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CT and MR Imaging of Benign Hepatic and Biliary Tumors

¹ Departments of Radiology (K.M.H., D.A.B., E.K.F.)
² Pathology (R.H.H.), Johns Hopkins Hospital, Baltimore, Md
³ Department of Body and Vascular Imaging, Hospital Lariboisiere, Paris, France (P.S.)

View larger version (123K): [in a new window]   Figure 1a.  Metastases to the liver in a 67-year-old man with colon cancer. (a) Unenhanced fast spin-echo T2-weighted (repetition time msec/echo time msec = 5,000/104) MR image demonstrates a 1.5-cm metastasis (curved arrow) in the posterior segment of the right hepatic lobe and a 3-cm cyst (straight arrow) in the left lobe. (b) Fast spin-echo T2-weighted (5,000/104) MR image obtained after administration of ferumoxide (Feridex; Advanced Magnetics, Cambridge, Mass) shows the normal liver and spleen with diffuse decreased signal intensity (cf a). The cyst (straight arrow) and the metastasis (curved arrow) do not take up the contrast agent and appear hyperintense.

View larger version (110K): [in a new window]   Figure 1b.  Metastases to the liver in a 67-year-old man with colon cancer. (a) Unenhanced fast spin-echo T2-weighted (repetition time msec/echo time msec = 5,000/104) MR image demonstrates a 1.5-cm metastasis (curved arrow) in the posterior segment of the right hepatic lobe and a 3-cm cyst (straight arrow) in the left lobe. (b) Fast spin-echo T2-weighted (5,000/104) MR image obtained after administration of ferumoxide (Feridex; Advanced Magnetics, Cambridge, Mass) shows the normal liver and spleen with diffuse decreased signal intensity (cf a). The cyst (straight arrow) and the metastasis (curved arrow) do not take up the contrast agent and appear hyperintense.

View larger version (109K): [in a new window]   Figure 2a.  FNH. (a) Unenhanced fast multiplanar spoiled gradient-echo (FMPSPGR) (110/4.2) MR image demonstrates a slightly hypointense, 8 x 6-cm mass in the right lobe of the liver (arrows). (b) Unenhanced fast spin-echo (5,454/105) MR image demonstrates the mass (arrows) with signal intensity characteristics similar to those of normal liver. A small central scar with high signal intensity is also seen. (c) FMPSPGR (170/4.2) MR image obtained after the administration of mangafodipir trisodium demonstrates increased signal intensity within the liver due to uptake of the agent by hepatocytes. The mass (arrows) shows increased signal intensity because FNH contains hepatocytes. The central scar now has decreased signal intensity.

View larger version (126K): [in a new window]   Figure 2b.  FNH. (a) Unenhanced fast multiplanar spoiled gradient-echo (FMPSPGR) (110/4.2) MR image demonstrates a slightly hypointense, 8 x 6-cm mass in the right lobe of the liver (arrows). (b) Unenhanced fast spin-echo (5,454/105) MR image demonstrates the mass (arrows) with signal intensity characteristics similar to those of normal liver. A small central scar with high signal intensity is also seen. (c) FMPSPGR (170/4.2) MR image obtained after the administration of mangafodipir trisodium demonstrates increased signal intensity within the liver due to uptake of the agent by hepatocytes. The mass (arrows) shows increased signal intensity because FNH contains hepatocytes. The central scar now has decreased signal intensity.

View larger version (125K): [in a new window]   Figure 2c.  FNH. (a) Unenhanced fast multiplanar spoiled gradient-echo (FMPSPGR) (110/4.2) MR image demonstrates a slightly hypointense, 8 x 6-cm mass in the right lobe of the liver (arrows). (b) Unenhanced fast spin-echo (5,454/105) MR image demonstrates the mass (arrows) with signal intensity characteristics similar to those of normal liver. A small central scar with high signal intensity is also seen. (c) FMPSPGR (170/4.2) MR image obtained after the administration of mangafodipir trisodium demonstrates increased signal intensity within the liver due to uptake of the agent by hepatocytes. The mass (arrows) shows increased signal intensity because FNH contains hepatocytes. The central scar now has decreased signal intensity.

View larger version (210K): [in a new window]   Figure 3a.  Hepatic cyst. Illustrations demonstrate the appearance of a liver cyst at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). The liver parenchyma enhances, but the cyst does not. The walls of the cyst are imperceptible.

