Specific considerations in the interpretation of single-photon-emission computed tomography of the normal liver

In our hospital, single-photon-emission computed tomography (SPECT) has been routinely used instead of conventional scintigraphy in the examination of the liver and spleen in more than 3,000 patients. This technique is preferred because it provides more detailed information and better contrast resolution than planar views. However, using the SPECT technique, normal variations in liver anatomy are more apparent, and certain cases--in particular those with a wide main lobar fissure combined with a prominent gall bladder fossa as well as cases with a large hilus--may erroneously be interpreted as having a focal lesion. In order to facilitate the interpretation of SPECT examinations of the liver, the most common difficulties and pitfalls arising from normal variations in hepatic anatomy, indentations caused by surrounding organs and partial-volume effects are described and compared with the findings of corresponding transmission computed tomograms.