Sazgar Burhan

@article{RN5472,
   author = {Kren, Jessica;Skambath, Isabelle;Kuppler, Patrick;Buschschlüter, Steffen;Detrez, Nicolas;Burhan, Sazgar;Huber, Robert;Brinkmann, Ralf and Bonsanto, Matteo Mario},
   title = {Mechanical characteristics of glioblastoma and peritumoral tumor-free human brain tissue},
   journal = {Acta Neurochirurgica},
   volume = {166},
   number = {1},
   pages = {102},
   ISSN = {0942-0940},
   DOI = {10.1007/s00701-024-06009-x},
   url = {https://doi.org/10.1007/s00701-024-06009-x},
   year = {2024},
   type = {Journal Article}
}

@article{Burhan:24,
author = {Sazgar Burhan and Nicolas Detrez and Katharina Rewerts and Paul Strenge and Steffen Buschschl\"{u}ter and Jessica Kren and Christian Hagel and Matteo Mario Bonsanto and Ralf Brinkmann and Robert Huber},
journal = {Biomed. Opt. Express},
keywords = {High speed imaging; Imaging systems; In vivo imaging; Magnetic resonance imaging; Phase noise; Phase shift},
number = {2},
pages = {1038--1058},
publisher = {Optica Publishing Group},
title = {Phase unwrapping for MHz optical coherence elastography and application to brain tumor tissue},
volume = {15},
month = {Feb},
year = {2024},
url = {https://opg.optica.org/boe/abstract.cfm?URI=boe-15-2-1038},
doi = {10.1364/BOE.510020},
abstract = {During neuro-oncologic surgery, phase-sensitive optical coherence elastography (OCE) can be valuable for distinguishing between healthy and diseased tissue. However, the phase unwrapping process required to retrieve the original phase signal is a challenging and critical task. To address this issue, we demonstrate a one-dimensional unwrapping algorithm that recovers the phase signal from a 3.2\&\#x2005;MHz OCE system. With a processing time of approximately 0.11 s per frame on the GPU, multiple 2\&\#x03C0; wraps are detected and corrected. By utilizing this approach, exact and reproducible information on tissue deformation can be obtained with pixel accuracy over the entire acquisition time. Measurements of brain tumor-mimicking phantoms and human ex vivo brain tumor samples verified the algorithm\&\#x0027;s reliability. The tissue samples were subjected to a 200\&\#x2005;ms short air pulse. A correlation with histological findings confirmed the algorithm\&\#x0027;s dependability.},
}

@inproceedings{10.1117/12.2670957,
author = {Sazgar Burhan and Nicolas Detrez and Madita G{\"o}b and Matteo Mario Bonsanto and Ralf Brinkmann and Robert Huber},
title = {{Advanced FFT-based contrast approach for MHz optical coherence elastography}},
volume = {12632},
booktitle = {Optical Coherence Imaging Techniques and Imaging in Scattering Media V},
editor = {Benjamin J. Vakoc and Maciej Wojtkowski and Yoshiaki Yasuno},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {1263215},
abstract = {Optical coherence elastography represents mechanical characteristics of biological tissue in so-called mechanical contrast maps. In addition to the standard intensity image, the contrast map illustrates numerous mechanical tissue features that would otherwise be undetectable. This is of great interest as abnormal physiological changes influence the mechanical behavior of the tissue. We demonstrate an advanced mechanical contrast approach based on the phase signal of our 3.2 MHz optical coherence tomography system. The robustness and performance of this contrast approach is evaluated and discussed based on preliminary results. },
keywords = {Optical Coherence Tomography, OCT, Megahertz OCT, Fourier Domain Mode Locking, Optical Coherence Elastography, OCE, Phase-sensitive OCT, Biomechanics},
year = {2023},
doi = {10.1117/12.2670957},
URL = {https://doi.org/10.1117/12.2670957}
}

