Visibility of Transcondylar Screw Fractures in Standard and Extended Scale Computed Tomography Images.

OBJECTIVE: Application of extended computed tomography scale (ECTS) reconstruction to diagnose metal implant failure has been described in a single case report. The purpose of this study was to compare the features and visibility of humeral transcondylar screw fractures in standard CT scale (SCTS) and ECTS images. STUDY DESIGN: Case series: CT images of dogs with fractured transcondylar screws were retrospectively reviewed and described in both SCTS and ECTS images. RESULTS: Five dogs with a total of six transcondylar screw failures (five right and one bilateral) were reviewed. All cases had an ongoing humeral intercondylar fissure with varying degrees of stress remodelling. The fracture was seen in all screws on ECTS images, however only in three implants on SCTS images. The measured fracture gap was larger in ECTS images in all cases (range: + 0.14 mm to + 0.28mm). The three smallest fracture gaps were not seen on SCTS images. A subtle hypoattenuating streak (artefact) was visible adjacent to the screw fracture in 5/6 of cases using SCTS images. All screw fractures occurred parallel and often slightly medial to the humeral intercondylar fissure. CONCLUSION: Implant failure is only seen with larger fracture gaps in SCTS images, with 3/6 screw fractures not visible in SCTS compared with ECTS. A hypoattenuating streak extending perpendicular to the implant in SCTS images is suggestive of screw fracture even if this is not directly visible.

MRI in 30 cats with traumatic brain injury.

OBJECTIVES: The aim of this study was to evaluate the MRI findings in cats following traumatic brain injury (TBI), and establish which features identified might correlate with prognosis. METHODS: The magnetic resonance images of 30 cats with clinical signs attributed to the brain following TBI were retrospectively reviewed to assess the imaging features seen and their correlation with outcome. RESULTS: Twenty-one of 30 cats had a good outcome (full recovery or minor ongoing neurological deficits); the other nine either died or had ongoing neurological deficits that significantly affected quality of life. There was evidence of parenchymal injury in only 20/30 cats, including 8/9 that had a poor outcome. The frequency of bilateral or multifocal parenchymal lesions on T2-weighted imaging, and mass effect, particularly caudal transtentorial herniation, was statistically significantly higher in patients with a poorer outcome. Extra-axial haemorrhage was not identified. Concurrent soft tissue injury was noted in all cats, with a poorer prognosis statistically associated with a peripharyngeal pattern of injury and orbital trauma. CONCLUSIONS AND RELEVANCE: The number of cases with MRI-identified brain pathology, the patterns of injuries identified and the specific imaging features that appear to have effects on prognosis differ in this series of cats from those published in similar case series of dogs. Further work is needed to establish if cat-specific guidelines are needed to assess brain MRI following trauma.