Point shear wave elastography of the liver in healthy adult cats.

OBJECTIVE: To evaluate stiffness of the liver parenchyma in healthy adult cats by means of point shear wave elastography (PSWE). ANIMALS: 18 client-owned adult (1- to 6-year-old) healthy cats. PROCEDURES: Echogenicity and echotexture of the liver parenchyma were assessed by means of conventional B-mode ultrasonography. The shear wave velocity (Vs) of the right and left portions of the liver were measured by means of PSWE. RESULTS: B-mode ultrasonography revealed no abnormalities in echotexture or echogenicity of the liver parenchyma in any cat. Mean (95% CI) Vs in the liver parenchyma was 1.46 m/s (1.36 to 1.55 m/s) for the right portion, 1.36 m/s (1.26 to 1.47 m/s) for the left portion, and 1.43 m/s (1.35 to 1.51 m/s) overall. The difference in mean Vs between the 2 portions of the liver was significant. No significant correlation was found between Vs and body weight or between Vs and the depth at which this variable was measured. CONCLUSIONS AND CLINICAL RELEVANCE: Quantitative PSWE of the liver was feasible in healthy adult cats. The obtained values for Vs may be useful for interpretation of and comparison with values measured in cats with liver disease. Additional research is needed to explore the potential usefulness of PSWE for diagnostic purposes.

Effect of catheter diameter and injection rate of flush solution on renal contrast-enhanced ultrasonography with perfluorobutane in dogs.

OBJECTIVE: To assess effects of catheter diameter and injection rate of flush solution (saline [0.9% NaCl] solution) on renal contrast-enhanced ultrasonography (CEUS) with perfluorobutane in dogs. ANIMALS: 5 healthy Beagles. PROCEDURES: CEUS of the kidneys was performed by IV injection of contrast medium (0.0125 mL/kg) followed by injection of 5 mL of saline solution at rates of 1, 3, and 5 mL/s through a 20-gauge or 24-gauge catheter; thus, CEUS was repeated 3 times for each catheter diameter. Time-intensity curves were created for regions of interest drawn in the renal cortex and medulla. Repeatability was determined by calculating the coefficient of variation (CV). Statistical analysis was used to assess whether perfusion variables or CV of the perfusion variables was associated with catheter diameter or injection rate. RESULTS: Perfusion variables did not differ significantly between catheter diameters. Time to peak enhancement (TTP) in the renal cortex was affected by injection rate, and there were significantly lower values for TTP at higher injection rates. The CEUS variables with the lowest CVs among injection rates were TTP for the renal cortex; the CV for TTP of the renal cortex was the lowest at an injection rate of 5 mL/s. CONCLUSIONS AND CLINICAL RELEVANCE: Use of a 24-gauge catheter did not alter CEUS with perfluorobutane; therefore, such catheters could be used for CEUS of the kidneys of small dogs. Moreover, a rate of 5 mL/s is recommended for injection of flush solution to obtain greater accuracy for renal CEUS in Beagles.