Idiopathic granulomatous mastitis: magnetic resonance imaging findings with diffusion MRI.
BACKGROUND
Idiopathic granulomatous mastitis (IGM) is a rare benign breast disease with unknown etiology which can mimic breast carcinoma, both clinically and radiologically. Magnetic resonance imaging (MRI) findings of IGM have been previously described; however there is no study evaluating diffusion-weighted MRI findings of IGM.


OBJECTIVE
To analyze conventional, dynamic contrast-enhanced, and diffusion-weighted MRI signal characteristics of IGM by comparing it with the contralateral normal breast parenchyma.


METHODS
A total of 39 patients were included in the study. On dynamic contrast-enhanced MRI, the distribution and enhancement patterns of the lesions were evaluated. We also detected the frequencies of involving quadrants, retroareolar involvement, accompanying abscess, and skin edema. T2-weighted (T2W) and STIR signal intensities and both mean and minimum apparent diffusion coefficient (ADC) values were compared with the contralateral normal parenchyma.


RESULTS
IGM showed significantly lower mean and minimum ADC values when compared with the normal parenchyma. Signal intensities on T2W and STIR sequences of the lesion were significantly higher than the normal parenchyma. On dynamic contrast-enhanced MRI, 7.7% of the patients had mass-like contrast enhancement, 92.3% of the patients had non-mass-like contrast enhancement. Abscess was positive in 33.3% of the patients.


CONCLUSIONS
As a result, IGM showed commonly non-mass-like lesions with restricted diffusion. Although it is a benign pathology, it may show clustered ring-like enhancement like malignant lesions.
Department of Radiology, Baskent University Faculty of Medicine, Adana Teaching and Medical Research Center, Adana, Turkey hul_yaaslan@hotmail.com.
Hulya
H
Aslan
Department of Radiology, Baskent University Faculty of Medicine, Adana Teaching and Medical Research Center, Adana, Turkey.
Aysin
A
Pourbagher
Department of General Surgery, Baskent University Faculty of Medicine, Adana Teaching and Medical Research Center, Adana, Turkey.
Tamer
T
Colakoglu
D000328:Adult; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D058890:Granulomatous Mastitis / Q000000981:diagnostic imaging*; D006801:Humans; D061705:Image-Guided Biopsy; D008875:Middle Aged; D012189:Retrospective Studies
D003287:Contrast Media
Granulomatous mastitis; apparent diffusion coefficient (ADC); breast; magnetic resonance imaging (MRI) diffusion MRI