99mTc-DTPA uptake and electrical impedance measurements in verification of in vivo electropermeabilization efficiency in rat muscle.
OBJECTIVE
In vivo electropermeabilization of cell membranes in rat muscle tissue cause a significant decrease of the electrical impedance, in the frequency region of 1-10 kHz. We aimed to study how the 99mTc-DTPA uptake in the electropermeabilized region correlates to the change of admittance Y = 1/absZ, where Z is the measured impedance.


METHODS
The electropermeabilization was performed in vivo by applying high-voltage (0.5-2 kV) short (0.1-2 ms) pulses through gold-plated needle electrodes in skeletal muscle. The impedance was measured before and after each electropermeabilization pulse. The uptake of 99mTc-DTPA uptake in the electropermeabilized region was measured after 6 and 24 hours with a gamma camera.


RESULTS
The pulse shape (square and exponential), duration, and amplitude of the applied electric field were varied, and electropermeabilization efficiency was evaluated using the various measurement modalities. Good correlations were found (correlation coefficient approximately 0.9) between the 99mTc-DTPA uptake in the electropermeabilized and control "region of interest" the admittance ratio Y (post-treatment)/Y (pretreatment), and charge displacement parameter Q.


CONCLUSIONS
The electrical impedance measurements method can be utilized in clinical settings to verify the efficiency of electropermeabilization applied to chemotherapy and to power RNAi (RNA-interference) and DNA-plasmid transfection in vaccination, immunization, and gene-therapy.
Grafström
Gustav
G
Department of Medical Radiation Physics, Lund University, Lund, Sweden.
Engström
Per
P
Salford
Leif G
LG
Persson
Bertil R R
BR
D000818:Animals; D017097:Electric Impedance; D004583:Electrons; D018274:Electroporation; D005260:Female; D008297:Male; D009132:Muscles / Q000187:drug effects*; D051381:Rats; D016284:Technetium Tc 99m Pentetate / Q000494:pharmacology*; D013997:Time Factors
D016284:Technetium Tc 99m Pentetate