Radiation research
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The potential usefulness of gadopentetate dimeglumine (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for assessing hypoxia in tumors with significant necrosis was investigated. Small (100-350 mm(3)) and large (500-1000 mm(3)) D-12 and U-25 tumors were subjected to DCE-MRI, measurement of the fraction of necrotic tissue, and measurement of the fraction of radiobiologically hypoxic cells. Images of E. ⋯ F and lambda frequency distributions of the whole tissue, were consistent with the observation that the four groups of tumors showed similar fractions of radiobiologically hypoxic cells. E. F and lambda images may thus provide useful information on the extent of hypoxia in tumors provided that voxels in necrotic tumor regions are identified and excluded from the images.