Detection of hepatocellular carcinoma: Value of adding delayed phase imaging to dual-phase helical CT

OBJECTIVE. The purpose of our study was to determine the value of adding delayed phase imaging to dual-phase helical CT for the detection of hepatocellular carcinoma. SUBJECTS AND METHODS. One hundred thirteen patients with 131 hepatocellular carcinomas underwent triple-phase helical CT. The diagnosis was established by pathologic examination after surgical resection in all patients. For triple-phase helical CT, hepatic arterial, portal venous, and delayed phase scanning began 30, 60, and 180 sec, respectively, after the injection of 120 mL of iodinated contrast material. Dual-phase helical CT excluding delayed phase and triple-phase helical CT images were reviewed independently by three radiologists on a segment-by- segment basis. Diagnostic accuracy was assessed using receiver operating characteristic analysis in 330 resected segments. Sensitivities and specificities were calculated. The value of the delayed phase images in the characterization of hepatocellular carcinoma was also assessed. RESULTS. The diagnostic accuracy of triple-phase helical CT including delayed phase (area under the curve [A(Z)], 0.973) was significantly higher than that of dual-phase helical CT (A(Z), 0.954). The mean sensitivity of triple-phase CT (89%) was also significantly higher than that of dual-phase CT (86%). The mean specificities of triple-phase CT (99%) and dual-phase CT (99%) were equal. Delayed phase images were helpful in the characterization of hepatocellular carcinoma in 14% of patients. CONCLUSION. The addition of delayed phase imaging to dual-phase helical CT is valuable for the detection and characterization of hepatocellular carcinoma.