TRIPLE‐PHASE HELICAL COMPUTED TOMOGRAPHY IN DOGS WITH HEPATIC MASSES

The purpose of this study was to determine the utility of triple‐phase helical computed tomography (CT) for differentiating canine hepatic masses. Seventy dogs with hepatic masses underwent triple‐phase CT followed by surgical removal of the hepatic masses. Triple‐phase helical CT scans for each dog included precontrast, arterial phase, portal venous phase, and delayed phase studies. The removed hepatic masses were histopathologically classified as hepatocellular carcinoma (n = 47), nodular hyperplasia (n = 14), and hepatic metastatic tumors (n = 9) in dogs. Of the 47 hepatocellular carcinomas, the most common CT findings included a heterogeneous pattern with hyper‐, iso‐, and hypoenhancement in both the arterial and portal venous phases (40/47, 85.1%). Of the 14 nodular hyperplasias, the most common CT findings were a homogeneous pattern with hyper‐ and isoenhancement in both the portal venous and delayed phases (13/14, 92.9%). Of nine hepatic metastatic tumors, the most common CT findings included a homogeneous hypoenhancement pattern in both the arterial and portal venous phases (8/9, 88.9%). In addition, 5 (55.6%) showed homogeneous hypoenhancement patterns in the delayed phase. Findings from our study indicated that triple‐phase CT is a useful tool for preoperative differentiation of hepatocellular carcinoma, nodular hyperplasia, and hepatic metastatic tumors in dogs.     

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHY FINDINGS IN A DOG WITH SPONTANEOUS TRANSMURAL MIGRATION OF A TEXTILOMA INTO THE CECUM

A 3‐year‐old spayed female dog was presented with 3‐month history of severe bilateral uveitis subsequent to previous ovariohysterectomy. Physical examination revealed moderate abdominal pain. Computed tomography showed a nonobstructive heterogeneous mass‐like lesion with a speckled gas pattern (spongiform pattern) within the cecum. Exploratory laparotomy revealed a surgical swab in the lumen of the cecum with severe adhesions. Histopathological examination demonstrated a chronic inflammatory pyogranulomatous reaction to the retained swab embedded within the intestinal wall, consistent with transmural migration of the swab from the peritoneal cavity into the cecum.     

IMAGING DIAGNOSIS—USE OF MULTIPHASIC CONTRAST‐ENHANCED COMPUTED TOMOGRAPHY FOR DIAGNOSIS OF MESENTERIC VOLVULUS IN A DOG

A 4‐year‐old German shorthaired pointer presented with collapse and hematochezia. Radiographs showed gas and fluid‐distended small intestines and loss of serosal detail. Ultrasound examination showed hypomotile, fluid‐distended small intestines, and thrombosed jejunal veins. Multiphasic contrast‐enhanced computed tomography was performed and showed a CT “whirl sign,” an important but nonspecific sign of intestinal volvulus in human patients. At surgery, the majority of the small intestine was entangled in the volvulus and showed black discoloration. The patient was euthanized. Postmortem evaluation yielded a diagnosis of jejunoileal mesenteric volvulus secondary to a congenital omphalomesenteric duct remnant.     

IMAGING DIAGNOSIS—CONGENITAL LOBAR EMPHYSEMA IN A DOG

A 14‐week‐old female West Highland White Terrier developed acute dyspnea. Radiographically there was an enlarged, hyperlucent caudal portion of the left cranial lung lobe and a diffuse, severe interstitial‐to‐alveolar pattern in the remaining lung lobes that was accentuated caudodorsally. Computed tomography confirmed the presence of the emphysematous lobe and further showed it to have focal lobar bronchial collapse. Lung lobe resection was performed, and the diagnosis was congenital lobar emphysema secondary to bronchial cartilage hypoplasia.     

