Search Results

Abstract

Objective—To provide a detailed anatomic description of the thorax in clinically normal dogs by means of computed tomography.

Animals—4 clinically normal adult German Shepherd Dogs weighing 28 to 37 kg.

Procedure—Dogs were anesthetized and positioned in ventral recumbency for computed tomographic (CT) examination of the thorax. A CT image from the thoracic inlet to the diaphragm was made by use of a third-generation scanner with a slice thickness of 5 mm. Individual images were reviewed by use of soft tissue (window width, 250 Hounsfield units; window level, 35 Hounsfield units) and lung (window width, 1,000 Hounsfield units; window level, –690 Hounsfield units) settings. One dog, weighing 28 kg, was euthanatized, bound on a wooden frame in the same position as used for CT examination, and frozen at –14oC until solid. By use of an electric band saw, the frozen thorax was sectioned at 10-mm-thick intervals. Slab sections were immediately cleaned, photographed, and compared with corresponding CT images.

Results—Anatomic sections were studied, and identified anatomic structures were matched with structures on corresponding CT images. Except for some blood vessels and details of the heart, most of the bony and soft tissue structures of the thorax discerned on anatomic slices could be found on matched CT images.

Conclusions and Clinical Relevance—Because CT images provide detailed information on most structures of the canine thorax, results of our study could be used as a guide for evaluation of CT images of the thorax of dogs with thoracic diseases. (Am J Vet Res 2005;66:512–524)

Abstract

Objective—To provide a detailed anatomic description of brain structures in clinically normal dogs by means of computed tomography (CT).

Animals—4 clinically normal adult German Shepherd Dogs weighing 30 to 35 kg.

Procedure—Each dog was anesthetized and positioned in ventral recumbency for CT examination of the brain; transverse scans were completed at 2-mm intervals from the cribriform plate of the ethmoid bone to the cranial part of the atlas by use of a thirdgeneration CT scanner. Contrast material was injected IV, and a second series of scans was completed. Images (with or without contrast) from all dogs were reviewed by use of a soft tissue setting (window width, 150 Hounsfield units; window level, 50 Hounsfield units). One of the dogs was euthanatized, and a 3.5% formaldehyde solution was perfused via the common carotid arteries. After fixation, the brain was embedded in gelatin and sectioned into 5-mm thick transverse sections by use of a stainless-steel knife. Anatomic sections were photographed and compared with the corresponding CT views.

Results—Most features of the brain that were identified on anatomic sections could be identified on the corresponding CT scans despite the low contrast between structures, particularly if adjacent bony and soft tissue structures were used as landmarks. Additional anatomic structures surrounding the brain were also identifiable on the CT images.

Conclusions and Clinical Relevance—Images obtained in this study could be used as a guide for evaluation of CT images of the brain in dogs with brain diseases. (Am J Vet Res 2005;66;1743–1756)

Abstract

Objective—To use computed tomography (CT) to provide a detailed description of elbow joint structures in clinically normal dogs.

Animals—6 clinically normal adult mixed-breed dogs weighing 24 to 37 kg and one 12-month-old Labrador Retriever weighing 27 kg.

Procedure—To perform CT of both elbow regions, dogs were anesthetized and placed in lateral recumbency. One- and 2-mm contiguous slices were obtained by use of a third generation computed tomographic scanner. Good resolution and anatomic detail were acquired from the computed tomographic images by use of a bone (window width, 3,500 Hounsfield units; window level, 500 Hounsfield units) and soft-tissue setting (window width, 400 Hounsfield units; window level, 66 Hounsfield units). After euthanasia, the forelimbs from the Labrador Retriever were removed and frozen in water at –18oC. Elbow joints were sectioned into approximately 1- mm-thick slab sections by use of an electric planer. Anatomic sections were photographed and compared with the corresponding computed tomographic images. Computed tomographic reconstructions of the elbow joint were created in sagittal and dorsal planes.

Results—Structures on the computed tomographic images were matched with structures in the corresponding anatomic sections. The entire humeroradioulnar joint surface could be evaluated on the reconstructed images in the sagittal and dorsal plane.

Conclusions and Clinical Relevance—Computed tomographic images provide full anatomic detail of the bony structures of the elbow joint in dogs. Muscles, large blood vessels, and nerves can also be evaluated. These results could be used as a basis for evaluation of computed tomographic images of the forelimbs of dogs with elbow joint injuries. (Am J Vet Res 2002;63:1400–1407)

Abstract

Objective—To use computed tomography (CT) and magnetic resonance imaging (MRI) to provide a detailed description of the nasal cavities and paranasal sinuses in clinically normal mesaticephalic dogs.

Animals—2 clinically normal Belgian Shepherd Dogs that weighed 25 and 35 kg, respectively.

Procedure—The first dog was anesthetized and positioned in ventral recumbency for CT and MRI examinations, and transverse slices were obtained from the caudal part of the frontal sinuses to the nares. For MRI, T1-weighted, T2-weighted, and proton-density sequences were obtained. The second dog was anesthetized and positioned in dorsal recumbency with the head perpendicular to the table, and CT and MRI examinations were again conducted. At the completion of the MRI examination, each dog received an IV injection of heparin and then was euthanatized. A 4% solution of formaldehyde was perfused IV immediately after each dog was euthanatized. The skull was prepared, decalcified, embedded with gelatin, and sectioned into 5-mmthick sections by use of a stainless-steel knife. Each anatomic section was photographed and compared with the corresponding CT and MRI views.

