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 ± 0.6 s) than anaesthetised (4.8 ± 1.0 s) 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 30 s 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.