This study aimed to estimate the frequency and timing of washout in a series of pathologically proven benign mass-like breast lesions at dynamic magnetic resonance imaging.
Institutional review board approval was obtained for this retrospective study. We evaluated enhancement kinetics of 33 pathologically confirmed benign breast lesions: fibroadenomas (n = 22), adenosis (n = 6), typical ductal hyperplasia (n = 2), fibroadenoma with ductal hyperplasia (n = 1), fibrosclerosis (n = 1), and inflammatory lesion (n = 1). Coronal 3-dimensional T1-weighted gradient-echo sequences were acquired before/after intravenous injection of 0.1 mmol/ kg gadoterate meglumine (time resolution, 111 seconds), 1 before and 5 after contrast injection. The time point at which the kinetic curve demonstrated a washout was recorded. Cumulative distribution of lesions showing washout was built. Paired comparisons of specificity for washout kinetics were performed using the McNemar test.
Of 33 lesions, washout was never observed in 20 (61%), whereas 13 (39%) showed washout during the study. Of these 13 lesions, only 1 (inflammatory mass) exhibited washout within the first 3 minutes (specificity, 97%), 9 within 6 minutes (specificity, 73%), and 13 within 8 minutes (specificity, 61%). Specificity of washout kinetics within 3 minutes (97%) was significantly larger than that from the sixth minute (73%) and thereafter (P < 0.016).
A prolonged observation for dynamic breast magnetic resonance imaging may result in false-positive washout, especially after 6 minutes. Late washout should not be considered a reliable marker of malignancy.
From the *Unità di Radiologia, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; †Department of Radiology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; ‡Scuola di Specializzazione in Radiodiagnostica, Università degli Studi di Milano; and §Dipartimento di Scienze Medico-Chirurgiche, Università degli Studi di Milano, San Donato Milanese, Milan, Italy.
Received for publication November 26, 2011; accepted February 15, 2012.
Reprints: Francesco Sardanelli, MD, Università degli Studi di Milano, Dipartimento di Scienze Medico-chirurgiche, IRCCS Policlinico San Donato, Unità di Radiologia, Piazza E. Malan 2, 20097 San Donato Milanese, Milan, Italy (e-mail: firstname.lastname@example.org).
Dr Sardanelli has received research grants from and is a member of the speakers’ bureaus for Bracco Group and Bayer Pharma. The other authors report no conflicts of interest.