Modification and application of a Pelorus Mark III Stereotactic System forCT-guided brain biopsy in 50 dogs

The Pelorus Mark III Stereotactic System is a commercially available device for CT-guided stereotactic brain biopsy in people. With relatively minor m odifications, this de,ice was used to safely and accurately perform CT-guid ed stereotactic brain biopsies in 50 dogs with intracranial lesions, Modifi cations were necessary to accommodate a 90 degrees shift in orientation of the canine head compared to the human head during the imaging phase of the procedure, and to facilitate other phases of the biopsy procedure that are affected by the uneven and variable topography of the canine skull. Descrip tion of a typical CT-guided brain biopsy procedure in dogs using the modifi ed Pelorus Mark III Stereotactic System is provided. Accuracy of biopsy nee dle placement was determined by comparing the x, y and z coordinates of the biopsy target site with the actual coordinates of the needle tip on CT ima ges, Mean needle placement error was 3.5 +/- 1.6 mm. Needle placement error was not significantly related to operator experience, dog size (body weigh t), or needle path length, however, needle placement error was significantl y affected by lesion location.