Imaging diagnosis: CT characteristics of a retrobulbar hibernoma in a dog.

A 12-year-old female spayed Beagle was referred for investigation of exophthalmos. CT revealed a well-defined, retrobulbar mass causing rostro-dorsal displacement of the left globe. The mass had a mildly heterogeneous precontrast soft tissue attenuation with mild heterogeneous enhancement following iohexol administration. The mass was surgically removed en bloc with an orbital exenteration. Histopathology confirmed the mass to be a hibernoma, a benign tumor of brown adipose tissue. Hibernomas have CT characteristics consistent with both benign and malignant adipose tumors and may be underrecognized by radiologists.

Computed tomographic imaging of a maxillary sinus mucocele in an 8-year-old French Bulldog.

An 8-year-old male neutered French Bulldog was referred for continued nasal dyspnea following a staphylectomy revision performed one month prior to presentation. The patient had a prior history of skin allergies and underwent brachycephalic airway surgery performed at one year of age. Computed tomography (CT) revealed an osseous-encased, cystic mass arising from the right maxillary sinus. Surgical biopsies were performed and a mucocele with sinusitis and glandular hyperplasia was diagnosed. Based on our systematic review of the literature, maxillary sinus mucocele has not been reported in the dog and should be among the differentials for sinus cystic masses.

Portable Sleep Study Device Versus Polysomnography: A Meta-analysis.

OBJECTIVE: To provide an updated comparison of apnea-hypopnea index (AHI), oxygen desaturation index (ODI), respiratory disturbance index (RDI), oxygen saturation (O2 sat), and lowest oxyhemoglobin saturation (LSAT) measured by portable sleep study devices (PSSDs) compared to polysomnography (PSG). DATA SOURCES: Primary studies were identified through PubMed, Scopus, CINAHL, and Cochrane. REVIEW METHODS: A systematic review was performed by searching databases from inception through August 2021. Only studies examining simultaneous monitoring of a PSSD and PSG were included.  Respiratory indices AHI, ODI, RDI, O2 sat, and LSAT was collected Meta-correlations and meta-regressions were conducted to compare sleep variable measurements between PSSD and PSG. RESULTS: A total of 24 studies (N = 1644 patients) were included. The mean age was 49.5 ± 12.0 (range = 13-92), mean body mass index (BMI) was 30.4 ± 5.7 (range = 17-87), and 69.4% were male. Meta-correlation showed significant associations between PSSD and PSG for AHI (n = 655, r = .888; p < .001), ODI (n = 241, r = .942; p < .001), RDI (n = 313, r = .832; p < .001), O2 sat (n = 171, r = .858; p < .001), and LSAT (n = 197, r = .930; p < .001). Meta-regressions indicated significant predictive correlations for AHI (n = 655; r = .96; p < .001), ODI (n = 740; r = .75; p = .031), RDI (n = 197; r = .99; p = .005), and LSAT (n = 197; r = .85; p = .030), but not for O2 sat (n = 171; r = .31; p = .692). CONCLUSIONS: Respiratory indices correlate strongly between PSSD and PSG, which is further supported by meta-regressions results. PSSD might be a valuable cost and time-saving OSA screening tool.

Extruded gallbladder mucoceles have characteristic ultrasonographic features and extensive migratory capacity in dogs.

Limited information is available on the ultrasonographic characteristics of extruded gallbladder mucoceles. The objective of this retrospective case series study was to describe the ultrasonographic features of extruded gallbladder mucoceles in a group of dogs. Medical records of four veterinary centers were searched between June 2010 and January 2018 for all dogs with a suspected extruded gallbladder mucocele based on abdominal ultrasound. Seven client-owned dogs met the inclusion criteria. All seven dogs had a discrete, heteroechoic, multilayered, stellate, or striated mass within the peritoneal cavity. Blood flow was not present in these structures. Four of these structures were identified in the caudal abdomen. In five cases, the gallbladder lumen was filled with material similar in appearance to the free-floating peritoneal mass. Four cases were confirmed surgically and one case was confirmed at necropsy. Histopathology of the gallbladder wall was evaluated in all surgical cases and analysis of the free-floating material was performed in one of the four cases. Extruded gallbladder mucoceles have common imaging characteristics that may be helpful in establishing a presumptive diagnosis. Additionally, these structures may have extensive migratory capacity. The results of the study justify the recommendation for exploration of the entire abdomen during cholecystectomy for gallbladder mucocele removal.

Evaluation of standard magnetic resonance characteristics used to differentiate neoplastic, inflammatory, and vascular brain lesions in dogs.

Magnetic resonance (MR) imaging characteristics are commonly used to help predict intracranial disease categories in dogs, however, few large studies have objectively evaluated these characteristics. The purpose of this retrospective study was to evaluate MR characteristics that have been used to differentiate neoplastic, inflammatory, and vascular intracranial diseases in a large, multi-institutional population of dogs. Medical records from three veterinary teaching hospitals were searched over a 6-year period for dogs that had diagnostic quality brain MR scans and histologically confirmed intracranial disease. Three examiners who were unaware of histologic diagnosis independently evaluated 19 MR lesion characteristics totaling 57 possible responses. A total of 75 dogs with histologically confirmed intracranial disease were included in analyses: 51 with neoplasia, 18 with inflammatory disease, and six with cerebrovascular disease. Only strong contrast enhancement was more common in neoplasia than other disease categories. A multivariable statistical model suggested that extra-axial origin, T2-FLAIR mixed intensity, and defined lesion margins were also predictive of neoplasia. Meningeal enhancement, irregular lesion shape, and multifocal location distinguished inflammatory diseases from the other disease categories. No MR characteristics distinguished vascular lesions and these appeared most similar to neoplasia. These results differed from a previous report describing seven MR characteristics that were predictive of neoplasia in dogs and cats. Findings from the current study indicated that the high performance of MR for diagnosing canine intracranial diseases might be due to evaluator recognition of combinations of MR characteristics vs. relying on any one MR characteristic alone.

