Nuclear Medicine and Liver Lesions

Remembering which lesions do what with which radiotracers can be more difficult than understanding this sentence. Some (perhaps over-simplified) points:

• Tc-99m sulfur colloid: Shows Kupffer cell activity.
• Tc-99m HIDA: Shows hepatocyte function.
• Tc-99m red blood cell: Shows tumor vascularity.

Focal nodular hyperplasia (FNH) has hepatocytes but disorganized biliary canaliculi. As a result, it will take up HIDA rapidly, but because of the disorganized biliary canaliculi, will keep the tracer around longer than the rest of the liver. FNH also has Kupffer cells of varying function; therefore, most are indistinguishable from the rest of the liver on sulfur colloid, but they may infrequently be cold or hot. FNH is a vascular tumor, so tagged red blood cell scans will show early uptake with or without persistent uptake on delayed images.

Adenomas are derived from hepatocytes, but and may show uptake on HIDA. They don't have that many Kuppfer cells, however, so the majority will be cold on sulfur colloid, but about 20% will be warm. Adenomas are vascular tumors, so tagged red blood cell scans will show early uptake with or without persistent uptake on delayed images.

Hepatocellular carcinoma (HCC) is also derived from hepatocytes, but these mutated hepatocytes may or may not function that well, so about 50% of HCCs will show uptake on HIDA and may be associated with a better prognosis. Whatever Kuppfer cells there may have been in the beginning are overrun by the cancer, so HCC is usually cold on sulfur colloid imaging in cirrhotic livers. HCC is a vascular tumor, so tagged red blood cell scans will show early uptake with or without persistent uptake on delayed images.

Hemangiomas are a tangle of vessels that takes up space amidst normal hepatocytes and Kuppfer cells, so they will be cold on sulfur colloid and HIDA scans. Tagged red blood cell scans will show a focal cold spot on early images and persistent filling on delayed images. This is the same as its behavior on dynamic CT, since we're basically following blood in both modalities.

Finally, liver metastases are alien to the liver, so they will not pick up hepatocyte or Kuppfer cell agents, appearing cold on sulfur colloid and HIDA scans.

References

• Mettler FA and Guiberteau MJ. Chapter 8. In Essentials of Nuclear Medicine Imaging. Fifth Edition. Saunders, Philadelphia. 2006. pp 203-242.
• Schulze PJ, Stritzke P, Stolzenbach G. Liver imaging and detection of liver metastases with 99mTc-HIDA. Nuklearmedizin. 1981 Oct;20(5):214-9.