Ashok Gowda PhD, Presenter: Stockholder, BioTex, Inc Stockholder, Visualase, Inc

Agatha T. Borne PhD, Abstract Co-Author: Nothing to Disclose

Matthew Fox BS, Abstract Co-Author: Stockholder, BioTex, Inc Stockholder, Visualase, Inc

Roger McNichols PhD, Abstract Co-Author: Stockholder, BioTex, Inc Stockholder, Visualase, Inc

Roger Jason Stafford, Abstract Co-Author: Nothing to Disclose

Kamran Ahrar MD, Abstract Co-Author: Research grant, BioTex, Inc Speakers Bureau, Tyco Healthcare (Valleylab)

The purpose of this study was to characterize the performance of a new rapid laser ablation system in an in vivo tumor model.

The ablation system used in these studies consisted of a 15W 980nm diode laser (PhoTex15), flexible diffusing tipped fiberoptic, and 17Ga internally cooled catheter (Visualase Cooled Laser Applicator System, Visualase, Inc.). A tubing pump is included for internal cooling of the applicator. A subcutaneous transmissible veneral tumor (TVT) model was used for evaluating system performance. Eight immunosuppressed canines were inoculated with TVT fragments in eight dorsal locations. Laser therapy was scheduled when the largest tumors reached 5cm(avg. 6 weeks). For treatment, animals were anesthetized and applicators were placed centrally in tumors either by palpation or US guidance. Ablations were performed at 64 sites using powers of 10W, 12.5W, and 15W with exposure times between 60 and 180 seconds. Applicator cooling was maintained using sterile saline at 15 ml/min . In 15 cases multiple overlapping ablations were performed using either one applicator or two applicators spaced 1.5 cm apart. Animals were kept on anesthesia for 90 minutes after the last ablation to allow lesion maturation. At sacrifice, tumors were harvested, sectioned along the applicator tract, measured, photographed, and stored for histological analysis.

Laser applicators were easily identifiable under US. Ablation zones were distinguishable in sectioned tumors and were consistently spherical. Gross pathology confirmed well circumscribed lesions with sharp demarcation between normal and thermally necrosed tissue. Using a single applicator, average ablation diameters ranged from 12.5mm at the lowest dose (10W, 60sec) to 25mm at the highest dose (15W, 180sec). Multiple applicators created larger ablation zones of up to 35mm in diameter using 15W for 240 seconds exposure time.

Laser ablation with a new 980nm laser and internally cooled applicator is effective at creating large spheroid thermal ablations in tumors in less than 3 minutes.

Fast laser ablation offers an alternative choice for thermal ablation of tumors with advantages over current systems.

Gowda, A, Borne, A, Fox, M, McNichols, R, Stafford, R, Ahrar, K, Rapid Interstitial Laser Ablation in a Subcutaneous Tumor Model.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5009614.html