Mohs micrographic surgery (MMS) is a precise oncological technique where layers of tissue are resected and examined with intraoperative histopathology to minimize the removal of normal tissue while completely excising the cancer. To achieve intraoperative pathology, the tissue is frozen, sectioned and stained over a 20- to 60-minute period, then analyzed by the MMS surgeon. Surgery is continued one layer at a time until no cancerous cells remain, meaning MMS can take several hours to complete. Ideally, it would be desirable to circumvent or augment frozen sectioning methods and directly visualize subcellular morphology on the unprocessed excised tissues. Employing photoacoustic remote sensing (PARS) microscopy, we present a non-contact label-free reflection-mode method of performing such visualizations in frozen sections of human skin. PARS leverages endogenous optical absorption contrast within cell nuclei to provide visualizations reminiscent of histochemical staining techniques. Presented here, is the first true one to one comparison between PARS microscopy and standard histopathological imaging in human tissues. We demonstrate the ability of PARS microscopy to provide large grossing scans (>1 cm2, sufficient to visualize entire MMS sections) and regional scans with subcellular lateral resolution (~300 nm).

physics.med-ph↗

arXiv2020

Improving Maximal Safe Brain Tumor Resection with Photoacoustic Remote Sensing Microscopy

Malignant brain tumors are among the deadliest neoplasms with the lowest survival rates of any cancer type. In considering surgical tumor resection, suboptimal extent of resection is linked to poor clinical outcomes and lower overall survival rates. Currently available tools for intraoperative histopathological assessment require an average of 20 minutes processing and are of limited diagnostic quality for guiding surgeries. Consequently, there is an unaddressed need for a rapid imaging technique to guide maximal resection of brain tumors. Working towards this goal, presented here is an all optical non-contact label-free reflection mode photoacoustic remote sensing (PARS) microscope. By using a tunable excitation laser, PARS takes advantage of the endogenous optical absorption peaks of DNA and cytoplasm to achieve virtual contrast analogous to standard hematoxylin and eosin (H and E) staining. In conjunction, a fast 266 nm excitation is used to generate large grossing scans and rapidly assess small fields in real-time with hematoxylin-like contrast. Images obtained using this technique show comparable quality and contrast to the current standard for histopathological assessment of brain tissues. Using the proposed method, rapid, high-throughput, histological-like imaging was achieved in unstained brain tissues, indicating PARS utility for intraoperative guidance to improve extent of surgical resection.

eess.IV↗

arXiv2020

Reflection-mode virtual histology using photoacoustic remote sensing microscopy

Histological visualizations are critical to clinical disease management and are fundamental to biological understanding. However, current approaches that rely on bright-field microscopy require extensive tissue preparation prior to imaging. These processes are labor intensive and contribute to delays in clinical feedback that can extend to two to three weeks for standard paraffin-embedded tissue preparation and interpretation. Here, we present a label-free reflection-mode imaging modality that reveals cellular-scale morphology by detecting intrinsic endogenous contrast. We accomplish this with the novel photoacoustic remote sensing (PARS) detection system that permits non-contact optical absorption contrast to be extracted from thick and opaque biological targets with optical resolution. PARS was examined both as a rapid assessment tool that is capable of managing large samples (>1 cm2) in under 10 minutes, and as a high contrast imaging modality capable of extracting specific biological contrast to simulate conventional histological stains such as hematoxylin and eosin (H&E). The capabilities of the proposed method are demonstrated in a variety of human tissue preparations including formalin-fixed paraffin-embedded tissue blocks and unstained slides sectioned from these blocks, including normal and neoplastic human brain, and breast epithelium involved with breast cancer. Similarly, PARS images of human skin prepared by frozen section clearly demonstrated basal cell carcinoma and normal human skin tissue. Finally, we imaged unprocessed murine kidney and achieved histologically relevant subcellular morphology in fresh tissue. This represents a vital step towards an effective real-time clinical microscope that overcomes the limitations of standard histopathologic tissue preparations and enables real-time pathology assessment.

physics.med-ph↗

arXiv2020

Label-free, non-contact, in-vivo ophthalmic imaging using photoacoustic remote sensing microscopy

We present the first label-free, non-contact, in-vivo imaging of the ocular vasculature using photoacoustic remote sensing (PARS) microscopy. Both anterior and posterior segments mouse eye were imaged. Vasculature of iris, sclera and retina tissues were clearly resolved. To best of our knowledge this the first study showing non-contact photoacoustic imaging conducted on in-vivo ocular tissue. We believe that PARS microscopy has the potential to advance the diagnosis and treatment of ocular diseases.

physics.med-ph↗