Demonstration of the effects of localized overexposure by magnetic resonance imaging of the skin tissue

Over-exposures with gamma rays of a 192 Ir source performed on pig skin, have been followed by magnetic resonance imaging. A group of 3 minipigs was given single doses of 96, 32 and 64 Gy applied to the back skin (between T7 and L4) from bottom to neck respectively. NMR images were taken from a Siemens Magnetom 63 SP system operating at 1.5 tesla. T2 - weighted spin echo images showed that signal intensities in the irradiated areas were significantly decreased during the three weeks following irradiation. The signal evolution was similar in skeletal striated muscle, subcutaneous adipose tissue and skin but with noticeably different amplitudes. The larger variation was observed on skin. This observation, which can be done in the early days after the exposure, suggests that the method could be an important aid to diagnose or to predict tissue necrosis and fibrosis. (author)