Dual phase helical CT versus portal venous phase CT for the detection of colorectal liver metastases: Correlation with intra-operative sonography, surgical and pathological findings

AIM: To assess whether dual phase helical computed tomography (DPCT) of the liver improves the detection of colorectal liver metastases compared with portal venous phase (PVP) imaging alone. MATERIALS AND METHODS: DPCT was performed in 33 consecutive patients before laparotomy for resection of colorectal liver metastases. CT comprised 8-mm slice collimation with a pitch of 1 to 1.25; imaging was commenced 20-25 a nd 65-70 s after the start of injection of 150 mi of contrast medium at 5 m l/s to coincide with hepatic arterial phase (HAP) and PVP contrast enhancem ent, respectively. Four blinded observers independently reviewed the HAP, P VP and DPCT images recording the site and size of all lesions. Alternative- free response receiver operating characteristic (AFROC) methodology was use d to analyse the results, which were correlated with surgery, intra-operati ve ultrasound and histology. RESULTS: The mean observer sensitivities for malignant lesion detection wer e 75.3% for DPCT, 69.7% for PVP imaging and 66.7% for HAP imaging alone. Th ere was a statistically significant improvement in malignant lesion detecti on using DPCT when compared with PVP imaging alone (P < 0.05). The mean are as under the AFROC curves were 0.84 for DPCT and 0.82 for PW (P < 0.03) ima ging alone. CONCLUSION: The detection of colorectal liver metastases was marginally bet ter with DPCT than with PVP imaging alone, but the discovery of additional lesions did not affect the management of any of the patients in this study. (C) 2001 The Royal College of Radiologists.