Helical computed tomography of the liver: techniques, applications and pitfalls

Helical computed tomography (CT) of the liver has greatly improved both the accuracy and characterization of focal liver masses. This paper focuses on specific techniques for helical CT, including dual helical CT (acquisition of scans during both the arterial and portal venous phases of contrast enhancement), high-dose helical CT, delayed iodine CT, and helical CT angiography and portography. Techniques of generating three-dimensional helical CT angiograms from axial datasets are also discussed here. The clinical applications and results of these different techniques will also be discussed. In addition, helical CT produces or reveals some specific hepatic perfusion abnormalities that can lead to erroneous diagnoses; caveats for avoiding these pitfalls in interpretation are offered.