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Prediction of subtle thermal histopathological change using a novel analysis of Gd‐DTPA kinetics
Author(s) -
Cheng HaiLing Margaret,
Purcell Carrie M.,
Bilbao Juan M.,
Plewes Donald B.
Publication year - 2003
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.10388
Subject(s) - histopathology , kinetics , thermal ablation , nuclear medicine , ultrasound , ablation , materials science , magnetic resonance imaging , nuclear magnetic resonance , chemistry , medicine , pathology , radiology , physics , quantum mechanics
Purpose To investigate Gd‐DTPA kinetics as predictors of histopathological changes following focused ultrasound (FUS) thermal ablation for improved planning and assessment. Materials and Methods Twenty‐nine FUS lesions were created in the thigh muscle of eight rabbits under MR‐guidance at 1.5 Tesla. Three rabbits were killed at four hours; and 11 lesions were analyzed with histopathology. Temperature‐sensitive MRI using proton‐resonant frequency‐shift was used for time‐dependent temperature measurements. Analysis of the uptake kinetics of Gd‐DTPA was performed after Gd‐DTPA injection, within 20 minutes after heating and again at two hours after heating. The resulting kinetic maps, permeability ( K trans ) and leakage space ( v e ), were correlated to peak temperatures, T 2 ‐weighted MR, and histopathology. Results Images of K trans and v e reveal regions of histopathological change not visible on conventional post‐therapy MR. At early times after heating, v e predicts the area of injury more accurately than T 2 (7 ± 2% vs. 25 ± 6% underestimation). A circular region of extensive structural/vascular disruption is indicated only on K trans maps. The sharp decrease in K trans at the boundary of this region occurs at 47.5 ± 0.5°C, and may be a better estimate of cell death than the conventional method of temperature threshold (55°C for coagulation) used in therapy planning. Conclusion Our results suggest Gd‐DTPA kinetics can predict different histopathological changes following FUS ablation and may be valuable for early prediction. J. Magn. Reson. Imaging 2003;18:585–598. © 2003 Wiley‐Liss, Inc.