The role of FDG PET-CT in the preoperative work up of colorectal liver metastases

Introduction: More than 50% of colorectal carcinoma metastasize to the liver. Surgical resection of the colorectal liver metastasis (CLM) is the mainstay of treatment for CLM. Important conditions for effective liver resection and other curative treatment options are the possibility of radical resection and no presence of untreatable metastasis outside the liver (extra hepatic). Therefore, accurate pre-operative imaging and staging are necessary. This is mainly performed by Computed Tomography (CT). With the addition of the tracer 18- fluorodeoxyglucose (FDG) to the imaging modality Positron Emission Tomography (PET) tumours are identified by the accumulation of metabolized glucose in tumour cells. FDG PET-CT is a software fusion of PET data with CT images, which makes precise tumour localisation possible. It might be useful in the preoperative work up for CLM. Current literature is not ambiguous on the proper role of PET-CT in the diagnosis and management of CLM. The primary aim of this study was to investigate whether PET-CT is of added value in the pre-operative work up for CLM. Material and Methods: Data were searched for in electronically stored patient files of a Dutch secondary referral centre. Radiology reports of CT and PET-CT were evaluated for differences and also patient management after CT and after PET-CT were compared. Data from histopathology outcome of suspected metastatatic lesions were used to calculate sensitivity and specificity of CT and PET-CT imaging on a lesion by lesion basis. Results: We included 80 patients with potentially resectable CLM, that had undergone both CT as PET-CT Six patients, which had completed chemotherapy less than 2 weeks prior to PET-CT examination, were excluded. In the remaining study group five patients underwent surgery twice and were evaluated twice with PET-CT. Therefore, 79 cases were included. Extra hepatic metastasis was detected by PET-CT in 17/79 (21.5%) of cases. PET-CT results changed patient management in 13/79 (16.5%) cases. Sensitivity and specificity of CT were respectively 90.8% and 35.3% and respectively 62.2% and 82.6% for PET-CT. Discussion and conclusion: FDG PET-CT can be properly used in the preoperative work up of patients with colorectal liver metastasis as it changes patient management substantially. Whether this is cost-effective when performed routinely, considering the increasing burden of health care cost, is open for debate.