Basic Science: BPH/LUTS
Moderated Poster Session
MP3-1 - Tissue effects of different laser fibre diameters using 1.94 µm Tm:fibre lasers in a pig kidney model
Thursday, September 20
4:00 PM - 6:00 PM
Location: Room 243
Dmitry Enikeev, MD, PhD
Deputy Director for Science
Institute for Urology and Reproductive health, Sechenov University
Andreas J. Gross
Head of Department
Asklepios Klinik Barmbek, Abteilung für Urologie
Introduction & Objective : Aim of this study was to evaluate the ablation capacity and coagulation depth of different laser fibre diameters using a high peak power pulsed Thulium (Tm):fibre laser and a continuous wave (cw) Tm:fibre laser in a pig kidney model.
Methods : All soft tissue samples were obtained from a pig kidney and mounted on a motorized translation XY stage to ensure a precise speed of cutting (2 mm/s). A cw Tm:fibre laser (120-W peak power) and a prototype high peak power pulsed Tm:fibre laser (1000-W peak power) both emitting at 1.94 µm were used at the same average power of 60-W and 120-W, respectively. Energy was delivered using a 200 µm and a 600 µm bare-ended fibre. After Lactat Dehydrogenase (LDH)-staining of the embedded specimens, histological evaluation was performed to compare vaporization volume, ablation depth, thermo-mechanical damage zone, coagulation zone and the depth of necrotic tissue layer between both Tm:fibre lasers and fibre diameters, respectively.
Results : Using the cw Tm:fibre laser at 120-W (cutting speed 2 mm/s), no significant differences were seen between both fibre diameters with regard to vaporization volume (24.6 vs. 28.2 mm3/s), ablation depth (5.7 vs. 5.6 mm), thermo-mechanical damage zone (0 vs. 0 mm2) and the coagulation zone (18.1 vs. 11.3 mm2). Regarding the high peak power pulsed Tm:fibre laser, no differences were found between both fibre diameters with regard to vaporization volume (4 vs. 3 mm3/s), ablation depth (2.7 vs. 2.5 mm), thermo-mechanical damage zone (1 vs. 1.3 mm2) and the coagulation zone (3.1 vs. 2.2 mm2) at 120-W, respectively. Regarding the laser fibre diameters, there were also no differences between the histologically measured parameters at 60-W in both Tm:fibre lasers. However, comparing the power of both lasers, the vaporization volume of the cw Tm:fibre laser at 60-W was significantly lower compared to 120-W using 200 and 600 µm fibres, respectively, whereas the high peak power pulsed Tm:fibre laser did not show significant differences at 60-W compared to 120-W with regards to the vaporization volume.
Conclusions : The laser fibre (200 or 600 µm) diameter did not affect vaporization volume, ablation depth, the thermo-mechanical damage zone and the coagulation zone in cw or high peak power pulsed Tm:fibre lasers. However, the cw Tm:fibre laser produces a coagulation zone five times larger than the high peak power pulsed Tm:fibre laser regardless of the fibre core diameter.