Time Reversal cavities (TRC) have been investigated in medical ultrasounds in the past, for either shockwave therapy or imaging. They indeed allow small foci formation in large regions of interest with a limited number of transducer elements. This paper is a preliminary study, establishing the proof of concept of a dual-mode TRC for both shockwave therapy and 3D imaging. A 128-element, 1 MHz power transducer placed in a reverberating cavity along with a multiply scattering medium was used. We were able to create lesions on a simple target over a 10 cm² area, and to create a 3D image of highly reflective structures such as the ribcage within a   cm² area.