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DePaoli D, Gasecka A, Bahdine M, Deschenes JM, Goetz L, Perez-Sanchez J, Bonin RP, De Koninck Y, Parent M, Côté DC. Anisotropic light scattering from myelinated axons in the spinal cord. NEUROPHOTONICS 2020; 7:015011. [PMID: 32206678 PMCID: PMC7063473 DOI: 10.1117/1.nph.7.1.015011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 01/14/2020] [Indexed: 06/10/2023]
Abstract
Optogenetics has become an integral tool for studying and dissecting the neural circuitries of the brain using optical control. Recently, it has also begun to be used in the investigation of the spinal cord and peripheral nervous system. However, information on these regions' optical properties is sparse. Moreover, there is a lack of data on the dependence of light propagation with respect to neural tissue organization and orientation. This information is important for effective simulations and optogenetic planning, particularly in the spinal cord where the myelinated axons are highly organized. To this end, we report experimental measurements for the scattering coefficient, validated with three different methods in both the longitudinal and radial directions of multiple mammalian spinal cords. In our analysis, we find that there is indeed a directional dependence of photon propagation when interacting with organized myelinated axons. Specifically, light propagating perpendicular to myelinated axons in the white matter of the spinal cord produced a measured reduced scattering coefficient ( μ s ' ) of 3.52 ± 0.1 mm - 1 , and light that was propagated along the myelinated axons in the white matter produced a measured μ s ' of 1.57 ± 0.03 mm - 1 , across the various species considered. This 50% decrease in scattering power along the myelinated axons is observed with three different measurement strategies (integrating spheres, observed transmittance, and punch-through method). Furthermore, this directional dependence in scattering power and overall light attenuation did not occur in the gray matter regions where the myelin organization is nearly random. The acquired information will be integral in preparing future light-transport simulations and in overall optogenetic planning in both the spinal cord and the brain.
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Affiliation(s)
- Damon DePaoli
- CERVO Brain Research Center, Québec City, Québec, Canada
- Center for Optics, Photonics and Lasers, Québec City, Québec, Canada
| | - Alicja Gasecka
- CERVO Brain Research Center, Québec City, Québec, Canada
- Center for Optics, Photonics and Lasers, Québec City, Québec, Canada
| | - Mohamed Bahdine
- CERVO Brain Research Center, Québec City, Québec, Canada
- Center for Optics, Photonics and Lasers, Québec City, Québec, Canada
| | - Jean M. Deschenes
- CERVO Brain Research Center, Québec City, Québec, Canada
- Center for Optics, Photonics and Lasers, Québec City, Québec, Canada
| | - Laurent Goetz
- CERVO Brain Research Center, Québec City, Québec, Canada
| | | | - Robert P. Bonin
- University of Toronto, Leslie Dan Faculty of Pharmacy, Toronto, Ontario, Canada
| | - Yves De Koninck
- CERVO Brain Research Center, Québec City, Québec, Canada
- Center for Optics, Photonics and Lasers, Québec City, Québec, Canada
| | - Martin Parent
- CERVO Brain Research Center, Québec City, Québec, Canada
| | - Daniel C. Côté
- CERVO Brain Research Center, Québec City, Québec, Canada
- Center for Optics, Photonics and Lasers, Québec City, Québec, Canada
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Rashnavadi T, Macnab A, Cheung A, Shadgan A, Kwon BK, Shadgan B. Monitoring spinal cord hemodynamics and tissue oxygenation: a review of the literature with special focus on the near-infrared spectroscopy technique. Spinal Cord 2019; 57:617-625. [PMID: 31164734 DOI: 10.1038/s41393-019-0304-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 01/05/2023]
Abstract
STUDY DESIGN Review. OBJECTIVES Clinical studies have shown that the hemodynamic management of patients following acute spinal cord injury (SCI) is an important aspect of their treatment for maintaining spinal cord (SC) perfusion and minimizing ischemic secondary injury to the SC. While this highlights the importance of ensuring adequate perfusion and oxygenation to the injured cord, a method for the real-time monitoring of these hemodynamic measures within the SC is lacking. The purpose of this review is to discuss current and potential methods for SC hemodynamic monitoring with special focus on applications using near-infrared spectroscopy (NIRS). METHODS A literature search using the PubMed database. All peer-reviewed articles on NIRS monitoring of SC published from inception to May 2019 were reviewed. RESULTS Among 125 papers related to SC hemodynamics monitoring, 26 focused on direct/indirect NIRS monitoring of the SC. DISCUSSION Current options for continuous, non-invasive, and real-time monitoring of SC hemodynamics are challenging and limited in scope. As a relatively new technique, NIRS has been successfully used for monitoring human cerebral hemodynamics, and has shown promising results in intraoperative assessment of SC hemodynamics in both human and animal models. Although utilizing NIRS to monitor the SC has been validated, applying NIRS clinically following SCI requires further development and investigation. CONCLUSIONS NIRS is a promising non-invasive technique with the potential to provide real-time monitoring of relevant parameters in the SC. Currently, in its first developmental stages, further clinical and experimental studies are mandatory to ensure the validity and safety of NIRS techniques.
