Gastrointestinal ❯ Incidental Liver Mass
CT Protocol for Incidental Liver Mass
| Problem | Evaluate an incidental liver lesion that is indeterminate on a routine CT scan |
| Protocol | The key to the identification of the specific etiology of a hepatic mass is based on its enhancement pattern ranging from the non contrast CT thru the arterial, venous and delayed phase imaging. The protocol involves injection of 100-120 cc of Omnipaque-350 at 5cc/sec and looking at enhancement pattern across the various phases. Typical we will scan the entire liver to look at the vascular map (including hepatic artery and portal vein) in all phases. The enhancement patterns of lesions like hemangioma, FNH, hepatic adenoma and even hepatoma may be classic in 90% of cases. In other cases the specific diagnosis may not be possible but identification of a lesion as malignant is indeed possible. |
| Pearls | 1. CT is ideal for defining the etiology of liver lesions but in some cases MR or even PET/CT may be helpful 2. The pattern of specific hepatic lesions ranges from peripheral pudding and a peripheral to central fill in for hemangiomas to a fully vascular lesion on early phase imaging which is only as bright as the IVC (not aorta) and fills in very quicky. The later lesion often has a central scar and is consistent with FNH. 3. Tumors like hepatoma have neovascularity best seen on arterial phase with MIP imaging. There is overlap between vascular metastases from neuroendocrine tumors and hepatoma. 4. Tumors like cholangiocarcinoma often have intrahepatic duct dilatation and are hypovascular. 5. Some lesions have classic appearances like hydatid disease where multiple daughter cysts occur. 6. One challenge at times is to distinguish tumor (especially metastases) from an abscess. Biopsy will often be necessary 7. 3D imaging including MIP, VRT and cinematic rendering may be helpful in lesion analysis. Thicker slap MIP is often very valuable in vascular mapping. 8. Extrahepatic findings like splenic lesions and/or adenopathy can be helpful in defining lesions like lymphoma. Obviously the presence of an extrahepatic mass (i.e. renal cell carcinoma, small bowel mass) will be helpful in suggesting the diagnosis of metastases. 9. Certain primary tumors have classic patterns of metastases while in many cases the pattern of metastasis is not helpful in diagnosis. |