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
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
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
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
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)
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)
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.
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)
Objective—To use computed tomography to provide
a detailed description of tarsal joint structures in clinically
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
Objective—To determine the spectrum and frequency of abnormalities for low-field magnetic resonance imaging (MRI) examinations of clinically normal Doberman Pinschers and Foxhounds.
Animals—37 clinically normal dogs (20 Doberman Pinschers and 17 Foxhounds).
Procedures—For each dog, MRI of the cervical vertebrae (sagittal, dorsal, and transverse T1- and T2-weighted images) was performed. Variables assessed were intervertebral disk degeneration, disk-associated compression, compression of the dorsal portion of the spinal cord, vertebral body abnormalities, and changes in intraparenchymal signal intensity. Associations between these variables and age, breed, sex, and location of the assessed intervertebral disk spaces were evaluated.
Results—Severe MRI abnormalities were detected in 17 dogs, including complete disk degeneration (n = 4 dogs), spinal cord compression (3), or both (10). Vertebral body abnormalities were detected in 8 dogs, and hyperintense signal intensity was detected in 2 dogs. Severity of disk degeneration and disk-associated compression was significantly associated with increased age. There was a significant association between disk degeneration, disk-as-sociated compression, and compression of the dorsal aspect of the spinal cord and location of the assessed intervertebral disk space, with the intervertebral disk spaces in the caudal portion of the cervical region being more severely affected.
Conclusions and Clinical Relevance—Abnormalities were commonly seen on MRI examinations of the caudal portion of the cervical vertebral column and spinal cord of clinically normal Doberman Pinchers and Foxhounds. Such lesions were probably part of the typical spinal cord degeneration associated with the aging process of dogs.
Objective—To provide a detailed computed tomography (CT) reference of the anatomically normal equine stifle joint.
Sample—16 hind limbs from 8 equine cadavers; no horses had evidence of orthopedic disease of the stifle joints.
Procedures—CT of the stifle joint was performed on 8 hind limbs. In all limbs, CT was also performed after intra-articular injection of 60 mL of contrast material (150 mg of iodine/mL) in the lateral and medial compartments of the femorotibial joint and 80 mL of contrast material in the femoropatellar joint (CT arthrography). Reformatted CT images in the transverse, parasagittal, and dorsal plane were matched with corresponding anatomic slices of the 8 remaining limbs.
Results—The femur, tibia, and patella were clearly visible. The patellar ligaments, common origin of the tendinous portions of the long digital extensor muscle and peroneus tertius muscle, collateral ligaments, tendinous portion of the popliteus muscle, and cranial and caudal cruciate ligaments could also be consistently evaluated. The cruciate ligaments and the meniscotibial ligaments could be completely assessed in the arthrogram sequences. Margins of the meniscofemoral ligament and the lateral and medial femoropatellar ligaments were difficult to visualize on the precontrast and postcontrast images.
Conclusions and Clinical Relevance—CT and CT arthrography were used to accurately identify and characterize osseous and soft tissue structures of the equine stifle joint. This technique may be of value when results from other diagnostic imaging techniques are inconclusive. The images provided will serve as a CT reference for the equine stifle joint.
Objective—To determine radiographic, magnetic resonance
imaging (MRI), computed tomography (CT),
and rhinoscopic features of nasal aspergillosis in
Animals—15 client-owned dogs.
Procedure—All dogs had clinical signs of chronic
nasal disease; the diagnosis of nasal aspergillosis was
made on the basis of positive results for at least 2
diagnostic tests (serology, cytology, histology, or fungal
culture) and detection of typical intrasinusal and
intranasal fungal colonies and turbinate destruction
via rhinoscopy. Radiography, MRI, and CT were performed
under general anesthesia. Rhinoscopy was
repeated to evaluate lesions and initiate treatment.
Findings of radiography, MRI, CT, and rhinoscopy
Results—MRI and CT revealed lesions suggestive of
nasal aspergillosis more frequently than did radiography.
Computed tomography was the best technique for
detection of cortical bone lesions; the nature of abnormal
soft tissue, however, could not be identified.
Magnetic resonance imaging allowed evaluation of
lesions of the frontal bone and was especially useful for
differentiating between a thickened mucosa and secretions
or fungal colonies; however, fungal colonies could
not be differentiated from secretions. Rhinoscopy
allowed identification of the nature of intranasal and
intrasinusal soft tissue but was not as useful as CT and
MRI for defining the extent of lesions and provided no
information regarding bone lesions.
Conclusions and Clinical Relevance—The value of
CT and MRI for diagnosis of nasal aspergillosis was
similar and greater than that of radiography.
Rhinoscopy is necessary because it is the only technique
that allows direct visualization of fungal
colonies. (J Am Vet Med Assoc 2004;225:1703–1712)
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.