A prospective trial was performed to assess the accuracy of Tc-99(m)-methoxyisobutyl isonitrile (Tc-99(m)-MIBI) scintimammography and X-ray mammography in 18 patients (mean age 58 years, range 46-79 years) with suspected recurrent breast cancer in the breast and/or loco-regional tissues. All patients had been diagnosed to have breast cancer 1-23 years before scintimammography. Two patients had undergone mastectomy, so that a total of 34 breasts were studied with X-ray mammography and with prone-lateral and anterior scintimammography. Any abnormalities on X-ray mammograms and scintimammograms were noted, as was any additional local or nodal uptake of Tc-99(m)-MIBI. The nature of any lesion seen with either modality, or in which there was a clinical suspicion of recurrence, was confirmed by cytological or histological examination of tissue samples. There were nine breasts with recurrent cancer in eight patients. X-ray mammography identified six of these cancers. Tc-99(m)-MIBI scintimammography identified eight of nine recurrent breast cancers (the one cancer not seen was positive on X-ray mammography). in the 26 breasts without cancer, two were reported as having changes consistent with cancer and one was reported equivocal. There were three false-positive and one equivocal scintimammograms. The accuracy of Tc-99(m)-MIBI scintimammography within the breast (85%) was similar to X-ray mammography (82%). Axillary lymph node recurrence occurred in five patients, four of whom were positive with Tc-99(m)-MIBI. An additional patient had focal uptake of Tc-99(m)-MIBI at the site of recurrent cancer on the anterior chest wall. In conclusion Tc-99(m)-MIBI scintimammography may provide useful complementary information in patients with suspected recurrence of cancer in the breast or loco-regional tissues. ((C) 1998 Lippincott-Raven Publishers).
