Combined transducer arrays for imaging features of tissue include a transducer array configured for transmit-receive ultrasound imaging, and a transducer array configured for receive-only thermoacoustic imaging. The transmit-receive transducer array includes a plurality of transmit-receive array elements, and the receive-only transducer array includes a plurality of receive-only array elements. The receive-only array elements are registered with and surround the transmit-receive array elements. The receive-only transducer array and transmit-receive transducer array may be housed in an ultrasound probe. The combined transducer arrays may be used in composite imaging of tissue, based on the registration of the transmit-receive array elements and the receive-only array elements. Registration of the transmit-receive array and the receive-only array may involve physical alignment or proximity of these transducer arrays, and may use data representative of known geometry and positions of elements of the two arrays in reconstructing respective images (ultrasound and thermoacoustic) in composite imaging.
