Primary Liver Cancer
Fast Facts:
- Hepatocellular Carcinoma (≈ 80%)
- Cholangiocarcinoma (≈ 20%)
Hepatocellular Carcinoma:
Avidity:
- PET/CT has an overall poor sensitivity for HCC (50-65%).
- HCC demonstrates extremely variable FDG avidity, with 30-50% of lesions demonstrating little or no uptake (low-grade lesions).
- Most HCC metastases are FDG-avid, even if the primary is a low-grade tumor.
Role of PET/CT:
- Best considered a complimentary modality for staging & restaging.
- Strength lies in its detection of regional and distant metastatic disease (most commonly to nodes, lungs and skeleton).
- Post-chemoembolization and post-ablation assessment (addressed here).
False Positives:
On extremely rare occasion, hepatic adenomas and geographic focal fatty infiltration can be FDG-avid (addressed here). We do not include these very rare possibilities in our differential, unless there are unusual circumstances suggesting these entities.
Cholangiocarcinoma:
Avidity:
Avidity depends on both morphology and location of lesion.
- Nodular morphology > infiltrating lesions.
- Peripheral lesions > centrally located lesions.
Role of PET/CT:
- While limited in the assessment of some primary lesions (infiltrating, central), it is valuable for the detection of regional and distant metastatic disease (most commonly to nodes, lungs, skeleton, adrenal glands and brain).
False Positives:
- Cholangitis
- Inflammation associated with biliary catheters.
False Negatives:
- Infiltrating morphology
- Centrally located lesions.
Case 1
Case 1 (Image 2)
Axial images confirm an intensely FDG-avid liver mass, consistent with the patient’s reported clinical history of hepatocellular carcinoma (note the cirrhotic appearance of the liver periphery). Caveat: While HCC can be only mildly avid, they are often very hypermetabolic.
Case 1 (Image 3)
FDG-avid metastatic lung nodule.
Case 2
Case 2 (Image 2)
Axial images confirm an FDG-avid left lobe liver mass, consistent with the patient’s reported clinical history of hepatocellular carcinoma
Case 3
Case 3 (Image 2)
Axial images demonstrate a small and extremely subtle FDG-avid HCC.
Case 4
Case 4 (Image 2)
Axial images confirm an intensely avid hepatic mass (biopsy proven cholangiocarcinoma).
Case 5
Case 5 (Image 2)
Axial images confirm a large, intensely avid hepatic mass (biopsy proven cholangiocarcinoma).
Case 5 (Image 3)
MIP image after chemoembolization demonstrates a decrease in size of the patient’s mass. A new hypermetabolic focus projects within (or superimposed upon) the bladder.
Case 5 (Image 4)
Axial images confirm an interval decrease in the size of the patient’s cholangiocarcinoma (note the non-avid changes of chemoembolization). The persistent hypermetabolic activity of this mass is consistent with persistent active malignancy.
Case 5 (Image 5)
Axial images demonstrate interval development of a solitary FDG-avid osseous metastasis.
Case 6
Case 6 (Image 2)
Axial images confirm a solitary, hypermetabolic liver mass (biopsy proven adenoma). Although this patient was a 31-year old woman on oral contraceptive pills, hypermetabolic adenomas are so rare that this must be considered a metastasis until proven otherwise.
Case 7
Case 7 (Image 2)
Axial images demonstrate a solitary hypermetabolic left lobe liver lesion. The study was interpreted as “highly suspicious for a solitary hepatic metastasis”. Biopsy revealed focal fatty infiltration. Even though this is a classic location for geographic fatty infiltration (abutting the falciform ligament), FDG-avid focal fatty infiltration is so rare that this must be considered a metastasis until proven otherwise.
Case 7 (Image 3)
As the medical team was suspicious of the pathology results, MRI evaluation was performed. This lesion demonstrates a homogeneous drop in signal on out-of-phase imaging, consistent with geographic fatty infiltration.
Case 8
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