Monitoring blood volume fraction and oxygen saturation in port-wine stains during vascular targeted photodynamic therapy with diffuse reflectance spectroscopy: Results of a preliminary case study

Abstract

Objective: Monitoring dynamic changes during vascular targeted photodynamic therapy (V-PDT) for port-wine stains (PWS) is crucial for achieving an optimal therapeutic outcome. The present investigation is a preliminary research study designed to quantify and monitor the vascular parameters, e.g., blood volume fraction (BVF) and oxygen saturation (StO 2 ), of a PWS lesion by using diffuse reflectance spectroscopy (DRS) before and during V-PDT. Material and methods: A portable DRS detection system was developed with an appropriate source-detector distance of 520 μm for fiber-optic probe. The diffuse reflectance spectra from 450 to 800 nm in specific regions of interest (ROIs) within a PWS lesion were recorded before and 3, 5, 10, 15, and 20 min during V-PDT. In order to extract the optical properties and vascular parameters of the PWS lesion, a modified well-known diffusion theory model with a correction factor for the vessel package effect was employed to analyze the steady state-diffuse reflectance spectra. Results: The corrected reflectance spectra of the PWS lesion can be fitted very well with the modified diffusion theory model. Differences in pretreatment values of BVF and StO 2 as well as changes in these parameters were observed between two ROIs during V-PDT. Conclusion: The ability of using DRS for quantifying and monitoring the BVF and StO 2 of a PWS lesion has been assessed. The preliminary data suggest that the clinical V-PDT efficiency is affected by the heterogeneity of the PWS lesion. DRS may have the potential to characterize the PWS lesion and to monitor V-PDT response. ZusammenfassungZiel: Die Überwachung dynamischer Veränderungen wäh-rend der gezielt-vaskulären photodynamischen Therapie (vascular targeted photodynamic therapy, V-PDT) von Feuermalen ist für das Erreichen eines optimalen Therapieerfolgs von entscheidender Bedeutung. Die vorliegende Untersuchung ist eine vorläufige Forschungsstudie zur Quantifizierung und Überwachung von Gefäßparame-tern, wie z. B. Blutvolumenanteil (BVF) und Sauerstoffsät-tigung (StO 2 ), mittels diffuser Reflexionsspektroskopie (DRS) vor und während der V-PDT von Feuermalen. Material und Methoden: Es wurde ein tragbares DRSMesssystem mit faseroptischer Sonde und geeignetem Quelle-Detektor-Abstand von 520 μm entwickelt. Im Wellenlängenbereich von 450 bis 800 nm wurden für spezifische Bereiche (regions of interest, ROIs) innerhalb eines Feuermals diffuse Reflexionsspektren vor sowie 3, 5, 10, 15 und 20 min während der V-PDT aufgezeichnet. Um die stationären diffusen Reflexionsspektren zu analysieren und daraus die optischen Eigenschaften und Gefäß-parameter des untersuchten Feuermals extrahieren zu Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 7/4/15 4:33 AM 274 Z. Qiu et al.: Monitoring V-PDT for port-wine stains with DRS können, wurde das bekannte Diffusionstheoriemodell mit einem Korrekturfaktor für den Gefäßüberlagerungseffekt modifiziert. Ergebnisse: Die korrigierten Reflexionsspektren des untersuchten Fe...

Monitoring perfusion and oxygen saturation in port-wine stains during vascular targeted photodynamic therapy

“…The details of the DRS system and the analyzing model used could be found elsewhere (24,25). Briefly, a customized quadfurcated assembly, which consisted of four optical Ultra-Violet/Visible fibers arranged in a linear array, was used to deliver the input and output light.…”

“…The remitted light was collected and fed back to the miniature spectrometer (QE65000; Ocean Optics, Inc.) through another fiber. The source-detector fiberoptic distance (520 μm) was chosen in accordance with the previous studies (24,28). The backscattered spectra ranging from 450 to 800 nm were recorded for data processing.…”

“…Furthermore, the use of V-PDT in the treatment of PWS is well established, and its routine use in clinical practice has advanced beyond our understanding of what is happening in PWS lesion during V-PDT treatment (8,9). For this end, several noninvasive optical technologies have been proposed for the pre-, intra-, and post-operative evaluation of PWS, such as laser Doppler imaging (LDI) (15,17), laser speckle imaging (14,18), optical coherence tomography (19,20), photoacoustic imaging (21), spatial frequency domain imaging (22), fluorescence spectroscopy(23) and diffuse reflectance spectroscopy (DRS) (24,25).…”

“…The perfusion changes in PWS lesion before and during V-PDT can be monitored noninvasively and successfully by using LDI (15,17). The microvascular parameters such as oxygen saturation (StO 2 ) and blood volume fraction (BVF) of PWS lesions can be determined quantitatively by fitting the DRS by utilizing the established Farrell's equation with the vessel packaging correction factor (24,25). The feasibility of using DRS for assessing the StO 2 and BVF of PWS before and during V-PDT has been validated (24,25).…”

“…The microvascular parameters such as oxygen saturation (StO 2 ) and blood volume fraction (BVF) of PWS lesions can be determined quantitatively by fitting the DRS by utilizing the established Farrell's equation with the vessel packaging correction factor (24,25). The feasibility of using DRS for assessing the StO 2 and BVF of PWS before and during V-PDT has been validated (24,25). Therefore, monitoring the microvascular parameters (i.e., StO 2 and BVF) and perfusion in PWS before and during V-PDT by using DRS and LDI may provide a deeper understanding of the response of microcirculation and oxygenation in PWS lesions to V-PDT, and have the potential to guide clinical V-PDT (14,18).…”