Quantitative contrast-enhanced ultrasonographic analysis of perfusion in the kidneys, liver, pancreas, small intestine, and mesenteric lymph nodes in healthy cats.

OBJECTIVE: To evaluate perfusion of abdominal organs in healthy cats by use of contrast-enhanced ultrasonography. ANIMALS: 10 young healthy anesthetized cats. PROCEDURES: Contrast-enhanced ultrasonography of the liver, left kidney, pancreas, small intestine, and mesenteric lymph nodes was performed on anesthetized cats. RESULTS: Typical perfusion patterns were found for each of the studied organs. Differences in perfusion among organs were associated with specific physiologic features. The liver was enhanced gradually and had a more heterogeneous perfusion pattern because of its dual blood supply and close proximity to the diaphragm, compared with other organs. An obvious and significant difference in perfusion was detected between the renal cortex and medulla. No significant differences in perfusion were detected among the pancreas, small intestine, and mesenteric lymph nodes. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that contrast-enhanced ultrasonography can be used in cats to estimate organ perfusion as in other species. Observed differences in perfusion variables can be mostly explained by physiologic differences in vascularity.

Effect of anaesthesia on contrast-enhanced ultrasound of the feline spleen.

The spleens of 18 healthy cats were imaged using contrast-enhanced ultrasound (CEUS) to evaluate splenic perfusion and to compare perfusion patterns in awake and anaesthetised cats. Two groups of cats were imaged; the first (Group 1) consisted of 10 young, anaesthetised cats and the second (Group 2) comprised eight young to middle aged cats that were initially imaged when awake and later following anaesthesia. A two-phase enhancement of the spleen was observed both in awake and in anaesthetised cats. The time to first appearance of the contrast was significantly faster in awake (3.9±0.6s) than anaesthetised (4.8±1.0s) cats in Group 2 (P=0.031). A marked heterogeneous perfusion pattern was more prevalent in the anaesthetised (50%) compared to the awake (12.5%) animals in Group 2. The spleen was heterogeneous for approximately 30s in all groups. The results indicated that CEUS suspected focal perfusion defects of the spleen, especially during general anaesthesia, should be evaluated with caution and only after the initial heterogeneity has disappeared.

The effect of the sample size and location on contrast ultrasound measurement of perfusion parameters.

Contrast-enhanced ultrasound can be used to quantify tissue perfusion based on region of interest (ROI) analysis. The effect of the location and size of the ROI on the obtained perfusion parameters has been described in phantom, ex vivo and in vivo studies. We assessed the effects of location and size of the ROI on perfusion parameters in the renal cortex of 10 healthy, anesthetized cats using Definity contrast-enhanced ultrasound to estimate the importance of the ROI on quantification of tissue perfusion with contrast-enhanced ultrasound. Three separate sets of ROIs were placed in the renal cortex, varying in location, size or depth. There was a significant inverse association between increased depth or increased size of the ROI and peak intensity (P < 0.05). There was no statistically significant difference in the peak intensity between the ROIs placed in a row in the near field cortex. There was no significant difference in the ROIs with regard to arrival time, time to peak intensity and wash-in rate. When comparing two different ROIs in a patient with focal lesions, such as suspected neoplasia or infarction, the ROIs should always be placed at same depth and be as similar in size as possible.

Congestive heart failure and atrial fibrillation in a cat with myocardial fibro-fatty infiltration.

Congestive heart failure and atrial fibrillation were diagnosed in a 4-year-old castrated Birman cat with progressive signs of dyspnea, tachypnea, and lethargy. Echocardiography revealed massive right-sided heart dilatation with ascites and hydrothorax. Electrocardiogram recording showed atrial fibrillation. Medical therapy with diuretics, benazepril, and antithrombotic agents was unsuccessful. The owner requested euthanasia. In post-mortem examination, changes associated with myocardial fibro-fatty infiltration were confirmed. Changes were most marked in the right ventricular wall but with left ventricular involvement was detected.

The effect of contrast-enhanced ultrasound on the kidneys in eight cats.

Contrast-enhanced ultrasound (CEUS) of the left kidney was performed on eight non-anesthetized, young, purpose bred, domestic shorthaired cats. Each cat underwent a physical examination before and 4h and 48h after CEUS. Complete blood count (CBC), serum biochemical analysis, urinalysis, including evaluation of the enzymatic activities of urinary N-acetyl-ß-d-glucosaminidase (NAG) and gamma-glutamyl transferase (GGT), were also performed. No changes were observed in CBC or serum biochemical analyses, with the exception of a decrease in blood urea concentration at 48h post-contrast ultrasound. A small elevation in NAG (U/g creatinine) was observed with a mean (SD) increase from 0.53 (0.35) to 1.43 (0.59) U/g creatinine. The magnitude of the rise was less than the circadian variation reported earlier for healthy cats. These results suggest that CEUS can be safely used to assess kidney perfusion in cats. The changes observed in laboratory values after CEUS did not appear to be related to detrimental effects on the kidneys.