title: Fiber-based laser speckle imaging for the detection of pulsatile flow.
abstract: OBJECTIVE
  In endodontics, a major diagnostic challenge is the accurate assessment of pulp status. In this study, we designed and characterized a fiber-based laser speckle imaging system to study pulsatile blood flow in the tooth.
  
  
  METHODS
  To take transilluminated laser speckle images of the teeth, we built a custom fiber-based probe. To assess our ability to detect changes in pulsatile flow, we performed in vitro and preliminary in vivo tests on tissue-simulating phantoms and human teeth. We imaged flow of intralipid in a glass microchannel at simulated heart rates ranging from 40 beats/minute (bpm) to 120 bpm (0.67-2.00 Hz). We also collected in vivo data from the upper front incisors of healthy subjects. From the measured raw speckle data, we calculated temporal speckle contrast versus time. With frequency-domain analysis, we identified the frequency components of the contrast waveforms.
  
  
  RESULTS
  With our approach, we observed in vitro the presence of pulsatile flow at different simulated heart rates. We characterized simulated heart rate with an accuracy of and >98%. In the in vivo proof-of-principle experiment, we measured heart rates of 69, 90, and 57 bpm, which agreed with measurements of subject heart rate taken with a wearable, commercial pulse oximeter.
  
  
  CONCLUSIONS
  We designed, built, and tested the performance of a dental imaging probe. Data from in vitro and in -vivo tests strongly suggest that this probe can detect the presence of pulsatile flow. LSI may enable endodontists to noninvasively assess pulpal vitality via direct measurement of blood flow.
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California, 92612.|Department of Biomedical Engineering, University of California, Irvine, California, 92697.
authors.forename: Caitlin
authors.initials: C
authors.lastname: Regan
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California, 92612.
authors.forename: Bruce Y
authors.initials: BY
authors.lastname: Yang
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California, 92612.|Department of Biomedical Engineering, University of California, Irvine, California, 92697.
authors.forename: Kent C
authors.initials: KC
authors.lastname: Mayzel
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California, 92612.|Optics Department, Instituto Nacional de Astrofísica, Óptica y Electrónica, Puebla, México, 72840.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Ramirez-San-Juan
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California, 92612.|Department of Surgery, University of California, Irvine Medical Center, Orange, California, 92868.
authors.forename: Petra
authors.initials: P
authors.lastname: Wilder-Smith
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California, 92612.|Department of Biomedical Engineering, University of California, Irvine, California, 92697.|Department of Surgery, University of California, Irvine Medical Center, Orange, California, 92868.|Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, California, 92697.
authors.forename: Bernard
authors.initials: B
authors.lastname: Choi
mesh_terms: D003782:Dental Pulp / Q000098:blood supply*; D004867:Equipment Design; D064368:Healthy Volunteers; D006801:Humans; D066298:In Vitro Techniques; D054020:Lasers, Gas; D055100:Optical Fibers; D061848:Optical Imaging / Q000295:instrumentation* / Q000379:methods; D017156:Photoplethysmography / Q000295:instrumentation / Q000379:methods; D011673:Pulsatile Flow
keywords: cold test; dental photoplethysmography; electric pulp test; endodontics; leached fiber bundle; pulpal vitality; pulsatile blood flow; root canal