Methods and systems to analyze soft tissue or vasculature in a subject, form images with enhanced soft tissue contrast, determine blood flow parameters in soft tissue or vasculature, and to aid in the diagnosis of disease using thermoacoustic methods. Pulsed electromagnetic energy is administered to tissue to excite a thermoacoustic signal in the soft tissue or vasculature. An acoustic receiver or receiver array is coupled to a subject to detect and record the thermoacoustic signals produced. Thermoacoustic data are acquired after administration of a physiologically-tolerable tracer or contrast agent. The acquired data may be analyzed to produce images of the soft tissue and vasculature (angiogram), to determine blood flow parameters, and/or to diagnose disease in a subject.
