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

Aim: 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. Materials and methods: 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. Results: 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±0.476×10−3 mm2/s and 0.855±0.190×10−3 mm2/s, respectively, in the early postoperative period, and 1.357±0.416×10−3 mm2/s and 0.829±0.201×10−3 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 trans-sphenoidal resection of pituitary macroadenomas may be more helpful than early MRI in differentiating residual adenoma from post-surgical changes.