Minimally-Invasive Excisional Brain Biopsy and Intracranial Brachytherapy Catheter Placement in Dogs
A novel technique for minimally-invasive excisional brain biopsy and intracranial placement of a balloon-tipped brachytherapy catheter was evaluated in 5 purpose-bred dogs. CT-guidance was used to plan biopsy trajectory to a predetermined target with reference to a localizer grid affixed to a craniotomy stand. The procedure was performed through a 1 cm skin incision and 6 mm burr hole using a 9-gauge biopsy device. Five cylindrical samples, measuring 3-4 mm in diameter by 7-12 mm in length were removed over 5 cycles of the vacuum-assisted ATEC® breast biopsy and excision system [Hologic Inc., Indianapolis, IN], leaving approximately a 1 cm3 resection cavity. A GliaSite® [Proxima Therapeutics, Inc., Alpharetta, GA] balloon-tipped intracranial catheter was placed through the burr hole into the resection cavity to simulate 125-I liquid brachytherapy, and explanted after 7 days.
Four of 5 dogs had favorable outcomes, and were evaluated for 4 weeks post-operatively. One dog died within hours due to misguided biopsy. Neurological deficits were unilateral, focal and mild/moderate. Three dogs developed proprioceptive deficits; 2 had menace deficits, 2 developed circling, and 1 had horizontal nystagmus and reduced response to noxious nasal stimulation. Neurological status improved throughout the study period.
Histologic quality of the biopsy specimens was excellent. Histologic healing response of the brain at necropsy 4 weeks post-operatively was narrowly confined to the margins of the biopsy defect and catheter trajectory.
This simple technique can be used to target lesions and obtain high-quality tissue samples efficiently, with minimal morbidity. Clinical trials and adjunctive studies are underway.