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

• Published in: European journal of radiology 2012-10, Vol.81 (10), p.2730-2736
• Main Authors: Koda, Masahiko, Tokunaga, Shiho, Miyoshi, Kennichi, Kishina, Manabu, Fujise, Yuki, Kato, Jun, Matono, Tomomitsu, Okamoto, Kinya, Murawaki, Yoshikazu, Kakite, Suguru
• Format: Article
• Language: English
• Subjects: Ablative margin; Aged; Aged, 80 and over; Carcinoma, Hepatocellular - pathology; Carcinoma, Hepatocellular - surgery; Contrast Media; Feasibility Studies; Female; Hepatectomy - methods; Hepatocellular carcinoma; Humans; Image Enhancement; Liver - pathology; Liver - surgery; Liver Neoplasms - pathology; Liver Neoplasms - surgery; Magnetic resonance image; Magnetic Resonance Imaging - methods; Male; Middle Aged; Radiofrequency ablation; Radiology; Reproducibility of Results; Sensitivity and Specificity; Surgery, Computer-Assisted - methods; Treatment Outcome
• ISSN: 0720-048X; 1872-7727
• DOI: 10.1016/j.ejrad.2011.11.013

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.