View larger version (199K): [in a new window]   Figure 3b.  Hepatic cyst. Illustrations demonstrate the appearance of a liver cyst at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). The liver parenchyma enhances, but the cyst does not. The walls of the cyst are imperceptible.

View larger version (194K): [in a new window]   Figure 3c.  Hepatic cyst. Illustrations demonstrate the appearance of a liver cyst at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). The liver parenchyma enhances, but the cyst does not. The walls of the cyst are imperceptible.

View larger version (127K): [in a new window]   Figure 4.  Hepatic cyst. Contrast-enhanced spiral CT scan reveals a large cyst with water attenuation in the right hepatic lobe (arrows). The cyst is unenhanced with imperceptible walls.

View larger version (135K): [in a new window]   Figure 5.  Hepatic cysts in a patient with polycystic liver disease. T2-weighted (5,000/104) MR image demonstrates numerous cysts with water signal intensity.

View larger version (201K): [in a new window]   Figure 6a.  Hemangioma. Illustrations demonstrate the appearance of a hemangioma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Peripheral puddling of contrast material is characteristic of hemangiomas on early-phase images. The hemangioma subsequently fills in from the periphery. On delayed images, the mass may fill in completely and be isoattenuating or slightly hyperattenuating. Hemangiomas may not enhance completely if they are large or have a central scar.

View larger version (182K): [in a new window]   Figure 6b.  Hemangioma. Illustrations demonstrate the appearance of a hemangioma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Peripheral puddling of contrast material is characteristic of hemangiomas on early-phase images. The hemangioma subsequently fills in from the periphery. On delayed images, the mass may fill in completely and be isoattenuating or slightly hyperattenuating. Hemangiomas may not enhance completely if they are large or have a central scar.

View larger version (227K): [in a new window]   Figure 6c.  Hemangioma. Illustrations demonstrate the appearance of a hemangioma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Peripheral puddling of contrast material is characteristic of hemangiomas on early-phase images. The hemangioma subsequently fills in from the periphery. On delayed images, the mass may fill in completely and be isoattenuating or slightly hyperattenuating. Hemangiomas may not enhance completely if they are large or have a central scar.

View larger version (144K): [in a new window]   Figure 7a. Figures 7, 8. Hemangioma. (7a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates a 3-cm, low-attenuation mass in the anterior segment of the right hepatic lobe (arrows). Note the characteristic peripheral nodular puddling of contrast material. (7b) Delayed CT scan obtained at the same level demonstrates complete enhancement of the mass (arrows), which now appears slightly hyperattenuating due to delayed washout of contrast material. (8a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates an 8.5-cm mass in the left hepatic lobe (arrows). Characteristic puddling of contrast material is seen (cf Fig 7a). (8b) CT scan obtained at the same level during the portal phase demonstrates progressive enhancement of the lesion (arrows).

View larger version (146K): [in a new window]   Figure 7b. Figures 7, 8. Hemangioma. (7a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates a 3-cm, low-attenuation mass in the anterior segment of the right hepatic lobe (arrows). Note the characteristic peripheral nodular puddling of contrast material. (7b) Delayed CT scan obtained at the same level demonstrates complete enhancement of the mass (arrows), which now appears slightly hyperattenuating due to delayed washout of contrast material. (8a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates an 8.5-cm mass in the left hepatic lobe (arrows). Characteristic puddling of contrast material is seen (cf Fig 7a). (8b) CT scan obtained at the same level during the portal phase demonstrates progressive enhancement of the lesion (arrows).

View larger version (156K): [in a new window]   Figure 8a. Figures 7, 8. Hemangioma. (7a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates a 3-cm, low-attenuation mass in the anterior segment of the right hepatic lobe (arrows). Note the characteristic peripheral nodular puddling of contrast material. (7b) Delayed CT scan obtained at the same level demonstrates complete enhancement of the mass (arrows), which now appears slightly hyperattenuating due to delayed washout of contrast material. (8a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates an 8.5-cm mass in the left hepatic lobe (arrows). Characteristic puddling of contrast material is seen (cf Fig 7a). (8b) CT scan obtained at the same level during the portal phase demonstrates progressive enhancement of the lesion (arrows).

