Jennifer A. Reetz

Computed tomographic features of oral squamous cell carcinoma in cats: 18 cases (2002–2008)

OBJECTIVE To describe the computed tomographic features of oral squamous cell carcinoma (SCC) in cats and identify imaging characteristics associated with survival time. DESIGN Retrospective case series. ANIMALS 18 cats with a diagnosis of oral SCC. PROCEDURES Information on history; clinical, laboratory, and diagnostic imaging findings; treatment; and survival time was obtained from medical records of 18 cats with oral SCC. Computed tomography (CT) studies were examined to identify features associated with oral SCC. The association of CT features with survival time was evaluated. RESULTS On CT images, SCC was centered at the following sites: sublingual or lingual region (n = 7), maxilla (5), buccal mucosa (4), mandible (4), pharyngeal mucosa (2), soft palate mucosa (1), and lip (1). These results were in agreement with the results of oral examination for all sites, except the soft palate (CT, 1 cat; oral examination, 4 cats). On CT images, extension of maxillary masses was most often observed to affect the orbit (5 cats). Heterogeneous contrast enhancement was most commonly identified (8/18). Osteolytic mass lesions were identified on CT images in 9 cats. None of the quantitative CT features that were identified, including mass size, attenuation, or lymph node width, were correlated with survival time. CONCLUSIONS AND CLINICAL RELEVANCE Common CT features of oral SCC in cats included sublingual and maxillary locations, marked heterogeneous contrast enhancement, and osteolysis. Computed tomography may be used to determine mass extension and lymph node enlargement, but results did not correlate with survival time.

Safety of contrast-enhanced ultrasonography in dogs and cats: 488 cases (2002-2011)

OBJECTIVE To determine the incidence of adverse events within 24 hours after contrast-enhanced ultrasonography (CEUS) in dogs and cats and compare the risk of death within 24 hours after imaging for animals that underwent ultrasonography with and without injection of a contrast agent. DESIGN Retrospective case-control study. ANIMALS 750 animals (411 case dogs, 238 control dogs, 77 case cats, and 24 control cats). PROCEDURES At 11 institutions, medical records were reviewed of dogs and cats that had CEUS performed (cases) as were medical records of dogs and cats with clinical signs similar to those of case animals that had ultrasonography performed without injection of a contrast agent (controls). Information regarding signalment; preexisting disease; type, dose, and administration route of contrast agent used; immediate (within 1 hour after CEUS) and delayed (> 1 and ≤ 24 hours after CEUS) adverse events; and occurrence and cause of death (when available) was extracted from each medical record. Risk of death within 24 hours after ultrasonography was compared between case and control animals. RESULTS Of the 411 case dogs, 3 had immediate adverse events (vomiting or syncope) and 1 had a delayed adverse event (vomiting). No adverse events were recorded for case cats. Twenty-three of 357 (6.4%) clinically ill case animals and 14 of 262 (5.3%) clinically ill control animals died within 24 hours after ultrasonography; risk of death did not differ between cases and controls. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that CEUS was safe in dogs and cats.

CT FEATURES OF PLEURAL MASSES AND NODULES

Pleural space masses and nodules are rarely described on computed tomography (CT) in veterinary medicine and have only been described in patients with neoplasia. Our purpose was to describe the CT findings and diagnoses in seven patients with pleural masses and nodules. Two patients had broad-based, plaque-like pleural masses, both of which were due to neoplasia (primary pleural carcinoma, metastatic thymoma). Two patients had well-defined pleural nodules and nodular pleural thickening, one of which had mesothelial hypertrophy, and another of which had metastatic hemangiosarcoma. Three patients had ill-defined pleural nodules to nodular pleural thickening, one of which had metastatic pulmonary carcinoma, while the other two had bacterial infection with mesothelial proliferation (n = 2), fibrinous pleuritis (n = 1), and severe mediastinal pleuritis/mediastinitis (n = 2). Five of the seven patients had focal, multifocal or diffuse smooth, and/or irregular pleural thickening. Five of seven patients had pleural effusion, and postcontrast CT was useful in several patients for delineating the pleural lesions from the effusion. All patients except one had additional lesions identified on CT besides those in the pleural space. CT is useful in identifying and characterizing pleural space lesions and could be used to guide further diagnostic procedures such as thoracoscopy or exploratory thoracotomy. Both neoplastic and nonneoplastic diseases should be considered in the differential diagnoses for pleural space masses and nodules found on CT.

