This recent publication by Shirinfard et al, uses a novel microbubbles injection technique to evaluate the feasibility of using dynamic contrast enhanced ultrasound (CEUS) to assess absolute perfusion of tissue in mice.
- CEUS allows non-invasive and longitudinal monitoring of diseases and treatments.
- Current two methods of perfusion estimation using CEUS (bolus perfusion and burst-replenishment) have only been used to measure relative perfusion in vivo.
- Purpose: To establish a method of measuring absolute tissue perfusion in mice using a modified burst-replenishment (BR) technique.
- A novel method of microbubbles administration was implemented, where non-targeted MicroMarker microbubbles were injection as a 20µL bolus followed by continues infusion at 9µl/min to achieve steady-state for BR.
- 10 CD-1 mice were imaged for two weeks, looking at perfusion in both kidneys, and week-to-week repeatability.
- Absolute kidney perfusion was estimated as the ratio of kidney blood density to 2 x microbubble transient time.
- CEUS detected kidney perfusion was within range of previously reported values, with no statistical difference observed between weeks.
- Assessment of absolute blood perfusion in other tissue was tested on a subcutaneous neuroblastoma tumor, with values normalized to the kidney.
This study demonstrates the possibility of measuring absolute tissue perfusion using CEUS in mice. This method of evaluation for kidney perfusion is robust and can be further used as reference for other tissues. Adjustment of injection volume and rate according to animal weight may help reduce variability, and should be further evaluated for other mouse strain and microbubble formulations.
Shirinifard, A., Thiagarajan, S., Johnson, M. D., Calabrese, C. & Sablauer, A. Measuring Absolute Blood Perfusion in Mice Using Dynamic Contrast-Enhanced Ultrasound. Ultrasound Med. Biol. 43, 1628–1638 (2017).