Results—Structures on the CT and MRI views matched structures on the corresponding anatomic sections. The CT scans provided good anatomic detail of the bony tissues, and MRI scans were superior to CT scans for determining soft-tissue structures.

Conclusions and Clinical Relevance—CT and MRI provide a means for consistent evaluation of all structures of the nasal cavities and frontal sinuses. Both techniques could be useful for evaluation of diseases that affect the nasal region. (Am J Vet Res 2003;64:1093–1098)

Abstract

Objective—To obtain a detailed anatomic description of the rabbit head by means of computed tomography (CT).

Animals—6 clinically normal Dendermonde White rabbits weighing 3 kg and raised for human consumption and 1 Netherland dwarf rabbit.

Procedures—The commercially raised rabbits were slaughtered in a slaughterhouse, flayed, and decapitated. The dwarf rabbit was euthanatized. Two hours later, each rabbit head was positioned with the ventral side on the CT table to obtain transverse and sagittal, 1-mm-thick slices. Dorsal images were obtained by placing each head perpendicular to the table. Immediately after the CT examination, 3 heads were frozen in an ice cube at −14°C until solid and then sectioned at 4-mm-thick intervals by use of an electric band saw. Slab sections were immediately cleaned, photographed, and compared with corresponding CT images. Anatomic sections were examined, and identified anatomic structures were matched with structures on corresponding CT images.

Results—The bone-window CT images yielded good anatomic detail of the dentition and the bony structures of rabbit skulls. The soft tissue structures that could be determined were not better identifiable on the soft tissue–window CT images than on the bone-window images.

Conclusions and Clinical Relevance—CT images of the heads of healthy rabbits yielded detailed information on the skull and some surrounding soft tissue structures. Results of this study could be used as a guide for evaluation of CT images of rabbits with various cranial and dental disorders.

Abstract

Objective—To use computed tomography to provide a detailed description of tarsal joint structures in clinically normal dogs.

Animals—6 clinically normal adult mixed-breed dogs weighing 25 to 35 kg and one 12-month-old Bullmastiff weighing 65 kg.

Procedure—To perform computed tomography (CT) of both tarsal regions, dogs were anesthetized and placed in ventral recumbency. One- and 2-mm contiguous slices were obtained, using a third generation CT scanner. Individual images were reviewed, using bone (window width = 3,500 Hounsfield units; window level = 500 Hounsfield units) and soft-tissue (window width = 400 Hounsfield units; window level = 66 Hounsfield units) settings. After euthanasia, the hind limbs from the Bullmastiff were removed and frozen at –18 C. Tarsal joints were sectioned into approximately 1-mmthick slab sections, using a cryomicrotome. Anatomic sections were photographed and compared with the corresponding CT images. Computed tomographic reconstructions of the tarsocrural joint were created in sagittal and dorsal planes.

Results—Structures on the CT images were matched with structures in the corresponding anatomic sections. The entire tarsocrural joint surface could be evaluated on the reconstructed images in the sagittal and dorsal planes.

Conclusions and Clinical Relevance—CT images provide full anatomic detail of the bony structures of the tarsal joint in dogs. Tendons and large blood vessels can also be evaluated. These results could be used as a basis for evaluation of CT images of the hind limbs of dogs with tarsal joint injuries. (Am J Vet Res 2001;62:1911–1915)

Abstract

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 dog's 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.

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 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 evaluate cartilage thickness of the talus (especially at sites predisposed to osteochondrosis dissecans [OCD]) in growing and adult dogs not affected with OCD.

Sample—Tarsocrural joints from cadavers of 34 juvenile (approx 3 months old) and 10 adult dogs.

Procedures—Tarsal cartilage thickness was examined via a stereophotography microscopic system. Articular cartilage thickness was determined at 11 locations on longitudinal slices of the trochlear ridges and the sulcus between the ridges and at 2 locations in the cochlea tibiae. Cartilage thickness was measured at the proximal, proximodorsal, dorsal, and distal aspects of the trochlear ridges; proximodorsal, dorsal, and distal aspects of the trochlear sulcus; and craniolateral and caudomedial aspects of the cochlea tibiae. Differences within a joint and between sexes were evaluated.

Results—Mean cartilage thickness decreased from proximal to distal in juvenile (lateral trochlear ridge, 1.52 to 0.41 mm; medial trochlear ridge, 1.10 to 0.40 mm) and from proximal to dorsal in adult (lateral trochlear ridge, 0.41 to 0.34 mm; medial trochlear ridge, 0.33 to 0.23 mm) dogs. Cartilage was thickest at the proximal aspect of the lateral trochlear ridge in both groups. Differences in proximodorsal, dorsal, and distal aspects of the ridges were not evident.

Conclusions and Clinical Relevance—Healthy tarsocrural joints did not have thicker cartilage in sites predisposed to development of OCD. Evaluation of affected tarsocrural joints is necessary to exclude influences of cartilage thickness. These data are useful as a reference for distribution of cartilage thickness of the trochlea of the talus in dogs.