title: 4D digital subtraction angiography: implementation and demonstration of feasibility.
abstract: OBJECTIVE
  Conventional 3D-DSA volumes are reconstructed from a series of projections containing temporal information. It was our purpose to develop a technique which would generate fully time-resolved 3D-DSA vascular volumes having better spatial and temporal resolution than that which is available with CT or MR angiography.
  
  
  METHODS
  After a single contrast injection, projections from the mask and fill rotation are subtracted to create a series of vascular projections. With the use of these projections, a conventional conebeam CT reconstruction is generated (conventional 3D-DSA). This is used to constrain the reconstruction of individual 3D temporal volumes, which incorporate temporal information from the acquired projections (4D-DSA).
  
  
  RESULTS
  Typically, 30 temporal volumes per second are generated with the use of currently available flat detector systems, a factor of ∼200 increase over that achievable with the use of multiple gantry rotations. Dynamic displays of the reconstructed volumes are viewable from any angle. Good results have been obtained by using both intra-arterial and intravenous injections.
  
  
  CONCLUSIONS
  It is feasible to generate time-resolved 3D-DSA vascular volumes with the use of commercially available flat detector angiographic systems and clinically practical injection protocols. The spatial resolution and signal-to-noise ratio of the time frames are largely determined by that of the conventional 3D-DSA constraining image and not by that of the projections used to generate the 3D reconstruction. The spatial resolution and temporal resolution exceed that of CTA and MRA, and the small vessel contrast is increased relative to that of conventional 2D-DSA due to the use of maximum intensity projections.
authors.affiliation: University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors.forename: B
authors.initials: B
authors.lastname: Davis
authors.forename: K
authors.initials: K
authors.lastname: Royalty
authors.forename: M
authors.initials: M
authors.lastname: Kowarschik
authors.forename: C
authors.initials: C
authors.lastname: Rohkohl
authors.forename: E
authors.initials: E
authors.lastname: Oberstar
authors.forename: B
authors.initials: B
authors.lastname: Aagaard-Kienitz
authors.forename: D
authors.initials: D
authors.lastname: Niemann
authors.forename: O
authors.initials: O
authors.lastname: Ozkan
authors.forename: C
authors.initials: C
authors.lastname: Strother
authors.forename: C
authors.initials: C
authors.lastname: Mistretta
mesh_terms: D015901:Angiography, Digital Subtraction / Q000295:instrumentation / Q000379:methods*; D000818:Animals; D016208:Databases, Factual; D005240:Feasibility Studies; D056973:Four-Dimensional Computed Tomography / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods*; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging*; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio