Diagnostic value of early postoperative MRI and diffusion-weighted imaging following trans-sphenoidal resection of non-functioning pituitary macroadenomas

Abstract

To establish the value of early contrast-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in differentiating residual pituitary adenoma from postoperative surgical changes. Thirty patients with non-functioning pituitary macroadenomas, who were undergoing trans-sphenoidal adenomectomy, were prospectively studied. 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 utilised to select the region of interest (ROI) for ADC calculations. Seventeen patients had postoperative surgical granulation tissue and 13 had residual adenoma based on the 6 months follow-up imaging. Mean ADC values of postoperative granulation tissue and residual adenoma were 1.476±0.476×10-3mm2/s and 0.855±0.190×10-3mm2/s, respectively, in the early postoperative period, and 1.357±0.416×10-3mm2/s and 0.829±0.201×10-3mm2/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. Early postoperative DWI after trans-sphenoidal resection of pituitary macroadenomas may be more helpful than early MRI in differentiating residual adenoma from post-surgical changes.