View larger version (158K): [in a new window]   Figure 8b. Figures 7, 8. Hemangioma. (7a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates a 3-cm, low-attenuation mass in the anterior segment of the right hepatic lobe (arrows). Note the characteristic peripheral nodular puddling of contrast material. (7b) Delayed CT scan obtained at the same level demonstrates complete enhancement of the mass (arrows), which now appears slightly hyperattenuating due to delayed washout of contrast material. (8a) Contrast-enhanced spiral CT scan obtained during the arterial phase demonstrates an 8.5-cm mass in the left hepatic lobe (arrows). Characteristic puddling of contrast material is seen (cf Fig 7a). (8b) CT scan obtained at the same level during the portal phase demonstrates progressive enhancement of the lesion (arrows).

View larger version (109K): [in a new window]   Figure 9a.  Hemangioma. T1-weighted (600/20) (a) and T2-weighted (2,500/60, 2,500/120) (b, c) MR images demonstrate the typical appearance of a liver hemangioma (arrow). Hemangiomas appear hyperintense on T2-weighted MR images with increasing echo time. b.

View larger version (119K): [in a new window]   Figure 9b.  Hemangioma. T1-weighted (600/20) (a) and T2-weighted (2,500/60, 2,500/120) (b, c) MR images demonstrate the typical appearance of a liver hemangioma (arrow). Hemangiomas appear hyperintense on T2-weighted MR images with increasing echo time. b.

View larger version (104K): [in a new window]   Figure 9c.  Hemangioma. T1-weighted (600/20) (a) and T2-weighted (2,500/60, 2,500/120) (b, c) MR images demonstrate the typical appearance of a liver hemangioma (arrow). Hemangiomas appear hyperintense on T2-weighted MR images with increasing echo time. b.

View larger version (129K): [in a new window]   Figure 10a.  Hemangioma. Dynamic T1-weighted (600/15) MR images demonstrate the classic enhancement pattern of a liver hemangioma (arrows). The hemangioma demonstrates early peripheral puddling of contrast material (a), then fills in from the periphery (b). The central area does not enhance due to a central scar.

View larger version (139K): [in a new window]   Figure 10b.  Hemangioma. Dynamic T1-weighted (600/15) MR images demonstrate the classic enhancement pattern of a liver hemangioma (arrows). The hemangioma demonstrates early peripheral puddling of contrast material (a), then fills in from the periphery (b). The central area does not enhance due to a central scar.

View larger version (161K): [in a new window]   Figure 11a.  FNH. Illustrations demonstrate the appearance of FNH at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). The mass enhances brightly during the arterial phase and may be completely isoattenuating on delayed scans. A central scar (if present) may demonstrate delayed enhancement that persists due to slow washout.

View larger version (218K): [in a new window]   Figure 11b.  FNH. Illustrations demonstrate the appearance of FNH at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). The mass enhances brightly during the arterial phase and may be completely isoattenuating on delayed scans. A central scar (if present) may demonstrate delayed enhancement that persists due to slow washout.

View larger version (248K): [in a new window]   Figure 11c.  FNH. Illustrations demonstrate the appearance of FNH at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). The mass enhances brightly during the arterial phase and may be completely isoattenuating on delayed scans. A central scar (if present) may demonstrate delayed enhancement that persists due to slow washout.

View larger version (154K): [in a new window]   Figure 12a. Figures 12, 13. FNH. (12) Contrast-enhanced spiral CT scans demonstrate the characteristic enhancement pattern of FNH (solid arrows) in the arterial phase (a), portal phase (b), and delayed phase (c). Notice that the mass enhances dramatically early but is nearly imperceptible on the delayed scan. There is also a small, nonenhancing central scar (open arrow). (13a) Early-phase contrast-enhanced spiral CT scan demonstrates an 8-cm, isoattenuating hepatic mass (solid arrows) displacing adjacent vessels. A hypoattenuating central scar is also seen (open arrow). (13b) On a delayed CT scan obtained at the same level, the mass (solid arrows) is almost imperceptible except for persistent enhancement of the central scar (open arrow).