Complication rate, outcome, and risk factors associated with surgical repair of fractures of the lateral aspect of the humeral condyle in dogs

OBJECTIVE To determine outcome, report complications, and risk factors for complications associated with the surgical treatment of fractures of the lateral aspect of the humeral condyle (FLHC) in dogs. STUDY DESIGN Fifty dogs with FLHC that had been repaired surgically were included in this retrospective case series. METHODS The medical records and radiographs from 50 dogs with FLHC from 1990--2006 were analyzed. RESULTS The complication rate was 30%. For every 30-minute increase in surgical time the odds of a complication increased by 2.00 (95% CI: 1.06, 3.77). For every 10 degrees increase in the angle between the transcondylar screw and a line between the epicondyles viewed on a craniocaudal radiograph there was a 4.82 (95% CI: 1.23, 18.86) greater odds of an intracondylar fracture gap appearing on postoperative radiographs. When an intracondylar fracture gap was present after surgery there was a 25% long-term radiographic outcome failure rate, whereas there was a 0% radiographic failure rate in the dogs in which an intracondylar fracture gap was not present. In conclusion, transcondylar screw placement parallel to the epicondylar line should be attempted for the repair of FLHC. An increase in surgical time leads to an increase in postoperative complication rate. The presence of an intracondylar fracture gap may be associated with fracture failure. CLINICAL SIGNIFICANCE Screw angulation predisposed to postoperative intracondylar fracture gap which in turn may be associated with higher fracture fixation failure rate. The dogs that had prolonged surgical times had an increased complication rate.

Acute Biological Effects of Simulating the Whole-Body Radiation Dose Distribution from a Solar Particle Event Using a Porcine Model

In a solar particle event (SPE), an unshielded astronaut would receive proton radiation with an energy profile that produces a highly inhomogeneous dose distribution (skin receiving a greater dose than internal organs). The novel concept of using megavoltage electron-beam radiation to more accurately reproduce both the total dose and the dose distribution of SPE protons and make meaningful RBE comparisons between protons and conventional radiation has been described previously. Here, Yucatan minipigs were used to determine the effects of a superficial, SPE-like proton dose distribution using megavoltage electrons. In these experiments, dose-dependent increases in skin pigmentation, ulceration, keratinocyte necrosis and pigment incontinence were observed. Five of 18 animals (one each exposed to 7.5 Gy and 12.5 Gy radiation and three exposed to 25 Gy radiation) developed symptomatic, radiation-associated pneumonopathy approximately 90 days postirradiation. The three animals from the highest dose group showed evidence of mycoplasmal pneumonia along with radiation pneumonitis. Moreover, delayed-type hypersensitivity was found to be altered, suggesting that superficial irradiation of the skin with ionizing radiation might cause immune dysfunction or dysregulation. In conclusion, using total doses, patterns of dose distribution, and dose rates that are compatible with potential astronaut exposure to SPE radiation, animals experienced significant toxicities that were qualitatively different from toxicities previously reported in pigs for homogeneously delivered radiation at similar doses.

COMPUTED TOMOGRAPHIC CHARACTERISTICS OF ODONTOGENIC NEOPLASMS IN DOGS

Odontogenic neoplasms are locally invasive oral tumors in dogs. The purpose of this retrospective study was to describe CT characteristics for varying histopathologic types of canine odontogenic neoplasms. A board-certified veterinary radiologist who was unaware of histologic findings reviewed and scored imaging studies. A total of 29 dogs were included in the study. Twenty-three of these dogs had concurrent dental radiographs. The most common CT characteristics for all tumor types were a direct association with or in the region of multiple teeth in 96.4% (27/28), contrast enhancement in 96.3% (26/27), alveolar bone lysis in 93.1% (27/29), and mass-associated tooth displacement in 85.2% (23/27). Mass-associated cyst-like structures were identified in 53.6% (15/28) and were only present in tumors containing odontogenic epithelium. Canine acanthomatous ameloblastomas (n = 15) appeared as extra-osseous (10/15) or intra-osseous (5/15) masses. Intra-osseous canine acanthomatous ameloblastomas were more likely to have mass-associated cyst-like structures and were subjectively more aggressive when compared with extra-osseous canine acanthomatous ameloblastomas. Amyloid-producing odontogenic tumors (n = 3) had subjectively uniform CT imaging characteristics and consisted of round soft tissue and mineral attenuating masses with multiple associated cyst-like structures. Fibromatous epulides of periodontal ligament origin (n = 4) were contrast enhancing extra-osseous masses that were rarely referred for CT examinations and 25% (1/4) were not visible with CT. Other odontogenic tumors were less represented or had more variable CT imaging characteristics. Mass-associated tooth destruction was appreciated more often with dental radiographs and extra-oral tumor extension was identified more often with CT.

COMPARISON BETWEEN BOLUS TRACKING AND TIMING-BOLUS TECHNIQUES FOR RENAL COMPUTED TOMOGRAPHIC ANGIOGRAPHY IN NORMAL CATS

Renal dual-phase computed tomograpic angiography (CTA) is used to assess suitability of feline donors prior to transplantation. A prerequisite for successful CTA is optimal synchronization between the arterial passage of contrast material and CT data acquisition. This retrospective study was conducted to compare quality of renal vascular enhancement at dual-phase CTA in normal cats between two techniques of timing of data acquisition: the timing-bolus and the bolus tracking method. Nine cats were scanned using the timing-bolus technique and 14 with the bolus tracking technique using otherwise similar scanning parameters in a 16-slice multidetector row CT scanner. The quality of enhancement of the renal vessels at the scanned arterial phase and venous phase was assessed both subjectively and objectively by three board-certified radiologists. Arterial enhancement was not observed at the scanned arterial phase in three of the nine cats with the timing-bolus technique but only 1 of the 14 cats with the bolus tracking technique. Early venous enhancement at the scanned arterial phase was common with the bolus tracking technique. Data acquisition was significantly faster with the bolus tracking technique. We conclude that the bolus tracking technique is a valid technique that could be integrated into the routine protocol for 16-detector row CT renal angiography in cats.

