SBA with anastomosis, SBA is used in a 69-year-old woman with unruptured cerebral aneurysm. The SBA branches off a point in the central third of the brachial artery. The anastomosis forms a loop, meaning that the catheter could not be passed through it. The SBA is slightly narrower than the radial artery, so the examination was performed by inserting the catheter into the SBA after arterial infusion of vasodilator.