The differenciation of benign from malignant lesions is based on lipid content of cells. Adenomas contain lipid, metastases do not. How you pick up the lipid content is the basis of all imaging. With CT three criteria are used: size of >5cm is malignant, threshold of 0 HU has a specificity of 100% in differentiating and delayed CECT with a cut off > 24 HU is malignant. MRI too has three criteria: signal intensity ratio of metastases/liver > adenoma/liver on T2 images, metastases have marked enhancement and slow washout and signal drop off in adenomas on chemical shift imaging. Finally iodomethylnorcholesterol scintigraphy helps with the adenomas taking up the cholesterol esters.
To read more: Clinical Radiology Nov 1998
Saturday, December 15, 2007
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