The cancer-imaging agent and method of radioimaging relates to the use of a radioimaging agent for the imaging increased choline uptake to detect cancerous tissue. The radioimaging agent includes choline or a pharmaceutically acceptable salt thereof labeled with technetium-99m. Preferably, the radioimaging agent is [methyl]-choline chloride labeled with 99mTcO4, which carries technetium-99m. In use, a patient is administered an effective amount of the radioimaging agent by injection and then scanned with a radioimaging device. The radioimaging agent is used to image select soft tissues in the patient, such as the liver or gallbladder, the upper abdominal organs, or the like, and to detect increased choline uptake. Choline is known to accumulate in cancerous cells. Thus, the radioimaging agent is particularly effective in the detection of potentially cancerous tissues.