Abstract:Cushing's disease is a rare neuroendocrine disorder with an incidence of (1.2- 2) ×10 -6 per year,and the most common cause of CD is ACTH-secreting adenoma. ACTH-secreting adenomas which smaller than 10mm are regarded as microadenomas. For those smaller than 6mm, conventional pituitary magnetic resonance imaging cannot visible. During 2018 to March 2022, there are 9 patients diagnosed as ACTH-secreting adenomas in our hospital, of which 6 patients were diagnosed as microadenomas by conventional pituitary magnetic resonance imaging and 1 patient were macroadenomas. Between 2 patients with no visible tumors though conventional MRI, one patient showed a tiny nodule with a diameter of 2mm on high-resolution vessel wall imaging (HR-VWI), which was difficult to be seen on conventional pituitary MRI. On November 1, 2021, the patient underwent neuro-endoscopic tumor resection surgery and the right anterior pituitary nodule shown in HR-VWI was confirmed by pathology to be ACTH-secreting adenoma. As a rare neuroendocrine tumor, the early diagnosis of ACTH adenoma is of great significance for the follow-up treatment selections. HR-VWI would be helpful in the diagnosis of pituitary microadenoma.