Kaatje Kromhout

Intraobserver, interobserver, and intermethod agreement for results of myelography, computed tomography-myelography, and low-field magnetic resonance imaging in dogs with disk-associated wobbler syndrome

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.

Computed Tomography Atlas of the Normal Cranial Canine Abdominal Vasculature Enhanced by Dual‐phase Angiography

This study was performed to provide a detailed atlas of the normal arterial and venous canine vasculature in the cranial abdomen by dual‐phase computed tomographic angiography. Five adult beagles were positioned in dorsal recumbency on a multislice helical CT scanner. An unenhanced survey CT scan from the diaphragm to the pelvic inlet was performed. Bolus‐tracking software was used for the dual‐phase angiogram, and contrast medium was administered in a cephalic vein. The arterial phase was scanned from the mid‐abdomen to the cranial aspect of the diaphragm; the portal phase was scanned a few seconds after the arterial phase in the opposite direction. The DICOM studies from all dogs were analysed. Representative images were selected and anatomic structures labelled. Maximum intensity projections and three‐dimensional images were generated using software techniques. A detailed atlas of the venous and arterial vasculature of the cranial canine abdomen was created with the help of bolus‐tracking dual‐phase computed tomographic angiography (CTA). Practitioners can use this anatomic atlas with its detailed venous and arterial phase CT angiograms of the canine cranial abdomen to compare normal versus abnormal vascular anatomy.

Magnetic resonance and computed tomography imaging of a carotid body tumor in a dog

A 5-year-old castrated male Labrador Retriever was presented to a referring veterinarian for a swelling in the neck region. Based on the results of histopathology, a carotid body tumor, was diagnosed. The dog was referred to a medical imaging unit for further staging and follow up. This report describes the magnetic resonance (MR) and computed tomographic (CT) appearance of a carotid body tumor.

Low-Field MRI and Multislice CT for the Detection of Cerebellar (Foramen Magnum) Herniation in Cavalier King Charles Spaniels

Background Cavalier King Charles Spaniels (CKCS) have a high prevalence of Chiari‐like malformation (CM). Herniation of the cerebellum into the foramen magnum is a key diagnostic feature for CM. Midsagittal MR images are the preferred technique for visualizing cerebellar herniation (CH). Objective To investigate whether CT can be used to diagnose CH. Animals Fifteen client‐owned CKCS dogs referred for investigation of the brain and cranial cervical spine on MRI and CT. Methods Two reviewers retrospectively analyzed midsagittal T1WSE and T2WSE MR images and midsagittal pre‐ and postcontrast 2D multiplanar reformatted CT images from each dog for the presence of CH. And, if present, the length (mm, CHL) of the herniation was measured. The results were analyzed statistically. Results There was no significant difference between the different observers and techniques for the detection of CH and measurement of CHL. Overall, the CHL was longer on the CT images. Conclusion and Clinical Importance Both techniques are useful for detecting CH and measuring CHL. Because CHL does not have a known direct impact on the clinical presentation of CM, CT can be used as a diagnostic tool in a routine clinical practice for CM in CKCS when MRI is not available. We emphasize that MRI is the standard screening technique in CKCS for breeding purposes to detect the presence of CM and SM and, at the current time, CT cannot replace MRI.

Detection of compressive hydrated nucleus pulposus extrusion in dogs with multislice computed tomography

Compressive hydrated nucleus pulposus extrusion (HNPE) in dogs is defined as acute extradural compression by hydrated nucleus pulposus material at the level of the associated intervertebral disc. Magnetic resonance imaging (MRI) is the imaging modality of choice for diagnosis of HNPE. The aims of this study were to determine the usefulness of unenhanced computed tomography (CT) and contrast enhanced CT (CE-CT), and the sensitivity and specificity of CE-CT, for detection of compressive HNPE. Using CE-CT, HNPE was visualised as a hypodense extradural compressive lesion with rim enhancement immediately dorsal to the intervertebral disc space, with a sensitivity of 91% and a specificity of 100%. CE-CT is a useful technique to detect compressive HNPE in dogs. However, if no clear lesion is identified with CE-CT, or if additional information about intramedullary changes is required, MRI still needs to be performed.

Magnetic resonance imaging of primary and concomitant flexor enthesopathy in the canine elbow

Flexor enthesopathy is a recently recognized elbow disorder in dogs and considered to be an important differential diagnosis for elbow lameness. Primary and concomitant forms of the disease have been previously described and treatments differ for the two forms. The goal of this prospective study was to compare magnetic resonance imaging (MRI) findings for dogs with primary flexor enthesopathy (n = 17), concomitant flexor enthesopathy (n = 23), elbow dysplasia alone (n = 13), and normal elbows (n = 7). Each elbow joint underwent MRI using the same low-field scanner. Sequences included transverse and sagittal T1-weighted (before and after IV contrast), transverse and sagittal T2-weighted, and dorsal STIR. For each elbow, MRI lesions were recorded based on a consensus of two observers unaware of group status. Magnetic resonance imaging lesions involving flexor tendons were found in 100% of clinically affected joints with primary flexor enthesopathy and 96% of clinically affected joints with concomitant flexor enthesopathy. Thickened flexor muscles were the most common lesions, followed by hyperintense tendon signal and contrast enhancement. Irregular, thickened medial humeral epicondyle, edema, and calcified body lesions were less frequently observed. Magnetic resonance imaging characteristics of flexor enthesopathy were not found in normal joints or those affected by elbow dysplasia alone. No significant differences in frequencies and details of individual MRI characteristics were found between primary and concomitant flexor enthesopathy groups. Findings indicated that MRI is a sensitive technique for detection of flexor enthesopathy lesions in dogs, however, MRI characteristics do not allow differentiation of primary versus concomitant forms of the disease.

Agreement between low-field MRI and CT for the detection of suspected intracranial lesions in dogs and cats

OBJECTIVE To assess the agreement between CT and MRI for enabling detection of intracranial lesions in cats and dogs. DESIGN Evaluation study. ANIMALS 51 dogs and 7 cats with suspected intracranial lesions. PROCEDURES During a 2-year-period, dogs and cats with suspected intracranial pathological changes underwent MRI and CT (single slice) of the head. Radiologists evaluated images produced with both techniques without awareness of subject identity. Agreement between methods was assessed for allowing detection of solitary or multiple lesions, selected lesion characteristics (via the Cohen κ statistic), and lesion dimensions (via Bland-Altman plots). RESULTS CT and MRI had substantial agreement for allowing detection of lesions and identification of whether the lesions were solitary or multiple. The techniques agreed almost perfectly for allowing identification of a mass effect and contrast medium enhancement, which were considered principal diagnostic imaging signs. A lower degree of agreement was attained for allowing identification of enhancement patterns and aspects of lesion margins. Agreement was substantial to almost perfect for lesion visualization in most anatomic brain regions but poor for identification of lesion dimensions. CONCLUSIONS AND CLINICAL RELEVANCE Degrees of agreement between CT and MRI for allowing the detection and characterization of intracranial lesions ranged from poor to almost perfect, depending on the variable assessed. More investigation is needed into the relative analytic sensitivity and possible complementarities of CT and MRI in the detection of suspected intracranial lesions in dogs and cats.

Idiopathic sterile inflammation of the epidural fat and epaxial muscles causing paraplegia in a mixed-breed dog

CASE DESCRIPTION A 4-year-old sexually intact male mixed-breed dog was evaluated because of clinical signs of acute-onset pelvic limb ataxia, rapidly progressing to paraplegia with severe spinal hyperesthesia. CLINICAL FINDINGS General physical examination revealed pyrexia, tachycardia, and tachypnea. Neurologic examination demonstrated severe spinal hyperesthesia and paraplegia with decreased nociception. Magnetic resonance imaging revealed extradural spinal cord compression at T13-L1 and hyperintense lesions on T1- and T2-weighted images in the epaxial musculature and epidural space. TREATMENT AND OUTCOME Decompressive surgery, consisting of a continuous dorsal laminectomy, with copious lavage of the vertebral canal was performed. Cultures of blood, urine, and surgical site samples were negative. Histologic examination results for samples obtained during surgery demonstrated suppurative myositis and steatitis. These findings confirmed a diagnosis of sterile idiopathic inflammation of the epidural fat and epaxial muscles with spinal cord compression. The dogs neurologic status started to improve 1 week after surgery. After surgery, the dog received supportive care including antimicrobials and NSAIDs. The dog was ambulatory 1 month after surgery and was fully ambulatory despite signs of mild bilateral pelvic limb ataxia 3 years after surgery. CLINICAL RELEVANCE Although idiopathic sterile inflammation of adipose tissue, referred to as panniculitis, more commonly affects subcutaneous tissue, its presence in the vertebral canal is rare. Specific MRI findings described in this report may help in reaching a presumptive diagnosis of this neurologic disorder. A definitive diagnosis and successful long-term outcome in affected patients can be achieved by decompressive surgery and histologic examination of surgical biopsy samples.

