RADI-08. DIAGNOSTIC VALUE OF EARLY POSTOPERATIVE MR IMAGING AND DIFFUSION-WEIGHTED IMAGING FOLLOWING TRANSSPHENOIDAL RESECTION OF NON-FUNCTIONING PITUITARY MACROADENOMAS

Abstract BACKGROUND AND PURPOSE The value of early contrast enhanced magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI) in differentiating residual pituitary adenoma from postoperative surgical changes has not been established. PATIENTS AND METHODS We prospectively studied 30 patients with non-functioning pituitary macroadenomas who were undergoing transsphenoidal adenomectomy. Patients were imaged with both MRI and DWI in the early postoperative period, as well as 6 months post-surgery. Patterns of postoperative contrast enhancement were described (non-enhancement, peripheral enhancement, and nodular enhancement). Apparent diffusion coefficient (ADC) maps were utilized to select the region of interest (ROI) for ADC calculations. RESULTS Seventeen patients had postoperative surgical granulation tissue and 13 had residual adenoma based on the 6 month follow up imaging. Mean ADC values of postoperative granulation tissue and residual adenoma were 1.476 ± 0.476 x 10 -3 mm2/s and 0.855 ± 0.190 x 10 -3 mm2/s, respectively, in the early postoperative period, and 1.357 ± 0.416 x 10 -3 mm2/sand 0.829 ± 0.201x 10 -3 mm2/s, respectively, at the 6 month follow-up. ADC values of granulation tissue were significantly different from that of residual adenoma at both time points (P< 0.001). Sensitivity, specificity, positive and negative predictive values of early MRI were 84.6%, 94.1%, 91.7%, and 88.9% respectively, and of early DWI were 91%, 97%, 94.3%, and 93%, respectively. CONCLUSION Early postoperative DWI after transsphenoidal resection of pituitary macroadenomas may be more helpful than early MRI in differentiating residual adenoma from post-surgical changes.