Accuracy of Contrast Enhanced CT Portal Venous Phase Alone Compared with Multiphase for Follow Up Liver Metastases of Various Primary Malignancies

OBJECTIVES: This study was designed to evaluate the accuracy of portovenous phase-computed tomography (CT) scanning compared with the conventional multiphase scanning in post-treatment imaging of metastatic liver lesions. MATERIALS AND METHODS: Medical records and imaging of patients with metastatic liver disease were obtained by searching an ICD-10 coding. Imaging was first retrospectively reviewed only in portovenous phase (PVP). After a 7 days interval, imaging was reviewed again in all phases [Multiphase; non-contrasted (NECT), portovenous phase (PVP), hepatic arterial phase (HAP) and delayed phase (DP)]. Imaging of each patient was interpreted by consensus of two advanced diagnostic body imaging radiologists. All data were recorded and analyzed by the researcher. RESULTS: A total of 274 patients were diagnosed with secondary malignant neoplasm of the liver and intrahepatic bile duct by ICD-10 coding during the study period. After reviewing the medical records, 127 patients were excluded. Among the 147 patients included, the lesions were further categorized as isolated-lesion group (80 patients, 245 lesions) and overall-lesion group (67 patients). Most patients had colorectal primary site (84 patients, 57.14%). For the isolated-lesion group, PVP showed the highest performance to detect metastatic lesion and the highest conspicuity (90.2%, 221 lesions) followed by HAP (26.5%, 65 lesions). Similar findings were noted in the overall-lesion group, PVP had the highest detection rate of 85.1% (57 patients) followed by HAP (10 patients, 14.9%) while NECT and DP showed no superiority over the other phases in lesion detection. About one-third of breast cancer patients had better visualized lesions in HAP than PVP. CONCLUSION: In most malignancies, PVP was the best phase of CT scan both in terms of detection rate and conspicuity, particularly in colorectal primary. However, HAP should be added in some specific kinds of malignancies to increase the lesion detection rate, especially in breast cancer (about one-third of patients). NECT and DP had no superiority over other phases in term of lesion detection rate in follow-up CT scan of metastatic liver disease. However, there were some limitations in this study due to a small number of patients of some primary sites.