IMAGING DIAGNOSIS—SPINAL CORD CHONDROSARCOMA ASSOCIATED WITH SPIROCERCOSIS IN A DOG

A 7‐year‐old neutered female Boerboel cross was examined for progressive left pelvic limb lameness. There was no left patellar reflex but the remaining pelvic limb reflexes were hyperreflexic. Radiographically, there was a poorly mineralized opacity occupying the intervertebral foramen at L4–L5. On computed tomography images there was a hyperattenuating intramedullary lesion at L4–L5 that continued caudally, lateralized to the left and became extramedullary, terminating at L5–L6. In addition, well marginated, hyperattenuating lesions were noted at two muscular sites. The dog underwent euthanasia and a caudal esophageal mass was found at post mortem examination. The tumors in the spinal cord, the esophagus, and the skeletal muscles were diagnosed histologically as low‐grade chondrosarcoma undergoing endochondral ossification. Spirocerca lupi‐induced esophageal chondrosarcoma was believed to be the primary site from which the other, presumably metastatic, lesions originated.     

IMAGING DIAGNOSIS—PULMONARY ALVEOLAR PROTEINOSIS IN A DOG

A young dog was presented for cyanosis and right heart failure. Radiographic and CT characteristics included right heart/pulmonary artery enlargement, hepatomegaly, abdominal effusion, and severe, generalized air‐space filling. Focal increased opacities were present in the peripheral lung, as were multiple pulmonary blebs and bullae. Echocardiographic findings were consistent with cor pulmonale and pulmonary hypertension. Bronchoscopic findings were consistent with chronic inflammation. Pulmonary alveolar proteinosis (PAP) was confirmed at necropsy. Pulmonary alveolar proteinosis is an interstitial lung disease that results in accumulation of phospholipoproteinaceous material and should be included as a differential diagnosis for dogs with these clinical and imaging characteristics.     

IMAGING DIAGNOSIS—CT MYELOGRAPHY IN A DOG WITH INTRAMEDULLARY INTERVERTEBRAL DISC HERNIATION

A 5‐year‐old Chihuahua was examined for peracute pain and paraparesis. Neuroanatomic localization was consistent with a symmetric T3‐L3 myelopathy. Computed tomography (CT) of the T9‐L5 vertebrae was normal. Myelography disclosed attenuation of the subarachnoid space from T11 to L1, consistent with spinal cord swelling. CT following the myelogram disclosed a focal area of intramedullary iodinated contrast medium at T13‐L1. At surgery, intervertebral disc material was removed from the spinal cord. Based on the findings in this patient, intramedullary disc herniation should be considered a cause for focal intramedullary contrast medium accumulation.     

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHY OF TRACTION BRONCHIECTASIS SECONDARY TO PULMONARY FIBROSIS IN A PATTERDALE TERRIER

An 8‐year‐old, Patterdale terrier was referred for evaluation of tachypnoea, exercise intolerance, and weight loss. Computed tomographic images showed pneumomediastinum, diffuse pulmonary ground glass opacity, and marked dilatation of peripheral bronchi, but no evidence of thickened bronchial walls. The histopathologic diagnosis was diffuse pulmonary interstitial fibrosis, type II pneumocyte hyperplasia, and bronchiectasis. The lack of evidence of primary bronchitis supported a diagnosis of traction bronchiectasis. Traction bronchiectasis can occur as a sequela to pulmonary fibrosis in dogs.     

IMAGING DIAGNOSIS—RADIOGRAPHY AND COMPUTED TOMOGRAPHY OF RADIOULNAR ISCHEMIC NECROSIS IN A JACK RUSSELL TERRIER

A 7‐year‐old Jack Russell Terrier with a history of minor trauma was presented for lameness of the left forelimb. Radiography and computed tomography demonstrated a localized radioulnar osteolytic lesion with cortical bone loss and enthesiophytes. Based on results of diagnostic imaging and histopathological examination, the final diagnosis was radioulnar ischemic necrosis (RUIN), complicated by pathologic fracture. A rare disorder of unknown etiology, RUIN may be secondary to tearing of the interosseous ligament and potential ischemia. It should be differentiated from neoplastic or fungal disease. To the authors´ knowledge, this is the first canine case report describing RUIN.     

