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Bisht A, Simone K, Bains JS, Murari K. Distinguishing motion artifacts during optical fiber-based in-vivo hemodynamics recordings from brain regions of freely moving rodents. NEUROPHOTONICS 2024; 11:S11511. [PMID: 38799809 PMCID: PMC11123205 DOI: 10.1117/1.nph.11.s1.s11511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 03/25/2024] [Accepted: 04/29/2024] [Indexed: 05/29/2024]
Abstract
Significance Motion artifacts in the signals recorded during optical fiber-based measurements can lead to misinterpretation of data. In this work, we address this problem during in-vivo rodent experiments and develop a motion artifacts correction (MAC) algorithm for single-fiber system (SFS) hemodynamics measurements from the brains of rodents. Aim (i) To distinguish the effect of motion artifacts in the SFS signals. (ii) Develop a MAC algorithm by combining information from the experiments and simulations and validate it. Approach Monte-Carlo (MC) simulations were performed across 450 to 790 nm to identify wavelengths where the reflectance is least sensitive to blood absorption-based changes. This wavelength region is then used to develop a quantitative metric to measure motion artifacts, termed the dissimilarity metric (DM). We used MC simulations to mimic artifacts seen during experiments. Further, we developed a mathematical model describing light intensity at various optical interfaces. Finally, an MAC algorithm was formulated and validated using simulation and experimental data. Results We found that the 670 to 680 nm wavelength region is relatively less sensitive to blood absorption. The standard deviation of DM (σ D M ) can measure the relative magnitude of motion artifacts in the SFS signals. The artifacts cause rapid shifts in the reflectance data that can be modeled as transmission changes in the optical lightpath. The changes observed during the experiment were found to be in agreement to those obtained from MC simulations. The mathematical model developed to model transmission changes to represent motion artifacts was extended to an MAC algorithm. The MAC algorithm was validated using simulations and experimental data. Conclusions We distinguished motion artifacts from SFS signals during in vivo hemodynamic monitoring experiments. From simulation and experimental data, we showed that motion artifacts can be modeled as transmission changes. The developed MAC algorithm was shown to minimize artifactual variations in both simulation and experimental data.
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Affiliation(s)
- Anupam Bisht
- University of Calgary, Biomedical Engineering Graduate Program, Calgary, Alberta, Canada
- University of Calgary, Hotchkiss Brain Institute, Calgary, Alberta, Canada
| | - Kathryn Simone
- University of Calgary, Biomedical Engineering Graduate Program, Calgary, Alberta, Canada
- University of Calgary, Hotchkiss Brain Institute, Calgary, Alberta, Canada
| | - Jaideep S. Bains
- University of Calgary, Hotchkiss Brain Institute, Calgary, Alberta, Canada
- University of Calgary, Cumming School of Medicine, Department of Physiology and Pharmacology, Calgary, Alberta, Canada
| | - Kartikeya Murari
- University of Calgary, Biomedical Engineering Graduate Program, Calgary, Alberta, Canada
- University of Calgary, Hotchkiss Brain Institute, Calgary, Alberta, Canada
- University of Calgary, Electrical and Software Engineering, Calgary, Alberta, Canada
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Ooms M, Winnand P, Heitzer M, Peters F, Bock A, Katz MS, Hölzle F, Modabber A. Attached compared with unattached surface probes for monitoring flap perfusion in microvascular head and neck reconstruction: a feasibility study. Sci Rep 2023; 13:15939. [PMID: 37743387 PMCID: PMC10518317 DOI: 10.1038/s41598-023-43151-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 09/20/2023] [Indexed: 09/26/2023] Open
Abstract
Unattached surface probes are commonly used with the O2C analysis system (LEA Medizintechnik, Germany) to monitor microvascular free flap perfusion. This study compared attached and unattached surface probes for extraoral free flaps. The study included 34 patients who underwent extraoral microvascular head and neck reconstruction between 2020 and 2022. Flap perfusion was monitored postoperatively using the O2C analysis system at 0, 12, 24, 36, and 48 h, with an attached surface probe at 3 mm tissue depth and an unattached surface probe at 2 mm and 8 mm tissue depths. Clinical complications, technical errors, and perfusion measurement values were compared. No clinical complications (attachment suture infections) or technical errors (probe detachment) occurred. Flap blood flow values of the probes were partially different (3 mm vs. 2 and 8 mm: p < 0.001; p = 0.308) and moderately correlated (3 mm with 2 and 8 mm: r = 0.670, p < 0.001; r = 0.638, p < 0.001). Hemoglobin concentration and oxygen saturation values were generally different (3 mm vs. 2 and 8 mm: all p < 0.001) and variably correlated (3 mm with 2 and 8 mm: r = 0.756, r = 0.645; r = 0.633, r = 0.307; all p < 0.001). Both probes are comparable in terms of technical feasibility and patient safety, with flap perfusion values dependent on tissue measurement depth.
