Fig. 5.

Photoacoustic (PA) imaging with needle insertions into human fingers in vivo with conventional reconstruction, U-Net enhancement, and standard Hough Transform. Signals from the skin surface are indicated by triangle wide arrows, and signals that may be from digital arteries are indicated by hollow triangle wide arrows. The outcomes of U-Net enhancement and standard Hough Transform are denoted by green lines in PA and ultrasound (US) overlays. (a) - (d) are from a reconstructed PA image sequence recorded during needle insertions in real time.