title: Magnetic resonance fluid dynamics for intracranial aneurysms--comparison with computed fluid dynamics.
abstract: BACKGROUND
  Hemodynamics in intracranial aneurysms is thought to play an important role in their growth and rupture. Usual computed fluid dynamics (CFD) based on three-dimensional (3D) computed tomographic (CT) angiography requires a time-consuming process for analysis. Magnetic resonance fluid dynamics (MRFD) based on MR images is a new tool for analyzing flow dynamics and a promising method for obtaining such information more easily. We compared the data from MRFD and CFD and studied the clinical feasibility of MRFD.
  
  
  METHODS
  A total of 15 aneurysms, including two ruptured ones, in 15 patients were investigated with MR imaging and 3D-CT angiography. The flow data of MRFD and CFD, 3D stream lines, flow velocity profile and wall shear stress (WSS) were extracted from the image reconstruction and were compared each other.
  
  
  RESULTS
  Both flow dynamics images showed quite similar 3D flow pattern and WSS map. However, the calculated value of maximum WSS was quite different and there was no significant correlation. Further, in one ruptured case, CFD showed less visualization to evaluate the intra-aneurysmal flow. Interestingly, one delayed rupture case showed a particular flow pattern with abnormal secondary flow in the bottom of the aneurysm before rupture, which might suggest the specific finding of rupture risk.
  
  
  CONCLUSIONS
  MRFD is a valuable and less invasive tool to evaluate aneurysmal fluid dynamics. It can be obtained from the usual MRI examination without contrast medium and exposure to radiation. Although there is a problem of consistency of the absolute value of WSS between MRFD and conventional CFD, it may be useful to predict the risk of enlargement or rupture of aneurysms based on the information of the similar distribution of WSS and flow patterns. The quantifiable analysis and establishment of a meaningful threshold for high risk should be further studied.
authors.affiliation: Department of Neurosurgery, Nagoya University Graduate School of Medicine, Showa-ku, Aichi, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Naito
authors.forename: Shigeru
authors.initials: S
authors.lastname: Miyachi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Matsubara
authors.forename: Haruo
authors.initials: H
authors.lastname: Isoda
authors.forename: Takashi
authors.initials: T
authors.lastname: Izumi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Haraguchi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takahashi
authors.forename: Katsuya
authors.initials: K
authors.lastname: Ishii
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Wakabayashi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002533:Cerebral Angiography / Q000379:methods; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D003198:Computer Simulation; D005260:Female; D006801:Humans; D057446:Hydrodynamics; D021621:Imaging, Three-Dimensional / Q000379:methods*; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000503:physiopathology* / Q000628:therapy; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods; D013345:Subarachnoid Hemorrhage / Q000503:physiopathology / Q000517:prevention & control; D014057:Tomography, X-Ray Computed / Q000379:methods*