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Affiliation(s)
- Mark Ooms
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany.
| | - Philipp Winnand
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Marius Heitzer
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Florian Peters
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Anna Bock
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Marie Sophie Katz
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Frank Hölzle
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Ali Modabber
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
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Ooms M, Winnand P, Heitzer M, Peters F, Bock A, Katz M, Hölzle F, Modabber A. Flap perfusion monitoring with an attached surface probe in microvascular reconstruction of the oral cavity. Clin Oral Investig 2023; 27:5577-5585. [PMID: 37522990 PMCID: PMC10492739 DOI: 10.1007/s00784-023-05177-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 07/17/2023] [Indexed: 08/01/2023]
Abstract
OBJECTIVES Postoperative flap monitoring is essential in oral microvascular reconstruction for timely detection of vascular compromise. This study investigated the use of attached surface probes for the oxygen-2-see (O2C) analysis system (LEA Medizintechnik, Germany) for intraoral flap perfusion monitoring. MATERIALS AND METHODS The study included 30 patients who underwent oral reconstruction with a microvascular radial-free forearm flap (RFFF) or anterolateral thigh flap (ALTF) between 2020 and 2022. Flap perfusion was measured with attached (3-mm measurement depth) and unattached surface probes (2- and 8-mm measurement depths) for the O2C analysis system at 0, 12, 24, 36, and 48 h postoperatively. Flap perfusion monitoring with attached surface probes was evaluated for cut-off values for flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation indicative of vascular compromise and for accuracy and concordance with unattached surface probes. RESULTS Three RFFFs were successfully revised, and one ALTF was unsuccessfully revised. The cut-off values indicative of vascular compromise for flap perfusion monitoring with attached surface probes were for RFFF and ALTF: blood flow < 60 arbitrary units (AU) and < 40AU, hemoglobin concentration > 100AU and > 80AU (both > 10% increase), and hemoglobin oxygen saturation < 40% and < 30%. Flap perfusion monitoring with attached surface probes yielded a 97.1% accuracy and a Cohen's kappa of 0.653 (p < 0.001). CONCLUSIONS Flap perfusion monitoring with attached surface probes for the O2C analysis system detected vascular compromise accurately and concordantly with unattached surface probes. CLINICAL RELEVANCE Attached surface probes for the O2C analysis system are a feasible option for intraoral flap perfusion monitoring.
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Affiliation(s)
- Mark Ooms
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany.
| | - Philipp Winnand
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Marius Heitzer
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Florian Peters
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Anna Bock
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Marie Katz
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Frank Hölzle
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
| | - Ali Modabber
- Department of Oral and Maxillofacial Surgery, University Hospital RWTH Aachen, Pauwelsstraße 30, 52074, Aachen, Germany
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Setchfield K, Gorman A, Simpson AHRW, Somekh MG, Wright AJ. Relevance and utility of the in-vivo and ex-vivo optical properties of the skin reported in the literature: a review [Invited]. BIOMEDICAL OPTICS EXPRESS 2023; 14:3555-3583. [PMID: 37497524 PMCID: PMC10368038 DOI: 10.1364/boe.493588] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/07/2023] [Accepted: 06/07/2023] [Indexed: 07/28/2023]
Abstract
Imaging non-invasively into the human body is currently limited by cost (MRI and CT scan), image resolution (ultrasound), exposure to ionising radiation (CT scan and X-ray), and the requirement for exogenous contrast agents (CT scan and PET scan). Optical imaging has the potential to overcome all these issues but is currently limited by imaging depth due to the scattering and absorption properties of human tissue. Skin is the first barrier encountered by light when imaging non-invasively, and therefore a clear understanding of the way that light interacts with skin is required for progress on optical medical imaging to be made. Here we present a thorough review of the optical properties of human skin measured in-vivo and compare these to the previously collated ex-vivo measurements. Both in-vivo and ex-vivo published data show high inter- and intra-publication variability making definitive answers regarding optical properties at given wavelengths challenging. Overall, variability is highest for ex-vivo absorption measurements with differences of up to 77-fold compared with 9.6-fold for the in-vivo absorption case. The impact of this variation on optical penetration depth and transport mean free path is presented and potential causes of these inconsistencies are discussed. We propose a set of experimental controls and reporting requirements for future measurements. We conclude that a robust in-vivo dataset, measured across a broad spectrum of wavelengths, is required for the development of future technologies that significantly increase the depth of optical imaging.
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Affiliation(s)
- Kerry Setchfield
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, NG7 2RD, UK
| | | | - A Hamish R W Simpson
- Department of Orthopaedics, Division of Clinical and Surgical Sciences, University of Edinburgh, EH8 9YL, UK
| | - Michael G Somekh
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, NG7 2RD, UK
| | - Amanda J Wright
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, NG7 2RD, UK
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