Research Article Continuous Dynamic Registration of Microvascularization of Liver Tumors with Contrast-Enhanced Ultrasound Lukas Philipp Beyer, Benedikt Pregler, Isabel Wiesinger, Christian Stroszczynski, Philipp Wiggermann, and Ernst-Michael Jung Department of Radiology, University Medical Center of Regensburg, Franz-Josef-Strauß-Allee 11, 93053 Regensburg, Germany Correspondence should be addressed to Lukas Philipp Beyer; lukas@lukasbeyer.com Received 17 December 2013; Revised 9 April 2014; Accepted 23 April 2014; Published 2 June 2014 Academic Editor: Sotirios Bisdas Copyright © 2014 Lukas Philipp Beyer et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Aim. To evaluate the diagnostic value of quantifcation of liver tumor microvascularization using contrast-enhanced ultrasound (CEUS) measured continuously from the arterial phase to the late phase (3 minutes). Material and Methods. We present a retrospective analysis of 20 patients with malignant ( = 13) or benign (=7) liver tumors. Te tumors had histopathologically been proven or clearly identifed using contrast-enhanced reference imaging with either 1.5 T MRI (liver specifc contrast medium) or triphase CT and follow-up. CEUS was performed using a multifrequency transducer (1–5 MHz) and a bolus injection of 2.4 mL sulphur hexafuoride microbubbles. A retrospective perfusion analysis was performed to determine TTP (time-to-peak), RBV (regional blood volume), RBF (regional blood fow), and Peak. Results. Statistics revealed a signifcant diference ( < 0.05) between benign and malignant tumors in the RBV, RBF, and Peak but not in TTP ( = 0.07). Receiver operating curves (ROC) were generated for RBV, RBF, Peak, and TTP with estimated ROC areas of 0.97, 0.96, 0.98, and 0.76, respectively. Conclusion. RBV, RBF, and Peak continuously measured over a determined time period of 3 minutes could be of valuable support in diferentiating malignant from benign liver tumors. 1. Introduction Te radiomorphological diferentiation between benign and malignant liver tumors with contrast-enhanced ultrasound is based on a continuous, dynamic evaluation of microvascular- ization of the tumor [1] and has been shown to be extremely reliable [2, 3]. Malignant liver tumors (HCC, CCC, and metastasis) ofen have an irregular, sometimes chaotic, early-arterial and arterial (15–45 secs) microvascularization showing a hyperenhancement or rim enhancement [4] in the arterial phase and a hypoechogenic pattern in the portal-venous and the late (2–5 mins) venous phases [4–6]. Metastasis can be hypovascular (e.g., adenocarcinoma) with necrotic, nonenhanced areas or hypervascular (e.g., neuroendocrine tumors) with complete or partial hyperenhancement in the arterial phase. A common feature of almost all metastases is hypo- or nonenhancement in the portal and late phases [7–9]. Most benign hepatic lesions (haemangioma, focal nodu- lar hyperplasia, and adenoma) show a rapid enhancement in the arterial phase with a prolonged enhancement in the late venous phase. Tey display mainly not only hypere- chogenic but also isoechogenic patterns in the late phase [4–6]. Classical patterns include nodular, wheel-spike, or mixed accumulations as seen in haemangioma, focal nodular hyperplasia (FNH), and adenoma, respectively [5]. Te use of the 2nd generation contrast medium, for exam- ple, sulphur hexafuoride microbubbles (SonoVue, Bracco, Italy), enables the detection of strictly intravascular, capillary microvascularization from the early-arterial phase to the late phase [10]. Continuously recorded images can be used for a computer-assisted perfusion analysis. Histopathologic fndings obtained from percutaneous biopsy or surgical specimens are recommended as the gold standard in the characterization of malignant liver tumors. Te imaging techniques contrast-enhanced CT (ceCT) and Hindawi Publishing Corporation Radiology Research and Practice Volume 2014, Article ID 347416, 5 pages http://dx.doi.org/10.1155/2014/347416