Optimizing Scanning Phases in Detecting Small (<2 cm) Hepatocellular Carcinoma: Whole-liver Dynamic Study With Multidetector Row Ct

Objective: To define the optimal scanning phases for detecting small hepatocellular carcinomas (HCCs) with whole-liver dynamic helical computed tomography. Methods: Sixty-one patients with 112 hypervascular HCCs smaller than 2 cm underwent 7-phase dynamic study from the early arterial to the late equilibrium phases of the entire liver. Proof of neoplasms was based on biopsy results and computed tomography with iodized oil. Time-density curves of the individual tumor and the liver were compared. Results: Of 112 hypervascular nodules, the late arterial phase had the best liver-tumor conspicuity (P < 0.001). Ninety-one nodules (81%) had peak liver-tumor contrast in late arterial phase, and only 21 (19%) in the early arterial phase. All the hypervascular HCCs became isoattenuating to the regional parenchyma before the late portal venous phase (120th second). Conclusion: The late arterial and late portal venous phases are recommended for detecting small HCC smaller than 2 cm.