View larger version (151K): [in a new window]   Figure 12b. Figures 12, 13. FNH. (12) Contrast-enhanced spiral CT scans demonstrate the characteristic enhancement pattern of FNH (solid arrows) in the arterial phase (a), portal phase (b), and delayed phase (c). Notice that the mass enhances dramatically early but is nearly imperceptible on the delayed scan. There is also a small, nonenhancing central scar (open arrow). (13a) Early-phase contrast-enhanced spiral CT scan demonstrates an 8-cm, isoattenuating hepatic mass (solid arrows) displacing adjacent vessels. A hypoattenuating central scar is also seen (open arrow). (13b) On a delayed CT scan obtained at the same level, the mass (solid arrows) is almost imperceptible except for persistent enhancement of the central scar (open arrow).

View larger version (147K): [in a new window]   Figure 12c. Figures 12, 13. FNH. (12) Contrast-enhanced spiral CT scans demonstrate the characteristic enhancement pattern of FNH (solid arrows) in the arterial phase (a), portal phase (b), and delayed phase (c). Notice that the mass enhances dramatically early but is nearly imperceptible on the delayed scan. There is also a small, nonenhancing central scar (open arrow). (13a) Early-phase contrast-enhanced spiral CT scan demonstrates an 8-cm, isoattenuating hepatic mass (solid arrows) displacing adjacent vessels. A hypoattenuating central scar is also seen (open arrow). (13b) On a delayed CT scan obtained at the same level, the mass (solid arrows) is almost imperceptible except for persistent enhancement of the central scar (open arrow).

View larger version (143K): [in a new window]   Figure 13a. Figures 12, 13. FNH. (12) Contrast-enhanced spiral CT scans demonstrate the characteristic enhancement pattern of FNH (solid arrows) in the arterial phase (a), portal phase (b), and delayed phase (c). Notice that the mass enhances dramatically early but is nearly imperceptible on the delayed scan. There is also a small, nonenhancing central scar (open arrow). (13a) Early-phase contrast-enhanced spiral CT scan demonstrates an 8-cm, isoattenuating hepatic mass (solid arrows) displacing adjacent vessels. A hypoattenuating central scar is also seen (open arrow). (13b) On a delayed CT scan obtained at the same level, the mass (solid arrows) is almost imperceptible except for persistent enhancement of the central scar (open arrow).

View larger version (134K): [in a new window]   Figure 13b. Figures 12, 13. FNH. (12) Contrast-enhanced spiral CT scans demonstrate the characteristic enhancement pattern of FNH (solid arrows) in the arterial phase (a), portal phase (b), and delayed phase (c). Notice that the mass enhances dramatically early but is nearly imperceptible on the delayed scan. There is also a small, nonenhancing central scar (open arrow). (13a) Early-phase contrast-enhanced spiral CT scan demonstrates an 8-cm, isoattenuating hepatic mass (solid arrows) displacing adjacent vessels. A hypoattenuating central scar is also seen (open arrow). (13b) On a delayed CT scan obtained at the same level, the mass (solid arrows) is almost imperceptible except for persistent enhancement of the central scar (open arrow).

View larger version (160K): [in a new window]   Figure 14a.  Classic appearance of FNH. (a, b) Unenhanced T1-weighted (198/4.2) (a) and T2-weighted (4,500/85) (b) MR images show a lesion (arrow) with signal intensity characteristics similar to those of normal liver. (c, d) Contrast-enhanced T1-weighted (198/4.2) MR images show the lesion (arrow) enhancing brightly during the arterial phase (c), then once again becoming indistinguishable from normal liver during the delayed phase (d).

View larger version (137K): [in a new window]   Figure 14b.  Classic appearance of FNH. (a, b) Unenhanced T1-weighted (198/4.2) (a) and T2-weighted (4,500/85) (b) MR images show a lesion (arrow) with signal intensity characteristics similar to those of normal liver. (c, d) Contrast-enhanced T1-weighted (198/4.2) MR images show the lesion (arrow) enhancing brightly during the arterial phase (c), then once again becoming indistinguishable from normal liver during the delayed phase (d).

View larger version (142K): [in a new window]   Figure 14c.  Classic appearance of FNH. (a, b) Unenhanced T1-weighted (198/4.2) (a) and T2-weighted (4,500/85) (b) MR images show a lesion (arrow) with signal intensity characteristics similar to those of normal liver. (c, d) Contrast-enhanced T1-weighted (198/4.2) MR images show the lesion (arrow) enhancing brightly during the arterial phase (c), then once again becoming indistinguishable from normal liver during the delayed phase (d).

