Abstract. Liver metastases are an advanced stage of several types of cancer, usually treated with surgery. Intra-operative localization of these lesions is currently facilitated by intra-operative ultrasound (IOUS) and palpation, yielding a high rate of false positives due to benign abnormal regions. In this paper we present the integration of functional nuclear information from a gamma probe with IOUS, to provide a synchronized, real-time visualization that facilitates the detection of active metastases intra-operatively. We evaluate the system in an ex-vivo setup employing a group of physicians and medical technicians and show that the addition of functional imaging improves the accuracy of localizing and identifying malignant and benign lesions significantly. Furthermore we are able to demonstrate that the inclusion of an advanced, augmented visualization provides more reliability and confidence on classifying these lesions in the presented evaluation setup.
MotivationLiver metastases are a common consequence of cancer cells spreading from primary tumors. Surgical resection is the indicated therapy if possible, as it results in a cure with high probability [1]. To facilitate extraction, intra-operative localization of the tumorous regions is achieved by a combination of palpation and intra-operative ultrasound (IOUS). This technique is considered the gold standard as it has been in successful clinical practice for years already with a proved high sensitivity [2,3]. However, in the presence of benign abnormal structures, a considerable false-positive detection rate still remains. These abnormalities may be cysts, hemangiomas, scar tissue, or even metastases, which were previously diagnosed by e.g. PET/CT and treated successfully with chemotherapy or other neoadjuvant therapies [3]. This problem, although reduced, is still present when using contrast-enhanced ultrasound [2], which has a promising potential for better image quality, but still remains a mostly anatomical imaging modality.To reduce the detection rate of false-positives, the integration of a functional modality to complement the standard localization technique is a promising approach. A prime candidate for this is nuclear imaging, as there are tracers with