Methods: Blood films were imaged in reflection and transmission with monochromatic red-blue epi-illumination wavelengths (Spectromaster), recording greyscale images via a constant parameter monochrome CCD camera (Cohu). In vivo oral sub-mucosal vascular tissue imaging was undertaken via a Hopkins pattern miniature endoscope and a novel imaging arm. To model vascular change, the vasoconstrictor effect of adrenaline bearing local anaesthetic agents were used, imaging being undertaken before and over an hour after localised administration.
Results: Haemoglobin absorbed the majority of non-red wavelengths in transmission as expected, confirming it as a suitable contrast agent for real time epi-illumination in vivo imaging. Despite being in a reflection imaging configuration, the contrast difference was maintained in vivo as the majority of illuminating wavelengths were additionally reflected from deeper tissues. Hence, real time monochromatic CCD detection of micro-endoscopically imaged oral mucosal vasculature showed red blood cells (black) moving through capillary arcades (bright background) in vivo, clearly defining the local vascular arcade patterns. Image analysis showed significant arteriolar shut down in the presence of adrenaline and reduction in overall local blood flow as expected. This patern resolved within one hour as expected.
Conclusions: The ability to image red blood cells micro-endoscopically and without prior labelling or preparation in vivo, demonstrates the potential for development of non-surgical and possibly diagnostic sub-surface lesion vascularisation or neovascularisation imaging, in the clinic; of particular benefit to immuno-compromised patients.