Blood perfusion of the intraocular structures and the retrobulbar region can be quantitatively and qualitatively analyzed by CEUS. CEUS may be a useful, noninvasive, and sensitive tool for the evaluation of blood perfusion in ocular diseases.

Rapid contrast injection is recommended for triple-phase helical computed tomography (CT) of the liver. However, a large-gauge catheter is needed for faster contrast injection and this is not practical for small breed dogs or cats. The purpose of this crossover group study was to evaluate applicability of a lower injection rate with a small-gauge (G) catheter for triple-phase hepatic CT in small dogs. Triple-phase CT images were acquired for six beagle dogs using three protocols: an injection rate of 1.5 ml/s with a 24 G catheter, 3.0 ml/s with a 22 G catheter, and 4.5 ml/s with a 20 G catheter. Enhancement of the aorta, portal vein, and hepatic parenchyma was measured in each phase (arterial, portal, and delayed) and image quality was scored subjectively by two observers. Injection duration, time to scan delay, and time to peak enhancement were also recorded. Contrast injection duration decreased with a higher injection rate (n = 6, P ≤ 0.01), but time to peak enhancement and time to scan delay were not significantly affected by injection rates and catheter sizes. Contrast injection rate did not significantly affect aortic, portal, and hepatic enhancement. In addition, separation between each phase and quality of images was subjectively scored as good regardless of injection rate. Findings from the current study supported using an injection rate of 1.5 ml/s with a catheter size of 24 G for triple-phase hepatic CT in small dogs (weight < 12 kg).

This study was performed to optimize scan delays for canine kidney by using a bolus-tracking technique. In six beagle dogs, computed tomography (CT) of the kidney was performed three times in each dog with different scan delays after a bolus-tracking trigger of 100 Hounsfield units (HU) of aortic enhancement. Delays were 5, 20, 35, and 50 sec for the first scan, 10, 25, 40, and 55 sec for the second scan, and 15, 30, 45, and 60 sec for the third scan. The renal artery-to-vein contrast difference peaked at 5 sec, and the renal cortex-to-medulla contrast difference peaked at 10 sec. The renal cortex-to-medulla contrast difference approached zero at a scan delay of 30 sec after the bolus trigger. For the injection protocol used in this study, the optimal scan delay times for renal arterial, corticomedullary, and nephrographic phases were 5, 10, and 30 sec after triggering at 100 HU of aortic enhancement using the bolus-tracking technique. The bolus-tracking technique is useful in multi-phase renal CT study as it compensates for different transit times to the kidney among different animals, requires a small dose of contrast media, and does not require additional patient radiation exposure.

OBJECTIVE To investigate the effects of respiratory phase, body position, beam center location, and gastric distention on radiographic assessment of liver size in dogs. ANIMALS 12 Beagles. PROCEDURES Liver length and the ratio of liver length to T11 length were determined on lateral radiographic views obtained with various techniques. Images were acquired at maximal expiration or maximal inspiration, with dogs in right or left recumbency, with the beam centered on the caudal border of the scapula or the 13th rib, and after food was withheld or with gastric distention. Effects on organs adjacent to the liver were assessed with CT. Changes of the thoracic cavity during the respiratory cycle were investigated with fluoroscopy. RESULTS Liver length was significantly greater on radiographs obtained at maximal expiration than at maximal inspiration, but there was no increase in the ratio of liver length to T11 length. Body position, beam center location, and gastric distention did not significantly affect liver size. For CT, location of the spleen and stomach and location or size of the liver did not change markedly between right and left recumbency. Fluoroscopy revealed that thoracic width was less at maximal expiration than maximal inspiration. CONCLUSIONS AND CLINICAL RELEVANCE Liver length was greater at maximal expiration than at maximal inspiration because of a smaller thoracic width. Body position, beam center location, and gastric distention did not affect liver length. The ratio of liver length to T11 length was not significantly affected by any of the factors investigated.