September 30, 2011 – The Molecular Imaging Biomarker Research Group of Siemens Medical Solutions recently completed a Phase II multi-center clinical trial of its HX4 positron emission tomography (PET) imaging biomarker, which is designed to detect hypoxia – a reduction in tissue oxygen levels – in solid tumors. The trial’s primary objective was to test the reproducibility of HX4’s uptake in tumors by conducting PET/computed tomography (CT) scans of the same patient on sequential days in a test-retest protocol. The trial enrolled 40 patients with head and neck, lung, liver, rectal or cervical cancers, who were scheduled to receive chemotherapy, radiation therapy or a combination of the two.