Positron emission tomography with F-18 fluorodeoxyglucose in evaluating colorectal hepatic metastasis down-staged by chemotherapy.

BACKGROUND The efficacy of positron emission tomography with 18F fluoro-2-deoxy-D-glucose (FDG-PET) is obscure in evaluating viability or the extent of colorectal hepatic metastasis (CHM), down-staged by chemotherapy. PATIENTS AND METHODS A retrospective lesion-by-lesion analysis was performed for seven consecutive patients, who had received rescue hepatectomy for initially unresectable CHM, in order to evaluate the correlation between results of imaging modalities and the corresponding pathology. RESULTS The sensitivity and positive predictive value of the conventional modalities (CT and MRI) were 92% and 42%, respectively, while the sensitivity, specificity, positive predictive value and negative predictive value of FDG-PET were 58%, 100%, 100% and 75% respectively. The sensitivity of FDG-PET was 100% in evaluating the viability of tumors >2 cm, however, this fell to 17% in tumors <2 cm. CONCLUSION FDG-PET is effective in assessing the viability of tumors >2 cm, but not those <2 cm, in patients with CHM down-staged by chemotherapy.