Advanced

AJNR - American Journal of Neuroradiology

This Article Abstract Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Cashen, T.A. Articles by Carroll, T.J. Search for Related Content PubMed PubMed Citation Articles by Cashen, T.A. Articles by Carroll, T.J.

Intracranial Time-Resolved Contrast-Enhanced MR Angiography at 3T

T.A. Cashen^a, J.C. Carr^b, W. Shin^a, M.T. Walker^b, S.F. Futterer^b, A. Shaibani^b, R.M. McCarthy^b and T.J. Carroll^a,b

^a Department of Biomedical Engineering, Northwestern University, Feinberg School of Medicine of Northwestern University, Chicago, Ill
^b Department of Radiology, Feinberg School of Medicine of Northwestern University, Chicago, Ill

View larger version (36K): [in a new window]   Fig 1. Comparison of the TRICKS and TREAT acquisition schemes. The segmentation methods are shown in panel A. In panel B, the distance of each sample from the center of k-space (kr) is plotted as a function of time to demonstrate the different ordering methods. Notice that the TREAT scheme acquires data without discontinuities in kr.

View larger version (31K): [in a new window]   Fig 2. For enhanced intra-arterial blood: signal intensity versus flip angle at 1.5T and 3T (A), signal intensity versus flip angle and TR at 3T (B), and the ratio of 3T to 1.5T signals versus normalized flip angle and TR (C). The normalized flip angle was that which yielded an equivalent SAR at 1.5T. Missing values at high flip angles and low TRs were experimentally determined to exceed the SAR threshold.

View larger version (123K): [in a new window]   Fig 3. A qualitative comparison of S/N at 1.5T (A and C) and 3T (B and D) with timed coronal acquisitions is shown in these arterial phase mask subtraction MIP images. Magnified views (C and D) demonstrate better depiction of small distal middle cerebral arterial branches (circled) at 3T because of increased S/N.

View larger version (112K): [in a new window]   Fig 4. Timed coronal (A) and sagittal (B) MRAs at 3T of different AVM patients are shown in these subtracted MIP images. Despite high S/N and spatial resolution, low temporal resolution makes it difficult to determine the order in which vessels fill and the direction of flow. Early venous enhancement (arrows) due to arteriovenous shunting is present and "degrades" the arterial phase.

View larger version (143K): [in a new window]   Fig 5. Time-resolved sagittal MRA at 3T of healthy volunteer. Consecutive timeframes are shown with temporal resolution of 2.5 seconds/frame and spatial resolution of 1.0 x 1.0 x 2.5 mm.

View larger version (141K): [in a new window]   Fig 6. Time-resolved sagittal MRA at 3T of an AVM patient. Consecutive MIP timeframes are shown with temporal resolution of 2.5 seconds/frame and spatial resolution of 1.0 x 1.0 x 2.5 mm. Notice subtle early venous enhancement in the sagittal sinus during the early arterial phase (A, arrows) before enhancement of the basal vein of Rosenthal (C, arrow).

View larger version (77K): [in a new window]   Fig 7. Consecutive timeframes of a conventional radiographic angiogram (A–D) and a 3D MIP MR angiogram (E and F) of the same patient with an arteriovenous malformation. The MR imaging is displayed with inverse grayscale contrast for better comparison. Conventional radiographic images are temporally blurred (G and H) for comparison with the MR images. For the radiographic and MR angiograms, respectively, the spatial resolutions are 0.1 x 0.1 and 1.0 x 1.0 x 2.5 mm and the temporal resolutions are 0.3 seconds/frame and 2.5 seconds/frame, respectively.