Detection of Hypervascular Hepatocellular Carcinoma with Non-enhanced Magnetic Resonance Imaging Including Diffusion-weighted Imaging

Abstract

AIM: To evaluate the usefulness of non-enhanced magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) for detecting hypervascular hepatocellular carcinomas (HCCs). METHODS: A total of 121 consecutive patients with 149 initial HCCs definitely diagnosed by dynamic computed tomography underwent non-contrast MRI including DWI and ultrasound (US). Detection rates for hypervascular HCC were calculated for all non-enhanced MRI sequences including DWI and US. Then, the correlations between tumor negativity on DWI and other MRI sequences and tumor location were analyzed to clarify the characteristics of negative HCC on DWI. RESULTS: The detection rates for HCC by US, all MRI sequences without DWI, and all MRI sequences including DWI were 85%, 91%, and 99%, respectively. The HCC detection rate was significantly higher by all MRI sequences including DWI than by US (p<0.001) and all MRI sequences without DWI (p<0.001). All negative HCCs on DWI were isointense or hyperintense on T1-weighted imaging (p<0.001). Negative HCCs on DWI showed significantly higher rates of positive chemical shift (p=0.013) on T1-weighted imaging and hypointense or isointense tumors on T2-weighted imaging (p<0.001). The HCC detection rate by DWI was 83% in S2, lower than in other segments. CONCLUSIONS: The detection of hypervascular HCCs on nonenhanced MRI including DWI was superior to that on non-enhanced MRI without DWI and US. However, a well-differentiated HCC or a nodule in S2 influenced by cardiac motion artifact may not be detected on DWI.