RADIOGRAPHIC APPEARANCE OF BRONCHOALVEOLAR CARCINOMA IN NINE CATS

Thoracic radiographs of nine cats with confirmed bronchoalveolar carcinoma (BAC) were reviewed retrospectively. Radiographic appearance of BAC was divided into three categories: mixed bronchoalveolar pattern, ill-defined alveolar mass, or mass with cavitation. In addition to these radiographic signs, all nine cats had evidence of some form of bronchial disease. Cavitary lesions were the most common finding (n = 5). In addition, three cats in this category had diffuse bronchointerstitial opacity and one cat had focal peribronchial cuffing. Five cats had either a mixed bronchoalveolar pattern with bronchiectasis (n = 3) or an ill-defined alveolar mass with peribronchial cuffing (n = 2). One cat had both a mixed bronchoalveolar pattern and a cavitary mass. Each of these nine cats had some form of bronchial disease (bronchointerstitial pattern, peribronchial cuffing, or bronchiectasis), which aids in the radiographic diagnosis of bronchoalveolar carcinoma and may represent airway metastasis.     

RADIOGRAPHIC AND HISTOPATHOLOGIC CHARACTERISTICS OF PULMONARY FIBROSIS IN NINE CATS

Pulmonary fibrosis is a progressive fatal interstitial lung disease that is often idiopathic, occurs in multiple species, and may be caused by a number of inciting factors. The purpose of this retrospective, multicenter study was to describe the radiographic and histopathologic characteristics of idiopathic and induced pulmonary fibrosis in a group of cats. Cats with thoracic radiographs and histopathologically confirmed pulmonary fibrosis were recruited using the American College of Veterinary Radiology list serve. A board‐certified veterinary radiologist and diagnostic imaging intern reviewed radiographs and recorded characteristics by consensus. Findings from additional imaging modalities were also recorded when available. All histopathology samples were re‐reviewed by a veterinary pathology resident. A total of nine cats met inclusion criteria. All patients had a broad range of radiographic characteristics that included broncho‐interstitial pattern, alveolar pattern, pulmonary masses, pulmonary bullae, pleural effusion, and cardiomegaly. Cats with available echocardiographic studies had characteristics that included right ventricular dilation and hypertrophy and pulmonary arterial hypertension interpreted to be secondary to primary lung disease. Cats with available CT studies had characteristics that included focally increased soft tissue attenuation, masses, and ventral consolidation that exhibited no improvement with dorsal versus ventral recumbency. Histopathology showed pulmonary fibrosis, type II pneumocyte hyperplasia, and smooth muscle hypertrophy in all patients. Epithelial metaplasia was present only in one patient. Findings from the current study indicated that cats with pulmonary fibrosis have highly variable radiographic characteristics and that these characteristics may mimic other diseases such as asthma, pneumonia, pulmonary edema, or neoplasia.     

RADIOGRAPHIC APPEARANCE OF CONFIRMED PULMONARY LYMPHOMA IN CATS AND DOGS

Herein we describe the thoracic radiographic appearance of confirmed pulmonary lymphoma. Patients with thoracic radiographs and cytologically or histologically confirmed pulmonary lymphoma were sought by contacting American College of Veterinary Radiology members. Seven cats and 16 dogs met the inclusion criteria, ranging in age from 4 to 15 years. Method of diagnosis was via ultrasound‐guided cytology (four), surgical biopsy (two), ultrasound‐guided biopsy (one), and necropsy (16). Radiographic findings varied but ranged from normal (one) to alveolar (six) and/or unstructured interstitial infiltrates (11), nodules and/or masses (eight), and bronchial infiltrates (four). Additional thoracic radiographic findings included pleural effusion and lymphadenopathy. The results of this evaluation indicate a wide variability in thoracic radiographic abnormalities in cats and dogs with pulmonary lymphoma.     

RADIOGRAPHIC APPEARANCE OF PRIMARY LUNG TUMORS IN CATS

The radiographic findings in 41 feline primary lung tumors are reported. Case material includes 29 adenocarcinomas, six bronchiolog-alveolar carcinomas, and six squamous cell carcinomas. Adenocarcinomas tended to occur as focal, solitary, well-circumscribed masses (eight cats), as localized consolidations (six cats), or as multiple, poorly circumscribed masses (five cats). Bronchiolo-alveolar cell carcinomas and squamous cell carcinomas were radiographically pleomorphic. Calcification was recognized in only five cats, four with adenocarcinomas and one with bronchiolo-alveolar carcinoma. Cavitation was identified in seven adenocarcinomas, one squamous cell carcinoma, and one bronchiolo-alveolar carcinoma. Nearly 50% (20 cats) of the patients had radiographic evidence of pleural involvement. Fifteen cats had evidence of regional lymph node involvement.     

THE RADIOGRAPHIC APPEARANCE OF THE PULMONARY VASCULATURE IN THE CAT

The purpose of this study was to determine the dimensions of the pulmonary arteries and veins in the cat, both in normal animals and those with evidence of intrathoracic disease. The radiographs of 50 normal cats, 35 cats with hypertrophic cardiomyopathy (HCM), and 15 cats with other intrathoracic disease were assessed. The normal range for the right cranial lobar artery compared with the proximal third of the fourth rib was 0.5-1.0, with a mean artery-to-rib ratio of 0.70 (standard deviation +/- 0.13). Normal cats had a mean vein diameter of (0.20 +/- 0.03 cm) (P = 0.034) compared with cats with HCM, which had a significantly greater mean vein diameter (0.22 +/- 0.04 cm).     

RADIOGRAPHIC DIAMETER OF THE COLON IN NORMAL AND CONSTIPATED CATS AND IN CATS WITH MEGACOLON

Radiographs of 50 cats with no history of gastrointestinal disease were evaluated to establish a normal reference range for radiographic diameter of the feline colon. Thirteen cats with constipation and 26 with megacolon were also evaluated and compared with the normal cats to characterize the accuracy of the reference range and to identify a cutoff to distinguish constipation from megacolon. A ratio of maximal diameter of the colon to L5 length was the most repeatable and accurate measurement. A ratio <1.28 is a strong indicator of a normal colon (sensitivity 96%, specificity 87%). A value >1.48 is a good indicator of megacolon (sensitivity 77%, specificity 85%).     

RADIOGRAPHIC AND ECHOCARDIOGRAPHIC MEASUREMENT OF THE HEART IN OBESE CATS

A prospective study was undertaken to reconcile radiographic cardiomegaly and normal echocardiography in obese cats and to test a radiographic technique for better distinguishing between pericardial fat and the heart. Ten obese, but otherwise normal cats and 10 non-obese normal cats were used. A body condition scoring system was used to objectively group obese and non-obese normal cats. Two-dimensional echocardiograms were made to verify that all cats had a normal heart. Thoracic radiographs then were made using standard and altered exposure techniques. The hearts were measured on these radiographs using the metric and a vertebral scale system. Obese cats consistently had excessive fat around the heart especially if they also had a large amount of falciform fat. Altering exposure technique by increasing mAs and decreasing kVp sometimes enhanced the radiographic contrast between fat and myocardium. Enhanced radiographic contrast accentuated the double silhouette identifying the true cardiac silhouette within the fat expanded silhouette. Pericardial fat usually was distinguished more readily in lateral than in VD radiographs. In two cats, pericardial fat had a characteristic prominent square corner to the right cranial margin of the cardiac silhouette in VD radiographs. Obesity caused increased width and depth of the thoracic cage. 2D echocardiograms revealed normal cardiac dimensions in both groups of cats and increased precordial distance in the obese group.     

MENSURATION OF THE PITUITARY GLAND FROM MAGNETIC RESONANCE IMAGES IN 17 CATS

The objective of this retrospective study was to estimate using magnetic resonance imaging the size range of the pituitary gland in cats who had no evidence of pituitary disease. The pituitary gland was measured from transverse and sagittal magnetic resonance postgadolinium T1-weighted images in 17 cats. The cats were 0.83 to 15 years of age and weighed between 2.9 and 6.5 kg. Linear pituitary measurements were performed on a dedicated workstation using electronic calipers. Mean (+/- standard deviation) pituitary gland length was 0.54 cm (+/- 0.06 cm) and mean width was 0.50 cm (+/- 0.08 cm). Mean pituitary gland height measured on sagittal images was 0.34 cm (+/- 0.05) and measured on transverse images was 0.32 cm (+/- 0.04 cm). Mean pituitary volume was 0.05 cm3 (+/- 0.01 cm3). There was no significant correlation between cat weight (kg) and pituitary volume or age and pituitary volume. The pituitary gland appearance varied on pre- and postcontrast T1-weighted images. On the precontrast images, the majority of pituitary glands had a mixed signal intensity. On postcontrast images, uniform pituitary gland enhancement was seen commonly.     

THORACIC METASTASES OF CANINE MAMMARY GLAND TUMORS

The absence or presence of metastases on thoracic radiographs in 55 female dogs with mammary gland tumors was assessed by comparing the results of a single radiographic examination, using dorsoventral and left lateral views, with clinical and histologic follow-up data. Radiographic abnormalities found in dogs with thoracic metastases were classified as well-defined pulmonary nodules, ill-defined pulmonary nodules, and involvement of pleural effusion. No obvious difference in the effect on the right or left lung lobes was found. The sensitivity, specificity and accuracy for the detection of thoracic metastases were 65%, 97%, and 87%, respectively.     

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.     

RADIOGRAPHIC HEART-VOLUME ESTIMATION IN NORMAL CATS

Heart volume mensuration was evaluated on conventional radiographs from eight normal cats in different body positions using computed tomography (CT). Heart volumes were calculated from orthogonal thoracic radiographs in ventral and dorsal recumbency and from radiographs exposed with a vertical X-ray beam in dorsal and lateral recumbency using the formula for an ellipsoid body. Heart volumes were also estimated with CT in ventral, dorsal, right lateral and left lateral recumbency. No differences between heart volumes from CT in ventral recumbency and those from CT in right and left lateral recumbency were seen. In dorsal recumbency, however, significantly lower heart volumes were obtained. Heart volumes from CT in ventral recumbency were similar to those from radiographs in ventral and dorsal recumbency and dorsal/left lateral recumbency. Close correlation was also demonstrated between heart volumes from radiographs in dorsal/ left lateral recumbency and body weights of the eight cats.     

RADIOGRAPHIC AND ULTRASONOGRAPHIC FEATURES OF HYPERTROPHIC FELINE MUSCULAR DYSTROPHY IN TWO CATS

Hypertrophic fellne musculer dystrophy has been reported as an X-linked inherited deficiency of a cytoskeletal myofiber protein called dystrophin. This report deserlbes the radiographic and ultrasonographic abnormalities of two male littermate domestic short-hair cats and reviews the previous reported findings assoclated with hypertrophic feline muscular dystrophy. The thoracic radiographic abnormalities included: progressive cardiomegaly, large convex, scalloped irregularities associated with the vetral aspect of the diaphragm, and variable degrees of esophageal dilation (megaesophagus) with associated cranioventral aspiration pneumonia. Echocardiographic features included: concentric left vetricular wall thickening, increased left ventricular and diastolic and systolic dimensions, and an increase in endocardial echogenicity. Abdominal radiographic abnormalities included: hepatosplenomegaly, peritoneal effusion, renomegaly, adrenal gland mineralization, and paralumbar and diaphragmatic musculature enlargement. Abdomlnal ultrasonographic abnormalities included: irregularly thickened muscular portion of the diaphragm; hypoechogenicity of the liver; peritoneal effusion; hepatosplenomegaly; renomegaly with hyperechoic cortex and medulla; and adrenal gland mineralization. The irregular scalloped appearance of the diaphragm (particularly along the ventral/sternal margin) was a consistenl radiographic abnormlity in the two cats with hypertrophic feline muscular dystrophy after the age of 7 months. This finding was confirmed by ultrasound as a thickened irregular, hyperechoic diaphragm. A diagnosis of hypertrophic feline muscular dystrophy should be strongly suspected if this abnormality is identified.     

MAGNETIC RESONANCE IMAGING FEATURES OF INTRAVENTRICULAR EPENDYMOMAS IN Five CATS

Intraventricular ependymoma is a rare type of feline intracranial neoplasia and published information on magnetic resonance imaging (MRI) characteristics is currently lacking. The purpose of this retrospective case series study was to describe the clinical and MRI characteristics of histopathologically confirmed intraventricular ependymomas in a group of cats. Five cats met inclusion criteria. In relation to normal gray matter, ependymomas appeared hyperintense on T2W, T2W‐FLAIR, PD, and DW‐EPI images; isointense on ADC images; and had subtle to strong contrast enhancement. Some variability was seen on T2*GRE and on T1W images with masses being isointense to hyperintense. Four ependymomas were small and homogeneous, and one was centrally cavitated. All cats had obstructive hydrocephalus, transtentorial herniation, and foramen magnum herniation. Perilesional edema was identified in most cats but was questionable in one. Intraventricular ependymoma should be considered as a differential diagnosis for cats with this combination of MRI signs.     

ULTRASONOGRAPHIC OBSERVATION OF SECRETIN-INDUCED PANCREATIC DUCT DILATION IN HEALTHY CATS

Secretin is a polypeptide hormone that stimulates secretion of bicarbonate from the exocrine pancreas and, in healthy human subjects, causes transient pancreatic duct dilation observable sonographically. In humans with chronic pancreatitis, secretin administration fails to cause pancreatic duct dilation, theoretically due to the restrictive effects of periductal fibrosis. We characterized the effect of exogenous secretin administration on the width of the pancreatic duct in nine healthy domestic cats. Cats were given a commercially available secretin product (ChiRho Stim™) while the pancreatic duct was monitored sonographically. Mean pancreatic duct diameter increased from 0.77±0.33 to 1.42±0.40 mm after secretin administration ( P =0.0017). The mean percent increase in pancreatic duct diameter over basal diameter for all time points up to 15 min postsecretin administration was 101.9±58.8%. Applicability of this technique to diagnose chronic pancreatitis in cats will need to be investigated.     

RADIOGRAPHIC AND 2-D ECHOCARDIOGRAPHIC FINDINGS IN EIGHTEEN CATS EXPERIMENTALLY EXPOSED TO D. ZMMZTZS VIA MOSQUITO BITES

Eighteen cats were exposed to Dirofikria immitis infected mosquitoes. Thoracic radiography was performed prior to exposure and at 5, 7, and 9 month intervals following exposure. Immunologic testing for adult heartworm antigen was performed on days 168,195,210,224,237,254 and 271 post infection. Necropsies were performed on all cats. Adult heartworms were found in 61% of the exposed cats. Radiographic findings in heartworm positive cats included bronchointerstitial lung disease, lobar pulmonary arterial enlargement and pulmonary hyperinflation. In most heartworm positive cats, lobar arterial enlargement resolved as the disease progressed while pulmonary hyperinflation progressively became more common. Pulmonary patterns in heartworm positive cats remained abnormal throughoutthe study while abnormal pulmonary patterns resolved in over 50% of the heartworm negative cats. Cardiomegaly was seen in less than 50% of the cats with adult heartworms at necropsy. This study suggests that the radiographic appearance of heartworm disease is variable and radiographic changes are dependent on the time post infection at which cats are evaluated. Echocardiographic examinations were randomly performed on 16 of 18 cats. Heartworms were identified in 7 cats. No false positive identifications were made. Persistent pulmonary disease accompanied by resolving vascular disease in heartworm cats with pulmonary hyperinflation may be difficult to distinguish from cats with feline allergic lung disease. Echocardiograms may be helpful in identifying adult heartworms in cats in which the radiographic signs or immunodiagnostic data are insufficient to provide a diagnosis.     

THE EFFECT OF DEXMEDETOMIDINE ON RADIOGRAPHIC CARDIAC SILHOUETTE SIZE IN HEALTHY CATS

Dexmedetomidine, an alpha₂‐adrenergic agonist, may be used in companion animals for chemical restraint, including cardiac evaluation. Echocardiographic changes associated with alpha₂‐adrenergic agonists have been described; however reports of radiographic changes in cats were not found at the time of this study. Aims of this observational, prospective, experimental study were to describe the effects of dexmedetomidine on the radiographic appearance of the cardiac silhouette in healthy, adult cats. Fourteen healthy adult cats received dexmedetomidine 40 mcg/kg IM. Right lateral, left lateral, ventrodorsal, and dorsoventral thoracic radiographs were obtained for each cat at three time points: presedation, intrasedation, and postsedation (≥ two hours after reversal with atipamezole). Radiographs were evaluated in a blinded, randomized fashion by two independent observers using the vertebral heart score on all four views, the number of intercostal spaces on lateral projections, and the percent width of thorax on ventrodorsal and dorsoventral projections. Median vertebral heart score on right lateral view was significantly increased intrasedation (median = 7.8; range = 7.25–8.25) compared to presedation (median = 7.5; range = 7–8 [P = 0.001]). Median percentage width was significantly higher intrasedation (70% on VD; range 65–80 [P = 0.001], and 75% on DV; range 65–80 [P = 0.006]) compared to presedation (65%; range 65–75 on both projections). Dexmedetomidine was associated with a small but significant increase in cardiac silhouette size on right lateral (vertebral heart score), ventrodorsal (percentage width), and dorsoventral (percentage width) radiographs in healthy adult cats. This effect should be taken into consideration for future interpretation of thoracic radiographs in dexmedetomidine‐sedated cats.     

RADIOGRAPHIC CHARACTERIZATION OF PRESUMED PLATE‐LIKE ATELECTASIS IN 75 NONANESTHETIZED DOGS AND 15 CATS

Discrete discoid or linear areas of increased soft opacity have been observed within the pulmonary parenchyma in thoracic radiographs of dogs and cats. Similar radiographic findings have been described in humans and termed plate‐like atelectasis. The purpose of this retrospective study was to describe locations and characteristics of presumed plate‐like atelectasis, presence of concurrent thoracic disease(s), and presence of persistent pulmonary changes on recheck thoracic radiographic studies in a cohort of dogs and cats. Hospital records between 2004 and 2011 were searched and a total of 90 cases were included (75 dogs and 15 cats, 2–17 years of age). Plate‐like atelectasis was most commonly found in left lateral radiographs. Plate‐like atelectasis was observed in the cranial thorax and was oriented in a dorsocranial to ventrocaudal direction in 68 (75%) patients. Plate‐like atelectasis averaged 29.6 ± 14.4 mm in length and 2.6 ± 1.3 mm in width. In 57 of the 90 patients (63%), plate‐like atelectasis was the only abnormality found. Plate‐like atelectasis was present in 7 of 22 cases where follow‐up radiographs were available. Findings from the current study indicated that, while the etiology of plate‐like atelectasis remains unknown, anatomic variations in sublobar pulmonary anatomy might account for pleural areas of atelectasis. The authors propose that the presence of plate‐like atelectasis may represent areas of atelectasis that track along sublobar lung lobe separations, an area of hypoventilation or decreased collateral ventilation, and/or area of decreased localized surfactant deficiency.     

EVALUATION OF QUANTITATIVE THYROID SCINTIGRAPHY FOR DIAGNOSIS AND STAGING OF DISEASE SEVERITY IN CATS WITH HYPERTHYROIDISM: COMPARISON OF THE PERCENT THYROIDAL UPTAKE OF PERTECHNETATE TO THYROID‐TO‐SALIVARY RATIO AND THYROID‐TO‐BACKGROUND RATIOS

Thyroid scintigraphy is commonly used for evaluation of cats with hyperthyroidism, with the thyroid‐to‐salivary ratio (T/S) being the most common method to quantify the degree of thyroid activity and disease. Calculation of thyroid‐to‐background ratios (T/B) or percent thyroidal uptake of ^99mTcO^?₄ (TcTU) has only been reported in a few studies. The purpose of this prospective, cross‐sectional study was to evaluate a number of quantitative scintigraphic indices as diagnostic tests for hyperthyroidism, including the T/S, three different T/B, TcTU, and estimated thyroid volume. Of 524 cats referred to our clinic for evaluation of suspected hyperthyroidism, the diagnosis was confirmed (n = 504) or excluded (n = 20) based on results of a serum thyroid panel consisting of thyroxine (T₄), triiodothyronine (T₃), free T₄ (fT₄), and thyroid‐stimulating hormone (TSH) concentrations. In the hyperthyroid cats, median values for TcTU, T/S, and three T/B ratios were all significantly higher (P < 0.001) than values in euthyroid suspect cats or clinically normal cats. All scintigraphic parameters were relatively sensitive and specific as diagnostic tests for hyperthyroidism, but the T/S ratio had the highest test accuracy. The T/S ratio correlated strongly with the TcTU (r = 0.85). However, the TcTU had a higher and more significant correlation (P < 0.01) with serum T₄ (r = 0.76 vs. 0.64), T₃ (r = 0.77 vs. 0.64), and estimated thyroid volume (r = 0.62 vs. 0.38). Overall, calculation of TcTU is an accurate diagnostic test, but also appears to be the best parameter to predict the functional volume and metabolic activity of the feline adenomatous thyroid gland.     

COMPARISON OF TWO- VS. THREE-VIEW THORACIC RADIOGRAPHIC STUDIES ON CONSPICUITY OF STRUCTURED INTERSTITIAL PATTERNS IN DOGS

Three-view thoracic radiography is often used to evaluate patients for pulmonary metastatic disease. Although use of three views has been reported to be more sensitive than two views for focal lung disease, it also requires increased time, effort, and radiographic exposure of patients and personnel. This study was performed to evaluate the conspicuity of lesions on two-view vs. three-view radiographic procedures to determine the proportion of diagnoses that would change. One hundred three-view radiographic studies of the canine thorax were randomized, and four protocols were reviewed for each study: right lateral and ventrodorsal views, left lateral and ventrodorsal views, both lateral views, and all three views. Radiographs were interpreted as either positive or negative for structured interstitial pulmonary disease, and the certainty of the reading was recorded using a visual analog scale. There was 85-88% agreement between each two-view group and the three-view group, with the kapp statistic ranging from 0.698 to 0.758. There were no differences in certainty of diagnosis among the groups, though within each group there was more certainty for positive diagnoses than negative diagnoses. These findings indicate that three-view studies should be continued when evaluating for possible structured interstitial pulmonary disease, including metastatic disease, as eliminating one view from a three-view study would change the diagnosis in 12-15% of patients.     

THE RADIOGRAPHIC APPEARANCE OF PULMONARY HISTOPLASMOSIS IN THE CAT

A retrospective study of 18 cats with pulmonary histoplasmosis was conducted to evaluate radiographic patterns of disease and to determine age, breed, and sex distributions. All cats had active disease confirmed by biopsy/aspiration cytology (lung, bone marrow, peripheral lymph nodes, pleural fluid) or necropsy examination. Cats 3 years of age or less had the highest incidence of disease; females outnumbered males 2 to 1. Radiographically, most cats had an interstitial pattern which appeared as a fine, diffuse or linear pattern, or as a more distinct nodular pattern. An alveolar pattern was an uncommon radiographic finding. Tracheobronchial lymphadenopathy and calcified lymph nodes or pulmonary parenchymal lesions were not identified in these cats.