Fig. 1

The MR performance of non-invasive and invasive pituitary adenomas. a Knosp grade 0. b Knosp grade 1. c Knosp grade 2. d Knosp grade 3. e Knosp grade 4. Pituitary adenomas classified as Knosp grades 0–2 constitute the N-invasion group, and pituitary adenomas classified as Knosp grades 3–4 constitute the invasion group (N-invasion non-invasive pituitary adenomas, Invasion invasive pituitary adenomas)