Temperature-monitored optical treatment for radial tissue expansion

Abstract

Esophageal stricture occurs in 7-23% of patients with gastroesophageal reflux disease. However, the current treatments including stent therapy, balloon dilation, and bougienage involve limitations such as stent migration, formation of the new strictures, and snowplow effect. The purpose of the current study was to investigate the feasibility of structural expansion in tubular tissue ex vivo during temperature-monitored photothermal treatment with a diffusing applicator for esophageal stricture. Porcine liver was used as an ex vivo tissue sample for the current study. A glass tube was used to maintain a constant distance between the diffuser and tissue surface and to evaluate any variations in the luminal area after 10-W 1470-nm laser irradiation for potential stricture treatment. The 3D goniometer measurements confirmed roughly isotropic distribution with less than 10% deviation from the average angular intensity over 2π (i.e., 0.86 ± 0.09 in arbitrary unit) from the diffusing applicator. The 30-s irradiation increased the tissue temperature up to 72.5 °C, but due to temperature feedback, the interstitial tissue temperature became saturated at 70 °C (i.e., steady-state error = ±0.4 °C). The irradiation times longer than 5 s presented area expansion index of 1.00 ± 0.04, signifying that irreversible tissue denaturation permanently deformed the lumen in a circular shape and secured the equivalent luminal area to that of the glass tube. Application of a temperature feedback controller for photothermal treatment with the diffusing applicator can regulate the degree of thermal denaturation to feasibly treat esophageal stricture in a tubular tissue.

Impact of residual air trap in balloon on laser treatment of tubular tissue

“…14,16 An optical diffuser has been developed and used to deliver laser light to tubular tissue circumferentially and not only to treat stenosis developed in the cylindrical structure but also to induce the stenosis. [21][22][23][24] To avoid the perforation during laser therapy that includes PDT using a diffuser on the tubular tissue, dilation was an integral part in terms of uniform irradiation of low power laser light onto the large area. 18,19,25 Recent studies introduced a balloon-integrated diffusing applicator (BDA) to treat tubular tissues (bile duct and esophagus) by inflating the balloon for tissue dilation and simultaneously irradiating the light on the inner lumen for irreversible thermal coagulation.…”

“…Laser ablation is an effective and minimally invasive method that can treat tissue stenosis in a hemostatic manner because of its inherent optical features 14,16 . An optical diffuser has been developed and used to deliver laser light to tubular tissue circumferentially and not only to treat stenosis developed in the cylindrical structure but also to induce the stenosis 21–24 . To avoid the perforation during laser therapy that includes PDT using a diffuser on the tubular tissue, dilation was an integral part in terms of uniform irradiation of low power laser light onto the large area 18,19,25 .…”

Feasibility study of endoscopic thermal coagulation with circumferential laser irradiation for treating esophageal tissue

“…Recently, an optical diffusing applicator was developed and fabricated to attain cylindrical light emissions for the treatment in the structure of tubular organs [15][16][17]. Micromachining the fiber surface was able to uniformly scatter the incident laser light in a radial direction along the fiber.…”