Unenhanced Dynamic MR Angiography: High Spatial and Temporal Resolution by Using True FISP–based Spin Tagging with Alternating Radiofrequency

Abstract

Purpose:To present an unenhanced four-dimensional time-resolved dynamic magnetic resonance (MR) angiography technique with true fast imaging with steady-state precession-based spin tagging with alternating radiofrequency (STAR), also called TrueSTAR. Materials and Methods:This study received Institutional Review Board approval and was HIPAA compliant. Informed consent was obtained from all study subjects. In eight healthy volunteers, the spatial and temporal resolution of the TrueSTAR technique were optimized. In another six healthy volunteers, the contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) of the TrueSTAR dynamic MR angiography images were compared with those acquired by using a standard Look-Locker echo-planar technique by using the Wilcoxon signed rank test. Finally, one patient with an arteriovenous malformation (AVM) was studied by using this technique. Results:The SNR and CNR of the TrueSTAR dynamic MR angiography images were 29% and 39% higher, respectively, compared with those acquired by using a standard LookLocker echo-planar imaging sequence (both P = .028).In the AVM patient, TrueSTAR dynamic MR angiography delineated the dynamic course of labeled blood fl owing through feeding arteries into the nidus and draining veins. Conclusion:The results suggest that TrueSTAR is a promising unenhanced dynamic MR angiography technique for clinical evaluation of cerebrovascular disorders such as AVM, steno-occlusive disease, and aneurysm.q RSNA, 2010Supplemental material: http://radiology.rsna.org/lookup /suppl

Nonenhanced ECG-gated time-resolved 4D Steady-state free precession (SSFP) MR angiography (MRA) for assessment of cerebral collateral flow: comparison with digital subtraction angiography (DSA)

“…By comparison, 4D SSFP MRA might provide both anatomical and hemodynamic information using a reasonably short MR sequence lasting 4-6 min. As axial, sagittal and coronal MIP images are immediately available for analysis due to in-line post processing [17] this imaging technique can be easily implemented in routine clinical care.…”

“…For 4D SSFP MR angiography, two magnetizationprepared and ECG-triggered 4D datasets were acquired with a TrueFISP CINE sequence in segmented fashion [17]. In each cardiac cycle, upon detection of the ECG R-wave, an inversion preparation pulse was played out followed by acquisition of N temporal phases.…”

“…With ASL, imaging contrast depends on the difference from measurements with and without magnetic labelling [15]. ASL techniques with varying delay times in combination with ECG-gated SSFP MRA techniques may provide dynamic MR angiographies, yielding both hemodynamic and anatomical information [16,17]. The purpose of this study was to evaluate a noncontrast-enhanced time-resolved 4D steady-state free precession MRA (4D SSFP MRA) for dynamic visualization of intracranial collateral flow in patients with stenoocclusive disease of brain-supplying arteries in comparison to conventional DSA.…”

Noninvasive Evaluation of Cerebral Arteriovenous Malformations by 4D-MRA for Preoperative Planning and Postoperative Follow-Up in 56 Patients: Comparison with DSA and Intraoperative Findings

“…Other techniques have been developed for time-resolved MRA of intracranial vessels including undersampling k-space techniques such as time-resolved imaging of contrast kinetics (TRICKS), 33 timeresolved echo-shared angiography technique (TREAT), 12,34 phase contrast highly constrained back-projection reconstruction (PC-HYPR), 35 flow-sensitive 4D-MRA, 36 and, more recently, unenhanced dynamic MRA by using true free induction with steady-state precession-based spin-tagging with alternating radio-frequency. 37 Promising first results have been presented by using these techniques, which will require further evaluation in clinical trials with the ultimate goal of substituting them for DSA in the future. 38,39 The change of equipment and contrast agents during the recruitment period of this study allows evaluation of the impact of 2 different scan protocols and the application of a highmolar macrocyclic contrast agent instead of a standard-molarity linear contrast agent.…”

Hemodynamic Quantification in Brain Arteriovenous Malformations With Time-Resolved Spin-Labeled Magnetic Resonance Angiography

“…4,5 Recently, unenhanced time-resolved spin-labeled MRA (4D-SL-MRA) has been reported to allow anatomic AVM characterization reliably 3 and to overcome previous limitations by achieving high temporal resolutions of 50 to 100 ms, [6][7][8] thus reducing vessel superposition 9 and increasing the accuracy of further quantitative analysis.…”