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHY FINDINGS IN A CASE OF METASTATIC OVARIAN ADENOCARCINOMA IN A DOG

A 5‐year‐old female entire German Shepherd presented for otitis and lethargy. An incidental abdominal mass was identified on examination. Ultrasound examination (US) identified a heterogeneous left ovarian mass. Computed tomography (CT) was performed for surgical planning and staging. The reproductive tract was removed en bloc and submitted for histopathology. Multiple small (1–5 mm) nodules identified at coeliotomy on the surface of the liver, spleen and peritoneum were biopsied. The lesions were not visible on CT nor US on review. This is the first case report of the CT findings of ovarian papillary adenocarcinoma with carcinomatosis.     

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHIC,SURGICAL, AND HISTOPATHOLOGIC CHARACTERISTICS OF AN INFILTRATIVE ANGIOLIPOMA IN A DOG

A 6‐year‐old female spayed Shetland Sheepdog presented for evaluation of a subcutaneous mass over the right prescapular region. The mass had been cytologically diagnosed as a lipoma by the referring veterinarian 20 months prior, but had grown significantly and was very firm. CT scan of the mass was suggestive of neoplasia; however, the tissue of origin could not be determined. Histopathologic evaluation diagnosed infiltrative angiolipoma, and marginal resection of the tumor was performed. Infiltrative angiolipomas are benign but locally aggressive neoplasms uncommonly reported in veterinary medicine. This report correlates the clinical, CT, and histopathologic characteristics of an infiltrative angiolipoma.     

IMAGING DIAGNOSIS—MULTIMODALITY FINDINGS IN AN ADULT DOG WITH PRIMARY SARCOMA OF THE PULMONARY ARTERY AND MYOCARDIAL METASTASES

Intravascular pulmonary artery sarcomas in combination with myocardial metastasis are rare in dogs. We describe the radiographic, echocardiographic, and electrocardiographic‐gated (ECG‐gated) computed tomographic angiography (CTA) findings in a dog with pulmonary artery sarcoma. All imaging studies demonstrated severe main pulmonary artery enlargement. Echocardiography and ECG‐gated CTA revealed a mass occluding the lumen of the right pulmonary artery. In addition, CTA revealed focal left ventricular myocardial contrast enhancement and parenchymal lung changes. Postmortem examination confirmed the presence of a large thrombus associated with arteriosclerosis and an intravascular sarcoma in the right pulmonary artery with metastases to the myocardium, lungs and brain.     

IMAGING DIAGNOSIS–SCLEROSING ENCAPSULATING PERITONITIS IN A DOG

An approximately 5‐month‐old American Staffordshire terrier was presented with a history of recurrent peritoneal effusion. Abdominal radiographs and ultrasound showed a loculated effusion in the ventral abdomen with dorsal displacement of abdominal organs, hepatomegaly and rounding of liver and splenic margins. Computed tomography demonstrated centrally located gastrointestinal segments surrounded by a thin soft tissue band and a thickened peritoneal lining. At necropsy a fibrous membrane continuous with liver and splenic capsules encapsulated all abdominal organs. Microscopically the abdominal wall and fibrous capsule consisted of an irregular thick layer of hypocellular connective tissue. The final diagnosis was sclerosing encapsulating peritonitis.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC APPEARANCE OF SKELETAL MUSCLE METASTASES IN A DOG WITH HEMANGIOSARCOMA

A 13‐year‐old spayed female German shepherd dog was presented for acute onset of lethargy, anorexia, and disseminated erythematous skin lesions. Thoracic radiographs and abdominal ultrasonographic findings were consistent with metastatic hemangiosarcoma. Multiple, ill‐defined, irregularly shaped hypoechoic nodules were also detected within the thoracic and abdominal wall. Hemangiosarcoma metastases to the skeletal muscle were confirmed based on histopathological examination. Multivisceral involvement was also confirmed by necropsy. Metastatic neoplasia should be considered as a differential diagnosis for dogs with ill‐defined, irregular, hypoechoic, intramuscular nodules.     

