Abstract:
T2-weighted sequences are commonly relied upon in magnetic resonance (MR) imaging
protocols for the detection of brain lesions in dogs. Previously the effect of fluid suppression via
fluid attenuated inversion recovery (FLAIR) has been compared to T2-weighting with mixed
results. Short tau inversion recovery (STIR) has been reported to increase the detection of some
CNS lesion in people. The purpose of the current study was to evaluate the effect of fat
suppression on brain parenchymal contrast resolution and lesion detection in dogs. We
compared three sequences: T2-weighted images (T2w), STIR, and T2-weighted fluid attenuated
inversion recovery with chemical fat suppression (T2-FLAIR-FS) in dogs with
meningoencephalitis. Dogs with meningoencephalitis and dogs with idiopathic epilepsy were
retrospectively identified and anonymized. Evaluators recorded the presence or absence of
lesions within 12 predetermined brain regions on randomized sequences, viewing and scoring
each sequence individually. Additionally signal to noise ratios, contrast to noise ratios, and
relative contrast were measured in a reference population. STIR sequences had the highest
relative contrast between grey and white matter. While descriptively more lesions were
identified by evaluators on T2-FLAIR-FS images, there was no statistical difference in the
relative sensitivity of lesion detection between the sequences. Nor was there a statistical
difference in false lesion detection within our reference population. STIR may be favored for
enhanced anatomic contrast depiction in brain imaging. No benefit of the inclusion of a fat
suppressed T2-weighted FLAIR sequence was found.
