BACKGROUND: To identify and differentiate agenesis and severe atrophy of the right hepatic lobe on computed tomography (CT). METHODS: The CT examinations of three cases of agenesis and 11 cases of severe atrophy of the right hepatic lobe were reviewed. We evaluated visibility of the three hepatic veins, the two main portal veins (including their branches if necessary), the dilated intrahepatic ducts, enlargement of the medial and lateral segments of the left lobe and caudate lobe of the liver, presence of a retrohepatic gallbladder, hyperattenuation of the atrophic liver parenchyma, posterolateral interposition of the hepatic flexure of the colon, and upward migration of the right kidney. RESULTS: In the three cases of agenesis, no structure can be recognized as the right hepatic vein, right portal vein, or dilated right intrahepatic ducts. In the 11 cases of severe lobar atrophy, the right portal vein (or its branches) was recognized in eight cases, the right hepatic vein in four cases, and the dilated right intrahepatic ducts in 11 cases. The degree of enlargement of the lateral segment does not necessarily change inversely with the size of the medial segment and the caudate lobe. The retrohepatic gallbladder is present in eight cases (two in agenesis and six in atrophy). The phenomenon of hyperattenuation of the atrophic liver parenchyma was noted in six cases. CONCLUSION: Even though a retrohepatic gallbladder and a severely distorted hepatic morphology due to compensatory hypertrophy of the left and caudate lobes may raise a suspicion of agenesis of the right lobe of the liver, absence of visualization of all of the right hepatic vein, right portal vein and its branches, and dilated right intrahepatic ducts is a prerequisite of the diagnosis of agenesis of the right hepatic lobe on CT. In severe lobar atrophy, at least one of these structures is recognizable.
BACKGROUND: To identify and differentiate agenesis and severe atrophy of the right hepatic lobe on computed tomography (CT). METHODS: The CT examinations of three cases of agenesis and 11 cases of severe atrophy of the right hepatic lobe were reviewed. We evaluated visibility of the three hepatic veins, the two main portal veins (including their branches if necessary), the dilated intrahepatic ducts, enlargement of the medial and lateral segments of the left lobe and caudate lobe of the liver, presence of a retrohepatic gallbladder, hyperattenuation of the atrophic liver parenchyma, posterolateral interposition of the hepatic flexure of the colon, and upward migration of the right kidney. RESULTS: In the three cases of agenesis, no structure can be recognized as the right hepatic vein, right portal vein, or dilated right intrahepatic ducts. In the 11 cases of severe lobar atrophy, the right portal vein (or its branches) was recognized in eight cases, the right hepatic vein in four cases, and the dilated right intrahepatic ducts in 11 cases. The degree of enlargement of the lateral segment does not necessarily change inversely with the size of the medial segment and the caudate lobe. The retrohepatic gallbladder is present in eight cases (two in agenesis and six in atrophy). The phenomenon of hyperattenuation of the atrophic liver parenchyma was noted in six cases. CONCLUSION: Even though a retrohepatic gallbladder and a severely distorted hepatic morphology due to compensatory hypertrophy of the left and caudate lobes may raise a suspicion of agenesis of the right lobe of the liver, absence of visualization of all of the right hepatic vein, right portal vein and its branches, and dilated right intrahepatic ducts is a prerequisite of the diagnosis of agenesis of the right hepatic lobe on CT. In severe lobar atrophy, at least one of these structures is recognizable.