View larger version (139K): [in a new window]   Figure 14d.  Classic appearance of FNH. (a, b) Unenhanced T1-weighted (198/4.2) (a) and T2-weighted (4,500/85) (b) MR images show a lesion (arrow) with signal intensity characteristics similar to those of normal liver. (c, d) Contrast-enhanced T1-weighted (198/4.2) MR images show the lesion (arrow) enhancing brightly during the arterial phase (c), then once again becoming indistinguishable from normal liver during the delayed phase (d).

View larger version (143K): [in a new window]   Figure 15a.  Hepatic adenoma. Illustrations demonstrate the appearance of a hepatic adenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Overall, the enhancement pattern is similar to that of FNH. However, many hepatic adenomas have a more complex appearance due to the presence of acute or chronic hemorrhage.

View larger version (159K): [in a new window]   Figure 15b.  Hepatic adenoma. Illustrations demonstrate the appearance of a hepatic adenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Overall, the enhancement pattern is similar to that of FNH. However, many hepatic adenomas have a more complex appearance due to the presence of acute or chronic hemorrhage.

View larger version (211K): [in a new window]   Figure 15c.  Hepatic adenoma. Illustrations demonstrate the appearance of a hepatic adenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Overall, the enhancement pattern is similar to that of FNH. However, many hepatic adenomas have a more complex appearance due to the presence of acute or chronic hemorrhage.

View larger version (149K): [in a new window]   Figure 16a.  Hepatic adenoma. (a) Unenhanced CT scan demonstrates an 8-cm, low-attenuation mass in the right lobe of the liver (arrows). (b) On a contrast-enhanced spiral CT scan, the mass demonstrates intense early enhancement.

View larger version (152K): [in a new window]   Figure 16b.  Hepatic adenoma. (a) Unenhanced CT scan demonstrates an 8-cm, low-attenuation mass in the right lobe of the liver (arrows). (b) On a contrast-enhanced spiral CT scan, the mass demonstrates intense early enhancement.

View larger version (135K): [in a new window]   Figure 17a.  Hepatic adenoma. (a) Contrast-enhanced CT scan demonstrates an ill-defined, heterogeneously enhanced liver mass (arrows) with a central area of low attenuation. (b) T2-weighted MR image demonstrates high signal intensity within the mass as well as small, nodular satellite lesions. At surgery, a hepatic adenoma with hemorrhage was diagnosed.

View larger version (102K): [in a new window]   Figure 17b.  Hepatic adenoma. (a) Contrast-enhanced CT scan demonstrates an ill-defined, heterogeneously enhanced liver mass (arrows) with a central area of low attenuation. (b) T2-weighted MR image demonstrates high signal intensity within the mass as well as small, nodular satellite lesions. At surgery, a hepatic adenoma with hemorrhage was diagnosed.

View larger version (91K): [in a new window]   Figure 18a.  Hemangioendothelioma. Illustrations demonstrate the appearance of an infantile hemangioendothelioma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These tumors are usually large and demonstrate an enhancement pattern similar to that of hemangiomas, but they occur in young children.

View larger version (76K): [in a new window]   Figure 18b.  Hemangioendothelioma. Illustrations demonstrate the appearance of an infantile hemangioendothelioma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These tumors are usually large and demonstrate an enhancement pattern similar to that of hemangiomas, but they occur in young children.

View larger version (96K): [in a new window]   Figure 18c.  Hemangioendothelioma. Illustrations demonstrate the appearance of an infantile hemangioendothelioma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These tumors are usually large and demonstrate an enhancement pattern similar to that of hemangiomas, but they occur in young children.

View larger version (124K): [in a new window]   Figure 19a.  Hemangioendothelioma in a neonate with congestive heart failure. (a) Early-phase contrast-enhanced CT scan demonstrates a 20-cm hemangioendothelioma with peripheral lobular areas of intense enhancement. (b) Delayed CT scan shows inhomogeneous enhancement of the mass.

View larger version (127K): [in a new window]   Figure 19b.  Hemangioendothelioma in a neonate with congestive heart failure. (a) Early-phase contrast-enhanced CT scan demonstrates a 20-cm hemangioendothelioma with peripheral lobular areas of intense enhancement. (b) Delayed CT scan shows inhomogeneous enhancement of the mass.

