Measurement of hypoxia in vivo using a 2-nitroimidazole (NITP).

Abstract

The vascularisation of tumours is relatively poor and disordered compared with that normal tissues, leading to inefficient delivery of oxygen and other nutrients to many tu-mour cells. As oxygen diffuses from blood capillaries through the mass of surrounding cells it is depleted by normal cell metabolism. In the pioneering work of Thomlinson and Gray an effective diffusion distance of about 150 µrn was calculated (Thomlinson and Gray 1955) which closely matched the radii of viable tumour cords. Beyond this distance lie radioresistant hypoxic tumour cells at the boundary between viable and necrotic cells. Transient changes in the perfusion of individual blood vessels may further reduce oxygen transport and change the oxygenation status of some cells near to blood vessels over rela-tively short time scales (e.g. Chaplin et al. 1986). Moderate levels of radiobiological hy-poxia are also known to exist in some normal tissues e.g. murine skin (Stewart et al 1982) and liver (Arteel et al. 1995).