title: MR angiography of aneurysm models of various shapes and neck sizes.
abstract: OBJECTIVE
  To investigate the signal intensity of lateral and terminal saccular aneurysm models with differing neck sizes using three-dimensional time-of-flight (TOF) MR angiography with various imaging parameters.
  
  
  METHODS
  The study included four lateral and four terminal saccular aneurysm models with pulsatile flow. The height and fundus diameter were 10 mm; the neck diameters were 2.5 mm, 5 mm, 7.5 mm, and 10 mm, respectively. Each aneurysm model was examined with fast imaging with steady-state precession MR sequences with parameters of 20-140/7 (repetition time/echo time) and flip angles of 10 degrees to 30 degrees. Signal intensity was measured and compared among the models.
  
  
  RESULTS
  Three-dimensional TOF MR angiography with the shorter repetition time and/or larger flip angle showed weaker signal intensity in the aneurysm models. Stronger signal intensity was obtained in the terminal saccular aneurysm models and/or the models with a wider neck than in the lateral saccular aneurysm models and/or the models with a narrower neck. In some aneurysm models, longer repetition times produced greater signal intensity than that of background brain models, but not in aneurysms with narrow necks.
  
  
  CONCLUSIONS
  Noncontrast 3-D TOF MR angiography delineated terminal saccular aneurysms and/or aneurysms with wider necks and did not delineate lateral saccular aneurysms and/or aneurysms with narrower necks. Longer repetition times are recommended to allow the spins flowing into the aneurysms to recover.
authors.affiliation: Department of Radiology, Hamamatsu University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Isoda
authors.forename: R G
authors.initials: RG
authors.lastname: Ramsey
authors.forename: Y
authors.initials: Y
authors.lastname: Takehara
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: M
authors.initials: M
authors.lastname: Kaneko
mesh_terms: D016477:Artifacts; D002536:Cerebral Arteries / Q000473:pathology; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002532:Intracranial Aneurysm / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D011673:Pulsatile Flow / Q000502:physiology; D012680:Sensitivity and Specificity