Most ACTH-secreting pituitary adenomas are less than 1cm in size and enhance with CT contrast in the same manner as normal pituitary tissue. High-resolution CT scanning identifies only a minority of adenomas; MRI with gadolinium enhancement is probably superior (Fig. 8.17). It must be noted, however, that incidental adenomas are present in twenty-five per cent of pituitaries at post-mortem and therefore abnormalities identified on CT or MRI cannot automatically be assumed to be functional. The biochemical data must also be consistent with the imaging results.
