Presumed mediastinal cysts have a low prevalence in canine thoracic computed tomographic studies.

Mediastinal cysts (MCs) are rare lesions that can arise from embryonic remnants of various mediastinal structures. MCs usually are incidental findings in dogs and cats; however, they can reach a mass-like appearance. The description of MCs on CT in dogs is limited. This retrospective, single-center, descriptive, prevalence study aimed to determine the prevalence of presumed mediastinal cysts (PMCs) in dogs and assess their CT characteristics. Dogs that underwent a thoracic CT scan from January 2019 to August 2021 were included. CT images were evaluated for the presence of PMCs by two diagnostic imaging interns, two last year diagnostic imaging residents, and a board-certified veterinary radiologist. Number, location, margins, shape, volume, size, mass effect, and attenuation values of PMCs were assessed. A total of 866 CT scans were reviewed, and 49 PMCs were identified. The prevalence of PMCs in dogs was 5.66%. English Bulldog and mixed-breed dogs were subjectively overrepresented; however, the possibility of population bias could not be excluded. PMCs were subjectively more frequently observed in male dogs. The PMCs were predominantly round, small, solitary fluid-filled findings localized in the cranioventral mediastinum, with well-defined margins, homogeneous attenuation, and no contrast enhancement. The median attenuation value was 6.32 HU (range: -20.16 to 23.45 HU) precontrast and 7.58 HU (range: -2.45 to 20.79 HU) postcontrast, and the median volume was 1.19 cm3 (range: 0.02-45.32 cm3). Although the prevalence of PMCs was low in our sample population, findings supported prioritizing a differential diagnosis of incidental PMC for dogs with the above imaging characteristics.

B-mode ultrasound and colour Doppler findings in cats with gastric lymphoma.

OBJECTIVES: The purpose of this study was to describe B-mode and colour Doppler ultrasound (US) features of gastric lymphoma in cats. METHODS: Cats with histopathological or cytological confirmation of gastric lymphoma that underwent abdominal US were included in this retrospective study. Clinical signs were recorded and radiographs reviewed when available. Gastric lesions were ultrasonographically evaluated for location, distribution, wall layering, echogenicity and thickness. Colour Doppler assessment was based on vessels, location and direction. RESULTS: Forty-five cats were included. All presented with vomiting, 7/45 (15.5%) with haematemesis. Radiographs were available in 27/45 cases, and demonstrated a gastric mass in 19/27 (70.4%) cases. The most common US appearance was transmural wall thickening with absent layering 42/45 (93.3%) and hypoechogenicity 39/45 (86.7%). Median maximum thickness was 2.1 cm. Ulceration or erosion was suspected in 23/45 (51%) cases, two of which perforated. Colour Doppler images were available in 33/45 cases. The most common Doppler finding was transmural vessels coursing perpendicularly to the lumen in 14/33 (42.4%). Abdominal effusion was uncommon (n = 11/45; 24.4%). Regional lymphadenopathy was frequent, observed in 44/54 lymph nodes reviewed on US, and US suspicion of splenic, hepatic and intestinal lymphomatous infiltration was reported in 24/45 (53.3%) cases. CONCLUSIONS AND RELEVANCE: The most common US appearance of gastric lymphoma was transmural hypoechoic segmental wall thickening with layering loss. Location and distribution were variable. Colour Doppler displayed increased blood supply with a predominant pattern of perpendicular vessels, possibly representing aberrant arteries originating from subserosal and submucosal plexus. Lymphomatous infiltration of lymph nodes and other abdominal organs was frequent, confirming local and distant aggressiveness of gastric lymphoma in cats. Vomiting and haematemesis were frequently associated with the suspicion of ulcer on US. Perforation was a rare occurrence.

Periarticular histiocytic sarcoma with heart metastasis in a cat.

A 4-year-old intact female domestic short-haired cat was referred for recommendations about adjuvant medical treatment 1 month after left forelimb amputation due to periarticular histiocytic sarcoma (HS). At presentation, physical abnormalities were limited to enlarged ipsilateral superficial cervical and axillary lymph nodes. Routine blood analysis, abdominal ultrasound, and thoracic radiology were unremarkable. The cat initially received lomustine without any adverse events. Four weeks later, the cat developed severe acute respiratory distress. Results of thoracic radiographs and transthoracic echocardiographic analysis were suggestive of pulmonary and heart metastasis. Due to the cat's poor clinical condition and prognosis, the owner elected euthanasia, and a necropsy was performed. Based on gross pathology, histopathology, and immunohistochemistry, an HS with nodal, renal, pulmonary, and heart (right auricular and right ventricular) metastases was diagnosed. This case represents the first description of HS with a heart metastasis in a cat, providing further insight into the clinical course and metastatic behavior of this rare malignant neoplasm. Clinicians should be aware of this site of metastasis and consider HS in the list of differential diagnoses for secondary heart tumors in cats.

CT measures of adrenal gland length and caudal pole diameter are reproducible in large breed dogs: A pilot study.

Computed tomography (CT) is increasingly available to evaluate dogs with suspected adrenal disease, however, published studies describing the reproducibility of CT methods for quantifying adrenal gland (AG) measurements are lacking. This prospective, pilot, observer agreement study aimed to evaluate reproducibility and repeatability of two different methods of measurement of AGs on CT to establish a usable technique and define standard reference ranges. Multiplanar reformatted (MPR) CT images of both AGs of six large breed dogs were obtained with the MPR axis parallel to the spine and parallel to the long axis of the AG. Ten measurements were performed: maximal length and diameter at cranial and caudal poles on dorsal, sagittal, and transverse images; and minimal diameter of cranial and caudal poles on transverse images. Three observers with different levels of experience repeated these measurements three times for each dog. Intra- and interobserver variability were calculated through intraclass correlation coefficient (ICC). The differences in time to perform measurements between the two methods were tested with Student's t-test. Regardless of the measurement method used, length of AGs on dorsal and sagittal MPR images had the lowest intra- and inter-observer variability (ICC = 0.93-0.99), diameter of caudal pole on transverse plane showed low intra- and interobserver variability (ICC = 0.77-0.80) and diameter of cranial pole had the highest variability (ICC = 0.12-0.61). Although length was the less variable measurement, its use may be unrealistic in daily practice. Interestingly measurement of caudal pole on transverse plane was characterized by low intra- and interobserver variability. No difference in time performing the measurements was noted between the two methods.

Use of Contrast-Enhanced Ultrasonography for the Characterization of Tumor Thrombi in Seven Dogs.

Tumors of adrenal and thyroid glands have been associated with vascular invasions-so-called tumor thrombi, both in humans and dogs. The detection and characterization of venous thrombi is an important diagnostic step in patients with primary tumors for both surgical planning and prognosis. The aim of this study was to describe the use of contrast-enhanced ultrasonography (CEUS) for the characterization of tumor thrombi. Dogs with tumor thrombus who underwent bi-dimensional ultrasound (B-mode US) and CEUS were included. Seven dogs were enrolled in this retrospective case series. On B-mode US, all thrombi were visualized, and vascular distension and thrombus-tumor continuity were seen in three and two cases, respectively. On color Doppler examination, all thrombi were identified, seemed non-occlusive and only two presented vascularity. On CEUS, arterial-phase enhancement and washout in the venous phase were observed in all cases. Non-enhancing areas were identified in the tumor thrombi most likely representing non-vascularized tissue that could potentially be embolized in the lungs after fragmentation of the tumor thrombi. On the basis of these preliminary study, CEUS appeared to be useful for the characterization of malignant intravascular invasion.

Ultrasonographic honeycomb pattern of the spleen in cats: correlation with pathological diagnosis in 33 cases.

