Magnetic resonance imaging (MRI) is a sensitive, noninvasive diagnostic tool that helps to establish accurate diagnosis in neoplastic patients and enables the staging of tumourous diseases. MR mammography is widely used in the human oncologic practice. Since the introduction of contrast-enhanced MRI of the breast, this method has gained increased acceptance because it offers new and different information as compared with other imaging modalities. The aim of this study was to obtain the availability of the human mammographic MR protocol in the routine examination of canine mammary glands. Cancer-induced angiogenesis is the main feature that can be pictured in vivo by dynamic contrast enhanced (DCE)-MRI, and it plays an important role in the differentiation of benign mammary diseases from malignant ones. We examined whether this human characteristic could be applied to describe canine mammary tumours (contrast enhancement, morphological patterns and kinetic curves). After the imaging procedure the tumours were excised and typified by histopathological examinations. Eleven intact bitches of different breeds (4 German Shepherd, 2 Mongrel, 1 Giant Schnauzer, 1 Foxterrier, 1 Mastino Napolitano, 1 Pointer, 1 Tervueren) were examined during anoestrus. Average age was 10,2 years, the dogs weighed between 7-52kg. Examinations were performed with a Siemens Magnetom Vision Plus and a Siemens Avanto, 1.5 Tesla MRI scanner. The following sequences, adapted from the human protocol, proved to be suitable for MRI examination of the canine mammary glands:
T1 SE (TR: 450 s, TE: 9.6 s, Aq.: 2 s, SL: 4 mm, FoV: 350 × 200 mm) coronal, transversal planes
T2 SE (TR: 3800 s, TE: 110 s, Aq.: 2 s, SL: 4 mm, FoV: 350 × 350 mm) coronal, transversal planes
STIR (short T1 inversion recovery; TR: 4500 s, TE: 36 s, Aq.: 2 s, SL: 4 mm, FoV: 350 × 350 mm) coronal, transversal planes;
T1 GE (TR: 12 s, TE: 4.8 s, Aq.: 1 s, SL: 2 mm, FoV: 320 × 320 mm) in a dynamic fashion, coronal plane.
We found that using static sequences the neoplastic mammary gland and the neighboring anatomical structures could be examined in great detail with optimal contrast conditions. We can typify the morphological characteristics of neoplasms, which can be compared to the histological findings and help to plan the therapeutic (surgical) method. All the eleven animals had malignant lesions (malignant mixed tumours, carcinoma simplex and carcinoma complex) and the morphological patterns as well as the kinetic parameters proved to be satisfying for the diagnostic work. The contrast accumulation methods and curves prepared for human medicine are of great promise in veterinary use but a highly sensitive standard protocol should be completed. In all cases we found malignant morphology, so the method must be tested also on benign tumours and on a large number of patients.