A comparison of diagnostic imaging modalities for colorectal liver metastases

The aims of this study were to compare the diagnostic performance of CT scan, MR liver, PET-CT and intra-operative ultrasound (IOUS) for the detection of liver metastases against the histopathological findings, and to compare PET-CT with CT for the detection of distant disease in metastatic colorectal cancer patients eligible for surgical treatment.

A prospective study was performed that measured concordance between the number and stage of metastatic lesions identified with various preoperative imaging modalities and histology of patients undergoing surgical treatment for CRLM.

Compared with histopathology, concordance for the number of metastatic liver lesions was moderate for CT scan (K = 0.477, 95% CI: 0.28-0.66), moderate for MR scan (K = 0.574, 95% CI: 0.39-0.75), good for FDG PET-CT (K = 0.703, 95% CI: 0.52-0.87) and very good for IOUS (K = 0.904, 95% CI: 0.81-0.99). Additional CRLM were identified intraoperatively in six patients (9.1%) with IOUS and in 7.5% of the cases surgical strategy was changed according to the new intraoperative findings. The diagnosis of intra abdominal lymph node metastatic disease was made with PET-CT only in nine patients (13.6%)

Our study supports the recent recommendations of the Oncosurg Multidisciplinary International Consensus regarding the importance of high quality CT and MR in the staging of CRLM but provides further evidence for the added value of PET-CT, especially in detecting extrahepatic intra-abdominal metastatic disease that may be amenable to potentially curative resection. Despite these advances in preoperative staging, there still remains a role for IOUS in detecting additional metastases at the time of surgery.