IMAGING DIAGNOSIS—SPINAL CORD HEMANGIOMA IN TWO DOGS

Intramedullary masses are a dilemma due to the limited access for a nonsurgical biopsy, thus, accurate imaging characterization is crucial. Magnetic resonance imaging findings of two confirmed canine thoracic intramedullary hemangiomas are described. A capillary hemangioma was of mixed intensity but predominantly T2‐hyperintense and mildly T1‐hyperintense to spinal cord with strong contrast enhancement. A cavernous hemangioma had a target‐like appearance in both T1‐weighted (T1w) and T2‐weighted (T2w) images. In T2w images there was a small isointense center surrounded by a relatively large hyperintense area. In T1w images, there was a large isointense centre with a relatively small hyperintense periphery. Such characteristics should prioritize hemangioma as a consideration in a progressive myelopathy due to an intramedullary mass.     

ULTRASONOGRAPHIC ANATOMY OF THE BRACHIAL PLEXUS AND MAJOR NERVES OF THE CANINE THORACIC LIMB

A technique for ultrasonography of the brachial plexus and major nerves of the canine thoracic limb is described based on examination of five canine cadavers and three healthy dogs. The ventral branches of the spinal nerves that contribute to the brachial plexus are identifiable at their exit from the intervertebral foramina. These nerves may be followed distally, cranial to the first rib, until they form the brachial plexus. The musculocutaneous, ulnar, and median nerves are identified on the medial aspect of mid‐humerus and followed proximally to the axillary region and distally to the elbow. The radial nerve, formed by multiple nerve components, is seen on the mediocaudal aspect of the humerus. Nerves appear as hypoechoic tubular structures with an internal echotexture of discontinuous hyperechoic bands, surrounded by a thin rim of highly echogenic tissue. Improved understanding of the ultrasonographic anatomy of the brachial plexus and its main branches supports clinical use of this modality.     

LYMPHOMA AFFECTING THE URINARY BLADDER IN THREE DOGS AND A CAT

Three dogs and one cat with lymphoma affecting the urinary bladder are reported and the findings on abdominal radiographs and ultrasound are described. Mural lesions representing lymphoma affecting the urinary bladder were identified ultrasonographically in all animals. The most common complications associated with urinary bladder lymphoma were hydronephrosis and hydroureter. In two patients contrast radiography was necessary to detect leakage of urine in the peritoneal and retroperitoneal space. The radiographic and ultrasonographic signs were similar to those reported with other urinary bladder neoplasms; hence urinary bladder lymphoma could not be distinguished from the more common urinary bladder neoplasms, such as transitional cell carcinoma. It is important to include lymphoma in the differential diagnosis of urinary bladder wall thickening and mural mass in dogs and cats.     

IMAGING DIAGNOSIS—DEGENERATIVE INTRASPINAL CYST ASSOCIATED WITH AN INTERVERTEBRAL DISC

A 6-year-old neutered male Rottweiler had chronic episodic signs of thoracolumbar pain and inability to stand that did not improve after rest and nonsteroidal antiinflammatory medication. In magnetic resonance images, an extradural mass was identified between the spinal cord and the T13/L1 intervertebral disc; the mass was compressing the cord in a dorsoventral direction. The lesion had a low signal intensity rim that enhanced slightly after gadolinium administration, and contents with similar signal intensity to cerebrospinal fluid. The lesion was removed surgically by severing its attachments to the annulus fibrosus. The histologic diagnosis was degenerative intraspinal cyst. The origin of such cysts, and their relationship to synovial and ganglion cysts is discussed.     

ULTRASOUND IMAGE COMPOUNDING: EFFECT ON PERCEIVED IMAGE QUALITY

In order to determine the effect of different image compounding functions on perceived image quality, 84 pairs of ultrasound images were collected, mixed, and reviewed by four independent observers who were asked to identify the highest quality image of each pair. Each image in a pair was made using the same orientation, transducer, frequency, and gain settings but different compounding settings. Outcomes were analyzed using logistic regression. Observers judged compound images to be better quality than noncompound images in 69% cases, the same quality in 24%, and poorer quality in 7%. Overall, compound images were considered significantly better quality than noncompound images (P < 0.001). Compound images were more likely to be considered better quality than the corresponding noncompound images when combined transmit/receive spatial compounding was used rather than receive-only spatial compounding or transmit compounding, and when the vector transducer or the curvilinear transducer were used rather than the linear transducer. Observers considered improved border definition and increased signal to noise ratio to be the properties that accounted most often for higher quality of compound images compared with noncompound images.     

ULTRASONOGRAPHIC ASSESSMENT OF THE CANINE SCIATIC NERVE

To describe the ultrasonographic technique for investigation of the canine sciatic nerve, four canine cadaver pelvic limbs, two live healthy dogs, and five canine patients with suspected peripheral sciatic nerve lesions were examined with a high-resolution linear ultrasound transducer. The caudal part of the lumbosacral trunk and the origin of the sciatic nerve were visualized through the greater ischiatic foramen. The two components of the sciatic nerve, common peroneal and tibial nerves, were distinguished along the entire length of the nerve, until they branched at the level of the distal femur. In healthy live dogs they appeared as two adjacent hypoechoic tubular structures with internal echotexture of discontinuous hyperechoic bands, surrounded by a thin rim of highly echogenic tissue. The common peroneal component had a smaller diameter and was on the cranial aspect of the tibial component. An ultrasonographic lesion compatible with a peripheral nerve sheath tumor was found in one dog. Improved understanding of the ultrasonographic anatomy of the sciatic nerve supports clinical use of this modality.     

INCOMPLETE OSSIFICATION OF THE ATLAS IN DOGS WITH CERVICAL SIGNS

Osseous defects affecting the atlas were identified in computed tomography and magnetic resonance images of five dogs with cervical signs including pain, ataxia, tetraparesis, or tetraplegia. Osseous defects corresponded to normal positions of sutures between the halves of the neural arch and the intercentrum, and were compatible with incomplete ossification. Alignment between the portions of the atlas appeared relatively normal in four dogs. In these dogs the bone edges were smooth and rounded with a superficial layer of relatively compact cortical bone. Displacement compatible with unstable fracture was evident in one dog. Concurrent atlantoaxial subluxation, with dorsal displacement of the axis relative to the atlas, was evident in four dogs. Three dogs received surgical treatment and two dogs were treated conservatively. All dogs improved clinically. Incomplete ossification of the atlas, which may be associated with atlantoaxial subluxation, should be considered in the differential diagnosis of dogs with clinical signs localized to the cranial cervical region.