Objectives: To increase specificity of gadobenate dimeglumine-enhanced breast magnetic resonance (MR) imaging without losing sensitivity.
Materials and Methods: IRB approval was obtained for this retrospective study and informed consent was waived. Sixty-eight patients with 73 breast lesions underwent dynamic breast 1.5-T MR imaging with 0.1 mmol/kg of gadobenate dimeglumine and 103 or 111-second temporal resolution. A score system based on shape (round/oval/lobular = 0, linear/dendritic/stellate = 1), margins (defined = 0, undefined = 1), pattern (homogeneous = 0, inhomogeneous = 1, rim = 2), kinetics (continuous = 0, plateau = 1, washout = 2), and initial enhancement was used. Initial enhancement was evaluated with standard (<50% = 0, 50%–100% = 1, >100% = 2) or adjusted (<180% = 0, 180%–240% = 1, >240% = 2) thresholds. Scores 0–2, 3, 4 or 5, and from 6 to 8 were considered as equivalent to Breast Imaging Reporting and Data System 2, 3, 4, and 5, respectively. Pathologic examination (core-, vacuum-assisted, or surgical biopsy) served as a reference standard. Nonparametric tests were used.
Results: At histopathology, 52 lesions were malignant, 21 were benign. The initial enhancement for benign lesions was 141% ± 65% (mean ± SD), whereas for malignant lesions it was 210% ± 80% (P = 0.001). The median multifactorial score for benign lesions was 4 using the standard thresholds and 3 using the adjusted thresholds (P < 0.001) whereas for malignant lesions it was 7 and 6, respectively (P < 0.001). Specificity increased from 38% with standard thresholds to 71% with adjusted thresholds (gain of 33%; P = 0.016); positive predictive value 80% and 90%, negative predictive value 100% and 100%, and accuracy 82% and 92%, respectively. Sensitivity was 100% for both thresholds.
Conclusions: Specificity of gadobenate dimeglumine-enhanced breast MR imaging can be increased without limiting its high sensitivity.
From the Dipartimento di Scienze Medico-Chirurgiche, Università degli Studi di Milano; Radiology Unit, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy.
Received July 7, 2009; accepted for publication (after revision) October 24, 2009.
Reprints: Francesco Sardanelli, MD, Dipartimento di Scienze Medico-Chirurgiche, Università degli Studi di Milano; Radiology Unit, IRCCS Policlinico San Donato, Via Morandi 30–20097 San Donato Milanese, Milan, Italy. E-mail: email@example.com.