Port wine stain (PWS) birthmarks are progressive vascular malformations that occur in ∼12,000 live births per year in the United States. The majority (∼90%) of PWS birthmarks occur on the head and neck regions, and thus are difficult to conceal. The psychosocial development of individuals with PWS birthmarks is adversely affected. Facial PWS lesions have been associated with increased incidence of glaucoma and seizures. The progressive nature of PWS skin may be due to lack of neuronal regulation of blood vessel size. Progressive development of the PWS results in a darker appearance, soft tissue hypertrophy, nodularity, and overall further disfigurement. Current treatment options have significant limitations in terms of efficacy and risk. With laser therapy, a reduction in size and degree of redness of PWS skin occurs in ∼60% of treated patients. After ten treatment sessions, complete disappearance of the PWS occurs in only ∼10% of treated patients. To reduce the financial burden and potential risks of repeated treatments under general anesthesia, there is a need for innovative, personalized methods to maximize the reduction in PWS redness per treatment session. Without addressing this need, the overall efficacy of PWS laser therapy will remain variable, because treatment protocols will remain based primarily on the subjective impression and overall experience of the treating surgeon. To address this need, we propose use of laser speckle imaging (LSI) to provide real-time, quantitative feedback during laser surgery.

Recently, Laser Speckle Imaging (LSI) has been applied to measure blood perfusion in human skin. Attractive features of LSI are its temporal resolution and relatively simple instrumentation. The progressive reduction in the cost and size of camera technology now enables development of mobile LSI instrumentation. To reduce the size of LSI to a mobile platform, we are faced with new challenges in terms of reducing power consumption and heat without sacrificing detection accuracy. To address these challenges, we propose pulsed laser operation using a new automated power control (APC) circuit. By synchronizing the pulses to the laser diode driver with the camera shutter, the camera detects a similar raw speckle image as before while consuming only a small fraction of the power. Furthermore, the reduced power consumption in turn keeps the temperature of the case low, increasing the stability of the system. We validated our solution using simulations in Pspice, and we evaluated the operation of the circuit using a prototype APC board and a commercial camera.

We report a compact, high-power, fiber-based source for ultrahigh-resolution optical coherence tomography (OCT) near 1 microm. The practical source is based on a short-pulse, ytterbium-doped fiber laser and on generation of a continuum spectrum in a photonic crystal fiber. The broadband emission has an average power of 140 mW and offers an axial resolution of 2.1 microm in air (<1.6 microm in biological tissue). The generation of a broad bandwidth is robust and efficient. We demonstrate ultrahigh-resolution, time-domain OCT imaging of in vitro and in vivo biological tissues.

Background and objectives

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.

Study design/materials and 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.

Background

Pulsed dye laser (PDL) is the gold standard for treatment of port-wine stain (PWS) birthmarks but multiple treatments are required and complete resolution is often not achieved. Posttreatment vessel recurrence is thought to be a factor that limits efficacy of PDL treatment of PWS. Imiquimod 5% cream is an immunomodulator with antiangiogenic effects.

Objective

We sought to determine if application of imiquimod 5% cream after PDL improves treatment outcome.

Methods

Healthy individuals with PWS (n = 24) were treated with PDL and then randomized to apply posttreatment placebo or imiquimod 5% cream for 8 weeks. Chromameter measurements (Commission Internationale de l'Eclairage L∗a∗b∗ colorspace) for 57 PWS sites (multiple sites per patient) were taken at baseline and compared with measurements taken 8 weeks posttreatment. The Δa∗ (change in erythema) and ΔE (difference in color between normal-appearing skin and PWS skin) were measured to quantify treatment outcome.

Results

Two patients developed minor skin irritation. Other adverse effects were not noted. Average ∆a∗ was 0.43 for PDL + placebo sites (n = 25) and 1.27 for PDL + imiquimod sites (n = 32) (P value = .0294) indicating a greater reduction in erythema with imiquimod. Average ∆E was 2.59 for PDL + placebo and 4.08 for PDL + imiquimod (P value = .0363), again indicating a greater color improvement with imiquimod.

Limitations

Effects were evaluated after a single treatment and duration of effect is unknown.

Conclusion

Combined selective photothermolysis and antiangiogenic therapy may enhance PWS treatment efficacy.

Background and objective

During laser therapy of port wine stain (PWS) birthmarks, regions of perfusion may persist. We hypothesize that such regions are not readily observable even when laser surgery is performed by highly experienced clinicians. The objective of this study was to use objective feedback to assess the acute vascular response to laser therapy.

Study design/materials and methods

A clinic-friendly laser speckle imaging (LSI) instrument was developed to provide the clinician with real-time images of blood flow during laser therapy. Images were acquired from patients undergoing laser therapy of PWS birthmarks at Scripps Clinic and the Beckman Laser Institute and Medical Clinic. Blood flow maps were extracted from the acquired imaging data. Histogram-based analysis was applied in grading the degree of heterogeneity present in the blood flow maps after laser therapy.

Results

Collectively, two types of patient responses were observed in response to laser exposure: (1) an immediate increase in perfusion within minutes after laser therapy; and (2) an overall decrease in blood perfusion approximately 1 hour after laser therapy, with distinct regions of persistent perfusion apparent in the majority of post-treatment blood-flow images. A comparison of blood flow in PWS and adjacent normal skin demonstrated that PWS blood flow can be greater than, or sometimes equivalent to, that of normal skin.

Conclusion

In general, a decrease in skin perfusion is observed during pulsed laser therapy of PWS birthmarks. However, a heterogeneous perfusion map was frequently observed. These regions of persistent perfusion may be due to incomplete photocoagulation of the targeted vessels. We hypothesize that immediate retreatment of these regions identified with LSI, will result in enhanced removal of the PWS vasculature. Lasers Surg. Med. 41:563-571, 2009. (c) 2009 Wiley-Liss, Inc.

During laser therapy of port wine stain (PWS) birthmarks, regions of persistent perfusion may exist. We hypothesize that such regions, which are not readily visible, exist even during laser surgery performed by highly experienced clinicians. The objective of this study was to use objective feedback to assess the acute vascular response to laser therapy. We have developed a clinic-friendly laser speckle imaging (LSI) instrument to provide the clinician with real-time images of blood flow during laser therapy. We acquired images from patients undergoing laser therapy of PWS birthmarks at Scripps Clinic and Beckman Laser Institute and Medical Clinic. We extracted blood flow maps from the acquired imaging data. Collectively, we have observed two regimes of patient response to therapy: 1) an immediate increase in perfusion within minutes after laser therapy; and 2) an overall decrease in blood perfusion approximately one hour after laser therapy, with distinct regions of persistent perfusion apparent in the majority of post-treatment blood-flow images. A comparison of blood flow in PWS and adjacent normal skin demonstrated that PWS blood flow can be greater than or sometimes equivalent to that of normal skin. Regions of persistent perfusion frequently exist immediately after laser therapy of PWS birthmarks. Existence of these regions may be correlated to the need for multiple treatment sessions to improve substantially PWS skin appearance. With the use of intraoperative LSI, immediate retreatment of these regions may improve the outcome of each session. © 2009 SPIE.