A diagnostic imaging system includes oppositely disposed radiation detectors (32, 34) configured to detect coincidence radiation events caused by a substance injected into a subject which generates positron emissions. A coincidence data processor (40) collects and processes the radiation detected by the detectors (32, 34) and a coincidence circuitry (44) matches and compares the detected events to determine coincidence. Coincidence data is generated and stored in a coincidence data memory (46). A collimated radiation detector (50) is disposed at an angle to the coincidence radiation detectors (32, 34) and is configured to detect single photon radiation traveling along a selected projection path determined by a collimator (52) mounted on a front face of the collimated radiation detector (50). A single photon data processor (60) generates collimated data (74) based on the radiation detected by the collimated radiation detector (50). A combiner (80) selectively combines the coincidence data (46) and the collimated data (74) and the combined data is reconstructed into an image representation (84) of a region of interest.