Z-section and 3D rendering imaging using 130 and 50 MHz ultrasound and bacteria generated ultrasound contrast agents

Abstract

We present an ultrasound z-sectioning imaging approach to visualize small vasculature. The major difference between confocal and conventional microscopy is the sectioning capability to generate three-dimensional images by stacking multiple sections. To visualize small vessels, we used 130 and 50 MHz ultrasonic transducers and gas vesicles (GV) isolated from bacteria as contrast agents. We developed 130 and 50 MHz ultrasonic transducers using lithium niobate. The focus and aperture of 130 MHz transducer are 1.5 and 1 mm and 50 MHz transducer has 3 mm aperture and 4 mm focus. These transducers were attached to ultrasound biomicroscopy for scanning phantoms and mouse liver specimen ex vivo with 1 micrometer steps. Saved radiofrequency data was post-process to reconstruct B-mode images and mid-band fit (MBF) maps. Four types of GVs were isolated in house. GV sizes were ranging from 200 to 600 nm. Three GV species present unclustered morphology but GVs isolated from one bacteria species present clustered morphology. Distinct MBF maps were created from clustered and unclustered GVs which were suitable for multiplexed imaging. The results demonstrated that MBF and GV based ultrasound imaging approach can image thin slices of tissue specimen with multiplexed imaging capability.