Three-dimensional Reconstruction of Fine Vascularity in Ultrasound Breast Imaging Using Contrast-enhanced Spatial Compounding: In Vitro Analyses 1 Christian Hansen, Nils Hüttebräuker, Wilko Wilkening, PhD, Helmut Ermert, PhD Rationale and Objectives. Ultrasound image quality can be improved by imaging an object (here: the female breast) from different viewing angles in one image plane. With this technique, which is commonly referred to as spatial compounding, a more isotropic resolution is achieved while speckle noise and further artifacts are reduced. We present results obtained from a combination of spatial compounding with contrast-enhanced ultrasound imaging in three dimensions to reduce contrast specific artifacts (depth dependency, shadowing, speckle) and reconstruct vascu- lar structures. Materials and Methods. We used a conventional ultrasound scanner and a custom made mechanical system to rotate an ultrasound curved array probe around an object (360°, 36 transducer positions). For 10 parallel image planes, ultrasound compound images were generated of a flow-mimicking phantom consecutively supplied with water and contrast agent. These compound images were combined to form a volume dataset and postprocessed to obtain a sonographic subtraction angiography. Results. Image quality was significantly improved by spatial compounding for the native (ie, without contrast agent), and, in particular, for the contrast-enhanced case. After subtracting the native images from the contrast-enhanced ones, only structures supplied with contrast agent remain. This technique yields much better results for compound images than for conventional ultrasound images because speckle noise and an anisotropic resolution affect the latter. Conclusions. With the presented approach contrast specific artifacts can be eliminated efficiently, and a subtraction an- giography can be computed. A speckle reduced three-dimensional reconstruction of submillimeter vessel structures was achieved for the first time. In the future, this technique can be applied in vivo to image the vascularity of cancer in the female breast. Key Words. Sonography; contrast agent; echo tomography; subtraction angiography; female breast. © AUR, 2008 Acad Radiol 2008; 15:1155–1164 1 From the Institute for High Frequency Engineering, Ruhr-University, Gebäude IC, 6/140 Universitätsstr. 150, 44801 Bochum, Germany (C.H., N.H., H.E.); Ruhr Center of Excellence for Medical Engineering, Bochum, Germany (C.H., W.W., H.E.); Zentrum für medizinische Bildgebung Ruhr (C.H., H.E.), Bo- chum, Germany. Received December 12, 2007; accepted April 11, 2008. This work is a project of the Ruhr Center for Medical Imaging (Zentrum für mediz- inische Bildgebung Ruhr, ZMB-Ruhr) in cooperation with the Ruhr Center of Excellence for Medical Engineering (Kompetenzzentrum Medizintechnik Ruhr, KMR), Bochum, Germany. This work is funded by the state government of North Rhine-Westphalia, Germany, and by the European Community (European Regional Development Fund, ERDF). This work is supported by Siemens Medical Solutions, Mountain View, CA. Address correspondence to: C.H. e-mail: christian.hansen@rub.de © AUR, 2008 doi:10.1016/j.acra.2008.04.005 1155 Computer-Assisted Radiology and Surgery