MRI liver lesions

Hemangioma - most common benign hepatic tumor, asymptomatic

• T1 - hypointense
• T2 - marked hyperintense almost cystlike
• Post GD
  • Immediate uniform enhancement (small capillary hemangiomas)
  • Peripheral, nodular and interupted enhancement, progresses centripetally to uniform enhancement (most common)
  • Peripheral, nodular enhancement with centripetal progression, but central hypointensity (giant hemangioma)
• Histology - mass of blood filled spaces lined by endothelium, thrombus, calcium and fibrosis are variable

Focal nodular hyperplasia - benign, hyperplastic response to preexisting arterial malformation, most common in women of reproductive age, no malignant potential

• T1 - iso to hypointense
• T2 - iso to hyperintense
• Post GD - marked homogeneous enhancement, isointense during portal venous phase imaging
• Classic central scar is T1 hypointense and T2 hyperintense with delayed enhancement
• Histology - hyperplastic hepatocytes, small bile ducts surrounding a central scar

Hepatic adenoma - benign neoplasm most commonly in women taking OCP, more likely symptomatic than above, rare malignant transformation, tendency to spontaneous rupture, history (cirrhosis) often only way to distinguish from HCC.

• T1 - variable secondary to hemorrhage and intercellular lipid (loses signal on out of phase imaging)
• T2 - variable, often mildly hyperintense
• Post GD - heterogeneous hypervascularity during arterial phase, washout, possibly with a delayed enhancing pseudocapsule
• Histology - large cords of hepatocytes with dilated sinusoids, no bile ducts (differentiates from FNH, dark with Eovist)
• Cold on Tc-99m sulfur colloid

Hepatocellular carcinoma - most common primary malignancy of liver, a/w cirrhosis.

• T1
  • Small Lesions (<1.5cm, aka dysplastic nodule) - hyperintense
  • Large Lesions - may be hypointense secondary lipid (can have drop out on out of phase imaging), copper or glycogen
• T2 - hyper os isointense
• Post GD - smaller lesions (<2cm) can be homogeneously enhancing, while larger lesions tend to be heterogeneously enhancing. Washout during portal venous phase becoming iso or hypointense. Regenerative and dysplastic nodules do not demonstrate washout. Capsule can also be seen with progressive delayed enhancement (T1 and T2 hypointense).

Fibrolamellar HCC

• Central scar is T2 hypointense, don't confuse this entity with FNH
• Seen almost exclusively in younger patients
• Not associated with cirrhosis
• May contain calcification, avid enhancement

Biliary cystadenoma

• Multicystic lesion
• F:M 4:1

Nodular regenerative hyperplasia

Metastasis

Abcsess

• Peripheral edema
• Persistent peripheral enhancement, unlike metastasis which tend to fade on delayed imaging