Comparison between noncontrast computed tomography and magnetic resonance imaging for detection and characterization of thoracolumbar myelopathy caused by intervertebral disk herniation in dogs.

Magnetic resonance imaging (MRI) and computed tomography (CT) are commonly used to evaluate dogs with thoracolumbar myelopathy; however, relative diagnostic sensitivities for these two modalities have not been previously reported. The purpose of this prospective study was to compare diagnostic sensitivity and observer agreement for MRI and CT in a group of dogs with thoracolumbar myelopathy due to surgically confirmed intervertebral disk herniation (IVDH). All included dogs had magnetic resonance (MR) imaging followed by noncontrast CT using standardized protocols. Three experienced observers interpreted each imaging study independently without knowledge of clinical or surgical findings. The operating surgeon was aware of MR findings but not CT findings at the time surgical findings were recorded. Forty-four dogs met the inclusion criteria. The sensitivity of CT was 88.6% (79.5%-94.2%) and of MR was 98.5% (95% confidence interval, 94.1%-99.7%) for diagnosis of intervertebral disk herniation. Specificity was not calculated, as all dogs had IVDH at surgery. Magnetic resonance imaging was more accurate than CT for identifying the site of intervertebral disk herniation-associated spinal cord compression and differentiating disk extrusion vs. protrusion. Computed tomography was less accurate for lesion localization in per acute cases, as well as for chondrodystrophic, female, older and smaller (<7 kg) dogs. Inter-rater agreement was good for lesion lateralization for both MR and CT (κ = 0.687, 95% CI = 0.552, 0.822, P = 0.002, and κ = 0.692, 95% CI = 0.542, 0.842, P = 0.003). Findings from the current study indicated that MR imaging was more sensitive and accurate than noncontrast CT for diagnosis and characterization of thoracolumbar myelopathy due to IVDH in dogs.

Imaging diagnosis-synovial myxoma of lumbar vertebrae articular process joint.

Magnetic resonance (MR) imaging and histopathology were used to diagnose an articular process synovial myxoma in a dog. On MR images, the tumor was characterized by distortion of the left L1-L2 articular process, widening of the articular process joint, and the presence of a mass contiguous with the synovium of the articular process that displaced the spinal cord. The tumor was T2-hyperintense, T1-hypointense, relative to muscle, and had mild contrast enhancement. The MR features of articular process synovial myxoma may be distinct from other diseases of the articular process joint.

Magnetic resonance imaging features of intracranial astrocytomas and oligodendrogliomas in dogs.

Astrocytomas and oligodendrogliomas represent one third of histologically confirmed canine brain tumors. Our purpose was to describe the magnetic resonance (MR) imaging features of histologically confirmed canine intracranial astrocytomas and oligodendrogliomas and to examine for MR features that differentiate these tumor types. Thirty animals with confirmed astrocytoma (14) or oligodendroglioma (16) were studied. All oligodendrogliomas and 12 astrocytomas were located in the cerebrum or thalamus, with the remainder of astrocytomas in the cerebellum or caudal brainstem. Most (27/30) tumors were associated with both gray and white matter. The signal characteristics of both tumor types were hypointense on T1-weighted images (12 each) and hyperintense on T2-weighted images (11/14 astrocytomas, 12/16 oligodendrogliomas). For astrocytomas and oligodendrogliomas, respectively, common findings were contrast enhancement (10/13, 11/15), ring-like contrast enhancement (6/10, 9/11), cystic regions within the mass (7/14, 12/16), and hemorrhage (4/14, 6/16). Oligodendrogliomas were significantly more likely to contact the brain surface (meninges) than astrocytomas (14/16, 7/14, respectively, P=0.046). Contact with the lateral ventricle was the most common finding, occurring in 13/14 astrocytomas and 14/16 oligodendrogliomas. No MR features were identified that reliably distinguished between these two tumor types. Contrast enhancement was more common in high-grade tumors (III or IV) than low-grade tumors (II, P=0.008).

Accuracy of conventional radiography and computed tomography in predicting implant position in relation to the vertebral canal in dogs.

OBJECTIVE: To compare the accuracy of radiography and computed tomography (CT) in predicting implant position in relation to the vertebral canal in the cervical and thoracolumbar vertebral column. STUDY DESIGN: In vitro imaging and anatomic study. ANIMALS: Medium-sized canine cadaver vertebral columns (n=12). METHODS: Steinmann pins were inserted into cervical and thoracolumbar vertebrae based on established landmarks but without predetermination of vertebral canal violation. Radiographs and CT images were obtained and evaluated by 6 individuals. A random subset of pins was evaluated for ability to distinguish left from right pins on radiographs. The ability to correctly identify vertebral canal penetration for all pins was assessed both on radiographs and CT. Spines were then anatomically prepared and visual examination of pin penetration into the canal served as the gold standard. RESULTS: Left/right accuracy was 93.1%. Overall sensitivity of radiographs and CT to detect vertebral canal penetration by an implant were significantly different and estimated as 50.7% and 93.4%, respectively (P<.0001). Sensitivity was significantly higher for complete versus partial penetration and for radiologists compared with nonradiologists for both imaging modalities. Overall specificity of radiographs and CT to detect vertebral canal penetration was 82.9% and 86.4%, respectively (P=.049). CONCLUSIONS: CT was superior to radiographic assessment and is the recommended imaging modality to assess penetration into the vertebral canal. CLINICAL RELEVANCE: CT is significantly more accurate in identifying vertebral canal violation by Steinmann pins and should be performed postoperatively to assess implant position.