MRI features of presumed normal palatine tonsils in dogs.

OBJECTIVE

To describe the MRI characteristics of normal palatine tonsils in dogs.

MATERIALS AND

METHODS

Retrospective study of 95 dogs with presumed normal tonsils. Tonsillar margination, shape and signal intensity in pre- and postcontrast studies were assessed and the cross-sectional area was measured at the point of maximal size on transverse images.

RESULTS

In all cases the tonsils were located with their largest transverse cross-section at the level of the temporomandibular joints. Their margins were well-defined in all dogs; in 57 (60%) the borders were smooth and in 38 (40%) slightly irregular. The majority (96%) of the tonsils were rounded to oval in cross-section and the remainder were elongated. All tonsils were hyperintense to the medial pterygoid muscles in T1-weighted, T2-weighted, FLAIR and T2* gradient echo images and they showed either homogeneous (53%) or heterogeneous (47%) signal intensity. Contrast enhancement was marked (65%) or moderate (33%) in the majority of animals. Median tonsillar cross-sectional area was approximately 29 mm2 (90% confidence interval: 10.0 to 64.4 mm2 ). There was significant positive correlation between bodyweight and tonsillar cross-sectional area and a weak negative correlation between age and tonsillar cross-sectional area.

CLINICAL SIGNIFICANCE: MRI is of value in assessing normal palatine tonsils in dogs. This study could be used as a baseline for the investigation of the value of MRI in assessment of tonsillar disease in dogs.