Abdominal Computed Tomographic Abdominal Scan [CT/CAT Scan]
Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical test that, like traditional x-rays, produces multiple images or pictures of the inside of the body. No current evidence exists for routine use of computed tomographic (CT) abdominal scanning as a routine surveillance test for HCC. In contrast, for patients who have a liver nodule greater than 1 cm detected on ultrasound, many experts recommend using a 4-phase (unenhanced, arterial, venous, and delayed) dynamic contrast CT scan of the liver as a secondary test for diagnosis. During the arterial phase, HCC lesions enhance more intensely than the surrounding liver, but the opposite is observed during the venous and washout phases (where HCC lesions have little enhancement). The characteristic finding with HCC is presence of arterial hypervascularity (uptake) in the lesion followed by venous or delayed phase washout. The role of 4-phase CT scan in the diagnosis of HCC is particularly important since many experts rely on CT or magnetic resonance imaging (MRI) findings to establish the diagnosis, without the need for liver biopsy, if characteristic radiographic findings for HCC are present.