ultrasound guidance. There are four types of catheters that can be used: angled vertebral catheter for usual cases, Judkins right coronary catheter (Terumo) for tourtous vessels, Simmons's catheter and Mani's head hunter catheter (Terumo) for extremely tortous vessels. A 5Fr sheath is also placed within and flushed with heparinised saline to prevent clotting around the sheath. In terms of guidewire, Terumo hydrophilic Glidewire 0.035 inches can be used. To prevent embolism (either due to blood clot or air embolism, "double flush" and "wet connect" techniques are used. In "double flush" technique, a saline syringe is used to aspirate blood from the catheter. Then, a second heparinised saline syringe is used to flush the catheter. "Wet connect" is the technique that connects syringe to a sheath without air bubbles within. Digital subtraction angiography is the main technique of imaging the cerebral blood vessels. Catheter should be advanced over the guidewire. Rotating the catheter during advancement is also helpful. Roadmap (superimposing previous image on live fluoroscopic image) is used to advance catheters or guidewires before any vessel bifurcation can help to prevent vessel dissection. After the catheter is in position, guidewire is removed slowly with heparinised saline dripping into the catheter at the same time to prevent air embolism. Prior to contrast injection, backflow of the catheter should be established to ensure there is no wedging, dissection, or intracatheter clotting. During the catheterisation of vertebral artery, extra care should be taken to prevent vessel dissection or vasospasm. Delayed or incomplete contrast washout may indicate vasospasm or dissection. Radiographic views Cervical arch angiogram is taken if there is any suspicion of aortic arch narrowing, or any anatomical variants such as bovine arch (brachiocephalic trunk shares a common origin with left common carotid artery). If such abnormality is present, it results it difficulty in cannulation of the main branches of the aortic arch. The catheter of choice to cannulate this area is pigtail catheter with multiple side holes. Contrast injection rate of 20 to 25ml/sec is given with total volume of 40 to 50 ml of contrast. The frame rate of fluoroscopy is 4 to 6 frames per second. The image is taken in with the x-ray tube in left anterior oblique position. To image the vessels of the neck such as common carotid, internal and external carotid arteries, AP, lateral, and 45 degrees bilateral oblique positions are taken. Contrast injection rate is 3