title: Noninvasive blood flow imaging for real-time feedback during laser therapy of port wine stain birthmarks.
abstract: OBJECTIVE
  During laser therapy of port wine stain (PWS) birthmarks, regions of persistent perfusion may exist. Immediate retreatment of such regions may improve PWS laser therapeutic outcome. To address this need, we propose use of laser speckle imaging (LSI) to provide real-time, quantitative feedback during laser surgery. Herein, we present in vitro and in vivo data collected with a clinic-based LSI instrument.
  
  
  METHODS
  Prior to clinical implementation, we first investigated three aspects of LSI deemed important for clinical imaging: (1) instrument depth of field (DOF); (2) effects of laser irradiance on speckle flow index (SFI) values; and (3) measurement repeatability. Clinical measurements were acquired from the lesions of PWS patients immediately prior to and after laser therapy at the Beckman Laser Institute.
  
  
  RESULTS
  Our preclinical data suggest the following: (1) instrument DOF was approximately 1 cm; (2) quantitative flow characterization with LSI was practically unaffected at normalized irradiance values between 0.06 and 0.5; and (3) our LSI instrument was capable of highly reproducible SFI values. From our clinical measurements, we found that the relative difference between blood perfusion in PWS lesions and adjacent normal skin was highly variable. Based on SFI images, the perfusion of PWS skin is sometimes indistinguishable from that of adjacent normal skin. With laser therapy, we measured a global decrease in blood perfusion, and we frequently observed distinct regions of persistent perfusion.
  
  
  CONCLUSIONS
  Our results demonstrate the potential role of image-guided laser therapy of PWS birthmarks. LSI is a promising tool for noninvasive blood flow characterization during laser therapy due to its relative simplicity and low cost.
authors: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California 92612, USA.
authors: Yu-Chih
authors: YC
authors: Huang
authors: Tyson L
authors: TL
authors: Ringold
authors: J Stuart
authors: JS
authors: Nelson
authors: Bernard
authors: B
authors: Choi
mesh_terms: D000328:Adult; D000818:Animals; D005145:Face / Q000098:blood supply; D005260:Female; D018056:Hemorheology; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D051379:Mice; D008833:Microcirculation / Q000503:physiopathology; D019339:Port-Wine Stain / Q000503:physiopathology* / Q000601:surgery*; D012039:Regional Blood Flow / Q000502:physiology; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted