Case Series: Computed Tomography Features of Extraskeletal Osteosarcoma in Six Dogs.

The objective of the present case series was to investigate the various computed tomography findings of six dogs diagnosed with extraskeletal osteosarcoma (exOSA) at several locations. Among the tumors evaluated, four were subcutaneous, one was mammary, and one involved the intestinal tract. Intralesional mineralization was observed in all six dogs. Most of the tumors were moderately calcified, exhibited amorphous mineralization, and were heterogeneous on post-contrast imaging. Three of the tumors were peripherally enhanced, and regional lymphadenopathy was identified in two of the dogs, which was presumed to be metastatic. No lymph node calcification was reported. Although the presence of intralesional mineralization is not a pathognomonic finding, it was consistently identified in the present case series. Therefore, exOSA should be considered in the differential diagnosis when mineralization occurs in a mass unrelated to osseous structures.

Sonographic and computed tomographic features of intestinal mast cell tumors mimicking alimentary lymphoma in 2 dogs.

Two shih tzu dogs were referred to our clinic because of hematochezia and vomiting. Abdominal ultrasonography revealed a focal, asymmetric, exophytic small intestinal mass with loss of wall layering and muscular layer thickening of the adjacent intestine. Computed tomography (CT) in both dogs revealed a focal, asymmetric, homogenously contrast-enhanced exophytic jejunal and duodenal mass with an intact mucosal layer and generalized lymphadenopathy. Metastasis and ulceration were not detected on CT. The initial imaging diagnosis was lymphoma in both dogs; however, histopathological examination revealed the presence of intestinal mast cell tumors (iMCTs). Despite its similarity to alimentary lymphoma, iMCT should be considered a possible diagnosis, based on imaging characteristics, to ensure that proper treatments are selected. This is the first veterinary report describing detailed ultrasonographic and CT characteristics of iMCTs. Key clinical message: This is the first veterinary case report demonstrating sonographic and computed tomographic features of canine iMCT, which can be misdiagnosed as alimentary lymphoma. This report provides another differential diagnosis to consider when determining the appropriate patient treatment direction and histopathological examination.

Caractéristiques échographiques et tomodensitométriques de mastocytomes intestinaux imitant un lymphome alimentaire chez 2 chiens. Deux chiens shih tzu ont été référés à notre clinique en raison d'une hématochézie et de vomissements. L'échographie abdominale a révélé une masse focale, asymétrique et exophytique de l'intestin grêle avec perte de stratification pariétale et épaississement de la couche musculaire de l'intestin adjacent. La tomodensitométrie (TDM) chez les deux chiens a révélé une masse jéjunale et duodénale exophytique focale, asymétrique, homogène et contrastée avec une couche muqueuse intacte et une lymphadénopathie généralisée. Les métastases et les ulcérations n'ont pas été détectées par TDM. Le diagnostic initial d'imagerie était un lymphome chez les deux chiens; cependant, l'examen histopathologique a révélé la présence de mastocytomes intestinaux (iMCT). Malgré sa similitude avec le lymphome alimentaire, l'iMCT doit être considérée comme un diagnostic possible, basé sur les caractéristiques de l'imagerie, afin de garantir la sélection des traitements appropriés. Il s'agit du premier rapport vétérinaire décrivant les caractéristiques échographiques et tomodensitométriques détaillées des iMCT.Message clinique clé :Il s'agit du premier rapport de cas vétérinaire démontrant les caractéristiques échographiques et tomodensitométriques de l'iMCT canin, qui peuvent être diagnostiquées à tort comme un lymphome alimentaire. Ce rapport fournit un autre diagnostic différentiel à prendre en compte lors de la détermination de l'orientation thérapeutique et de l'examen histopathologique appropriés du patient.(Traduit par Dr Serge Messier).

Kilovoltage radiotherapy for companion animals: dosimetric comparison of 300 kV, 450 kV, and 6 MV X-ray beams.

Radiotherapy for the treatment of cancer in companion animals is currently administered by using megavoltage X-ray machines. Because these machines are expensive, most animal hospitals do not perform radiotherapy. This study evaluated the ability of relatively inexpensive kilovoltage X-ray machines to treat companion animals. A simulation study based on a commercial treatment-planning system was performed for tumors of the brain (non-infectious meningoencephalitis), nasal cavity (malignant nasal tumors), forefoot (malignant muscular tumors), and abdomen (malignant intestinal tumors). The results of kilovoltage (300 kV and 450 kV) and megavoltage (6 MV) X-ray beams were compared. Whereas the 300 kV and 6 MV X-ray beams provided optimal radiation dose homogeneity and conformity, respectively, for brain tumors, the 6 MV X-rays provided optimal homogeneity and radiation conformity for nasal cavity, forefoot, and abdominal tumors. Although megavoltage X-ray beams provided better radiation dose distribution in most treated animals, the differences between megavoltage and kilovoltage X-ray beams were relatively small. The similar therapeutic effects of the kilovoltage and 6 MV X-ray beams suggest that kilovoltage X-ray beams may be effective alternatives to megavoltage X-ray beams in treating cancers in companion animals.

Diffusion tensor imaging of white and grey matter within the spinal cord of normal Beagle dogs: Sub-regional differences of the various diffusion parameters.

Diffusion tensor imaging (DTI) is an advanced diffusion weighted imaging technique that can identify early stage lesions and Wallerian degeneration within the spinal cord; these changes are difficult to recognise on conventional magnetic resonance imaging (MRI). The only DTI parameters previously investigated in dogs are fractional anisotropy and mean diffusivity (MD). The aim of this study was to evaluate multiple DTI parameters in sub-regional areas of the spinal cord in normal Beagles. All imaging data were obtained from the lumbar spinal cord (L1-L3) of ten normal dogs using a 3 Tesla MRI scanner. Transverse multi-shot echo planar imaging sequences (b values = 0 and 800 s/mm(2); 12 directions) were used for DTI. Regions of interest were selected from sub-regions of the white and grey matter, and from the whole spinal cord, in the transverse plane in all DTI maps. The DTI parameters in spinal cord sub-regions in the transverse plane were significantly different amongst the white matter, grey matter and whole spinal cord (P < 0.05 for all DTI parameters except MD), as well as between white matter sub-regions (P < 0.05 for most DTI parameters except radial diffusivity, MD and planar index). DTI-based sub-regional analysis of white and grey matter may be useful for regional evaluation of the dog spinal cord.

IMAGING DIAGNOSIS--ACUTE MESENTERIC ISCHEMIA ASSOCIATED WITH HYPERTROPHIC CARDIOMYOPATHY IN A CAT.

A middle-aged cat was presented with vomiting, diarrhea, and pelvic limb paresis. Radiography showed cardiomegaly, interstitial pulmonary infiltration, distended intestinal loops, and portal venous gas. Hypertrophic cardiomyopathy (HCM) was confirmed. On CT, thrombi were identified at the abdominal aorta, superior mesenteric artery, bilateral renal arteries, and cauda vena cava at the level of the iliac vein bifurcation. Dilated and gas-filled loops of bowel with a "paper thin wall" were observed on CT images and were considered indicative of necrotic bowel. This case report describes the CT findings of acute mesenteric ischemia associated with HCM in a cat.

Positron emission tomography/computed tomography imaging features of renal cell carcinoma and pulmonary metastases in a dog.

A 9-year-old spayed female cocker spaniel dog was referred for hematuria. A large abdominal mass and multiple pulmonary nodules were identified radiographically. A whole-body 2-deoxy-2-[(18)F]fluoro-d-glucose positron emission tomography/computed tomography (PET/CT) scan revealed intensely increased uptake in a renal mass and the pulmonary nodules. Renal cell carcinoma was diagnosed on histological examination.

Caractéristiques de la tomographie à émission de positrons et de l'imagerie à tomographie par ordinateur des métastases du carcinome cellulaire rénal et pulmonaire chez un chien. Une chienne Cocker spaniel stérilisée âgée de 9 ans a été référée pour l'hématurie. Une grande masse abdominale et des nodules pulmonaires multiples ont été identifiés par radiographie. Un balayage par tomographie à émission de positrons et par tomographie par ordinateur de l'ensemble du corps en utilisant le fluoro-d-2-désoxie-2-glucose [18F] a révélé le captage accru intensif dans une masse rénale et des nodules pulmonaires. Le carcinome des cellules rénales a été diagnostiqué à l'examen histologique.(Traduit par Isabelle Vallières).

Doppler ultrasonographic evaluation of renal arterial resistive and pulsatility indices in overhydrated Beagles.

OBJECTIVE: To determine renal arterial resistive index (RI) and pulsatility index (PI) and clinical signs of overhydration induced by IV administration of saline (0.9% NaCl) solution and to assess RI and PI as variables for monitoring of dogs to detect overhydration. ANIMALS: 10 clinically normal Beagles. PROCEDURES: Each dog received saline solution at a maintenance rate (2.5 mL/kg/h) and a rate 3 times that of the maintenance rate (overhydration rate; 7. 5 mL/kg/h). Values of RI and PI were determined with pulsed-wave Doppler ultrasonographic examination of renal interlobar or arcuate arteries before saline solution administration, every hour during 5 hours of administration, and 1 hour after administration was stopped. RESULTS: No significant changes in RI or PI were detected during administration of saline solution at the maintenance rate. However, RI (starting 1 hour after the beginning of fluid administration [mean ± SD value, 0.589 ± 0.012]) and PI (starting 2 hours after the beginning of fluid administration [value, 0.867 ± 0.052]) were significantly lower during administration at the overhydration rate than they were during administration at the maintenance rate. Clinical signs of overhydration were observed in all dogs starting 4 hours after the beginning of fluid administration at the overhydration rate. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated overhydration of dogs caused significant decreases in RI and PI prior to detection of clinical signs of overhydration. Ultrasonographic determination of renal arterial RI and PI seemed to be a noninvasive and sensitive method for evaluation of overhydration in dogs.

