A photo-acoustic imaging apparatus (300) is provided for imaging a region (318) of a subject (306). The apparatus comprises: a light source (310) for directing light (314) at the region of the subject. A photo-acoustic transducer (320) senses photo-acoustic signals (404) induced in the region of the subject by the laser light, the photo-acoustic transducer being immersed in an ultrasound coupling medium and arranged to scan the region of the subject and to move in a curvilinear path (402) around the region of the subject. The light source is disposed within a volume (346) defined, at least in part, by the curvilinear path.
