Tips and tricks for standing MRI

Indications and case selection

Magnetic resonance imaging (MRI) of the foot can be used as a method of further evaluating known or suspected pathology, localised to the region by diagnostic local analgesia. Magnetic resonance imaging may be employed where other diagnostic imaging methods have failed to elucidate a cause for lameness related to this region or where further information may aid treatment or management protocols. Magnetic resonance imaging is not a time or cost effective ‘screening’ modality; therefore it is imperative the site of pain is localised as far as possible. In cases where lameness is not improved following intra-articular analgesia of the coffin joint, navicular bursa or pastern joint but is improved by perineural analgesia of the palmar nerves at the level of the proximal sesamoid bones (abaxial sesamoid nerve block) intra-articular anaesthesia of the metacarpophalangeal joint is recommended to ensure lameness is not emanating from the fetlock joint. Knowledge of the pattern of response to diagnostic local analgesia and the overlap between desensitisation of structures can help to decide on the main cause of lameness in cases with multiple findings. Discussion between the veterinary surgeon requesting the MR examination and the operator acquiring the images regarding lameness history and response to diagnostic local analgesia before the scan and regarding interpretation and management of the case after the scan, will maximise the likelihood of a successful examination and ensure operators retain job satisfaction! Most but not all horses are amenable to standing examinations and examination of the hindlimb is not without risk during magnet and coil positioning, particularly in yearlings, which are only scanned in exceptional circumstances under sedation at our facility  […]