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Affiliation(s)
- Tahereh Rashnavadi
- The University of British Columbia, School of Biomedical Engineering, Vancouver, BC, V6T 1Z1, Canada
| | - Andrew Macnab
- International Collaborations on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, Canada
| | - Amanda Cheung
- International Collaborations on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, Canada
| | - Armita Shadgan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Brian K Kwon
- International Collaborations on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, Canada.,Department of Orthopaedics, Faculty of Medicine, The University of British Columbia, Vancouver, Canada
| | - Babak Shadgan
- The University of British Columbia, School of Biomedical Engineering, Vancouver, BC, V6T 1Z1, Canada. .,International Collaborations on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, Vancouver, Canada. .,Department of Orthopaedics, Faculty of Medicine, The University of British Columbia, Vancouver, Canada.
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de Lima LAS, Lima KMG, de Oliveira LSS, Araújo AA, Fernandes de Araújo Junior R. Evaluation of the bony repair in rat cranial defect using near infrared reflectance spectroscopy and discriminant analysis. Biotechnol Prog 2017; 33:1160-1168. [DOI: 10.1002/btpr.2476] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 12/30/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Leomir A. S. de Lima
- Div. of Analytical Chemistry, Inst. of Chemistry, Biological Chemistry and Chemometrics; Federal University of Rio Grande do Norte; Natal RN 59072-970 Brazil
| | - Kássio M. G. Lima
- Div. of Analytical Chemistry, Inst. of Chemistry, Biological Chemistry and Chemometrics; Federal University of Rio Grande do Norte; Natal RN 59072-970 Brazil
| | - Lana S. S. de Oliveira
- Dept. of Biophysics and Pharmacology; Post-graduation programme in Public Health/Post graduation programme in Pharmaceutical Science, Federal University of Rio Grande do Norte; Natal RN 59072-970 Brazil
| | - Aurigena A. Araújo
- Dept. of Biophysics and Pharmacology; Post-graduation programme in Public Health/Post graduation programme in Pharmaceutical Science, Federal University of Rio Grande do Norte; Natal RN 59072-970 Brazil
| | - Raimundo Fernandes de Araújo Junior
- Dept. of Morphology, Post-graduation programme in Health Science/Post graduation programme in Structural and Functional Biology; Federal University of Rio Grande do Norte; Natal RN 59072-970 Brazil
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Tsiakaka O, Terosiet M, Romain O, Histace A, Benali H, Pradat PF, Vallette F, Feher M, Feruglio S. In vivo NIRS monitoring in pig Spinal Cord tissues. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:4262-5. [PMID: 26737236 DOI: 10.1109/embc.2015.7319336] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Little is known about the processes occurring after Spinal Cord damage. Whether permanent or recoverable, those processes have not been precisely characterized because their mechanism is complex and information on the functioning of this organ are partial. This study demonstrates the feasibility of Spinal Cord activity monitoring using Near Infra-Red Spectroscopy in a pig animal model. This animal has been chosen because of its comparable size and its similarities with humans. In the first step, optical characterization of the Spinal Cord tissues was performed in different conditions using a spectrophotometer. Optical Density was evaluated between 3.5 and 6.5 in the [500; 950] nm range. Secondly, adapted light sources with custom probes were used to observe autonomic functions in the spine. Results on the measured haemodynamics at rest and under stimulation show in real time the impact of a global stimulus on a local section of the Spinal Cord. The photoplethysmogram signal of the Spinal Cord showed low AC-to-DC ratio (below to 1 %).