Single Agent Polysaccharopeptide Delays Metastases and Improves Survival in Naturally Occurring Hemangiosarcoma

The 2008 World Health Organization World Cancer Report describes global cancer incidence soaring with many patients living in countries that lack resources for cancer control. Alternative treatment strategies that can reduce the global disease burden at manageable costs must be developed. Polysaccharopeptide (PSP) is the bioactive agent from the mushroom Coriolus versicolor. Studies indicate PSP has in vitro antitumor activities and inhibits the growth of induced tumors in animal models. Clear evidence of clinically relevant benefits of PSP in cancer patients, however, is lacking. The investment of resources required to complete large-scale, randomized controlled trials of PSP in cancer patients is more easily justified if antitumor and survival benefits are documented in a complex animal model of a naturally occurring cancer that parallels human disease. Because of its high metastatic rate and vascular origin, canine hemangiosarcoma is used for investigations in antimetastatic and antiangiogenic therapies. In this double-blind randomized multidose pilot study, high-dose PSP significantly delayed the progression of metastases and afforded the longest survival times reported in canine hemangiosarcoma. These data suggest that, for those cancer patients for whom advanced treatments are not accessible, PSP as a single agent might offer significant improvements in morbidity and mortality.

RELIABILITY OF T2‐WEIGHTED SAGITTAL MAGNETIC RESONANCE IMAGES FOR DETERMINING THE LOCATION OF COMPRESSIVE DISk HERNIATION IN DOGS

Magnetic resonance imaging is used commonly to diagnose intervertebral disk herniation in dogs. It is common to locate areas of suspected compression on sagittal T2-weighted (T2-W) images and then obtain limited transverse images in these areas to reduce the acquisition time (a step-by-step approach). Our objective was to assess the frequency of correct localization of spinal cord compression due to disk herniation using only the sagittal images. The results from isolated readings of the sagittal T2-W images alone or combined with a single-shot fast spin echo (SSFSE) slab in 118 dogs were compared with a gold standard, based on a consensual reading of all images available, including complete transverse images across the entire spinal segments under study. The sites of compression were localized correctly from the sagittal images in 89.8% of dogs. If only the most significant lesions were accounted for, the percentage increased up to 95.2%. In 54.9% of the readings with incorrect localization, the actual compressive site was immediately adjacent to the one suspected from review of the sagittal images. The frequency of correct localization was higher in the cervical region, and was increased by examination of the SSFSE slab. The most common cause of disagreement was the presence of multiple degenerate bulging disks. Based on these results we recommend obtaining transverse images across the entire segment when multiple bulging disks are present. It is also recommended to obtain transverse images across the spaces immediately adjacent to the suspected site of herniation from review of the sagittal images.

COMPUTED TOMOGRAPHIC FINDINGS IN 57 CATS WITH PRIMARY PULMONARY NEOPLASIA

Primary pulmonary neoplasia is relatively uncommon in cats and generally has a poor prognosis. In this multicenter, retrospective study of 57 cats with pulmonary neoplasia, the most frequent presenting signs were anorexia/inappetence (39%) and cough (37%). The pulmonary tumors were considered to be incidental findings in 9% cats. In computed tomographic (CT) images, primary pulmonary tumors appeared as a pulmonary mass in 55 (96%) cats and as a disseminated pulmonary lesion without a defined mass in two (4%) cats. Most pulmonary tumors were in the caudal lobes, with 28 (49%) in the right caudal lobe and 17 (30%) in the left caudal lobe. CT features associated with pulmonary tumors included mass in contact with visceral pleura (96%), irregular margins (83%), well-defined borders (79%), bronchial compression (74%), gas-containing cavities (63%), foci of mineral attenuation (56%), and bronchial invasion (19%). The mean (range) maximal dimension of the pulmonary masses was 3.5 cm (1.1-11.5 cm). Additional foci of pulmonary disease compatible with metastasis were observed in 53% cats. Pleural fluid was evident in 30% cats and pulmonary thrombosis in 12% cats. The histologic diagnoses were 47 (82%) adenocarcinomas, six (11%) tumors of bronchial origin, three (5%) adenosquamous cell carcinomas, and one (2%) squamous cell carcinoma. In this series, adenocarcinoma was the predominant tumor type, but shared many features with less common tumor types. No associations were identified between tumor type and CT features. Prevalence of suspected intrapulmonary metastasis was higher than in previous radiographic studies of cats with lung tumors.