Confocal laser scanning fluorescence topography: a new method for three-dimensional functional imaging of vascular structures

Abstract 

Three-dimensional topography of perfused vascular structures is possible via confocal laser scanning of intravascular fluorescence. The lateral resolution is given by the spot size of the scanning laser beam (optimally 10 µm at the retina). The axial resolution, however, depends on the accuracy of detection of the surface of the fluorescent structure, which is typically one order of magnitude higher (30 µm at the retina) than the confocal resolution. The vascular structure is stained with an appropriate fluorescent dye prior to the investigation using standard systemic dye injection. Confocal scanning of the fluorescence in planes of different depths within the vascular structure under investigation leads to a three-dimensional data set. Signal processing includes passive eye tracking, lateral averaging and axial determination of the surface of the fluorescent structure. The potential of this new technique is demonstrated by showing the topography of physiological vessel structures as well as of selected vascular diseases such as cone dystrophy, RPE detachment, choroidal haemangioma and retinal laser coagulation. Confocal laser angioscopic fluorescence topography (CLAFT) measures the three- dimensional surface structure of functional (perfused) vasculature and surrounding leakage. CLAFT may help to diagnose and quantify status and time course of vascular diseases.