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Piao D, Sultana N, Holyoak GR, Ritchey JW, Wall CR, Murray JK, Bartels KE. In vivo assessment of diet-induced rat hepatic steatosis development by percutaneous single-fiber spectroscopy detects scattering spectral changes due to fatty infiltration. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:117002. [PMID: 26538183 DOI: 10.1117/1.jbo.20.11.117002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/09/2015] [Indexed: 06/05/2023]
Abstract
This study explores percutaneous single-fiber spectroscopy (SfS) of rat livers undergoing fatty infiltration. Eight test rats were fed a methionine-choline-deficient (MCD) diet, and four control rats were fed a normal diet. Two test rats and one control rat were euthanized on days 12, 28, 49, and 77 following initiation of the diet, after percutaneous SfS of the liver under transabdominal ultrasound guidance. Histology of each set of the two euthanized test rats showed mild and mild hepatic lipid accumulations on day 12, moderate and severe on day 28, severe and mild on day 49, and moderate and mild on day 77. Livers with moderate or higher lipid accumulation generally presented higher spectral reflectance intensity when compared to lean livers. Livers of the eight test rats on day 12, two of which had mild lipid accumulation, revealed an average scattering power of 0.37±0.14 in comparison to 0.07±0.14 for the four control rats (p<0.01 ). When livers of the test rats with various levels of fatty infiltration were combined, the average scattering power was 0.36±0.15 0.36±0.15 in comparison to 0.14±0.24 of the control rats (0.05<p<0.1). Increasing lipid accumulation in concentration and size seemed to cause an increase of the scattering power prior to increasing total spectral reflectance.
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Affiliation(s)
- Daqing Piao
- Oklahoma State University, School of Electrical and Computer Engineering, 202 Engineering South, Stillwater, Oklahoma 74078, United States
| | - Nigar Sultana
- Oklahoma State University, Graduate Program on Interdisciplinary Sciences, Stillwater, Oklahoma 74078, United States
| | - G Reed Holyoak
- Oklahoma State University, Center for Veterinary Health Sciences, Department of Veterinary Clinical Sciences, 002 VTH, Stillwater, Oklahoma 74078, United States
| | - Jerry W Ritchey
- Oklahoma State University, Center for Veterinary Health Sciences, Department of Veterinary Pathobiology, 250 McElroy Hall, Stillwater, Oklahoma 74078, United States
| | - Corey R Wall
- Oklahoma State University, Center for Veterinary Health Sciences, Department of Veterinary Clinical Sciences, 002 VTH, Stillwater, Oklahoma 74078, United States
| | - Jill K Murray
- Oklahoma State University, Center for Veterinary Health Sciences, Department of Veterinary Clinical Sciences, 002 VTH, Stillwater, Oklahoma 74078, United States
| | - Kenneth E Bartels
- Oklahoma State University, Center for Veterinary Health Sciences, Department of Veterinary Clinical Sciences, 002 VTH, Stillwater, Oklahoma 74078, United States
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Piao D, McKeirnan KL, Sultana N, Breshears MA, Zhang A, Bartels KE. Percutaneous single-fiber reflectance spectroscopy of canine intervertebral disc: is there a potential for in situ probing of mineral degeneration? Lasers Surg Med 2014; 46:508-19. [PMID: 24889688 DOI: 10.1002/lsm.22261] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2014] [Indexed: 11/09/2022]
Abstract
BACKGROUND AND OBJECTIVES Intervertebral disc herniation is a common disease in chondrodystrophic dogs, and a similar neurologic condition also occurs in humans. Percutaneous laser disc ablation (PLDA) is a minimally invasive procedure used increasingly for prevention of disc herniation. Currently, PLDA is performed on thoracolumbar discs with the same laser energy applied regardless of the differing extent of degeneration among mineralized discs. In a previous study performed on 15 normal and 6 degenerated intervertebral discs in chondrodystrophoid canine species, it was demonstrated that percutaneous single-fiber reflectance spectroscopy (SfRS) detected increased light scattering from mineralized intervertebral discs when comparing to normal discs. The objective of this study is to evaluate how SfRS evaluation of mineralized discs in situ fairs with X-ray radiography and computed tomography (CT) diagnoses and if SfRS sensing of the scattering changes correlates with the level of mineral degeneration in nucleus pulposus. MATERIALS AND METHODS Percutaneous SfRS was performed on a total of 28 intervertebral discs of three dogs post-mortem, through a 20 gauge spinal needle standard to PLDA. The raw SfRS measurement was normalized to extract a dimension-less spectral intensity