Structure enhancement by subtraction in magnetic resonance imaging.

Two patients with tumours in the pituitary gland and the liver, respectively, were studied with MRI. Regions of different transverse relaxation times were found in the tumours. Subtraction of images recorded with different echo times demonstrated the tumour regions better than the original images although these were recorded with 2 repetition times and double and multiple echo sequences. Subtraction techniques may thus aid diagnosis in MRI.