Ultrasound (US) is the most commonly used liver imaging modality worldwide. Due to its low cost, it is increasingly used in the follow-up of cancer patients with metastases localized in the liver. In this contribution, we present the results of an interactive segmentation approach for liver metastases in US acquisitions. A (semi-) automatic segmentation is still very challenging because of the low image quality and the low contrast between the metastasis and the surrounding liver tissue. Thus, the state of the art in clinical practice is still manual measurement and outlining of the metastases in the US images. We tackle the problem by providing an interactive segmentation approach providing real-time feedback of the segmentation results. The approach has been evaluated with typical US acquisitions from the clinical routine, and the datasets consisted of pancreatic cancer metastases. Even for difficult cases, satisfying segmentations results could be achieved because of the interactive real-time behavior of the approach. In total, 40 clinical images have been evaluated with our method by comparing the results against manual ground truth segmentations. This evaluation yielded to an average Dice Score of 85% and an average Hausdorff Distance of 13 pixels.Compared to computed tomography (CT) or magnetic resonance imaging (MRI), ultrasound (US) is a more easily accessible and less expensive imaging procedure, and, for the liver, the most commonly used imaging modality worldwide. The preference for US is owed to the multiple access points of the liver for the US examination. The intercostal and subcostal route allow for the examination of the whole organ in most of the patients. Hence, the usage of US is also one of the first procedures for evaluating liver metastases, when a patient is diagnosed with cancer. After a subsequent initial staging using CT of the thorax and the abdomen, US is often used to evaluate for treatment response of cancer patients with metastases solely localized in the liver. In case of pancreatic cancer, additional staging of the primary tumor can be done with endoscopic ultrasound. Due to the good accuracy of US in diagnosis and follow-up of liver metastases compared to CT or MRI 1 , the current ESMO -ESDO clinical practice guideline recommend US for the response evaluation in the palliative setting of pancreatic cancer patients 2 . Additionally to the appearance of a new metastases during follow-up, the change in size of preexisting metastases plays an important role in the evaluation of treatment response. Nevertheless, the liver metastases appearance in US acquisitions is highly variable 3 . A schematic overview of the different echo-patterns is presented in Fig. 1: Compared to the surrounding liver tissue, metastases can appear, for example, hyperechoic/brighter (A) or hypoechoic/darker (C) in B-mode. However, isoechoic (B) masses can have a very similar echo-pattern compared to the surrounding liver tissue and can be hard to detect. Consequently, the size determination of isoechoic masse...