@inproceedings{10.1117/12.2670950,
author = {Madita G{\"o}b and Simon Lotz and Linh Ha-Wissel and Sazgar Burhan and Sven B{\"o}ttger and Floris Ernst and Jennifer Hundt and Robert Huber},
title = {{Advances in large area robotically assisted OCT (LARA-OCT): towards drive-by continuous motion imaging}},
volume = {12632},
booktitle = {Optical Coherence Imaging Techniques and Imaging in Scattering Media V},
editor = {Benjamin J. Vakoc and Maciej Wojtkowski and Yoshiaki Yasuno},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {126321N},
abstract = {Optical coherence tomography is a powerful imaging technique to visualize and localize depth-dependent tissue structure to differentiate between healthy and pathological conditions. However, conventional OCT systems are only capable of detecting small areas. To overcome this limitation, we have developed a large area robotically assisted OCT (LARA-OCT) system for automatic acquisition of large OCT images. Using mosaic pattern acquisition and subsequent stitching, we previously demonstrated initial in vivo OCT skin images beyond 10 cm². To improve acquisition speed and reduce dead times, we here demonstrate and analyze LARA-OCT with a new drive-by continuous motion imaging protocol.},
keywords = {Optical Coherence Tomography, Fourier Domain Mode Locking, Robotically Assisted Imaging Systems, Three-dimensional image acquisition, Large Area Scanning, Skin Imaging, OCT, FDML},
year = {2023},
doi = {10.1117/12.2670950},
URL = {https://doi.org/10.1117/12.2670950}
}

@inproceedings{10.1117/12.2648301,
author = {Sazgar Burhan and Nicolas Detrez and Katharina Rewerts and Madita G{\"o}b and Christian Hagel and Matteo Mario Bonsanto and Dirk Theisen-Kunde and Robert Huber and Ralf Brinkmann},
title = {{Characterization of brain tumor tissue by time-resolved, phase-sensitive optical coherence elastography at 3.2 MHz line rate}},
volume = {12368},
booktitle = {Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XXI},
editor = {Caroline Boudoux and James W. Tunnell},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {123680F},
abstract = {Optical coherence elastography (OCE) offers the possibility of obtaining the mechanical behavior of a tissue. When also  using a non-contact mechanical excitation, it mimics palpation without interobserver variability. One of the most frequently  used techniques is phase-sensitive OCE. Depending on the system, depth-resolved changes in the sub-µm to nm range can  be detected and visualized volumetrically. Such an approach is used in this work to investigate and detect transitions  between healthy and tumorous brain tissue as well as inhomogeneities in the tumor itself to assist the operating surgeon  during tumor resection in the future. We present time-resolved, phase-sensitive OCE measurements on various ex vivo brain tumor samples using an ultra-fast 3.2 MHz swept-source optical coherence tomography (SS-OCT) system with a frame rate of 2.45 kHz. 4 mm line scans are acquired which, in combination with the high imaging speed, allow monitoring and investigation of the sample's behavior in response to the mechanical load. Therefore, an air-jet system applies a 200 ms  short air pulse to the sample, whose non-contact property facilitates the possibility for future in vivo measurements. Since we can temporally resolve the response of the sample over the entire acquisition time, the mechanical properties are evaluated at different time points with depth resolution. This is done by unwrapping the phase data and performing subsequent assessment. Systematic ex vivo brain tumor measurements were conducted and visualized as distribution maps.  The study outcomes are supported by histological analyses and examined in detail.},
keywords = { Optical Coherence Tomography, Optical Coherence Elastography, Phase-sensitive OCT, Fourier Domain Mode Locking, Brain Tumor, Phase Unwrapping, Tissue Characterization, Biomechanics},
year = {2023},
doi = {10.1117/12.2648301},
URL = {https://doi.org/10.1117/12.2648301}
}

