Search Results

Abstract

Objective—To describe the anatomic features of dentition and surrounding structures of the head in rabbits assessed by use of a newly developed micro-computed tomography (CT) device.

Sample—Cadavers of 7 clinically normal adult Dendermonde White domestic rabbits raised for human consumption.

Procedures—The rabbits were slaughtered in a slaughterhouse, flayed, and decapitated; the rabbit heads were frozen for micro-CT examination. Transverse images were obtained from the nares to the occipital condyles with a custom-designed micro-CT scanner built at the Ghent University Centre for X-ray Tomography. Scan settings were chosen to highlight bony structures on the basis of the designers' experience. The micro-CT images were reviewed, and all recognizable anatomic features were labeled. Afterward, micro-CT images were used to create 3-D reconstructions by use of a custom-developed reconstruction package and 3-D rendering with dedicated software.

Results—Microstructures of the bones and teeth were clearly visible on micro-CT images. Conversely, soft tissue contrast was relatively poor on these images.

Conclusions and Clinical Relevance—Micro-CT appeared to be a promising technique for appropriate diagnosis of dental disease in rabbits. Further research is needed to determine the clinical applications of micro-CT imaging.

Abstract

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.

Abstract

Objective—To evaluate the evolution of clinical signs and their correlation with results of magnetic resonance imaging (MRI) and transcranial magnetic stimulation (TMS) and to assess potential prognostic variables after conservative medical treatment for disk-associated cervical spondylomyelopathy (DA-CSM) in dogs.

Design—Prospective cohort study.

Animals—21 client-owned dogs with DA-CSM.

Procedures—After neurologic grading, dogs underwent low-field MRI and TMS with measurement of onset latencies and peak-to-peak amplitudes from the extensor carpi radialis and cranial tibial muscles. Dimensions calculated from MRI images were remaining spinal cord area, spinal cord compression ratio, vertebral occupying ratio, vertebral canal height-to-body height ratio, vertebral canal height-to-body length ratio, and vertebral canal compromise ratio. Intraparenchymal signal intensity changes were graded. Dogs were reevaluated 1, 3, 6, 12, and 24 months after initial diagnosis.

Results—Outcome was successful in 8 of 21 dogs. Negative outcomes were characterized by rapid progression of clinical signs. All dogs with more severe clinical signs of DA-CSM 1 month after diagnosis had unsuccessful outcomes. Outcome was associated with the remaining spinal cord area and vertebral canal compromise ratio. Prognosis was not associated with severity of clinical signs or results of TMS. There were no significant correlations among clinical signs, MRI findings, and TMS results.

Conclusions and Clinical Relevance—Conservative medical treatment of DA-CSM was associated with a guarded prognosis. Selected MRI variables and clinical evolution 1 month after diagnosis can be considered prognostic indicators. The lack of correlation among clinical signs, results of diagnostic imaging, and results of electrophysiologic evaluation in dogs with DA-CSM warrants further investigation.

Abstract

Objective—To evaluate the use of transcranial magnetic stimulation for differentiating between clinically relevant and clinically irrelevant cervical spinal cord compression on magnetic resonance imaging (MRI).

Design—Validation study.

Animals—Clinically normal Doberman Pinschers without (n = 11) and with (6) spinal cord compression on MRI and 16 Doberman Pinschers with disk-associated wobbler syndrome (DAWS).

Procedures—After dogs were sedated, transcranial magnetic motor evoked potentials were recorded from the extensor carpi radialis muscle (ECRM) and cranial tibial muscle (CTM). Onset latencies and peak-to-peak amplitudes were measured. Magnetic resonance imaging was performed to identify spinal cord compression.

Results—There were significant differences in ECRM and CTM onset latencies between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM and CTM onset latencies between the 2 groups of clinically normal dogs. There were significant differences in CTM peak-to-peak amplitudes between Doberman Pinschers with DAWS and each of the 2 groups of clinically normal dogs, but there were no significant differences in ECRM peak-to-peak amplitudes among groups or in CTM peak-to-peak amplitudes between the 2 groups of clinically normal dogs. There was a significant correlation between severity of spinal cord compression and ECRM onset latency, CTM onset latency, and CTM peak-to-peak amplitude.

Conclusions and Clinical Relevance—Results suggested that transcranial magnetic stimulation may be a useful diagnostic tool to differentiate between clinically relevant and clinically irrelevant spinal cord compression identified on MRI alone.

Abstract

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).

Design—Validation study.

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.