Ultrasound is one of the workhorses in clinical cancer diagnosis. In particular, it is routinely used to characterize lesions in
liver, urogenital tract, head and neck and soft tissues. During the last years image quality steadily improved, which, among others, can be
attributed to the development of harmonic image analysis. Microbubbles were introduced as intravascular contrast agents and can be detected
with superb sensitivity and specificity using contrast specific imaging modes. By aid of these unspecific contrast agents tissues can
be characterised regarding their vascularity. Antibodies, peptides and other targeting moieties were bound to microbubbles to target sites
of angiogenesis and inflammation intending to get more disease-specific information. Indeed, many preclinical studies proved the high
potential of targeted ultrasound imaging to better characterize tumors and to more sensitively monitor therapy response. Recently, first
targeted microbubbles had been developed that meet the pharmacological demands of a clinical contrast agent.
This review articles gives an overview on the history and current status of targeted ultrasound imaging of cancer. Different imaging concepts
and contrast agent designs are introduced ranging from the use of experimental nanodroplets to agents undergoing clinical evaluation.
Although it is clear that targeted ultrasound imaging works reliably, its broad acceptance is hindered by the user dependency of ultrasound
imaging in general. Automated 3D-scanning techniques – like being used for breast diagnosis - and novel 3D transducers will
help to make this fascinating method clinical reality.