Embodiments of the invention provide apparatus, systems and methods for the detection of deep vein thrombosis (DVT) using photoacoustic measurement of hemoglobin in different states of oxgyenation within tissue. One embodiment of a system for DVT detection comprises at least a first and second light source that emit light at first and second wavelengths, an acoustic transducer, a data converter and a processor. The first and second light sources are directed on the patients skin to produce a photoacoustic signal (PS) correlated to an amount of absorbance of the first and second wavelengths by a target region of tissue beneath the patients skin. The acoustic transducer detects the PS and transduces it into an electrical signal which is correlated to the PS. The data converter converts the electrical signal into a digital signal which is analyzed by the processor to detect the presence of DVT within the target region.
