Scintimammography with Tc-99m-MIBI versus dynamic MRI for non-invasive characterization of breast masses

Although mammography remains the technique of choice for the early detectio n of breast cancer, several imaging techniques, including scintimammography and magnetic resonance imaging (MRI), have recently been proposed as adjun cts for this purpose and included in many diagnostic protocols. This study was undertaken to assess the clinical accuracy of scintimammography with te chnetium-99m methoxyisobutylisonitrile (MIBI) and contrast-enhanced MRI in the detection of primary breast carcinoma in patients with equivocal mammog raphic findings. Forty-nine patients with a suspicious breast mass detected either by physical examination or by mammography and ultrasound (US) were studied. All patients underwent scintimammography and dynamic contrast-enha nced MRI 1 week apart. The results of the two techniques were compared and correlated to the final diagnoses. Two independent readers reported the sca ns using a four-point confidence scale. The areas under the receiver operat or characteristic (ROC) curves were obtained. Scintimammography showed an a ccuracy for tumour detection of 84%, with a sensitivity of 80% and a specif icity of 88%. MRI showed an accuracy of 86%, with a sensitivity and specifi city of 96% and 75%, respectively. Comparison of the two areas under the RO C curves showed no significant differences between MRI, 0.91+/-0.05 (mean+/ -SD), and scintimammography, 0.88+/-0.05 (P=0.9). It is concluded that dyna mic MRI and scintimammography possess comparable accuracy in the diagnosis of primary breast carcinoma in patients with equivocal mammographic or US f indings.