A polymer gel for registration of the thermal profile in microwave ablation

1. MR department RADIOTHERAPY Laboratory for Quantitative and Molecular Nuclear Magnetic Resonance Imaging A polymer gel for registration of the thermal profile in microwave ablation prof. Yves De Deene

2. ACTIVE COMPONENTS Gelatine (0.75 % (w/w)) Bovine Serum Albumin (6 % (w/w)) Sodium Chloride (1 % (w/w)) 90” A thermal polymer gel: fabrication 2. 1. GELLATION AGENTS Acrylamide (7 % (w/w)) N,N’-methylene-bis-acrylamide (0.14 % (w/w)) 4. POURING THE GEL 3. HEATING 53 °C - 55 °C CATALYSTS Amonium-persulphate (NH4)2S2O8 (0.1 % (w/w)) TEMED (0.03 % (w/w))

3. The final touch ...

4. T T Denatured serum albumin Interpenetrating polymer-network BSA embedded in polyacrylamide network The mechanism Bovine Serum Albumin

5. T The mechanism: Why these chemicals ? CHEMICAL POLYMERIZATION Acrylamide Polyacrylamide catalysts + N,N’-methylene-bis-acrylamide PHYSICAL REACTION Bovine Serum Albumin + Denatured proteins gelatin

6. Change in light scattering Change in local water mobility Change in NMR spin-spin relaxation rate Interpenetrating polymer-network Macroscopic effects

7. B0 Magnetic Resonance E. Purcell 1946 F. Bloch 1946 I.I. Rabi 1938 Water H2O

8. B0 COIL Signal- processing COIL Magnetic Resonance signal F. Bloch 1946 E. Purcell 1946 E. Hahn 1949 I.I. Rabi 1938

9. Magnetic Resonance spin-spin relaxation N. Bloembergen E. Purcell R. Pound M T2 large t M T2 short t Polymer, protein, ...

10. Quantitative MR measurements  H S0 R2 = 1 / T2

11. Quantitative integrating thermometry using NMR (T2, Magnetization Transfer, ...) Change in dielectric properties ? (conductivity, permitivity, ...) Tuning the isothermal point ? (pH, gelatin concentration) Change in acoustic properties ? (Ultrasound ?) Other applications (laser treatments, hyperthermia) Possible research perspectives

12. CAUTION The gel may contain traces of acrylamide monomers Acrylamide = carcinogenic