profile, from which the average over 600-900 nm was used as the SfRS intensity index to compare among the measured discs. The discs were imaged prior to percutaneous SfRS by radiography and CT, and harvested after percutaneous SfRS for histopathologic examinations. RESULTS Five among 10 discs of dog #1, six among 9 discs of dog #2, and nine out of 9 discs of dog #3 were determined by histopathology to have central focal or multi-focal areas of mineralization occupying 5-75% of the examined area of nucleus pulposus. The overall numbers of discs with detectable and undetectable central mineralization were 20 and 8, respectively. CT resulted in one false positive (FP) and four false negative (FN) diagnoses for dog #1, three FP and zero FN diagnoses for dog #2, and zero FP and one FN diagnosis for dog #3. Of the total 28 discs the CT had an overall positive predictive value (PPV) of 78.8% and an overall negative predictive value (NPV) of 44.4%. X-ray radiography gave five FN diagnoses for dog #1, two FN diagnoses for dog #2, and eight FN diagnoses for dog #3. Of the total 28 discs the radiography had an overall PPV of 100% and an overall NPV of 30.4%. The receiver-operating-characteristic analysis of the SfRS measurement was performed on 24 discs that had a central mineralization not greater than 50%. An area-under-curve of 0.6758 infers that the SfRS intensity weakly indicates the level of mineralization. CONCLUSIONS Percutaneous SfRS may be useful as an in situ sensing tool for assessing the level of mineral degeneration in intervertebral discs for the prospect of disc-specific dosage adjustment in PLDA.
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Affiliation(s)
- Daqing Piao
- School of Electrical and Computer Engineering, Oklahoma State University, 202 Engineering South, Stillwater, Oklahoma, 74078
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Amiri AR, Lee CH, Leung TS, Hetreed M, Craggs MD, Casey ATH. Intraoperative assessment of human spinal cord perfusion using near infrared spectroscopy with indocyanine green tracer technique. Spine J 2013; 13:1818-25. [PMID: 23954558 DOI: 10.1016/j.spinee.2013.05.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 03/05/2013] [Accepted: 05/30/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Despite the significant interest in the assessment of human cerebral perfusion, investigations into human spinal cord perfusion (SCP) are scarce. Current intraoperative monitoring of spinal cord relies on the assessment of neural conduction as a surrogate for SCP. However, there are various inherent limitations associated with the use of these techniques. Near infrared spectroscopy (NIRS) has been successfully used for monitoring and assessment of human cerebral perfusion and has shown promising results in intraoperative assessment of SCP in animal models. PURPOSE The aim of this study was to investigate whether it is possible to monitor physiological changes in human SCP intraoperatively using NIRS with indocyanine green (ICG) tracer technique. We used this technique to calculate the human spinal cord carbon dioxide (CO₂) reactivity index. In addition, we investigated whether the lamina causes significant attenuation of NIRS signals. STUDY DESIGN/SETTING Intraoperative human experimental study. PATIENT SAMPLE Eighteen patients undergoing elective posterior cervical spine surgery. OUTCOME MEASURES Carbon dioxide reactivity of human SCP. METHODS Nine patients underwent transdural assessment of SCP, with an additional nine patients undergoing translaminar measurements. Patients' SCP was continuously monitored using an NIRO-500 NIRS monitor via a set of purpose built optodes. Their arterial ICG concentration was simultaneously assessed using a pulse dye densitometer. Patients' end-tidal CO₂ was gradually increased by 7.5 mm Hg and then returned back to baseline. Three sets of measurements were taken: baseline, hypercapnic, and return to baseline. RESULTS After hypercapnia, SCP increased by a mean of 57.2 ± 23.3% in the transdural group and 46.6 ± 36.3% in the translaminar group. Carbon dioxide reactivity index was 7.6 ± 3.2%ΔSCP/mm Hg in the transdural group and 6.4 ± 5.3 %ΔSCP/mm Hg in the translaminar group. There was no significant difference in the increase in SCP (p=.475) or the CO₂ reactivity index (p=.581) observed between the transdural and the translaminar groups. CONCLUSIONS Intraoperative NIRS with ICG tracer technique can identify an increase in the SCP in response to hypercapnia. It is possible to use this technique for monitoring SCP over the dura and the lamina. This technique could potentially be used to provide insight in to the pathophysiology and autoregulation of commonly acquired spinal cord conditions. Further research assessing the use of NIRS for monitoring of SCP is required.
