Published online May 7, 2015. doi: 10.3748/wjg.v21.i17.5345
Peer-review started: October 29, 2014
First decision: November 14, 2014
Revised: December 6, 2014
Accepted: February 11, 2015
Article in press: February 11, 2015
Published online: May 7, 2015
AIM: To investigate the feasibility and clinical value of magnetic resonance imaging (MRI)-MRI image fusion in assessing the ablative margin (AM) for hepatocellular carcinoma (HCC).
METHODS: A newly developed ultrasound workstation for MRI-MRI image fusion was used to evaluate the AM of 62 tumors in 52 HCC patients after radiofrequency ablation (RFA). The lesions were divided into two groups: group A, in which the tumor was completely ablated and 5 mm AM was achieved (n = 32); and group B, in which the tumor was completely ablated but 5 mm AM was not achieved (n = 29). To detect local tumor progression (LTP), all patients were followed every two months by contrast-enhanced ultrasound, contrast-enhanced MRI or computed tomography (CT) in the first year after RFA. Then, the follow-up interval was prolonged to every three months after the first year.
RESULTS: Of the 62 tumors, MRI-MRI image fusion was successful in 61 (98.4%); the remaining case had significant deformation of the liver and massive ascites after RFA. The time required for creating image fusion and AM evaluation was 15.5 ± 5.5 min (range: 8-22 min) and 9.6 ± 3.2 min (range: 6-14 min), respectively. The follow-up period ranged from 1-23 mo (14.2 ± 5.4 mo). In group A, no LTP was detected in 32 lesions, whereas in group B, LTP was detected in 4 of 29 tumors, which occurred at 2, 7, 9, and 15 mo after RFA. The frequency of LTP in group B (13.8%; 4/29) was significantly higher than that in group A (0/32, P = 0.046). All of the LTPs occurred in the area in which the 5 mm AM was not achieved.
CONCLUSION: The MRI-MRI image fusion using an ultrasound workstation is feasible and useful for evaluating the AM after RFA for HCC.
Core tip: One of the major factors that impact the therapeutic effectiveness of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) is local tumor progression (LTP), which is primarily attributed to insufficient ablative margins (AMs). Traditional image evaluation methods, including contrast-enhanced ultrasound and side-by-side comparison with computed tomography/magnetic resonance imaging (MRI) images, cannot quantitatively determine the AM in three dimensions. Our study was the first to report the feasibility of MRI-MRI image fusion using a commercial ultrasound workstation to assess the RFA AM for HCC. The results demonstrated that this method specifically describes the direction of the insufficient ablative zone and would be helpful for the early detection of LTP.