European Journal of Nuclear Medicine and Molecular Imaging Vol. 30, No. 10, October 2003 Abstract. This study was performed to evaluate the sen- sitivity and specificity of technetium-99m methoxyiso- butylisonitrile ( 99m Tc-MIBI) scintimammography (SMM) and contrast-enhanced magnetic resonance imaging (MRI) in patients with breast masses, using the histologi- cal findings as the gold standard. Forty-five consecutive patients with a breast lesion, detected by self-examina- tion, physical examination or screening mammography, underwent SMM and MRI. In 38 cases (84.5%), the his- topathology was malignant; the breast cancers ranged from 3 to 100 mm in diameter (mean 22 mm). In the overall patient group, MRI showed a slightly higher sen- sitivity than SMM (92% vs 84%), but SMM showed a better specificity: 71% vs 42%. The accuracy was 82% and 84% for SMM and MRI respectively. To evaluate the influence of lesion size on the results, patients with le- sions ≤20 mm and ≤15 mm were examined. In patients with lesions ≤20 mm, the sensitivity of SMM and MRI decreased to 64% and 82% respectively, while SMM again displayed considerably better specificity: 83% vs 50% for MRI. The accuracy of SMM and MRI was 64% and 82% respectively. In patients with lesions ≤15 mm, SMM again showed better specificity (75% vs 50%), while MRI displayed better sensitivity and accuracy (sen- sitivity, 81% vs 62%; accuracy, 75% vs 65%). In this study the specificity of SMM in patients with breast le- sions was thus superior to that of MRI. The combination of SMM and MRI may be used in those patients with equivocal findings at mammography and ultrasound to reduce the number of unnecessary surgical biopsies. Keywords: Breast cancer – Scintimammography – 99m Tc-MIBI – Magnetic resonance imaging Eur J Nucl Med Mol Imaging (2003) 30:1383–1388 DOI 10.1007/s00259-003-1262-6 Introduction Several imaging techniques are used to evaluate breast cancer in women. Mammography is the most frequently used screening method, and a decrease in mortality of 33% has been observed for breast cancer in women who have undergone mammographic screening [1]. Although mammography is capable of detecting cancer in its early stages, and has a reasonable cost, it displays low sensi- tivity and specificity in patients with dense breasts, those who have previously undergone surgery and those with breast implants [2, 3, 4]. Since a great number of benign lesions are found in pa- tients with suspicious mammographic findings, comple- mentary methods to increase diagnostic specificity have been proposed. Due to the high spatial resolution of the most recent ultrasound (US) transducers (7.5–13 MHz) and the use of echo-enhanced colour power Doppler US, suspicious areas at mammography can be more accurately evaluated on US, reducing the number of false positives [4, 5, 6, 7, 8, 9, 10]. However, variable values for sensitiv- ity and specificity are still reported in the literature, de- pending on the anatomical position and dimensions of the suspicious lesion, on the experience of the physician and on the quality of the US device [11]. Magnetic resonance imaging (MRI) has been demon- strated to further improve the sensitivity of mammogra- phy and US; in fact it gives excellent images of breast structure and can detect lesions of a few millimetres [12]. Even though the specificity of MRI is relatively B. Bagni ( ✉ ) Department of Nuclear Medicine, University Hospital, University of Modena and Reggio Emilia, Via del Pozzo 71, 41100 Modena, Italy e-mail: bagni.bruno@unimore.it Tel.: +39-59-4223722, Fax: +39-59-4224128 Original article Scintimammography with 99mTc-MIBI and magnetic resonance imaging in the evaluation of breast cancer B. Bagni 1 , A. Franceschetto 1 , A. Casolo 1 , M. De Santis 2 , I. Bagni 3 , F. Pansini 4 , C. Di Leo 5 1 Department of Nuclear Medicine, University Hospital, University of Modena and Reggio Emilia, Modena, Italy 2 Department of Radiology, University Hospital, University of Modena and Reggio Emilia, Modena, Italy 3 Department of Pathology, University of Ferrara, Ferrara, Italy 4 OBJ Department, University of Ferrara, Ferrara, Italy 5 Department of Nuclear Medicine, University Hospital of San Paolo, University of Milan, Milan, Italy Received: 2 March 2003 / Accepted: 18 June 2003 / Published online: 9 August 2003 © Springer-Verlag 2003