Objective—To determine intraobserver, interobserver, and intermethod agreement for results of myelography, computed tomography-myelography (CTM), and low-field magnetic resonance imaging (MRI) in dogs with disk-associated wobbler syndrome (DAWS).
Design—Prospective cross-sectional study.
Animals—22 dogs with DAWS.
Procedures—All dogs underwent myelography, CTM, and low-field MRI. Each imaging study was interpreted twice by 4 observers who were blinded to signalment and clinical information of the patients. The following variables were assessed by all 3 techniques: number, site, and direction of spinal cord compressions; narrowed intervertebral disk spaces; vertebral body abnormalities; spondylosis deformans; and abnormal articular facets. Intervertebral foraminal stenosis was assessed on CTM and MRI images. Intraobserver, interobserver, and intermethod agreement were calculated by κ and weighted κ statistics.
Results—There was very good to good intraobserver agreement for most variables assessed by myelography and only moderate intraobserver agreement for most variables assessed by CTM and low-field MRI. There was moderate to fair interobserver and intermethod agreement for most variables assessed by the 3 diagnostic techniques. There was very good or good intraobserver, interobserver, or intermethod agreement for the site and direction of the worst spinal cord compression as assessed by all the imaging modalities; abnormal articular facets and intervertebral foraminal stenosis were the least reliably assessed variables, with poor interobserver agreement regardless of imaging modality used.
Conclusions and Clinical Relevance—There was considerable variation in image interpretation among observers and between use of various imaging modalities; these imaging techniques should be considered complementary in assessment of dogs with DAWS.
Objective—To determine interobserver and intraobserver agreement for results of low-field magnetic resonance imaging (MRI) in dogs with and without disk-associated wobbler syndrome (DAWS).
Animals—21 dogs with and 23 dogs without clinical signs of DAWS.
Procedures—For each dog, MRI of the cervical vertebral column was performed. The MRI studies were presented in a randomized sequence to 4 board-certified radiologists blinded to clinical status. Observers assessed degree of disk degeneration, disk-associated and dorsal compression, alterations in intraspinal signal intensity (ISI), vertebral body abnormalities, and new bone formation and categorized each study as originating from a clinically affected or clinically normal dog. Interobserver agreement was calculated for 44 initial measurements for each observer. Intraobserver agreement was calculated for 11 replicate measurements for each observer.
Results—There was good interobserver agreement for ratings of disk degeneration and vertebral body abnormalities and moderate interobserver agreement for ratings of disk-associated compression, dorsal compression, alterations in ISI, new bone formation, and suspected clinical status. There was very good intraobserver agreement for ratings of disk degeneration, disk-associated compression, alterations in ISI, vertebral body abnormalities, and suspected clinical status. There was good intraobserver agreement for ratings of dorsal compression and new bone formation. Two of 21 clinically affected dogs were erroneously categorized as clinically normal, and 4 of 23 clinically normal dogs were erroneously categorized as clinically affected.
Conclusions and Clinical Relevance—Results suggested that variability exists among observers with regard to results of MRI in dogs with DAWS and that MRI could lead to false-positive and false-negative assessments.