IMAGING DIAGNOSIS—TRANSCRANIAL COLOR‐CODED DUPLEX SONOGRAPHY IN A DOG WITH HEPATIC ENCEPHALOPATHY

We report the use of transcranial Doppler ultrasonography in a dog with hepatic encephalopathy secondary to a congenital portosystemic shunt. A severe increase in the pulsatility index was measured in the right middle cerebral artery, left middle cerebral artery, and basilar artery. These values returned to normal following medical stabilization of the patient and resolution of the neurologic signs. Transcranial Doppler ultrasonography appears to have value for monitoring the status of intracranial hypertension in patients with hepatic encephalopathy.     

IMAGING DIAGNOSIS—MALIGNANT PERIPHERAL NERVE SHEATH TUMOR PRESENTING AS AN INTRA‐AXIAL BRAIN MASS IN A YOUNG DOG

A 3‐year‐old Labrador retriever was presented with acute onset seizures. Magnetic resonance imaging demonstrated an intra‐axial mass affecting the right temporal lobe of the brain. Surgical resection and histopathological findings were most consistent with a malignant peripheral nerve sheath tumor. After initial recovery, deterioration 3 months post surgery prompted euthanasia. Post‐mortem revealed a mass protruding from the ventral surface of the temporal lobe, encroaching upon the optic chiasm and invading the brain. Histopathology findings were again consistent with malignant peripheral nerve sheath tumor. Although rare, this tumor should be included as a possible differential diagnosis for intra‐axial brain masses in dogs.     

ASSOCIATIONS BETWEEN DUAL‐PHASE COMPUTED TOMOGRAPHY FEATURES AND HISTOPATHOLOGIC DIAGNOSES IN 52 DOGS WITH HEPATIC OR SPLENIC MASSES

Ability to noninvasively differentiate malignant from nonmalignant abdominal masses would aid clinical decision making. The aim of this retrospective, cross‐sectional study was to identify features in dual‐phase computed tomographic (CT) studies that could be used to distinguish malignant from nonmalignant hepatic and splenic masses in dogs. Medical records were searched for dogs that had an abdominal dual‐phase CT examination, a hepatic or splenic mass, and subsequent histopathologic diagnosis. Computed tomographic images for all included dogs were acquired prior to and <30 s (early phase) and >60 s (delayed phase) after intravenous contrast administration. Fifty‐two dogs with 55 masses were studied: 24 hepatic, including 14 (58%) malignant and 10 (42%) non‐malignant; 31 splenic, including 18 (58%) malignant and 13 (42%) nonmalignant. There was substantial overlap in the pre‐ and postcontrast CT features of malignant and nonmalignant hepatic and splenic masses. Regardless of histologic diagnosis, hepatic masses most frequently showed marked, generalized enhancement in early phase images that persisted in the delayed phase. Splenic hemangiosarcoma and nodular hyperplastic lesions most frequently showed marked, generalized enhancement in early phase images that persisted in delayed images whereas most splenic hematomas had slight enhancement in early phase images. All splenic hematomas and 77% of the hemangiosarcomas had contrast accumulation compatible with active hemorrhage. There were no other significant differences in quantitative or categorical CT data between malignant and nonmalignant hepatic or splenic masses. Dual‐phase CT of dogs with hepatic or splenic masses provides limited specific diagnostic information.     

COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING OF CAVERNOUS SINUS ENLARGEMENT IN A DOG WITH UNILATERAL EXOPHTHALMOS

Computed tomography (CT), magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were performed on a dog with a two year history of unilateral exophthalmos occurring two years following head trauma. On CT images, an expansile enhancing mass was present along the right intracranial cavernous sinus and extended through the orbital fissure into the retrobulbar space. With MRI, the structure appeared as a signal void due to the presence of rapidly flowing blood. Gadolinium enhancement of the adjacent brain was not present. A vascular origin of the lesion was confirmed with MRA. Based on the CT and MRI findings, the enlarged cavernous sinus and associated ophthalmic plexus were believed to represent an arterialized aneurysm, most likely the result of traumatic arteriovenous fistulization. Treatment consisted of surgical enucleation. At the time of this report, 29 mouths later, the dog remains free of clinical signs.