Endovascular surgical neuroradiology (ESN), also known as neurointerventional surgery or interventional neuroradiology, is an Accreditation Council for Graduate Medical Education (ACGME) accredited medical subspecialty specializing in minimally invasive image-based technologies and procedures used in diagnosis and treatment of diseases of the head, neck, and spine. While ESN programs can be ACGME accredited, fewer than five programs in the U.S. are accredited. The number of physicians in the United States with an active interest and special competency in this field is estimated to be around 600.