Pass-through Piston Driver for MR Elastography Assessment of Percutaneous Laser Ablation

Background: Percutaneous tumor ablation has become an important nonsurgical treatment for primary and secondary malignant hepatic tumors[1]. A critical part of the tumor ablation is intra-treatment monitoring to determine whether an adequate treatment is achieved[2]. A recent study looking at long term efficacy of radiofrequency ablation in treatment of liver tumors over a 6 year period demonstrated that there was a high concordance rate (87%) between the exact sites of local tumor progression and insufficient ablative margin[7]. However, measuring tissue temperature change with MRI remains difficult; it depends on calculated damage and cell death assumptions from the Arrehenius equation. Temperature change is only for a short time, and it is difficult to be sure that the tissue is reliably ablated. It would be desirable to monitor the treatment with a method that can potentially image cellular death. Thermal ablation has been linked to increased stiffness in tissue due to