CT more accurately detects foreign bodies within the equine foot than MRI or digital radiography

Abstract

Identification and characterization of foreign bodies in the distal limb of horses poses a diagnostic challenge. The aims of this prospective experimental cadaver study were to describe the appearance of five foreign body materials within the equine hoof using CT, MRI, and digital radiography (DR) and to compare interrater agreement among three reviewers. Fifty foreign bodies consisting of five materials were implanted at a solar location or a coronary location in 25 equine cadaver feet. The images were reviewed by three equine veterinarians experienced in advanced imaging interpretation, who were blinded to the material of the foreign body. Foreign bodies were graded on visibility and appearance. Sensitivity and specificity were calculated for accurate identification of the different materials. Interrater agreement was assessed using Fleiss’ kappa. Computed tomography had higher visibility score, sensitivity/specificity, and interrater agreement for detection of all materials; particularly slate, glass, and dry wood, compared to the other imaging modalities. Soaked wood and plastic had lower sensitivity (31‐33%) on CT with a similar attenuation of the two materials. Foreign bodies were often visible on MRI, although with similar appearance and unclear details. On DR, only slate and glass were visible. The interrater agreement for identifying the correct material was almost perfect for slate, glass, and dry wood (κ = 0.92‐1.00) and poor for plastic and soaked wood (κ < 0.20) on CT. Interrater agreement was poor for all materials on MRI and DR (κ < 0.20), with the except for fair (κ = 0.28) for slate on DR and moderate (κ = 0.28) for soaked wood on MRI.

Diffuse osteomyelitis of the fourth metacarpal bone in a horse caused by Clostridium perfringens

“…Computed tomography was utilised in addition to conventional imaging modalities in this case (Figs 3-5 ). CT allows cross-sectional imaging enabling earlier identification of fractures, compared to radiography (Crijns et al, 2014) and has also been shown to be superior for detection of foreign bodies in the distal limb of horses compared to radiography and MRI (Ogden et al, 2020) making it an appropriate diagnostic modality in this case. Initially, the unicortical fracture of the third metacarpal bone was not identifiable radiographically, likely due to summation.…”

Multi‐modality imaging of aggressive submural neoplasia of the hoof in two horses

“…It can however provide information regarding both the osseous and soft tissues in the area, provide helpful information for surgical planning and provide us with information around the likelihood of various differential diagnoses. Foreign bodies within the hoof capsule, for example have been shown to be more readily detected with CT than radiography but were not identifiable in either of these horses 21 . Other space occupying masses such as keratoma or epidermoid cyst were also considered unlikely on these advanced imaging studies.…”

“…These findings once again give the impression of a space occupying/expansile mass within the adjacent hoof wall EQUINE EQUINE hoof capsule, for example have been shown to be more readily detected with CT than radiography but were not identifiable in either of these horses. 21 Other space occupying masses such as keratoma or epidermoid cyst were also considered unlikely on these advanced imaging studies. The most noteworthy imaging finding in these horses was likely the expansile mineralised margins of the space occupying lesion and it is important to highlight that this finding was visible radiographically.…”

“…3 They have the potential to identify foreign material not visible radiographically. 21 This information can also assist with biopsy and surgical planning. 3,16,22,23 Although aggressive hoof wall neoplasia is rare, there are certain imaging features which may raise our index of suspicion for an aggressive submural lesion.…”

“…These modalities can provide additional information regarding the composition of the abnormal soft tissues in certain cases as well as further characterise the regional osseous pathology 3 . They have the potential to identify foreign material not visible radiographically 21 . This information can also assist with biopsy and surgical planning 3,16,22,23 …”