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Research Article Optoacoustichematomas Photoacoustics 2 (2014) 75…80 A R *Corresponding author: ScienceDirectepagevier brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Elsevier - Publisher Connector emergencyvehicle.UnlikeMRI,heavyshieldingandavoidancemagneticobjectsunnecessary.Althoughdiagnosisdelayedintracranialhematomashospitalizedpatientscande“nitivelyaccomplishedusingMRI,morerapidoptoacousticassessmentthatdoesnotrequiretransporttheradiologydepartmentcouldsavetimeandreducemorbidityhospitalizedpatientswhosuffersuddenneurologicdeterioration..……. The samepre-hospital device can both diagnose intracranial hematomas anddocument inadequate cerebral perfusion by detecting low SSShemoglobin saturation.Patients with mild, moderate or severe traumatic brain injuryand nontraumatic coma represent a population of at least2,000,000 patients who are likely to be emergently transportedto the hospital and for whom pre-hospital diagnosis of or exclusionof intracranial hematomas may dramatically reduce the timenecessary for de“nitive diagnosis and therapy after hospitalarrival. Formulating a preliminary diagnosis during pre-hospitaltransport could provide invaluable information to guide emergen-cy diagnosis and treatment after hospital admission. For instance,if a patient with a deteriorating level of consciousness beforehospital admission had an optoacoustic diagnosis of epiduralhematoma, surgeons and other hospital personnel could initiatepreparations for emergent craniotomy. If that patient were locatedin a rural area remote from a major medical center, evidence of anintracranial hematoma could prompt transport by helicopterrather than ambulance to speed arrival at a center that couldprovide emergency ne

urosurgical treatment.In thepresentstudy,usedprototypeoptoacousticsystemdetectblast-inducedextra-andintracranialhematomassmallanimalmodel.Themechanismsblastinjurieshumanscanclassi“edintoleasttypes[20]primaryinjuryresultsdirectlyfromblastover/underpressure.Secondaryblastinjuryresultsfromshrapnel(energizedfragmentsfromtheexplosive)debrisacceleratedtheblastwind.Tertiaryinjuriesresultfromaccelerationthebodytheblastwaveand/orwindandmayincludetumbling,impactontohardsurfaces,crushing.Quater-naryinjuriesincludeallothereffects,suchburnsandpoisoning.Alltheseclassi“cationsapplyanimalmodelswell.ll.. Irradiating a sample with multiple wavelengths willproduce acoustic signals that can be used for quantitative analysisof the samples absorption spectrum. For blood, we can determinethe oxygen saturation using the mavalues obtained from a multi-wavelength optoacoustic measurement and the spectra of oxy-and deoxyhemoglobin [10…15].The optoacoustic system used in this study (Fig. 1) wasdesigned for continuous monitoring of oxygenation in a variety ofblood vessels [11,12,15]. An optical parametric oscillator (OPO)(Opolette 532 II, Opotek Inc., Carlsbad, CA) outputs short ( 20 ns)pulses of near-infrared (NIR) light in the range from 680 to2400 nm, with pulse energy 8 mJ and repetition rate 20 Hz. Thisspectral range includes the 700…1064 nm spectral range which isbest for accurate oxygenation monitoring in deeper blood vesselsas shown in our previous studies in large animals (sheep) when wevalidated our noninvasive method using invasive measurements ofthe SSS blood oxygenation (blood sampling followed by Co-Oximeter measurements) [11,12,15]. As in the previous works, theratio of peak-to-peak optoacoustic amplitudes was used foraccurate oxygenation measuremen

ts. Although direct validationof noninvasive oxygenation measurements Fig. 1. Photo of the optoacoustic system. Laser/OPO block is mounted on the topshelf of the cart along with a box containing optical elements that direct light into 1-mm “ber. OPO controller, ampli“er and digitizer are located on the middle shelf,whereas OPO cooling tower and UPS occupy the lowest shelf.A. Petrov et al. / Photoacoustics 2 (2014) 75…8076 . To preventaccidental activation, the device only “res when an operatorsimultaneously presses two switches, which requires both hands.A solenoid drives a metal bar to strike the “ring pin against thecartridge (Fig. 2, bottom). In this study we used Ramset/Remingtonover/underpressureTheblastinjuryoftenwasfollowedtheformationhematoma(intracranial,extracranial,both)overtherighthemisphere,closetheSSS,whichwasrevealeduponthecompletiontheexperimentandanimaleuthanasia.EventhoughtheprobewasalignedovertheSSS,manycasesalsopickedoptoacousticsignalfromthehematoma.Thisallowedsimultaneous -0.40.00.0.81.1.62.0-0.60.00.1.21.2.4-0.8-0.6-0.4-0.20.00.20.40.60.8 swellin intracranialhematomaextracranialhematoma Depth, mm Energy-normalized OA Signal, a.u.Time, s fore blast blast + 5 min blast + 10 min blast + 20 minskin Fig. 3. Optoacoustic signals from a rats head before and after blast injury, acquiredat a wavelength of 800 nm. Fig. 2. Vandenberg blast device: external appearance (top); internal structure(bottom).A. Petrov et al. / Photoacoustics 2 (2014) 75…80 77 measurementbloodoxygenationtheSSSandthehematoma,wellmonitoringtheprogressionthehematoma.time-of-”ightmeasurements (t) = thickness of layer X (distance between boundaries)(t) - d)) / d) * 100% (% swelling in layer X) = d) - d = send) - s) = send sX/ t = /

