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AJNR - American Journal of Neuroradiology

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Contrast-enhanced MR Angiography: The Effects of k-Space Truncation on Luminal Representation in a Carotid Artery Phantom Model

Elias R. Melhem^a, Jean-Micheal Serfaty^a, Lisa Jones^a, Ryuta Itoh^a, Brian S. Kuszyk^a, Jean-Baptiste Martin^a, Philippe Gailloud^a, Kieran P.J. Murphy^a and Daniel A. Rufenacht^a

^a From the Department of Radiology and Radiological Sciences (E.R.M., J.-M.S., L.J., R.I., B.S.K., P.G., K.P.J.M.), The Johns Hopkins Hospital, Baltimore, MD, and the Department of Radiology (J.-B.M., D.A.R.), Geneva University Hospital, Geneva, Switzerland.

View larger version (73K): [in a new window]   FIG 1. Digital radiographs of the iodinated contrast-material–filled carotid artery phantom models. The measured degree of stenosis is 38% for phantom 1, 61% for phantom 2, 80% for phantom 3, and 92% for phantom 4

View larger version (79K): [in a new window]   FIG 2. 2D projectional images of 3D k-space data. A, Superimposed squares show the percentages of k-space used to generate corresponding different MR angiographic maximum intensity projections (4.1/1.5, flip angle of 30°) of the phantom. B, Inverse Fourier transform of 2D projectional image is an MR angiographic image of phantom 2. Adequate luminal representation is maintained at 50% k-space, but is lost at 10% k-space.

View larger version (55K): [in a new window]   FIG 3. MR angiographic maximum intensity projections (4.1/1.5, flip angle of 30°) of phantom 4 show that luminal representation is maintained at 60% k-space, but is lost at 50% k-space (arrows)

View larger version (20K): [in a new window]   FIG 4. Plot of the ratio of luminal stenosis in the four phantoms shown by MR angiography (4.1/1.5, flip angle of 30°) divided by the standard of reference as a function of percent k-space. The ratio deviates from unity at higher percent k-space for phantoms with greater severity of stenosis