Objective To evaluate the detectability of dual-arterial phase of MRI and single-artery phase of CT scan for hepatocellular carcinoma (HCC). Methods A total of 39 patients with HCC underwent CT and MR scan, and 59 lesions of HCC were confirmed definitely. According to lesion size, the lesions were divided into 3 groups: >3 cm group (n=20), 1-3 cm group (n=27) and <1 cm group (n=12). CT was performed with 25 seconds delaying for artery phase. MR imaging was performed with liver accelerate volume acquisition (LAVA) technique, dual-artery phases included early artery phase of 17 seconds delaying and a mid-artery phase of 24 seconds delaying. The detectability of dual-artery phase of MR was compared with that of single-artery phase of CT. Results In <1 cm group, the sensitivity of CT single-artery phase images and MR dual-artery phase images in detecting HCC lesions was 50.00% (6/12) and 75.00% (9/12), respectively;the later showed a higher sensitivity (P=0.04). In groups of 1-3 cm and ＞3 cm, the sensitivity of the two technique had no statistical difference (66.67% vs 81.48% and 95.00% vs 95.00%). Conclusion For the detection of <1 cm HCC, dual-artery phase MRI has higher detectability than single artery phase enhancement CT.