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Affiliation(s)
- Amir Reza Amiri
- Spinal Injury Unit, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex HA7 4LP, United Kingdom.
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Desjardins AE, van der Voort M, Roggeveen S, Lucassen G, Bierhoff W, Hendriks BHW, Brynolf M, Holmström B. Needle stylet with integrated optical fibers for spectroscopic contrast during peripheral nerve blocks. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:077004. [PMID: 21806284 DOI: 10.1117/1.3598852] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The effectiveness of peripheral nerve blocks is highly dependent on the accuracy at which the needle tip is navigated to the target injection site. Even when electrical stimulation is utilized in combination with ultrasound guidance, determining the proximity of the needle tip to the target region close to the nerve can be challenging. Optical reflectance spectroscopy could provide additional information about tissues that is complementary to these navigation methods. We demonstrate a novel needle stylet for acquiring spectra from tissue at the tip of a commercial 20-gauge needle. The stylet has integrated optical fibers that deliver broadband light to tissue and receive scattered light. Two spectrometers resolve the light that is received from tissue across the wavelength range of 500-1600 nm. In our pilot study, measurements are acquired from a postmortem dissection of the brachial plexus of a swine. Clear differences are observed between spectra acquired from nerves and those acquired from adjacent tissue structures. We conclude that spectra acquired with the stylet have the potential to increase the accuracy with which peripheral nerve blocks are performed.
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He JW, Kashyap D, Trevino LA, Liu H, Peng YB. Simultaneous absolute measures of glabrous skin hemodynamic and light-scattering change in response to formalin injection in rats. Neurosci Lett 2011; 492:59-63. [PMID: 21281696 DOI: 10.1016/j.neulet.2011.01.057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 01/21/2011] [Accepted: 01/23/2011] [Indexed: 12/20/2022]
Abstract
Subcutaneous injection of formalin is a well-known model to study the nature of inflammatory pain. One of the cardinal signs of inflammation is redness, as a result of increased blood perfusion. We used an optical technology, light reflectance spectroscopy, to noninvasively obtain absolute measures of cutaneous hemodynamic components, including the concentrations of oxy- ([HbO]), deoxy- ([Hb]), total-hemoglobin ([HbT]), oxygen saturation (SO(2)), and the reduced light-scattering coefficient (μs'). The objective is to assess the effect of formalin-induced skin inflammation on the aforementioned parameters. Six rats were injected with formalin (50 μl, 3%) into left hind paw under pentobarbital anesthesia. Our results indicate prolonged increases in [HbO], [HbT], and SO(2) post injection only in the ipsilateral side. No statistically significant changes in [Hb] and μ(s)' occurred in either side. The arterial blood influx tends to be the major attribute of local hyperemia during inflammation. Thereby, [HbO] appears to be superior to [Hb] in measuring inflammation. In conclusion, the needle-probe-based light reflectance can be a feasible means to obtaining absolute measures of skin hemodynamic and light-scattering parameters when studying inflammatory pain.
