Captivating Cases

Issue 21 - March 2016

Ultrasound

Animal Imaging ultrasound procedures are performed on MyLab Gold ultrasound systems with Doppler capabilities. The Doppler flow technology aids in the evaluation of the percentage of blood flow to any given region and aids in the generation of high quality diagnostic images of the internal organs and soft tissues. This affordable and painless procedure generally does not require patient sedation and is safer than x-rays in that it does not use any ionizing radiation.

Equipped for Success

Animal Imaging offers virtually every outpatient veterinary diagnostic imaging option available for small animal and equine, all in one location:

CT Scan
Fluoroscopy
MRI (3-Tesla)
Nuclear Medicine
Teleradiology
Ultrasound/Mobile Ultrasound

CT of the Feline Skull

History and clinical complaint:

Max is an 11 year old neutered male domestic longhair cat that presented to Animal Imaging in December 2015 for a CT examination of the skull. He had a history of chronic ear infections, a left sided head tilt, left sided facial paresis, and left sided facial swelling.

Findings:

On physical examination, Max was mentally dull with a mild left sided head tilt and left sided facial nerve paralysis. The menace response of the left eye was significantly decreased to absent. He also had blood tinged mucopurulent discharge from the left ear canal.

Image on left: Axial CT image. The green arrow shows osteolysis of the left ventrolateral calvarium. The orange arrow points to a fracture of the zygomatic process of the left temporal bone.

Image on the right: Collapsed left temporomandibular joint with osteolysis of the temportal bone.

A CT examination of the skull was performed and pre-and post-contrast images were obtained. There was marked lysis of the left lateral and ventral lateral calvarium, left temporal bone, and left condyloid process of the mandible. An area of hypoattenuation associated with the left zygomatic process of the temporal bone was consistent with a fracture. The left temporomandibular joint was collapsed and deviated dorsally, with lysis of the articular margin of the temporal bone.

Axial CT image at the level of the ears. The blue arrows point to areas of gas within the soft tissue surrounding the left ear. Soft tissue attenuating material was also noted in the left tympanic cavity (red arrow).

Soft tissue attenuating material filled the rostral left tympanic cavity. There was diffuse soft tissue swelling ventral to the left ear, with gas dissecting through the soft tissue layers surrounding the left ear canal. The soft tissue swelling extended from the left mid-maxillary bone caudally to the cranial cervical spine. No definitive mass was identified. These areas of soft tissue swelling are most likely consistent with cellulitis or edema.

Summary of findings:

1. Aggressive, moderate to marked osteolysis of the left calvarium, left temporal bone (tympanic bulla, mandibular fossa, zygomatic process) and condyloid process of the left mandible, with severe erosive osteoarthritis of the temporomandibular joint.

2. Cellulitis/myositis and/or edema along the left lateral aspect of the skull

3. Left otitis media

The primary differentials for the described osteolysis included osteomyelitis (bacterial vs fungal) and neoplasia. Under ultrasound guidance, fine needle aspirates of the soft tissue along the ramus of the left mandible were obtained. On histopathology, the sample contained a large amount of inflammation with necrosis. The diagnosis was probable carcinoma with pyogranulomatous inflammation and necrosis.