TITLE: Comparison of MR and PET imaging for the evaluation of liver metastases.

REF: J Magn Reson Imaging. 2003 Mar;17(3):343-9. http://www.ncbi.nlm.nih.gov/entrez/...5&dopt=Abstract

STUDY TYPE: prospective trial

PATIENTS: 30 consecutive patients with suspected liver metastases

FINDINGS: 16/30 were positive for metastases based on histology and/or clinical outcome. The sensitivity, specificity, and positive and negative predictive values on MRI were 85.7%, 100%, 100%, and 89%, respectively, compared to 71%, 93.7%, 90.9%, and 79% on FDG-PET. The difference between the two methods was not significant (X(2) = 0.2, P > 0.05).

CONCLUSION: For the evaluation of possible liver metastases, MRI and PET are equally sensitive, specific, and accurate.

COMMENT: The advantage of PET FDG imaging is partly due to the fact that you image the thorax, abdomen (including the liver), and pelvis in a single study. PET FDG gives the big picture of whether or not metastatic disease is present. This study has a big flaw-- it compared an MRI of the liver with an FDG PET scan. While the MRI will only focus on the liver, the PET scan images the thorax, abdomen, and pelvis in a single exam.

If the PET scan is positive, then focusing in on areas of concern with CT or MRI makes sense. But to only look at the liver with an MRI will end up missing metastatic disease at other sites such as the bones and lymph nodes.