Three-dimensional comparison of interventional MR radiofrequency ablation images with tissue response.
OBJECTIVE
Solid tumors are being treated using radiofrequency (RF) ablation under interventional magnetic resonance imaging (MRI) guidance. We are investigating the ability of MRI to monitor ablation treatments by comparing MR images of thermal lesions to histologically assayed tissue damage.


METHODS
An open MRI system was used to guide an ablation electrode into five rabbit thigh muscles and acquire post-ablation MR image volumes. We developed a methodology using a 3D computer registration to make spatial correlations. After MR and histology images were registered with an accuracy of 1.32+/-0.39 mm (mean+/-SD), a boundary of necrosis identified in the histology was compared with the outer boundary of the hyperintense region in MR images.


RESULTS
For 14 T2-weighted MR images, the absolute distance between boundaries was 0.96+/-0.34 mm (mean+/-SD). Since the small discrepancy between boundaries is comparable to our registration accuracy, the boundaries may match exactly. Similar correlations to histology were obtained with a deformable model segmentation method.


CONCLUSIONS
This is good evidence that MR thermal lesion images can be used during RF ablation treatments to accurately localize the zone of necrosis at the lesion margin.
Breen
Michael S
MS
Department of Biomedical Engineering, University Hospitals of Cleveland & Case Western Reserve University, Cleveland, Ohio 44106, USA.
Lazebnik
Roee S
RS
Nour
Sherif G
SG
Lewin
Jonathan S
JS
Wilson
David L
DL
D000818:Animals; D017115:Catheter Ablation; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000473:pathology* / Q000601:surgery*; D009336:Necrosis; D011817:Rabbits