(t(rate swelling) -20-15-100.00.51.01.52.02.53.0 (22.9) = 0.837 total = 0.043 mm total = 2.38 total t = 0.23 %/m = 0.094 mm int = 12.7 int 76 %/m (6.2) = .480 (6.2) = 0.743 mm = 0.187 = 39.0 sscalp/ 2.34 %/mintotal(-7) = 1.852 mm Depth (distance from skin) of optoacoustic peak Extracranial hematoma Intracranialmatom Timeom blast, min.Depth, total(-17.5) = 1.809 mm Fig. 4. Depths of the optoacoustic peaks, before and after blast, and de“nitions of swelling parameters. Table 1Blast-induced swelling rates by layer. d(start) and d(end) refer to the thickness atthe start and end of the monitoring period (either pre- or post-blast). Dd, Ds and Ds/Dt are de“ned in Fig. 4.Layer d(start), mm d(end), mm Dd, mm Ds, % Ds/Dt, %/minPre-blast total 1.809 1.852 0.043 02.4 0.23Post-blast total 2.128 2.459 0.331 15.6 0.93Scalp 0.480 0.667 0.187 39.0 2.34Skull 0.905 0.955 0.050 05.5 0.33Intracranial 0.743 0.837 0.094 12.7 0.76 -20-15-10100 MAP (mmHg) and oxygenation (%) Oxygenations: Extracranialmatom Intracranial hematoma SSSTime fromast, min Fig. 5. MAP and oxygenation of the SSS and hematomas, before and after blast.A. Petrov et al. / Photoacoustics 2 (2014) 75…8078 intracranial…fromwasduetheblast-inducedbraininjuryresultinginsuf“cientcerebralblood”ow.higherincreaseoxygenationtheextracranialhematomawasduelowoxygenconsumptionskintissuecomparedthatbraintissue.general,skintissueshavehigheroxygenationcomparedthatothertissues(includingbraintissues)becausetheloweroxygenconsumption.speculatethatthehematomaoxygenationwaslow40%)immediatelyaftertheblastbecause:thefreshhematomasconsistedprimarilyvenousblood70%cerebralbloodvenous)andtheblastmayresultrapidandtransientvasoconstrictionwithinminutesafterblast.Overtime,thepre

ssuregradientbetweenarterialandvenousbloodresultedleakagemorehighlysaturatedarterialandcapillarybloodintothehematoma.strongcorrelationbetweentheMAPandtheoxygenationeachhematomasupportsthishypothesis.measurementss and TBI patients [18] through intact scalp and skull. Thepenetration depth of our technique in these cases is 2 cm (up to1 cm scalp and 1 cm skull). In real clinical settings an optoacousticarray may be used to provide real-time, fast data acquisition forhematoma detection.Ourobservationshaveclinicaldiagnosticsigni“cance.Notonlywilltheoptoacousticdevicedetectintracranialhematomas,alsowillprovidevaluableinformationregardinghemoglobinsaturationthehematoma.Mostsubduralhematomasresultfromvenousbleedingandwouldexpectedhaverelativelylowhemoglobinsaturation.contrast,manyepiduralhematomasresultfromarterialdisruptionandwouldexpectedassociatedwithhemoglobinsaturationsimilararterialsaturation.Diagnosishematomaswithapparentarterialsourcecouldpromptmore Fig. 6. Extracranial (left) and intracranial (right) blast-induced hematomas on the right side of the brain. The scale bar is 1 cm.A. Petrov et al. / Photoacoustics 2 (2014) 75…80 79 rapidinterventionbecausearterialbleedingmaymorerapidlyprogressive.AcknowledgementsBioengineering)#W81XWH-10-1-1048), Andrey Petrov is a Research Technician at the Center forBiomedical Engineering, University of Texas MedicalBranch, USA. He received his B.S. in computer sciencefrom the University of Texas at Austin, USA, and hasextensive experience with software development inLabVIEW, C + + and other languages. He is currentlythe lead programmer in the Laboratory for OpticalSensing and Monitoring at UTMB, designing customsoftware for instrument control, data acquisition andsignal processing in multiple research projects. Kar

on E. Wynne is currently pursuing her Ph.D. inNeuroscience and a Masters in Public Health at TheUniversity of Texas Medical Branch (Galveston, TXUSA). She has been recognized as a Texas Space GrantConsortium Fellow and an Albert Schweitzer Fellow.Prior to attending graduate school Karon received abachelors degree in Mathematics from West VirginiaUniversity (WVU). After graduating from WVU, Karonworked for the U.S. Department of Energy at the Na-tional Energy Technology Laboratory and Argonne Na-tional Laboratory developing alternative energytechnology. M.S.degreeScientistInstituteapplications Katherine A. Ruppert received a Bachelor of Science inBiology from Texas A&M University (USA) in 2005. She iscurrently a PhD student in the Cell Biology GraduateProgram at the University of Texas Medical Branch(Galveston, TX, USA). Her dissertation research is fo-cused on the effects of blast-induced neurotrauma onblood-brain barrier permeability, tight junction proteinexpression and peroxynitrite formation in a rodentmodel. Rinat O. Esenaliev is Professor of the Department ofNeuroscience and Cell Biology and the Department ofAnesthesiology, Director of the Laboratory for OpticalSensing and Monitoring, and Director of High-resolutionUltrasound Imaging Core at the University of TexasMedical Branch (Galveston, TX, USA). He received hisM.S. degree in physics from the Moscow Institute ofPhysics and Technology and Ph.D. from Institute ofSpectroscopy (Moscow, Russia). He has more than 25years of experience in biomedical optoacousitcs, optoa-coustic instrumentation, and applications in monitor-ing, sensing, and imaging. He has pioneered a number ofoptoacoustic applications in biomedical imaging, sens-ing, and monitoring.A. Petrov et al. / Photoacoustics 2 (2014) 75…8080