@inproceedings{10.1117/12.2652616,
author = {Madita G{\"o}b and Simon Lotz and Linh Ha-Wissel and Sazgar Burhan and Sven B{\"o}ttger and Floris Ernst and Jennifer Hundt and Robert Huber},
title = {{Large area robotically assisted optical coherence tomography (LARA-OCT) for skin imaging with MHz-OCT surface tracking}},
volume = {12367},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVII},
editor = {Joseph A. Izatt and James G. Fujimoto},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {123670C},
abstract = {Optical coherence tomography (OCT) is a powerful imaging technique to non-invasively differentiate between healthy skin and pathological conditions. Unfortunately, commercially available OCT-systems are typically slow and not capable of scanning large areas at reasonable speed. Since skin lesions may extend over several square centimeters, potential inflammatory infiltrates remain undetected. Here, we present large area robotically assisted OCT (LARA-OCT) for skin imaging. Therefor a collaborative robot is combined with an existing, home-built 3.3 MHz-OCT-system and for surface tracking an online probe-to-surface control is implemented which is solely based on the OCT surface signal. It features a combined surface-distance and surface-orientation closed-loop control algorithm, which enables automatic positioning and alignment of the probe across the target while imaging. This allows to acquire coherent OCT images of skin areas beyond 10 cm<sup>2</sup>. },
keywords = {Optical Coherence Tomography, Fourier Domain Mode Locking, Robotically Assisted Imaging Systems, Three-dimensional image acquisition, Large Area Scanning, Skin Imaging , OCT, FDML},
year = {2023},
doi = {10.1117/12.2652616},
URL = {https://doi.org/10.1117/12.2652616}
}

@inproceedings{10.1117/12.2670944,
author = {Nicolas Detrez and Sazgar Burhan and Paul Strenge and Jessica Kren and Christian Hagel and Matteo Mario Bonsanto and Dirk Theisen-Kunde and Robert Huber and Ralf Brinkmann},
title = {{Air-jet based optical coherence elastography of brain tumor tissue: stiffness evaluation by structural histological analysis}},
volume = {12629},
booktitle = {Emerging Technologies for Cell and Tissue Characterization II},
editor = {Seemantini K. Nadkarni and Giuliano Scarcelli},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {126290M},
keywords = {Optical Coherence Elastography, Air-Jet, Phase-sensitive OCT, Histology Structure Analysis, Color-Deconvolution, Structural Tensors, Brain tumor, Tissue Characterization},
year = {2023},
doi = {10.1117/12.2670944},
URL = {https://doi.org/10.1117/12.2670944}
}

@inproceedings{10.1117/12.2649835,
author = {Nicolas Detrez and Sazgar Burhan and Katharina Rewerts and Jessica Kren and Christian Hagel and Matteo Mario Bonsanto and Dirk Theisen-Kunde and Robert Huber and Ralf Brinkmann},
title = {{Air-Jet based optical coherence elastography: processing and mechanical interpretation of brain tumor data}},
volume = {12381},
booktitle = {Optical Elastography and Tissue Biomechanics X},
editor = {Kirill V. Larin and Giuliano Scarcelli and Fr{\'e}d{\'e}rique Vanholsbeeck},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {1238105},
keywords = {Optical Coherence Elastography, Air-Jet, Air-Puff, biomechanics, viscoelasticity, rheology, brain tissue, brain tumor},
year = {2023},
doi = {10.1117/12.2649835},
URL = {https://doi.org/10.1117/12.2649835}
}

