Numerical Simulation for Blood Flow - Microsurgery: Advances, Simulations, and Applications - page 201

at systole phase ( t = 0.25 s) shows vortex low at larger branch after
bifurcation. Vortex low decreases blood low speed and causes the
stagnation of low.

5.5 Outlook for the Future of Computer Fluid

Dynamics

Computer luid dynamics (CFD) utilizing a supercomputer will play
an important role in the ield of medicine and have possibilities of
clinical applications. With the advancement of medical technique,
improvement of CT technology and high-resolution MRI make it
possible to detect a smaller unruptured aneurysm that was not
detected by previous medical devices. As for the frequency of
aneurysm rupture, in 1998, it was reported that the annual rupture
rate of an aneurysm smaller than 10 mm was approximately 0.05%
and for an aneurysm larger than 25 mm was around 6%. 1 Moreover,
according to ISUIA (International Study of Unruptured Intracranial
Aneurysm), 14 the rupture rate of an anterior aneurysm smaller
than 7 mm is less than 0.5% and for the aneurysm larger than 7
mm is from 0.5% to 8% depending on the size; the rupture rate of
posterior aneurysm smaller than 7 mm is from 0.5% to 0.7%, and for
aneurysm larger than 7 mm is around 3% . Also, the annual rupture
rate of giant aneurysm — deined as the aneurysm of size over 25
mm — is said to be around 10% independent of its location. It has
been clear that all aneurysms do not have possibilities of rupture.
There are some cases in which clinical follow-up ensures suficient
safety of aneurysm. Therefore, in some cases, an aggressive medical
treatment for aneurysm is more likely to cause rupture compared
with spontaneous rupture within a year. There is an urgent need of
guidelines for aneurysm treatment that help doctors make decisions
of therapeutic strategy by identifying the risk factor of rupture
based on the result of CFD. In the near future, with the advancement
of processing power and high-speed networks, it will be possible
to evaluate rupture risk of an aneurysm in a short time with high
degree of accuracy through a remotely connected server that has
large amount of patients' historical data of ruptured and unruptured
aneurysms. Therefore, “medical image data (CT, MRI, DSA) + CFD”
will be a medical standard for the diagnosis and management of
aneurysm. Moreover, with the advancement of technology for CFD