OBJECTIVES: The aim of this study was to evaluate the relationship between the ultrasonographic (US) diffuse honeycomb pattern (HCP) of the spleen and a pathological diagnosis in cats, and to assess the influence of transducer type on HCP visualisation. METHODS: Abdominal ultrasounds of cats with an HCP were reviewed and splenic size, shape, margination, other parenchymal alterations and splenic hilar lymphadenopathy were recorded. When applicable, images acquired with high-frequency linear and curvilinear transducers were compared to determine if an HCP was more frequently demonstrated on high-resolution images. A retrospective review of the corresponding splenic cytohistopathological samples was also performed. RESULTS: Thirty-three cats met the inclusion criteria. Five cases were diagnosed by histology and 28 by cytology, confirmed by PCR for antigen receptor rearrangements (PARR) in uncertain cases. There were 15 cases of lymphoid hyperplasia, eight cases of lymphoma (four B cell, three T cell and one large granular lymphocytes), six cats with splenitis, three with extramedullary haematopoiesis and one with histiocytic sarcoma. The prevalence of lymphoma in cats with an HCP of the spleen was 24%. Splenomegaly was the most frequent US feature associated with an HCP and was observed in all lymphoma cases. In the images obtained from both high-frequency linear and micro-convex transducers the visualisation of an HCP was enabled in all cases (24/24) and in 62.5% (15/24), respectively. CONCLUSIONS AND RELEVANCE: Based on our findings, a US HCP of the spleen in cats can be associated with benign and malignant disorders and is infrequently associated with lymphoma in comparison with dogs. Cytological or histological examination, possibly supplemented by PARR, should always be performed for diagnostic support. Use of high-frequency linear transducers is recommended to properly recognise an HCP or subtle changes in splenic parenchyma.

Two-dimensional and contrast-enhanced ultrasound of intestinal ischaemia in cats: four cases.

OBJECTIVES: The aim of this study was to describe the results of two-dimensional (2D) and contrast-enhancement ultrasound (CEUS) in four cats with intestinal ischaemia. METHODS: Data were collected from hospital records of all cats that had intestinal ischaemia between January 2012 and August 2018. The inclusion criteria were complete abdominal ultrasound examination, colour flow Doppler and CEUS of lesions, confirmation of intestinal ischaemia detected by visual assessment of avascular intestinal segment at surgery, and/or necropsy and histopathology. All images and video clips were reviewed by the same experienced operator. RESULTS: Four cats with different intestinal ischaemic lesions were included in the study: duodenal perforating ulcer, jejunal necrotising enteritis, necrosis secondary to jejunojejunal intussusception and iatrogenic damage of jejunal arteries. On the 2D ultrasound, all intestinal lesions were characterised by non-specific findings: focal hypoechoic wall thickening with loss of normal layering associated with hyperechoic mesentery surrounding the intestinal tract. CEUS showed a reduced or absent enhancement of the intestinal lesions in comparison to the surrounding perfused wall. CONCLUSIONS AND RELEVANCE: Intestinal ischaemia is a potentially fatal disorder. Grey-scale, colour and power Doppler ultrasonography are not sensitive for evaluating this condition. Our preliminary findings illustrate the usefulness of CEUS for the detection of intestinal wall impaired perfusion in cats.

Sensitivity, specificity, and interobserver variability of survey thoracic radiography for the detection of heart base masses in dogs.

OBJECTIVE To determine the sensitivity, specificity, and interobserver variability of survey thoracic radiography (STR) for the detection of heart base masses (HBMs) in dogs. DESIGN Retrospective case-control study. ANIMALS 30 dogs with an HBM and 120 breed-matched control dogs (60 healthy dogs and 60 dogs with heart disease and no HBM). PROCEDURES In a blinded manner, 2 observers (designated as A and B) evaluated STR views from each dog for a mass-like opacity cranial to the heart, tracheal deviation, cardiomegaly, findings suggestive of pericardial effusion or right-sided congestive heart failure, and soft tissue opacities suggestive of pulmonary metastases. Investigators subsequently provided a final interpretation of each dog's HBM status (definitely affected, equivocal, or definitely not affected). RESULTS Considering equivocal interpretation as negative or positive for an HBM, the sensitivity of STR for diagnosis of an HBM was 40.0% (95% confidence interval [CI], 22.5% to 57.5%) and 56.7% (95% CI, 38.9% to 74.4%), respectively, for observer A and 63% (95% CI, 46.1% to 80.6%) and 80.0% (95% CI, 65.7% to 94.3%), respectively, for observer B. The corresponding specificity was 96.7% (95% CI, 93.5% to 99.9%) and 92.5% (95% CI, 87.8% to 97.2%), respectively, for observer A and 99.2% (95% CI, 97.5% to 100%) and 92.5% (95% CI, 87.8% to 97.2%), respectively, for observer B. The presence of a mass-like opacity cranial to the heart or tracheal deviation, or both, was significantly associated with a true diagnosis of HBM. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that STR is a highly specific but not a highly sensitive predictor of HBM in dogs.