X-ray tomography, magnetic resonance imaging, and ultrasound are noninvasive biomedical imaging modalities commonly used in the clinic. These imaging modalities have resolutions of 10 to 1,000 mu m, which allows assessment of the gross (macro) structure of living tissue but not its detailed cellular and nuclear microstructures. Clinical assessment of cellular and nuclear microstructure (histology) requires a resolution of 0.1 to 10 mu m and is performed by conventional optical microscopy. Conventional microscopy is invasive: one must remove (biopsy) the tissue, fix or freeze, excise into thin sections (typically 5- mu m slices), and stain with dyes to enhance contrast. Biopsies destroy the site being investigated and prevent subsequent imaging of dynamic events. Tissue processing introduces artifacts and is expensive and time consuming. An alternative technique that potentially avoids biopsies or tissue processing is confocal reflectance microscopy. A confocal microscope can noninvasively image cellular and nuclear microstructures in thin sections within living tissue with high resolution and contrast (Pawley, 1995; Webb, 1996).
展开▼