View larger version (103K): [in a new window]   Figure 20a.  Mesenchymal hamartoma. Illustrations demonstrate the appearance of a mesenchymal hamartoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These tumors are typically large and have a complex cystic or solid imaging appearance that varies depending on the amount of stromal tissue present. It is these stromal elements that enhance.

View larger version (111K): [in a new window]   Figure 20b.  Mesenchymal hamartoma. Illustrations demonstrate the appearance of a mesenchymal hamartoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These tumors are typically large and have a complex cystic or solid imaging appearance that varies depending on the amount of stromal tissue present. It is these stromal elements that enhance.

View larger version (94K): [in a new window]   Figure 20c.  Mesenchymal hamartoma. Illustrations demonstrate the appearance of a mesenchymal hamartoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These tumors are typically large and have a complex cystic or solid imaging appearance that varies depending on the amount of stromal tissue present. It is these stromal elements that enhance.

View larger version (123K): [in a new window]   Figure 21a.  Large mesenchymal hamartoma in a young child. Contrast-enhanced CT scan (a), T1-weighted MR image (b), and T2-weighted MR image (c) show that the tumor is predominantly cystic but has a thick wall and some enhancing internal stromal components.

View larger version (145K): [in a new window]   Figure 21b.  Large mesenchymal hamartoma in a young child. Contrast-enhanced CT scan (a), T1-weighted MR image (b), and T2-weighted MR image (c) show that the tumor is predominantly cystic but has a thick wall and some enhancing internal stromal components.

View larger version (126K): [in a new window]   Figure 21c.  Large mesenchymal hamartoma in a young child. Contrast-enhanced CT scan (a), T1-weighted MR image (b), and T2-weighted MR image (c) show that the tumor is predominantly cystic but has a thick wall and some enhancing internal stromal components.

View larger version (108K): [in a new window]   Figure 22a.  Lipoma. Illustrations demonstrate the appearance of a liver lipoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Lipomas have fat attenuation and do not enhance with contrast material.

View larger version (113K): [in a new window]   Figure 22b.  Lipoma. Illustrations demonstrate the appearance of a liver lipoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Lipomas have fat attenuation and do not enhance with contrast material.

View larger version (106K): [in a new window]   Figure 22c.  Lipoma. Illustrations demonstrate the appearance of a liver lipoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Lipomas have fat attenuation and do not enhance with contrast material.

View larger version (148K): [in a new window]   Figure 23.  Lipoma in a patient with tuberous sclerosis. CT scan demonstrates a 1-cm lipoma with an attenuation value of -15 HU in the right hepatic lobe (straight arrow). The patient also had an angiomyolipoma in the left kidney (curved arrows).

View larger version (166K): [in a new window]   Figure 24a.  Angiomyolipoma. Illustrations demonstrate the appearance of a liver angiomyolipoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Angiomyolipomas are typically a mixture of fatty and mesenchymal elements. The soft-tissue components enhance, whereas the fat does not.

View larger version (166K): [in a new window]   Figure 24b.  Angiomyolipoma. Illustrations demonstrate the appearance of a liver angiomyolipoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Angiomyolipomas are typically a mixture of fatty and mesenchymal elements. The soft-tissue components enhance, whereas the fat does not.

View larger version (161K): [in a new window]   Figure 24c.  Angiomyolipoma. Illustrations demonstrate the appearance of a liver angiomyolipoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Angiomyolipomas are typically a mixture of fatty and mesenchymal elements. The soft-tissue components enhance, whereas the fat does not.

View larger version (227K): [in a new window]   Figure 25a.  Cystadenoma. Illustrations demonstrate the appearance of a cystadenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Cystadenomas typically appear as complex cystic masses with enhancing walls, septa, and stromal elements.

View larger version (211K): [in a new window]   Figure 25b.  Cystadenoma. Illustrations demonstrate the appearance of a cystadenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Cystadenomas typically appear as complex cystic masses with enhancing walls, septa, and stromal elements.

View larger version (217K): [in a new window]   Figure 25c.  Cystadenoma. Illustrations demonstrate the appearance of a cystadenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). Cystadenomas typically appear as complex cystic masses with enhancing walls, septa, and stromal elements.

View larger version (158K): [in a new window]   Figure 26.  Cystadenoma. Contrast-enhanced spiral CT scan demonstrates a large cystic mass in the left lobe of the liver. Enhancement of the lesion wall and of internal septations is seen.

