Diffusion-weighted imaging during MR-guided radiofrequency ablation of hepatic malignancies: analysis of immediate pre- and post-ablative diffusion characteristics

• Published in: Acta radiologica (1987) 2015-08, Vol.56 (8), p.908-916
• Main Authors: Hoffmann, Rüdiger, Rempp, Hansjörg, Schraml, Christina, Schwenzer, Nina, Grözinger, Gerd, Blumenstock, Gunnar, Rothgang, Eva, Pereira, Philippe L, Claussen, Claus D, Clasen, Stephan
• Format: Article
• Language: English
• Subjects: Ablation; Adult; Aged; Aged, 80 and over; Carcinoma, Hepatocellular - pathology; Carcinoma, Hepatocellular - surgery; Diffusion; Diffusion Magnetic Resonance Imaging - methods; Female; Guidelines; Humans; Imaging; Liver; Liver Neoplasms - pathology; Liver Neoplasms - surgery; Male; Middle Aged; Observer Variation; Patients; Postoperative Care - methods; Preoperative Care - methods; Radiofrequency; Reproducibility of Results; Retrospective Studies; Sensitivity and Specificity; Surgery, Computer-Assisted - methods; Treatment Outcome; Tumors
• ISSN: 0284-1851; 1600-0455
• DOI: 10.1177/0284185114545148

Background Previous studies have shown a benefit of magnetic resonance (MR)-diffusion-weighted imaging (DWI) for follow-up after liver radiofrequency (RF) ablation. However, no data are available concerning acute changes of DWI characteristics immediately after RF ablation. Purpose To analyze and compare the MR-diffusion characteristics of pre-interventional hepatic malignancies and the ablation zone during successful MR-guided RF ablation. Material and Methods This retrospective study was conducted in accordance with the guidelines of the local institutional review board. Forty-seven patients with 29 HCC (24 patients) and 30 hepatic metastases (23 patients) underwent MR-guided radiofrequency ablation including DWI before and immediately after ablation (b = 50, 400, 800 s/mm2). Two reviewers (A and B) analyzed DWI with focus on detectability of the tumor before ablation and characteristics of the coagulative area after treatment. Mean apparent diffusion coefficient (ADC) was compared between liver, untreated tumor, and hyperintense areas in post-ablative DWI (b = 800 s/mm2) with the paired Student’s t-test. Results Pre-ablative: the reviewers classified 19/29 (A) and 23/29 (B) HCC and 25/30 (A and B) metastases as detectable in DWI. Post-ablative: a hyperintense rim surrounding the ablation zone was observed in 28/29 treated HCC and 30/30 treated metastases (A and B). A homogenous hypointense central ablation zone was found in 18/29 (A) and 20/29 (B) treated HCC and 17/30 (A & B) treated metastases in DWI. ADC of the rim was significantly lower than ADC of the liver (P