Structural health monitoring (SHM) consists in embedding sensors in a structure in order to monitor its health status throughout its lifetime. The implementation of SHM systems is restricted in many situations by the necessity to store or to harvest the electric energy necessary to emit the waves which give information about the health of the structure. A promising way to tackle this constraint is to take advantage of the elastic noise naturally present in the structure in order to avoid the emission of the elastic waves by the SHM system. The complexity of the embedded SHM system is therefore reduced. We present here studies of a passive technique-the ambient elastic noise cross-correlation-applied to guided wave tomography. Experimental results which come from usual time-of-flight tomography as well as passive tomography will be described.