Assessment of ablative margin by unenhanced magnetic resonance imaging after radiofrequency ablation for hepatocellular carcinoma.

Abstract

PURPOSE:

The aim of this study was to evaluate the feasibility of magnetic resonance imaging (MRI) without a contrast agent to visualize the ablative margin after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), compared with enhanced CT.

METHODS:

Twenty-five HCCs in 19 patients were treated by RFA. T1-weighted MRI was performed before and after RFA, and the signal intensities of the tumors and surrounding liver tissues were measured. Treatment efficacy was assessed based on three grades: margin (+), a continuous high-intensity rim around the index tumor; margin zero, a partially discontinuous high-intensity rim; margin (-), the tumor extends beyond the high-intensity rim.

RESULTS:

Twelve (86%) of fourteen low-intensity tumors on the pre-MRI were visualized as low-intensity tumors on post-MRI, and the ablative margins were visualized as high-intensity rims. Two (67%) of three high-intensity tumors on pre-MRI were visualized as higher-intensity tumors in the high-intensity ablative margin. Because the signal intensities of tumors and surrounding tissues in 14 tumors that were low- or high-intensity tumors on pre-MRI increased to the same extent, the tumors and ablative margin could be distinguished on post images. In 6 (75%) of the 8 iso-intensity tumors on pre-MRI, the ablative margin and tumor could also not be discriminated on post-MRI. The overall agreement between MRI and CT for the ablative margin was good (κ coefficient=0.716, p=0.00002).

CONCLUSION:

In 82% of low- or high-intensity tumors on pre-MRI, post-MRI without a contrast agent enabled visualization of the ablative margin as a high-intensity rim, and it was possible to evaluate the ablative margin earlier and easier than with enhanced CT.

• Authors: Masahiko Koda, Shiho Tokunaga, Kennichi Miyoshi, Manabu Kishina, Yuki Fujise, Jun Kato, Tomomitsu Matono, Kinya Okamoto, Yoshikazu Murawaki, Suguru Kakite
• Journal: European journal of radiology (Eur J Radiol) Vol. 81 Issue 10 Pg. 2730-6 (Oct 2012) ISSN: 1872-7727 [Electronic] Ireland
• PMID: 22137612 (Publication Type: Clinical Trial, Journal Article)
• Copyright: Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Chemical References

• Contrast Media

Topics

• Aged
• Aged, 80 and over
• Carcinoma, Hepatocellular (pathology, surgery)
• Contrast Media
• Feasibility Studies
• Female
• Hepatectomy (methods)
• Humans
• Image Enhancement
• Liver (pathology, surgery)
• Liver Neoplasms (pathology, surgery)
• Magnetic Resonance Imaging (methods)
• Male
• Middle Aged
• Reproducibility of Results
• Sensitivity and Specificity
• Surgery, Computer-Assisted (methods)
• Treatment Outcome