Computed Tomographic and Low‐Field Magnetic Resonance Arthrography: A Comparison of Techniques For Observing Intra‐articular Structures of the Normal Canine Shoulder

OBJECTIVE To compare low-field magnetic resonance arthrography (MRA) and computed tomographic arthrography (CTA) for identification of intra-articular ligaments and joint cartilage in the normal canine shoulder with the aid of cross-sectional anatomy. ANIMALS Normal adult Foxhounds (n = 3) and 4 Foxhound cadaver shoulders. METHODS CTA of 3 dogs was performed after intra-articular administration of contrast medium in both shoulders. Transverse slices and reformatted sagittal and dorsal images were obtained. Later, an MRA study of all 6 shoulder joints was performed using a low-field system. T1- and T2-weighted images were made in 3 planes, arthrography performed, and T1-weighted images repeated. Unrelated cadaver shoulder joints were injected with red methylmethacrylate, frozen, and sectioned into dorsal, sagittal, and transverse sections. Representative anatomic images were compared with the CTA, MRA, and T2-weighted images. RESULTS The joint cartilage was identified on all CTA images. The glenohumeral ligaments were clearly visible on the transverse and dorsal CTA and MRA images but were not detected on the T2-weighted sequences. The biceps tendon could be evaluated on all images. The supraspinatus, infraspinatus, and subscapularis muscle tendons were most easily identified on the MRA and T2-weighted MR images. CONCLUSIONS CTA was useful for seeing articular cartilage and both CTA and MRA were useful for seeing the normal glenohumeral ligaments; however, further research is needed to examine each techniques sensitivity for diagnosing the pathology of these ligaments and any associated lesions of the capsule, tendon, and bone, and for determining the clinical importance of CTA for evaluating loose fragments or osteochondral lesions.Objective To compare low-field magnetic resonance arthrography (MRA) and computed tomographic arthrography (CTA) for identification of intra-articular ligaments and joint cartilage in the normal canine shoulder with the aid of cross-sectional anatomy. Animals Normal adult Foxhounds (n = 3) and 4 Foxhound cadaver shoulders. Methods CTA of 3 dogs was performed after intra-articular administration of contrast medium in both shoulders. Transverse slices and reformatted sagittal and dorsal images were obtained. Later, an MRA study of all 6 shoulder joints was performed using a low-field system. T1- and T2-weighted images were made in 3 planes, arthrography performed, and T1-weighted images repeated. Unrelated cadaver shoulder joints were injected with red methylmethacrylate, frozen, and sectioned into dorsal, sagittal, and transverse sections. Representative anatomic images were compared with the CTA, MRA, and T2-weighted images. Results The joint cartilage was identified on all CTA images. The glenohumeral ligaments were clearly visible on the transverse and dorsal CTA and MRA images but were not detected on the T2-weighted sequences. The biceps tendon could be evaluated on all images. The supraspinatus, infraspinatus, and subscapularis muscle tendons were most easily identified on the MRA and T2-weighted MR images. Conclusions CTA was useful for seeing articular cartilage and both CTA and MRA were useful for seeing the normal glenohumeral ligaments; however, further research is needed to examine each techniques sensitivity for diagnosing the pathology of these ligaments and any associated lesions of the capsule, tendon, and bone, and for determining the clinical importance of CTA for evaluating loose fragments or osteochondral lesions.

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 SM in 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%, κ = 0.54) and almost perfect agreement for CT (94%, κ = 0.87). There was a moderate intramodality agreement for both observers (observer 1 81%, κ = 0.59; observer 2 81%, κ = 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.