[en] Nuclear magnetic resonance imaging (MRI) is a new procedure for pictorial diagnosis without using x-rays. The authors utilized MRI for pictorial diagnoses of patients who had undergone augmentation mammaplasty. A silicone bag prosthesis, silicone gel, vaseline, paraffin, and pork were experimentally photographed using a Toshiba Super Conductor 0.5 tesla MRI device. Both T1-weighted and T2-weighted images of each substance were obtained. Ten patients who had undergone augmentation mammaplasty were examined in a similar manner and the foreign substances used in their treatment were analyzed on the basis of the results of the above experiment. Silicone presented a low intensity T1-weighted image and a high intensity T2-weighted image. In contrast, paraffin presented a high intensity T1-weighted image and a low intensity T2-weighted image. Vaseline presented both T1- and T2-weighted low intensity images. One case of normal breast and 9 cases of intramammary implants were studied. MRI images of the 10 cases were compared with mammograms. It was found that silicone and hydrocarbon can be distinguished by MRI. When implants existed as foreign body granulomas, however, it was difficult to distinguish vaseline and paraffin. (author)