[Optoacoustic imaging].

CLINICAL/METHODICAL ISSUE: Imaging modalities play an increasing role in today's medical diagnostics. Among them, ultrasound (US) is one the most widespread techniques although it has relatively poor soft tissue contrast. Furthermore, US is poorly suited as a modality for molecular imaging (MI). STANDARD RADIOLOGICAL
METHODS: Methods such as Doppler and contrast-enhanced US (CEUS) allow functional imaging of the vasculature; however, ultrasound-based MI remains limited to the vascular network due to the size of available contrast agents. METHODICAL INNOVATIONS: Optoacoustic imaging combines the benefits of optics (high contrast) with those of acoustics (low scattering and high resolution). In this technique, signals are generated in tissue with high contrast depending on the local optical absorption coefficient and detected with an acoustic procedure. PERFORMANCE: Optoacoustic imaging can intrinsically be scaled in terms of resolution and is therefore usable in various applications from in vitro microscopy, to preclinical small animal imaging up to clinical imaging. With a resolution in the range of clinical ultrasound systems (100-400 µm), highly scattering tissue can be imaged up to several centimeters in depth. ACHIEVEMENTS: In contrast to conventional ultrasound imaging, optoacoustic techniques are highly suitable for MI. Various contrast agents as well as different technical implementations of the approach have already been preclinically evaluated. The technique is currently close to being transferred to clinical implementation and the first studies have already been started. PRACTICAL RECOMMENDATIONS: Clinical studies are ongoing with respect to early diagnosis of breast cancer and arthritis. Furthermore, the suitability of the technique for skin imaging is currently being investigated.