ABSTRACT
The photoacoustic effect, first discovered by Alexander Bell in 1880, refers to the formation of sound waves following light absorption in an object. This chapter focuses on photoacoustic neuroimaging. It discusses the two most commonly used photoacoustic image reconstruction algorithms—the universal back projection algorithm and the time reversal algorithm. The chapter introduces the principle of photoacoustic tomography (PAT) and describes various photoacoustic neuroimaging systems. It highlights representative photoacoustic neuroimaging studies, and the chapter also discusses further improvements in photoacoustic neuroimaging. For photoacoustic computed tomography (PACT), whose receiving elements are unfocused and thus have a large acceptance angle, the initial pressure can be reconstructed only by merging data from all transducer elements. PACT is another major implementation of PAT. Compared to photoacoustic microscopy, PACT usually targets at deeper imaging depths with lower spatial resolution. A circular-view PACT system provides cross-sectional images of the brain. The first-generation circular-view PACT systems used a single-element transducer that scanned around the object’s head.
