The overall goal of this study is to determine if non-invasive imaging with state of the art CT coronary angiography can be used to screen for coronary artery disease in high risk patients prior to liver and lung transplantation. The current protocol for coronary artery disease assessment at UCSF before liver and lung transplantation involves screening with stress tests and/or coronary angiograms in patients with increased risk of coronary artery disease. Coronary angiogram will be used as gold standard for assessment of coronary CTA accuracy.