Published online Jun 27, 2021. doi: 10.4254/wjh.v13.i6.699
Peer-review started: February 4, 2021
First decision: February 24, 2021
Revised: March 9, 2021
Accepted: May 20, 2021
Article in press: May 20, 2021
Published online: June 27, 2021
Processing time: 138 Days and 22.9 Hours
In hepatocellular carcinoma (HCC), detection and treatment prior to growth beyond 2 cm are important as a larger tumor size is more frequently associated with microvascular invasion and/or satellites. In the surveillance of very small HCC nodules (≤ 2 cm in maximum diameter, Barcelona clinical stage 0), we demonstrated that the tumor markers alpha-fetoprotein and PIVKA-Ⅱ are not so useful. Therefore, we must survey with imaging modalities. The superiority of magnetic resonance imaging (MRI) over ultrasound (US) to detect HCC was confirmed in many studies. Although enhanced MRI is now performed to accurately diagnose HCC, in conventional clinical practice for HCC surveillance in liver diseases, unenhanced MRI is widely performed throughout the world. While, MRI has made marked improvements in recent years.
To make a comparison of unenhanced MRI and US in detecting very small HCC that was examined in the last ten years in patients in whom MRI and US examinations were performed nearly simultaneously.
In 394 patients with very small HCC nodules, those who underwent MRI and US at nearly the same time (on the same day whenever possible or at least within 14 days of one another) at the first diagnosis of HCC were selected. The detection rate of HCC with unenhanced MRI was investigated and compared with that of unenhanced US.
The sensitivity of unenhanced MRI for detecting very small HCC was 95.1% (97/102, 95% confidence interval: 90.9-99.3) and that of unenhanced US was 69.6% (71/102, 95% confidence interval: 60.7-78.5). The sensitivity of unenhanced MRI for detecting very small HCC was significantly higher than that of unenhanced US (P < 0.001). Regarding the location of HCC in the liver in patients in whom detection by US was unsuccessful, S7-8 was identified in 51.7%.
Currently, unenhanced MRI is a very useful tool for the surveillance of very small HCC in conventional clinical follow-up practice.
Core Tip: Recent technological development of magnetic resonance imaging (MRI) scanners has been excellent. The 3.0-tesla (T) MR scanner with a higher field strength has been increasingly used because improved lesion detection can be expected as a result of the increased signal-to-noise ratio, which is theoretically twice with 3.0-T compared with 1.5-T. Another important improvement in MRI is the practical use of diffusion-weighted imaging. In this study, a comparison of unenhanced MRI and ultrasound in detecting very small hepatocellular carcinoma (2 cm in maximum diameter) was made. The sensitivity of unenhanced MRI for detecting very small hepatocellular carcinoma was as high as 95.1% as compared with 69.6% of unenhanced ultrasound (P < 0.001).