Echocardiographic assessment of coronary artery flow in normal canines and model dogs with myocardial infarction.

This study was conducted to evaluate the usefulness of coronary arterial profiles from normal dogs (11 animals) and canines (six dogs) with experimental myocardial infarction (MI) induced by ligation of the left coronary artery (LCA). Blood velocity of the LCA and right coronary artery (RCA) were evaluated following transthoracic pulsed-wave Doppler echocardiography. The LCA was observed as an infundibular shape, located adjacent to the sinus of Valsalva. The RCA appeared as a tubular structure located 12 o'clock relative to the aorta. In normal dogs, the LCA and RCA mean peak diastolic velocities were 20.84 ± 3.24 and 19.47 ± 2.67 cm/sec, respectively. The LCA and RCA mean diastolic deceleration times were 0.91 ± 0.14 sec and 1.13 ± 0.20 sec, respectively. In dogs with MI, the LCA had significantly (p < 0.01) lower peak velocities (14.82 ± 1.61 cm/sec) than the RCA (31.61 ± 2.34 cm/sec). The RCA had a significantly (p < 0.01) rapid diastolic deceleration time (0.71 ± 0.06 sec) than that found in the LCA (1.02 ± 0.22 sec) of MI dogs. In conclusion, these profiles may serve as a differential factor for evaluating cardiomyopathy in dogs.

Comparison of echocardiography with dual-source computed tomography for assessment of left ventricular volume in healthy Beagles.

OBJECTIVE: To compare echocardiographic measurements of left ventricular (LV) volume obtained via a modified Simpson or Teichholz method with those obtained via dual-source CT (DSCT). ANIMALS: 7 healthy Beagles. PROCEDURES: Each dog was anesthetized for DSCT; LV volume was determined from contrast-enhanced images of the LV lumen during all phases of contraction. Echocardiography was performed with dogs awake and anesthetized. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume, and ejection fraction were measured via a modified Simpson method and Teichholz method. Each dog was anesthetized twice with a 1-week interval between anesthetic sessions. RESULTS: Results obtained while dogs were anesthetized revealed that the modified Simpson method underestimated LV volume (mean ± SD EDV, 24.82 ± 2.38 mL; ESV, 12.24 ± 1.77 mL), compared with that estimated by the Teichholz method (EDV, 32.57 ± 2.85 mL; ESV, 14.87 ± 2.09 mL) or DSCT (EDV, 34.14 ± 1.57 mL; ESV, 16.71 ± 0.76 mL). Ejection fraction (modified Simpson method, 48.53% ± 4.24%; Teichholz method, 54.33% ± 4.26%; DSCT, 51.00% ± 2.71%) differed significantly among the 3 methods. Echocardiographic results obtained while dogs were awake revealed that EDV, ESV, and stroke volume differed significantly between the modified Simpson and Teichholz methods. CONCLUSIONS AND CLINICAL RELEVANCE: LV volume determined via the Teichholz method was more similar to that determined via DSCT than was the LV volume determined via the modified Simpson method. The modified Simpson method underestimated LV volume, compared with that obtained via the Teichholz method, in both anesthetized and awake dogs.

Comparative study of cardiac anatomic measurements obtained by echocardiography and dual-source computed tomography.

The aim of this study was to verify the accuracy of echocardiography by dual-source computed tomography (DSCT). Seven normal beagles underwent DSCT and echocardiography. Echocardiographic measurements were obtained according to the American Society of Echocardiography guidelines. The DSCT images were reconstructed onto the same echocardiographic image plane by using a reconstruction program, and then anatomical measurements were obtained. Nonparametric analysis was used for verifying the significance of each of the measured parameters. The anatomical measurements obtained using echocardiography and DSCT were not significant (P>0.05), and the difference between the measurements obtained using both the methods were within 95% confidence intervals except those for interventricular septal thickness and left ventricular posterior wall thickness in end diastole. The reasons for these differences were considered to be the adjacent structures such as papillary muscles or chordae tendineae that may have influenced the echocardiographic findings, lower far-field image quality of echocardiography, low test-retest reproducibility of echocardiography, high-quality images of DSCT minimizing the motion artifact and the retrospective ECG gating technique of DSCT that offered an adequate timing decision for the systolic and diastolic phase during cardiac movement. Although there were differences in the measurements of interventricular septal thickness and left ventricular posterior wall thickness in end diastole obtained using echocardiography and DSCT, we could conclude that echocardiographic measurement is as accurate and reliable as DSCT for cardiac anatomical assessment.