Low-field magnetic resonance imaging and multislice computed tomography for the detection of cervical syringomyelia in dogs

Background: Syringomyelia (SM) is defined as the presence of fluid- containing cavities within the parenchyma of the spinal cord. Sagittal magnetic resonance (MR) images have been described as the preferred technique for visualizing SMin dogs and humans. Objective: To investigate whether computed tomography (CT) can be used to diagnose SM. Animals: Thirty- two client- owned dogs referred for investigation of the cervical spine on magnetic resonance imaging (MRI) and CT. Methods: Two reviewers retrospectively analyzed sagittal and transverse T1- weighted spin echo (T1WSE) MR images and CT images from each dog for the presence of SM and, if SM was present, the width (mm, syrinx width [ SW]) was measured. The results were analyzed statistically. Results: For the presence of SM there was a moderate interobserver agreement for MR (81%, j = 0.54) and almost perfect agreement for CT (94%, j = 0.87). There was a moderate intramodality agreement for both observers (observer 1 81%, j = 0.59; observer 2 81%, j = 0.57). For measurement of SW the repeatability was the best on the midsagittal T1WSE images (95% repeatability coefficient < 0.52 mm) and the reproducibility was the best on midsagittal images in both modalities (95% limits of agreement 0.55- 0.45; P = 0.002). Conclusion and Clinical Importance: Both techniques can be used to detect SM. Midsagittal MR and CT images are best used for measuring SW. Computed tomography can be used as a diagnostic tool for SM when MRI is not available, but CT cannot replace MRI as the standard screening technique for the detection of SM in Cavalier King Charles Spaniel for breeding purposes