Longitudinal, multimodal functional imaging of microvascular response to photothermal therapy

Abstract

Although studies have shown that photothermal therapy can coagulate selectively abnormal vasculature, the ability of this method to achieve consistent, complete removal of the vasculature is questionable. We present the use of multimodal, wide-field functional imaging to study, in greater detail, the biological response to selective laser injury. Specifically, a single-platform instrument capable of coregistered fluorescence imaging and laser speckle imaging was utilized to monitor vascular endothelial growth factor gene expression and blood flow, respectively, in a transgenic rodent model. Collectively, the longitudinal, in vivo data collected with our instrument suggest that the biological response to selective laser injury involves early-stage redistribution of blood flow, followed by increased vascular endothelial growth factor promoter activity to stimulate pro-angiogenic events.

Implanted Cell-Dense Prevascularized Tissues Develop Functional Vasculature That Supports Reoxygenation After Thrombosis

“…31,[34][35][36][37] Use of longer exposure times increases sensitivity to the relatively slow flow in small-caliber vessels. 36,38 Exposure times of 1000 ms enable detection of flow speeds as slow as 15 mm/s (unpublished data). Laser intensity was adjusted for each exposure time using a polarizer such that the entire dynamic range of the CCD camera was utilized without overexposure.…”

Longitudinal In Vivo Imaging to Assess Blood Flow and Oxygenation in Implantable Engineered Tissues

“…33 Briefly, two illumination sources were used for imaging, a 150 W quartz halogen lamp (Edmund Optics, Barrington, NJ) during MSI, and a 30 mW 633 nm helium-neon laser (Newport, Irvine, CA) during LSI. During MSI, light from the quartz halogen lamp was directed through an infrared filter to prevent heating the dorsal window chamber, followed by a plano-convex lens for spatial collimation.…”

“…27,29,35,36 Use of longer exposure times increases sensitivity to the relatively slow flow in small-caliber vessels. 33,36 One thousand millisecond exposure times are capable of detecting flow speeds as slow as 15 mm/s (unpublished data). Laser intensity was adjusted for each exposure time using a polarizer such that the entire dynamic range of the CCD camera was utilized without overexposure.…”

Wide-field functional imaging of blood flow and hemoglobin oxygen saturation in the rodent dorsal window chamber

“…10) (Bui et al, 2010). Briefly, the platform utilizes multiple illumination sources, a camera equipped with an electro-optic filter, and a modular design which allows the user to image the dorsal window chamber using broadband transillumination, LSI in epi and transillumination geometries, multispectral imaging in transillumination geometry, and fluorescence imaging in epi-illumination geometry.…”