Interlesion differences in the local photodynamic therapy response of oral cavity lesions assessed by diffuse optical spectroscopies

Abstract

Photodynamic therapy (PDT) efficacy depends on the local dose deposited in the lesion as well as oxygen availability in the lesion. We report significant interlesion differences between two patients with oral lesions treated with the same drug dose and similar light dose of 2-1[hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH)-mediated photodynamic therapy (PDT). Pre-PDT and PDT-induced changes in hemodynamic parameters and HPPH photosensitizer content, quantified by diffuse optical methods, demonstrated substantial differences between the two lesions. The differences in PDT action determined by the oxidative cross-linking of signal transducer and activator of transcription 3 (STAT3), a molecular measure of accumulated local PDT photoreaction, also showed >100-fold difference between the lesions, greatly exceeding what would be expected from the slight difference in light dose. Our results suggest diffuse optical spectroscopies can provide in vivo metrics that are indicative of local PDT dose in oral lesions.

Photodynamic Therapy-Induced Microvascular Changes in a Nonmelanoma Skin Cancer Model Assessed by Photoacoustic Microscopy and Diffuse Correlation Spectroscopy

“…We used DCS to monitor changes in blood flow caused by PDT [16,[28][29][30][31][32][33][34][35]. Briefly, the DCS setup consisted of a long coherence length, 785 nm laser (CrystaLaser), four photon-counting detectors (Perkin Elmer, Waltham, MA, USA) and a custom-built autocorrelator board (Correlator.com).…”

Blood flow dynamics during local photoreaction in a head and neck tumor model

“…The experimental aspect of DCS has been described elsewhere [35,36]. Briefly, it consisted of a high coherence length laser (785 nm, CrystaLaser, Reno, NV), four photon-counting detectors (Perkin Elmer, Waltham, MA) and a custom-built autocorrelator board (Correlator.com).…”

“…Among them, laser Doppler [10,[28][29][30][31][32] and optical coherence tomography [33] have shown to be useful approaches with some limitations for deep tissue applications. Recent work utilizing diffuse correlation spectroscopy (DCS), which is an extension of the dynamic light scattering technique for diffuse media, has proven that DCS allows deeper penetration depth making it an attractive tool for monitoring PDT at preclinical and clinical settings [17,[34][35][36][37].…”

Monitoring PDT response of head and neck lesions with diffuse optical spectroscopies

“…The details of the instrumentation and quantification models were described recently [7,8]. Briefly, the diffuse correlation spectroscopy (DCS) [9] instrument measured blood flow and consisted of a 785 nm, long coherence length laser, four photon-counting detectors and a custom autocorrelator board.…”