Ruolo della risonanza magnetica nella diagnosidi patologie correlate ad edema osseo nel cavallo

Magnetic Resonance (MR) is increasingly used in equine practice for diagnosis of orthopeadic diseases that can not be assessed with other techniques. The use of specific acquisition sequences, such as STIR (Short Tau Inversion Recovery), allows appreciation of bone lesions which are not seen radiographically The "bone marrow edema" type lesions result from localized microfracturing of trabecular bone with associated hemorrage. It commonly follows traumatic injuries (impact or avulsion type) but can also arise from degenerative processes that leads to intraosseus avascular necrosis. The aim of the study is to evaluate the prevalence and the distribution of the bone marrow edema type lesion in horses referred for MR foot and/or fetlock evaluation. All images were acquired using a low field magnet (0.2 T The retrospective assessment was performed independently by two observers. There were 21 horses with lameness localized only to the foot, 10 localized to the fetlock only, and 3 horses with lameness involving both regions. The results of the study revealed traumatic injuries in fetlock joints (n=8), equally distributed between the medial and lateral condyle, middle phalanx (n=2), distal phalanx (n=1) and navicular bone (n=8 There were avulsion type injuries, at both the origin and insertion of the distal impar sesamoidean ligament (DSIL) (n=8), and at the insertion of the collateral ligaments of the distal interphalangeal joint (DIPJ) (n=2 The prevalence of "bone marrow edema" type lesions was higher in our study in comparison to leterature, however their distribution was similar. Use of MR enabled detection of bone lesions not evident on radiography. Fat suppressed sequences were of greatest value in detecting this lesion type. It is important to note, however, that the underlying histopathology, be it edema, hemorrage, fibrosis and/or necrosis, responsible for the lesion can not be deduced by MR alone. Bone scintigraphy may give additional information to differentiate the cause pathology.