Learning Objectives: 1) To recognize the CT findings of acute urinary obstruction from stone disease. 2) To use radiological imaging for the characterization and management of cystic renal masses. 3) To use helical CT for optimal detection and treatment planning of small renal masses. 4) To describe patient selection with adrenal masses for biochemical testing and imaging and how to reliably distinguish adenomas and nonadenomas on CT and MRI. http://www.pennstateradiology.com/ rsna/index.html