Explanted Thiel Embalmed Human Liver as a Model to Study MR-guided Focused Ultrasound Surgery

1. IoannisKarakitsios, TimurSaliev, Helen McLeod, Sarfraz Ahmad, Andreas Melzer Institute for Medical Science & Technology, University of Dundee, United Kingdom Explanted Thiel Embalmed Human Liver as a Model to Study MR-guided Focused Ultrasound Surgery Background: MR-guided Focused Ultrasound Surgery (MRgFUS) is a useful method to ablate tumours noninvasively [1,2]. Treatment of liver disease is a very demanding treatment process with high death rates [3]. Studies on animals and human patients under general anaesthesia have reported the feasibility and accuracy of MRgFUS to coagulate tumour [4,5]. Thiel embalming is used to preserve human cadavers, giving the bodies a high degree of flexibility and life-like characteristics. Objectives: The focus of our study was to determine whether explanted Thiel embalmed human liver constitutes a reliable model for studying MRgFUS. For that purpose, the temperatures of the heated Thiel tissue were compared to the temperatures of fresh animal tissue. Absorber Methods: Four explanted livers: two fresh sheep livers and two Thiel embalmed human livers were scanned with MRI (1.5 T HDxt, GE Healthcare, USA) using Fast Spoiled Gradient Echo (FSPGR) imaging with TE: Minimum, TR: 60 msec, Flip Angle: 30o and acquisition matrix 256x256. The organs were heated for 20 sec with Focused Ultrasound (FUS) (ExAblate 2000, InSightec Ltd., Israel) at various acoustic energies: 253, 506 and 709 Joules. Proton Resonance Frequency (PRF) MR Thermometry was applied for temperature monitoring. Post-sonication maximum temperature values of the animal liver and Thiel human liver were compared. Liver Gel Pad HIFU transducer Results: Table shows the average value of the maximum temperatures after MRgFUS treatment of fresh animal liver and Thiel embalmed human liver at various acoustic energies, and their difference Conclusions: MRgFUS treatment of Thiel embalmed human liver at energies >506 J can induce tumour ablation with temperatures >56oC. There was a good correlation between temperatures achieved in the Thiel embalmed tissue and the temperatures in the fresh animal tissue. In overall, Thiel embalmed human liver constitutes a feasible, safe and reliable model to study MRgFUS treatment, ex vivo. Acknowledgements: Project FUSIMO (“Patient specific modelling and simulation of focused ultrasound in moving organs”) funded under the EU's 7th Framework Programme for Research and Technological Development. References [1] Cline HE, Schenck JF, Hynynen K, et al MR-guided Focused Ultrasound Surgery. Journal of Computer Assisted Tomography 1996;16:956-965.[2] Jolesz FA. MRI-Guided Focused Ultrasound Surgery. Annual Revew of Medicine 2009;60:417-430. [3] Fischer K, Gedroyc W, and Jolesz FA. Focused Ultrasound as a Local Therapy for Liver Cancer. Cancer Journal 2010;16:118-124. [4] Kopelman D, Inbar Y, Hanannel A, Freundlich D, Vitek S, Schmidt R, Sokolov A, Hatoum OA, and Rabinovici J. MR-guided Focused Ultrasound Surgery Using an enhanced SonicationTechniquein a Pig Muscle model. European Journal of Radiology 2006;59:190-197. [5] Gedroyc WM. New Clinical Applications of Magnetic Resonance-Guided Focused Ultrasound. Topics in Magnetic Resonance Imaging 2006;17:189-194. [6] Thiel W. The Preservation of the Whole Corpse with Natural Color. Annual Journal of Anatomy 1992;174:185-195.