TY - JOUR
T1 - Computer simulations of thermal tissue remodeling during transvaginal and transurethral laser treatment of female stress urinary incontinence
AU - Hardy, Luke A.
AU - Chang, Chun Hung
AU - Myers, Erinn M.
AU - Kennelly, Michael J.
AU - Fried, Nathaniel M.
PY - 2016
Y1 - 2016
N2 - Background and Objectives: A non-surgical method is being developed for treating female stress urinary incontinence by laser thermal remodeling of subsurface tissues with applied surface tissue cooling. Computer simulations of light transport, heat transfer, and thermal damage in tissue were performed, comparing transvaginal and transurethral approaches. Study Design/Materials and Methods: Monte Carlo (MC) simulations provided spatial distributions of absorbed photons in the tissue layers (vaginal wall, endopelvic fascia, and urethral wall). Optical properties (n,μa,μs,g) were assigned to each tissue at λ=1064nm. A 5-mm-diameter laser beam and incident power of 5W for 15 seconds was used, based on previous experiments. MC output was converted into absorbed energy, serving as input for finite element heat transfer simulations of tissue temperatures over time. Convective heat transfer was simulated with contact probe cooling temperature set at 0°C. Variables used for thermal simulations (κ,c,ρ) were assigned to each tissue layer. MATLAB code was used for Arrhenius integral thermal damage calculations. A temperature matrix was constructed from ANSYS output, and finite sum was incorporated to approximate Arrhenius integral calculations. Tissue damage properties (Ea,A) were used to compute Arrhenius sums. Results: For the transvaginal approach, 37% of energy was absorbed in the endopelvic fascia target layer with 0.8% deposited beyond it. Peak temperature was 71°C, the treatment zone was 0.8-mm-diameter, and 2.4mm of the 2.7-mm-thick vaginal wall was preserved. For transurethral approach, 18% energy was absorbed in endopelvic fascia with 0.3% deposited beyond the layer. Peak temperature was 80°C, treatment zone was 2.0-mm-diameter, and 0.6mm of 2.4-mm-thick urethral wall was preserved. Conclusions: Computer simulations suggest that transvaginal approach is more feasible than transurethral approach.
AB - Background and Objectives: A non-surgical method is being developed for treating female stress urinary incontinence by laser thermal remodeling of subsurface tissues with applied surface tissue cooling. Computer simulations of light transport, heat transfer, and thermal damage in tissue were performed, comparing transvaginal and transurethral approaches. Study Design/Materials and Methods: Monte Carlo (MC) simulations provided spatial distributions of absorbed photons in the tissue layers (vaginal wall, endopelvic fascia, and urethral wall). Optical properties (n,μa,μs,g) were assigned to each tissue at λ=1064nm. A 5-mm-diameter laser beam and incident power of 5W for 15 seconds was used, based on previous experiments. MC output was converted into absorbed energy, serving as input for finite element heat transfer simulations of tissue temperatures over time. Convective heat transfer was simulated with contact probe cooling temperature set at 0°C. Variables used for thermal simulations (κ,c,ρ) were assigned to each tissue layer. MATLAB code was used for Arrhenius integral thermal damage calculations. A temperature matrix was constructed from ANSYS output, and finite sum was incorporated to approximate Arrhenius integral calculations. Tissue damage properties (Ea,A) were used to compute Arrhenius sums. Results: For the transvaginal approach, 37% of energy was absorbed in the endopelvic fascia target layer with 0.8% deposited beyond it. Peak temperature was 71°C, the treatment zone was 0.8-mm-diameter, and 2.4mm of the 2.7-mm-thick vaginal wall was preserved. For transurethral approach, 18% energy was absorbed in endopelvic fascia with 0.3% deposited beyond the layer. Peak temperature was 80°C, treatment zone was 2.0-mm-diameter, and 0.6mm of 2.4-mm-thick urethral wall was preserved. Conclusions: Computer simulations suggest that transvaginal approach is more feasible than transurethral approach.
KW - Coagulation
KW - Incontinence
KW - Laser
KW - Monte Carlo
KW - Simulations
KW - Thermal remodeling
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U2 - 10.1002/lsm.22491
DO - 10.1002/lsm.22491
M3 - Article
C2 - 26900038
AN - SCOPUS:84959182767
SN - 0196-8092
JO - Lasers in Surgery and Medicine
JF - Lasers in Surgery and Medicine
ER -