View larger version (187K): [in a new window]   Figure 27a.  Cystadenoma. Coronal T1-weighted (a) and axial T2-weighted (b) MR images demonstrate a large cystic mass (arrowheads) compressing the adjacent normal liver tissue. At surgery, a cystadenoma was diagnosed.

View larger version (131K): [in a new window]   Figure 27b.  Cystadenoma. Coronal T1-weighted (a) and axial T2-weighted (b) MR images demonstrate a large cystic mass (arrowheads) compressing the adjacent normal liver tissue. At surgery, a cystadenoma was diagnosed.

View larger version (96K): [in a new window]   Figure 28a.  Classic appearance of bile duct adenoma or hamartoma. Illustrations demonstrate the appearance of bile duct adenomas or hamartomas at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These lesions are typically small (1–10 mm) and located near the periphery of the liver. They usually demonstrate little enhancement with contrast material.

View larger version (107K): [in a new window]   Figure 28b.  Classic appearance of bile duct adenoma or hamartoma. Illustrations demonstrate the appearance of bile duct adenomas or hamartomas at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These lesions are typically small (1–10 mm) and located near the periphery of the liver. They usually demonstrate little enhancement with contrast material.

View larger version (107K): [in a new window]   Figure 28c.  Classic appearance of bile duct adenoma or hamartoma. Illustrations demonstrate the appearance of bile duct adenomas or hamartomas at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These lesions are typically small (1–10 mm) and located near the periphery of the liver. They usually demonstrate little enhancement with contrast material.

View larger version (149K): [in a new window]   Figure 29. Figures 29, 30. Bile duct adenoma. (29) Contrast-enhanced CT scan reveals a 3-cm hypoattenuating mass (arrow) in the peripheral aspect of the liver. Bile duct adenoma was diagnosed at pathologic analysis. This tumor is larger than the typical bile duct adenoma. (30) Unenhanced CT scan demonstrates two 1.5-cm low-attenuation lesions (arrows) in the periphery of the liver. When bile duct adenomas or hamartomas are multiple, they can simulate metastatic disease.

View larger version (148K): [in a new window]   Figure 30. Figures 29, 30. Bile duct adenoma. (29) Contrast-enhanced CT scan reveals a 3-cm hypoattenuating mass (arrow) in the peripheral aspect of the liver. Bile duct adenoma was diagnosed at pathologic analysis. This tumor is larger than the typical bile duct adenoma. (30) Unenhanced CT scan demonstrates two 1.5-cm low-attenuation lesions (arrows) in the periphery of the liver. When bile duct adenomas or hamartomas are multiple, they can simulate metastatic disease.

View larger version (153K): [in a new window]   Figure 31a.  Papillary adenoma. Illustrations demonstrate the appearance of a papillary adenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These lesions are usually intraductal and may cause ductal obstruction. They are typically very small (<5 mm) and are often not visualized at cross-sectional imaging.

View larger version (150K): [in a new window]   Figure 31b.  Papillary adenoma. Illustrations demonstrate the appearance of a papillary adenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These lesions are usually intraductal and may cause ductal obstruction. They are typically very small (<5 mm) and are often not visualized at cross-sectional imaging.

View larger version (157K): [in a new window]   Figure 31c.  Papillary adenoma. Illustrations demonstrate the appearance of a papillary adenoma at contrast-enhanced spiral CT during the arterial phase (a), portal phase (b), and delayed phase (c). These lesions are usually intraductal and may cause ductal obstruction. They are typically very small (<5 mm) and are often not visualized at cross-sectional imaging.

View larger version (142K): [in a new window]   Figure 32a.  Papillary adenoma. (a) Contrast-enhanced spiral CT scan demonstrates an enhancing mass (arrow) dilating a central bile duct with local invasion of the liver. (b) On an axial T2-weighted (5,400/105) MR image, the mass (arrow) is again seen causing ductal obstruction.

View larger version (148K): [in a new window]   Figure 32b.  Papillary adenoma. (a) Contrast-enhanced spiral CT scan demonstrates an enhancing mass (arrow) dilating a central bile duct with local invasion of the liver. (b) On an axial T2-weighted (5,400/105) MR image, the mass (arrow) is again seen causing ductal obstruction.