Program Information
Investigation of MRI Derived Thermal Dose Models
C MacLellan1,2*, D Fuentes1,2 , H Espinoza1 , S Prabhu1 , G Rao1 , J Weinberg1 , R Stafford1,2 , (1) The University of Texas MD Anderson Cancer Center, Houston, Texas, (2) The University of Texas Graduate School of Biomedical Sciences, Houston, Texas,
Presentations
WE-AB-BRA-4 (Wednesday, August 3, 2016) 7:30 AM - 9:30 AM Room: Ballroom A
Purpose:To develop and investigate a novel thermal dose model methodology using MR temperature imaging (MRTI) and post-treatment MRI changes as a surrogate of tissue damage in clinical laser ablation of the brain.
Methods:Post-treatment contrast enhanced T1-weighted images were registered to MRTI acquired during two MR-guided thermal ablation procedures. The non-enhancing central region and hyperintense ring of vascular disruption characteristic of the thermal lesion were segmented manually and resampled into the 2D geometry of the MRTI. Regions immediately inside and outside the ring were classified as nonviable and viable tissue, respectively (N=1860). Logistic regression was performed on these classifications using thermal dose (Ω) calculated via four Arrhenius dose models from the literature (Henriques (H), Weaver & Stoll (WS), Diller & Klutke (DK), and Brown (B)). The optimal (O) Arrhenius dose model was found by iteratively changing the parameters of the Arrhenius model, Ea and A, until logistic model deviance was minimized.
Results:Deviance of the Henriques model was closest to the optimized model (360 (H), 630 (WS), 438 (DK), 803(B), 330(O)). The thermal dose required to achieve a 90% probability of nonviability was 1.4 (H), 2.65 (WS), 1.8 (D), 4.5 (B), 1.1 (O) for each model. Agreement between the area of >90% nonviability between each model and the optimal model was 0.97 (H), 0.89(WS), 0.94(DK), and 0.88(B) using the Dice Similarity Coefficient.
Conclusion:A methodology for deriving new thermal dose models from clinically used surrogates of tissue damage has been developed and tested. The logistic model suggests that the common dose threshold of Ω=1 may overestimate tissue damage. Good agreement is observed between the nonviable regions predicted by the optimized model and literature models. However, agreement between models is expected to decrease for longer ablation procedures designed to create larger thermal lesions and is an opportunity for further study.
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