Technetium-99m-MIBI scintimammography for suspicious breast lesions

The aim of this study was to evaluate the diagnostic accuracy of scintimammography with 99mTc-MIBI in patients with suspected primary breast cancer as monitored by SPECT or planar imaging.

Patients with a suspect lesion detected by palpation or mammography were entered in the study. Excisional biopsy was performed on all patients and a mammography was performed within three weeks prior to scintigraphy. All patients received intravenously 740 MBq 99mTc-MIBI in the arm, contralateral to the suspicious breast, and were subsequently examined in a prone position. At 5-10 min postinjection, planar images were obtained in both the lateral and anterior views with an acquisition time of 10 min. After planar imaging, SPECT imaging was performed using a two-head high-resolution gamma camera.

In the total patient group of 54 patients, 40 lesions were palpable and 14 were nonpalpable but were detected by mammography. Breast cancer was confirmed in 24 of the patients and 20 of the palpable masses were found to be carcinomas. The tumor size ranged from 6 to 90 mm in diameter. In scintigraphic studies, the overall sensitivity was 88% for planar imaging and 83% for SPECT. Specificity was 83% and 80%, respectively. Sensitivity for palpable lesions was 100%. The smallest detectable tumor measured was 9 mm in diameter and could only be visualized in the planar scintigram.

Scintigraphy with 99mTc-MIBI is extremely sensitive for the detection of primary breast cancer in patients with a palpable mass. SPECT, however, did not improve the diagnostic accuracy over planar scintimammography.