@inproceedings{10.1117/12.2652847,
author = {Sazgar Burhan and Nicolas Detrez and Katharina Rewerts and Madita G{\"o}b and Steffen Buschschl{\"u}ter and Christian Hagel and Matteo Mario Bonsanto M.D. and Dirk Theisen-Kunde and Robert Huber and Ralf Brinkmann},
title = {{Phase analysis strategies for MHz OCE in the large displacement regime}},
volume = {12367},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVII},
editor = {Joseph A. Izatt and James G. Fujimoto},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {123670Q},
abstract = {In neurosurgical tumor operations on the central nervous system, intraoperative haptic information often assists for discrimination between healthy and diseased tissue. Thus, it can provide the neurosurgeon with additional intraoperative source of information during resection, next to the visual information by the light microscope, fluorescent dyes and neuronavigation. One approach to obtain elastic and viscoelastic tissue characteristics non-subjectively is phase-sensitive optical coherence elastography (OCE), which is based on the principle of optical coherence tomography (OCT). While phase-sensitive OCE offers significantly higher displacement sensitivity inside a sample than commonly used intensity-based correlation methods, it requires a reliable algorithm to recover the phase signal, which is mathematically restricted in the -π to π range. This problem of phase wrapping is especially critical for inter-frame phase analysis since the time intervals between two referenced voxels is long. Here, we demonstrate a one-dimensional unwrapping algorithm capable of removing up to 4π-ambiguities between two frames in the complex phase data obtained from a 3.2 MHz-OCT system. The high sampling rate allows us to resolve large sample displacements induced by a 200 ms air pulse and acquires pixel-precise detail information. The deformation behavior of the tissue can be monitored over the entire acquisition time, offering various subsequent mechanical analysis procedures. The reliability of the algorithm and imaging concept was initially evaluated using different brain tumor mimicking phantoms. Additionally, results from human ex vivo brain tumor samples are presented and correlated with histological findings supporting the robustness of the algorithm.},
keywords = {Optical Coherence Tomography, Megahertz OCT, Fourier Domain Mode Locking, Optical Coherence Elastography, Phase-sensitive OCT, Phase Unwrapping, Brain tumor, Biomechanics},
year = {2023},
doi = {10.1117/12.2652847},
URL = {https://doi.org/10.1117/12.2652847}
}

@inproceedings{10.1117/12.2612171,
author = {Madita G{\"o}b and Sazgar Burhan and Simon Lotz and Robert Huber},
title = {{Towards ultra-large area vascular contrast skin imaging using multi-MHz-OCT}},
volume = {11948},
booktitle = {Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XXVI},
editor = {Joseph A. Izatt and James G. Fujimoto},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
pages = {1194807},
abstract = {We demonstrate ultra-large field of view OCT scanning using standard optics, a X-Y-galvanometer scanner and a synchronously driven motorized XYZ-positioning stage. The integration of a movable stage into our self-built 3.3 MHz- OCT system allows acquiring coherent ultra-large area images, fully leveraging the high speed potential of our system. For fast OCT-angiography, one galvanometer axis scanner is driven in a repetitive sawtooth pattern, fully synchronized to the movement of the linear stage, to obtain multiple measurements at each position. This technique requires exact synchronization, precise repositioning, and uniform movements with low tolerances to ensure a minimum revisitation error. We analyze error and performance of our setup and demonstrate angiographic imaging.},
keywords = {Optical Coherence Tomography, Fourier Domain Mode Locking, FDML, Optical Coherence Angiography, OCTA, Medical optics and biotechnology, Medical imaging, Three-dimensional image acquisition, Scanners, Microscopy},
year = {2022},
doi = {10.1117/12.2612171},
URL = {https://doi.org/10.1117/12.2612171}
}

@inproceedings{Gob:21,
author = {Madita G\"{o}b and Sazgar Burhan and Wolfgang Draxinger and Jan Philip Kolb and Robert Huber},
booktitle = {European Conferences on Biomedical Optics 2021 (ECBO)},
journal = {European Conferences on Biomedical Optics 2021 (ECBO)},
keywords = {AG-Huber_OCT;Fourier domain mode locking; Image processing; Image quality; Optical coherence tomography; Temporal resolution; Three dimensional imaging},
pages = {EW3C.4},
publisher = {Optical Society of America},
title = {Towards densely sampled ultra-large area multi-MHz-OCT for in vivo skin measurements beyond 1 cm$^2$/sec},
year = {2021},
url = {http://www.osapublishing.org/abstract.cfm?URI=ECBO-2021-EW3C.4},
abstract = {We demonstrate a 3.3 MHz A-scan rate OCT for rapid scanning of large areas of human skin. The mosaicking performance and different OCT imaging modalities including intervolume speckle contrast are evaluated.},
}