The AccuSizer® SPOS system is the most common instrument used to measure the size and concentration of microbubbles.
Microbubbles are used in medical diagnostics as a contrast agent for ultrasound imaging and as drug delivery vehicles. The size of micro-bubbles is typically in the 1-5 µm range, preferably with a narrow size distribution. To enhance the stability of microbubbles they are typically encapsulated in a shell composed of lipid or a protein.
The AccuSizer® SPOS system is the most common instrument used to measure the size and concentration of microbubbles used in a variety of applications including contrast agents and targeted drug delivery. Microbubbles can also be used to treat thrombosis and vascular plaques.
Figures 1 and 2 show how microbubbles are used to enhance ultrasonic imaging. These are 7 MHz CPS images (MI=0.09) acquired before and after imaging and destruction of targeted bubbles in a Met-1 tumor in vivo. Figure 1 shows 10 seconds after injection of a targeted agent. Figure 2 shows 24 hours after destruction of adherent agents and 10 seconds after re-injection flow is extremely slow within the tumor. The “black hole” indicates poorly perfused regions.
Figure 1: 10 seconds after injection
Figure 2: 24 hours after destruction of adherent agents
Microbubbles for Standard Clinical Imaging
Microbubbles for standard clinical imaging can be purchased, such as Definity and Optison. Other researchers prefer to create their own – typically for animal studies. Various publications detail methods for creating microbubbles. The AccuSizer SPOS system has proven to be the preferred method for quantifying the size and concentration of microbubbles. Figures 3 and 4 show AccuSizer system results for non-targeted and CRPPR targeted microbubbles, respectively.
Figure 3 and Figure 4
Figure 3: Non-targeted microbubbles Figure 4: Targeted microbubbles