Abstract: An apparatus (and method) is for monitoring blood perfusion. A plurality of photoplethysmography, PPG, signals are acquired indicative of light detected in a region of interest of tissue at a plurality of respective locations within the region. The PPG signals are processed to determine an amplitude and preferably also a phase of each of the plurality of PPG signals, and a blood perfusion level is determined at the region of interest based on the amplitudes and preferably also the phases of the PPG signals.