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Affiliation(s)
- Ji-Wei He
- Department of Psychology, College of Science, University of Texas at Arlington, Arlington, TX 76019-0528, USA
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Quantification of light reflectance spectroscopy and its application: determination of hemodynamics on the rat spinal cord and brain induced by electrical stimulation. Neuroimage 2011; 56:1316-28. [PMID: 21255660 DOI: 10.1016/j.neuroimage.2011.01.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 01/06/2011] [Accepted: 01/08/2011] [Indexed: 12/20/2022] Open
Abstract
Two quantification methods for light reflectance spectroscopy (LRS) were developed and validated to determine absolute and relative values of hemodynamic parameters and light scattering, followed by a specific application using in vivo animal experiments. A single-channel LRS system consisted of a light source, CCD-array detector, and a computer along with a bifurcated, 2-mm-diameter optical probe; this system was utilized to perform laboratory tissue phantoms for validation of the algorithms. In the animal study, a multi-channel, multisite approach was used to measure several reflectance spectra from rat brain and spinal cord on both the ipsi-lateral and contra-lateral sides, using thin 800-μm-diameter optic probes. The neuro-hemodynamic changes were induced by 10-V electrical stimulation in rat hind paw. The LRS data of the animals were analyzed using both absolute and relative methods. The results show that the relative method is computation-efficient and offers a quick estimation of changes in oxy-hemoglobin concentration for real-time monitoring. The absolute quantification method, on the other hand, provides us with an accurate computational tool to calculate absolute values of oxy-, deoxy-, total hemoglobin concentrations, and light scattering coefficients. We also observe that the hemodynamic responses in rat spinal cord were delayed with a few seconds and have an overall broader full width at half maximum, as compared to those from rat somatosensory cortex. LRS as a measurement system provides a robust method for studying local hemodynamic changes and a potential technique to investigate hemo-neural mechanisms in pain processing.
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Sharma V, Kashyap D, Mathker A, Narvenkar S, Bensalah K, Kabbani W, Tuncel A, Cadeddu JA, Liu H. Optical reflectance spectroscopy for detection of human prostate cancer. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:118-21. [PMID: 19964924 DOI: 10.1109/iembs.2009.5334830] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We present the method and application of optical reflectance spectroscopy to differentiate prostate cancer from normal tissue using a needle like, bifurcated, fiber-optic probe. An analytical expression to model light reflectance recently published by Zonios et. al. was used to derive optical properties of tissue. A total of 23 cases of human prostate specimens were investigated to analyze statistical differences between the respective cancerous tissues versus normal tissues. The results demonstrate that the derived hemodynamic parameters and optical properties can serve as good bio-markers to differentiate tumor tissue from normal tissue in human prostate.
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Affiliation(s)
- Vikrant Sharma
- International Techlink Group, Inc, Arlington, TX 76010, USA.
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Radhakrishnan H, Liu H, Senapati AK, Peng YB. Determination of hemoglobin oxygen saturation in rat sciatic nerve by in vivo near infrared spectroscopy. Brain Res 2006; 1098:86-93. [PMID: 16784732 DOI: 10.1016/j.brainres.2006.04.101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Revised: 04/14/2006] [Accepted: 04/23/2006] [Indexed: 11/16/2022]
Abstract
The purpose of this study is to investigate the values of hemoglobin oxygen saturation in the sciatic nerve of the rat following spinal nerve ligation. An optical spectroscopic technique along with a fiber optic probe was used to test the hypothesis that demyelination and degeneration after nerve injury lead to a significant decrease in the percentage of hemoglobin oxygen saturation. A modified spinal nerve ligation method was used to induce the degeneration, and three types of ligation on left spinal nerve (L4, L4 and L5, L5) were performed in rats. The optical reflectance measurements were taken from the left and right sciatic nerves on postoperative days 1, 4, 7, and 14. No significant difference was found among the three types of ligation, nor was between left and right sciatic nerve at postoperative day 1. Significant decreases in oxygen saturation percentages were found between left and right sciatic nerves at postoperative days 4, 7, and 14. This study continues to show the effectiveness of optical methods in determining/differentiating tissue properties, providing an excellent and robust in vivo technique that can have a potential clinical application in detecting demyelination and degeneration of the nervous system.
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Affiliation(s)
- Harsha Radhakrishnan
- University of Texas at Arlington/UT Southwestern Medical Center at Dallas, Joint Graduate Program of Biomedical Engineering, Arlington, TX 76019, USA
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