Liver tumor imaging. Liver tumor imaging is the paradigm of the dilemma of diagnostic decision-making in the current era of abundant high technology. In part, this is a reflection of the multiplicity of imaging techniques now in wide use worldwide. These include ultrasound (US), radionuclide scintigraphy (RNS), computed tomography (CT), magnetic resonance imaging (MRI), and techniques especially designed for staging the extent of known liver cancer, such as computed tomography during arterial portography (CTAP) and intraoperative ultrasound (IOUS). Most authorities concede that CT scanning is the single test most closely fitting the designation "gold standard" for liver tumor imaging, although MRI, a less mature technique, is already preferred by some. Local factors profoundly influence the selection and sequence of imaging studies, including available equipment, radiologic skills, institutional interests, and especially the specific clinical circumstances of the patient. Thus, diagnostic algorithms or decision trees for sequential imaging workup of liver tumor suspects tend to be somewhat institution specific. 