Prevalence and distribution of distal phalanx STIR hypersignal on MR images of 129 equine feet

The aim of this study was to describe prevalence and distribution of STIR hypersignal in P3 in a series of horses having undergone a foot MRI examination. MRI examinations of 96 lame and 33 non-lame feet were reviewed, for a total of 129 feet. Four STIR-signal patterns were identified (thin dorsal line, area restricted to the dorsodistal half of P3, large area extending within the body of P3, generalized hypersignal involving the entire P3). The results of this study confirmed that the presence of STIR hyperintensity in P3 is a common MRI finding in lame and non-lame feet, but signal patterns in the lame feet of this series suggest a tendency for the abnormal signal to extend either more proximal or deeper into the body of P3 when foot pain is considered to be at the origin of the lameness.