Sub-acute changes in lesion conspicuity and geometry following MR-guided radiofrequency ablation

Roee S. Lazebnik, Brent D. Weinberg, Michael S. Breen, Jonathan S. Lewin, David L. Wilson

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To evaluate MR signal and lesion zone volume evolution through the sub-acute phase following image-guided radiofrequency (RF) thermal ablation. Materials and Methods: For many tissues, including muscle and liver, thermal lesions that result from RF heating have a characteristic two-boundary appearance featuring an inner core (zone 1) surrounded by a hyper-intense margin (zone II) and normal tissue (zone III), found in both T2 and contrast enhanced (CE) T1-weighted MR images, both immediately post-ablation and four days later. First, we compared corresponding points between manually segmented zone boundaries apparent in T2- and CE T1-weighted images. Second, we examined the contrast-to-noise ratio (CNR) between all zone combinations. Third, we quantified the volume of zone I, zone II. and the entire lesion using a three-dimensional lesion geometry model fitted to segmented images. Results: On a slice-by-slice basis, no statistically significant differences were found between zone boundaries apparent in T2 and CE T1-weighted images. The contrast to noise ratio (CNR) of zone I vs. zone II, zone I vs. background muscle, and zone II vs. background muscle was always equal or greater for T2-weighted images than for CE T1-weighted images. In addition, by day four, zone II significantly increased in intensity compared to background muscle. The median Zone I volume increase was 44.2% (42.6%) using T2 weighted images and 55.5% (68.7% inter-quartile range) using CE T1-weighted images. This expansion likely corresponds to an enlargement of the ablated coagulative necrosis, region. The median Zone II volume increase was 15.0% (42.6%) using T2-weighted images 1.5% (38.80%) using CE T 1-weighted images. Conclusions: 1) There are no significant differences between the apparent zone boundaries in T2- and CE T 1-weighted images; 2) CNR is equal or greater for T 2-weighted images as compared to CE T1-images; and 3) both the inner and outer lesion zone volumes typically increase several days post-ablation.

Original languageEnglish (US)
Pages (from-to)353-359
Number of pages7
JournalJournal of Magnetic Resonance Imaging
Volume18
Issue number3
DOIs
StatePublished - Sep 1 2003

Keywords

  • Contrast enhanced T-weighted images
  • Image analysis
  • Interventional magnetic resonance imaging
  • Medical image processing
  • Radiofrequency thermal ablation
  • Segmentation
  • T-weighted images

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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