Aneurysm is the abnormal bulge of blood vessels. Cerebral stroke, which is caused mainly by cerebral aneurysm, is the third leading cause of death in Japan, and the leading cause of bedridden patients. More specifically, the progress in medical technology and popularization of comprehensive medical examination decreases the percentage of aneurysm as the cause of death. On the other hand, new problems have arisen: swelling medical expenses by the increasing number of bedridden people.
In the past, cerebral aneurysm was treated generally by craniotomy, and by clipping the root of aneurysm to stop the blood flow there. Recently, however, the new method 'endovascular treatment' has been introduced and now we take a new step in the treatment of cerebral aneurysm. Though endovascular treatment is not applicable to all kinds of aneurysm, this method has become noticeable as a less stressful way for patients because it does not require opening the skull.
Endovascular treatment has two main methods to improve the blood flow: placing a coil-like material in the aneurysm, or placing a stent at the entrance of aneurysm. In these methods, a surgical tube, 'catheter' is passed from the base of a foot into the aneurysm to make a path for a coil or a stent. Catheterization procedure requires high technique, and experiential knowledge as well as the operational method is necessary for using a catheter. For example, doctors must get the sense when a catheter touches the vascular wall. So, they need to do operational simulation training many times.
In stenting, it has not been proved which stent is the most appropriate for aneurysm.
In order to verify the effect of stent, we have to quantitatively analyze the stent design and the stent position in the aneurysm to reduce the blood flow effectively.
STENT 
The treatment for cerebral aneurysm, using a coil or a stent has two aims: blocking the blood vessel which flows into the aneurysm and decreasing the velocity of the blood flow in the aneurysm.
Though it is very important to know the change of the blood flow before and after the treatment, the barometer of how the blood flows has not been established.
PIV 
We are now researching the issues in endovascular treatment, especially the one related to the aneurysm treatment. We are also offering a new treatment for aneurysm.
