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Figure 12. Multiple cavernous hemangiomas. Utrasound performed for pain in this 41 year old woman showed multiple large liver masses. Early and late images from an infused CT (a and b) show progressive centripetal (lesion 1), globular (lesion 2) and inhomogeneous (lesion 3) enhancement. The larger lesions are incompletely opacified. The masses are hypovascular on the flow and immediate images (c and d) and uniformly filled with 99mTc-RBC on transaxial (e) and coronal (f) delayed SPECT images. Activity in the hemangiomas is equivalent to the cardiac chambers (H).

Figure 12. Multiple cavernous hemangiomas. Utrasound performed for pain in this 41 year old woman showed multiple large liver masses. Early and late images from an infused CT (a and b) show progressive centripetal (lesion 1), globular (lesion 2) and inhomogeneous (lesion 3) enhancement. The larger lesions are incompletely opacified. The masses are hypovascular on the flow and immediate images (c and d) and uniformly filled with 99mTc-RBC on transaxial (e) and coronal (f) delayed SPECT images. Activity in the hemangiomas is equivalent to the cardiac chambers (H).

outward from the center through the septa, unlike the peripheral origin and centripetal flow seen with adenomas and metastases.

Figure 13. Multiple hemangiomas. The infused CT (a) done for staging of lung cancer in this 70 year old man shows non-specific small peripherally enhancing lesions in the liver (white arrows) with a larger lesion centrally (black arrow). 99mTc-RBC activity is equivalent to that in major vessels on the transaxial (b) delayed SPECT image (arrows).

On anatomic imaging the appearance is often nonspecific. On US, FNH tends to be well defined and isoechoic or hyperechoic. Doppler may show increased flow but this is also seen with other masses including metastases and hepatoma. On CT, FNH is usually isodense or hypointense and become hyperintense during bolus infusion of contrast. The central scar with radiating septa is characteristic but inconsistently seen.

99mTc-sulfur colloid imaging (Fig 14) shows intense uptake in 10%, a finding that is diagnostic for FNH. Twenty to 30% show no demonstrable activity or are too small to assess confidently. In the remainder, there is variable activity confirming the benign nature of the mass. A more specific diagnosis can be made by also demonstrating 99mTc-IDA uptake in the lesion.

Hepatocellular adenoma

Heptatocellular adenoma (HA) is a rare neoplasm that occurs almost exclusively in young women or those receiving ovarian hormone replacement therapy. Unlike FNH, HA has a high risk of hemorrhage, necrosis, infarction and even rupture with significant morbidity and mortality. HA consists of normal appearing hepatocytes. Arterial supply is from the periphery. The appearance on anatomic imaging is nonspecific.

Kupffer cells may be present but not in sufficient quantities for the masses to demonstrate 99mTc-sulfur colloid uptake. The pattern on 99mTc-IDA imaging is similar to FNH. In the absence of 99mTc-sulfur colloid uptake, this appearance is nonspecific and can also be seen with well-differentiated hepatomas.

Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) in North America typically occurs in the presence of cirrhosis making diagnosis difficult using the standard anatomic imaging modalities. Patients exposed to aflatoxins or anabolic steroids, or those with the

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