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A light emitting diode (LED) based spatial frequency domain imaging system for optimization of photodynamic therapy
R B Saager1, D J Cuccia, S Saggese
1Beckman Laser Institute, UC Irvine, Irvine, California, USA.
Background:
Photodynamic therapy (PDT) offers the potential for enhanced treatment of nonmelanoma skin cancer (NMSC) with minimal scarring. Yet, PDT has not achieved consistent long term effectiveness to gain widespread clinical acceptance for treatment of skin cancer. Therapeutic response varies between practitioners, patients and lesions. One important contributing factor is the absence of quantitative tools to perform in vivo dosimetry. To this end, we have developed a new quantitative imaging device that can be used to investigate parameters related to optimizing dosimetry.
Methods:
We present a spatial frequency domain imaging (SFDI) based device designed to: (1) determine the optical properties at the therapeutic wavelength, which can inform variations in light penetration depth and (2) measure the spatially resolved oxygen saturation of the skin cancer lesions and surrounding tissue. We have applied this system to a preliminary clinical study of nine skin cancer lesions.
Results:
Optical properties vary greatly both spatially [101%, 48% for absorption and reduced scattering, respectively] and across patients [102%, 57%]. Blood volume maps determined using visible wavelengths (460, 525, and 630 nm) represent tissue volumes within ∼1 mm in tissue (1.17 ± 0.3 mm). Here the average total hemoglobin concentration is approximately three times greater in the lesion than that detected in normal tissue, reflecting increased vasculature typically associated with tumors. Data acquired at near infrared wavelengths (730 and 850 nm) reports tissue blood concentrations and oxygenations from the underlying dermal microvasculature (volumes reaching 4.36 ± 1.32 mm into tissue).
Conclusions:
SFDI can be used to quantitatively characterize in vivo tissue optical properties that could be useful for better informing PDT treatment parameters. Specifically, this information provides spatially resolved insight into light delivery into tissue and local tissue oxygenation, thereby providing more quantitative and controlled dosimetry specific to the lesion. Ultimately, by optimizing the execution of PDT, this instrument has the potential to positively improve treatment outcomes.
Insights
A new spatial frequency domain imaging (SFDI) device quantifies optical properties and oxygenation in skin cancer lesions. This quantitative data can optimize photodynamic therapy (PDT) dosimetry for improved treatment outcomes.
Area of Science:
- Biomedical Optics
- Medical Imaging
- Dermatology
Background:
- Photodynamic therapy (PDT) shows promise for nonmelanoma skin cancer (NMSC) treatment but lacks consistent long-term effectiveness due to variable therapeutic responses.
- A key limitation in PDT is the absence of quantitative tools for in vivo dosimetry, leading to inconsistent outcomes.
- This study introduces a novel quantitative imaging device to address these dosimetry challenges.
Purpose of the Study:
- To develop and apply a spatial frequency domain imaging (SFDI) device for quantitative in vivo dosimetry in nonmelanoma skin cancer (NMSC).
- To determine optical properties and spatially resolved oxygen saturation of NMSC lesions and surrounding tissues.
- To investigate the potential of SFDI for optimizing photodynamic therapy (PDT) parameters.
Main Methods:
- A spatial frequency domain imaging (SFDI) based device was developed to measure in vivo optical properties and oxygen saturation.
- The system was applied to a preliminary clinical study involving nine skin cancer lesions.
- The device utilizes visible and near-infrared wavelengths to assess tissue optical properties, blood volume, and oxygenation.
Main Results:
- Significant spatial and inter-patient variations in optical properties (absorption and scattering) were observed.
- Blood volume maps, determined using visible wavelengths, revealed approximately three times greater total hemoglobin concentration in lesions compared to normal tissue.
- Near-infrared data provided information on tissue blood concentrations and oxygenation at depths up to 4.36 mm.
Conclusions:
- Spatial frequency domain imaging (SFDI) effectively quantifies in vivo tissue optical properties relevant to PDT.
- The device provides spatially resolved insights into light delivery and tissue oxygenation, enabling more precise and lesion-specific dosimetry.
- Optimizing PDT execution through SFDI-guided dosimetry has the potential to significantly improve treatment outcomes for NMSC.
