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FIG 1. Acquisition geometry for precontrast (A) and postcontrast (B, C) 3D TOF MR angiography.
A, Two-slab acquisition used to cover the distal extracranial vessels as well as the intracranial circulation (dashed line indicates slab boundary).
B and C, Oblique-axial slabs used to image the intracranial circulation. Slab placement in C was optimal as it excludes the cavernous sinus and thus avoids venous enhancement (dotted line indicates slab position). Effective placement in C can be obtained by projection through only a subset of the sections acquired in B.
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