Effects after interstitial laser application in thyroid gland

Abstract

Abstract In animal lab experiments with pigs we evaluated the use of laser-induced thermotherapy (LITT) on thyroid tissue. A laser application using the Nd:YAG-Laser (1064 nm) was performed for 2 min with 5 W on both lobes of the thyroid gland in 5 pigs. This resulted in spheroid coagulation zones of 5–8 mm in diameter. No impairment of the conduction rate of the laryngeal recurrent nerve in the electro-physical survey through thermocoagulation was seen. Postoperatively plasma levels TSH, total T 3 (TT 3 ) and free T 4 (FT 4 ) were measured in regular time intervals. During this investigation there was a parallel decline of FT 4 and TSH during the first postoperative week. In some animals plasma levels of TT 3 decreased until they reached nearly the detection limit. All measurements showed a recovery during an interval of 10 days sometimes followed by an increase to levels higher than baseline. The necrotic zones of the thyroid tissue were demarcated from the vital tissue by a fibrous border. With progressive healing the coagulation zones showed shrinkage and changed to fibrous tissue. After 6 weeks the defect was almost completely replaced by scar tissue. Complications during or after the study did not occur. The effectiveness of this therapy has been demonstrated in animal experiments.