Impact of device geometry on the imaging characteristics of an intravascular photoacoustic catheter.

A basic requirement for intravascular photoacoustic (IVPA) imaging catheters is that the delivery of light lies within the ultrasonic field of view. Size and manufacturing constraints favor probe designs with offset optical and acoustic beams. This noncollinear dual beam arrangement leads to a curved PA point spread function (PSF). In this work, we characterize the three-dimensional shape of the PSF for IVPA imaging in clear and optically scattering media. We show that the product of the two beam profiles can accurately model the measured peak response in clear and scattering media. We discuss the impact of the PSF shape and its relation to probe construction. We test the imaging capability of the catheter on a phantom and a human artery ex vivo.