Magnetic Resonance Imaging Appearance and Mechanism of Action of Five Hemostatic Agents Used in Neurosurgery.

OBJECTIVE To describe the magnetic resonance (MR) image appearance of 5 hemostatic agents placed in the brain, and to review their clinical application. STUDY DESIGN Descriptive ex vivo and in vivo study. ANIMALS Canine cadavers (n=4), client-owned dogs (n=4). METHODS Heads from 4 canine cadavers were used, each with 5 hemostatic agents placed in specific locations in the brain. Hemostatic agents were used in their native form in 2 cadaveric brains, and in 2 others the materials were saturated with fresh whole blood prior to placement to mimic application in a field of active hemorrhage. The heads underwent MR imaging and the images were reviewed. Postoperative MRI images from 4 dogs undergoing brain tumor resection were retrospectively reviewed and compared to the images from the cadavers. All clinical cases and cadaveric specimens underwent surgical closure prior to MR imaging including placement of titanium mesh over the craniotomy defect with a dural graft of porcine small intestinal submucosa (SIS) sealed with Tisseel (fibrin sealant). RESULTS The SIS and Tisseel used in the dural graft were consistently indistinguishable from the surrounding tissues on MR images. The MR imaging appearance of the remaining 4 hemostatic agents (Gelfoam, Avitene, Surgicel, and Floseal) placed on the surface or in the parenchyma of canine brain, varied with MR sequence weighting and blood saturation. CONCLUSION Accurate evaluation of the degree of brain tumor resection on postoperative MR images requires careful differentiation between hemorrhage, residual tumor, and hemostatic agents implanted.