Rapid volumetric photoacoustic tomographic imaging with a Fabry-Perot ultrasound sensor depicts peripheral arteries and microvascular vasomotor responses to thermal stimuli.

Purpose: To determine if a new photoacoustic imaging (PAI) system successfully depicts (1) peripheral arteries and (2) microvascular circulatory changes in response to thermal stimuli.

Methods: Following ethical permission, 8 consenting subjects underwent PAI of the dorsalis pedis (DP) artery, and 13 completed PAI of the index fingertip. Finger images were obtained after immersion in warm (30-35 °C) or cold (10-15 °C) water to promote vasodilation or vasoconstriction.

Image vector histogram approach to nanoparticle sizing.

A novel approach to measuring the size distribution of particles in the range of a few nanometers to a few micrometers is described. The method is based on processing multiple images of a sample of particles suspended in a liquid and undergoing Brownian motion. From each image, the centers of the particle positions are measured, then a histogram of the vectors connecting the centers in each image with all the centers in the next image is formed.