Incremental value of arterial and equilibrium phase compared to hepatic venous phase CT in the preoperative staging of colorectal liver metastases: an evaluation with different reference standards

To evaluate the incremental value of arterial and equilibrium phase compared to hepatic venous phase multidetector row CT (MDCT) in the preoperative staging of colorectal liver metastases (CLM) and to determine the influence of the reference standard. Fifty-three consecutive CLM patients underwent 16 detector row CT in hepatic arterial, venous, and equilibrium phase before surgery between March 2003 and January 2007. Detected lesions were characterized by three independent radiologists. The reference standard consisted of intraoperative palpation and ultrasound of the liver, and histopathological examination of the resected specimen. Additionally, data of follow-up CT was added. Statistical analysis was performed on a per-lesion basis. According to the reference standard 251 lesions were present, of which 203 (81%) were malignant (mean size: 29.4 ± 22.5 mm), and 41 (16%) were benign (mean size: 8.3 ± 7.7 mm). Sensitivity rates for CLM were comparable between triphasic and hepatic venous phase CT (P>0.05). Sensitivity for the detection of CLM lowered from 60-77% to 52-68% when follow-up CT was added to the reference standard. Arterial and equilibrium phase CT have no incremental value compared to hepatic venous phase MDCT in the detection of CLM. Sensitivity rates are, however, influenced by the type of reference standard used