Because of the non-specificity of the clinical signs and laboratory findings, imaging techniques suchas portography, ultrasonography (US), nuclear scintigraphy, computed tomography (CT), or magneticresonance imaging (MRI) are required to provide a definitive diagnosis of portosystemic shunts (PSSs).Nuclear scintigraphy is the gold standard for detecting PSSs, but it is not useful in distinguishing the differenttypes of shunts. Due to its high sensitivity, portography has for a long time been considered the goldstandard for differentiation of PSSs, despite its invasive nature. However, the recent development of astandard protocol for US and the routine use of Doppler modalities have resulted in the same sensitivityas portography. Therefore, with the additional benefit of being fast and noninvasive, US is now more commonlyperformed. It may be considered a “new” gold standard, depending upon the experience of theradiologist. Computed tomography and MRI provide detailed anatomic information. In this fourth articleabout portosystemic shunts in dogs and cats a comprehensive overview of the literature covering US andnuclear scintigraphy will be given. Finally CT and MRI techniques will be explained briefly.