Scanning of a small polyp in gallbladder with dual energy

Case history

66-year-old male presents with gallbladder lesion. Multiple MRI scans and ultrasound scans were not able to definitively conclude the nature of the lesion.

Question

Can CT differentiate between cholesterol rich gallstone and polyp? Could the virtual non-enhanced technique possibly spare scanning sequences?

Diagnosis / Differential diagnosis

The ultrasound and MRI indicated that the lesion contained no calcium. No significant growth was documented, so that the major differential diagnosis for this entity was cholesterol rich gallstone vs. polyp.

Findings

In the portal venous phase, a lesion smaller than1 cm and high attenuation is seen in the ventral aspect of the gallbladder. The lesion takes up contrast when comparing it to the non-enhanced and arterial phase scan. These finding make the presence of a small polyp very likely.

Comment

In the portal venous phase the ventral aspect of the gallbladder a lesion smaller than 1 cm and high attenuation is seen. The lesion takes up contrast when comparing it to the non-enhanced and arterial phase scan. These finding make the presence of a small polyp very likely. When comparing it with previous exams, the missing growth makes a malignant lesion such as gallbladder carcinoma very unlikely.

[1] Conventional non-enhanced scan of the liver and gallbladder. The gallbladder is without signs of radiopaque gallstones. Presence of cholesterol stones not excluded.	[2] Conventional early arterial scan. Same slice as image 1. Note the apparent contrast enhancing nodular lesion of the ventral aspect of the gallbladder.
[3] Conventional portal venous phase scan. The lesion continuously takes up contrast media, confirming the presence of a polyp.	[4] Virtual non-enhanced analysis. The color coding confirms the iodine content of the polyp. The virtual non-enhanced image is not different from the conventional image.

Authors: Axel Kuettner, Katharina Anders, Michael Lell