|Time-Resolved (4D) Contrast-Enhanced MRA|
3D Phase Contrast MRA of the Thoracic Aorta at 3T:
Feasibility and Effect of Standard and Blood-Pool Contrast Agents
Jelena Bock1, Alex Frydrychowicz1, Thorsten A. Bley1, Aurelien F. Stalder1, Max F. Russe1, Manuela Keckeis1, Juergen Hennig1, Michael Markl1
1University Hospital Freiburg, Freiburg, Germany
Flow sensitive 4D MRI permits the measurements of three directional blood flow velocities. These data can be used to derive additional information on vascular geometry by phase contrast (PC) angiography. Detailed evaluation of PC angiography image quality in the thoracic aorta compared to the reference standard CE-MRA was performed in a study in 3 groups (without contrast agent, with extravascular and with blood pool contrast agent) on a collective of 31 volunteers. Quantitative and qualitative evaluation of image quality demonstrated that PC-MRA can provide reliable angiography of the thoracic aorta of good quality compared to CE-MRA.
Clinical Applications of Contrast Inflow Dynamics MRA
(CIDA): Novel Approach for ECG-Gated Dynamic Contrast Enhanced MRA
Maggie M. Fung1, Ehud J. Schmidt2, Maureen N. Hood3, Godtfred Holmvang4, Raymond Y. Kwong5, Vincent B. Ho3
1GE Healthcare, Bethesda, Maryland, USA; 2GE Healthcare, Boston, Massachusetts, USA; 3National Naval Medical Center, Bethesda, Maryland, USA; 4Massachusetts General Hospital, Boston, Massachusetts, USA; 5Brigham and Women’s Hospital, Boston, Massachusetts, USA
A novel multiple-temporal-phase ECG-gated 3D contrast enhanced MRA approach with automatic triggering is presented. The efficient use of cardiac cycle for imaging, and a variable-center slice ordering scheme, enable the acquisition of high resolution, motion suppressed, temporally-selective contrast-enhanced images in a parallel manner, thus allowing completion within a single breathhold. This increases the robustness of ceMRA and streamlines workflow in the clinical setting. The flexible temporal selectivity enables visualization of arterial and venous phase with short temporal separation. This technique can also be used to evaluate morphological changes of the vasculatures in different cardiac phases.
Highly Accelerated (>10x) Parallel Acquisition for 3D
Time-Resolved CE-MRA of the Calves
Clifton R. Haider1, Nobert G. Campeau1, James F. Glockner1, John Huston1, Stephen J. Riederer1
1Mayo Clinic, Rochester, Minnesota, USA
The purpose of this work is to describe how 2D SENSE with 2D homodyne processing can be applied to peripheral MRA to provide an order of magnitude (>10X) reduction of acquisition time. It is hypothesized that a 2D SENSE-accelerated CArtesian Projection Reconstruction-Like acquisition can provide a time series of diagnostic quality, 1 mm3 isotropic spatial resolution images of the lower legs with 5 sec update times and 20 sec image acquisition times. Results demonstrate high temporal fidelity, high spatial resolution, and the robust nature of the highly accelerated CE-MRA sequence which can readily distinguish arterial from and venous phase.
Quantification of the in Vivo Kinematics of the
Superficial Femoral Artery Due to Hip and Knee Flexion Using Magnetic
Gilwoo Choi1, Nathan M. Wilson1, Christopher P. Cheng1, Robert J. Herfkens1, Charles Anthony Taylor1
1Stanford University, Stanford, California , USA
The interaction between the musculoskeletal system and the vasculature in the lower extremities plays a major role in determining superficial femoral artery (SFA) deformation. We used magnetic resonance imaging to investigate whether the location of the SFA with respect to the femur contributes to the observed shortening of the SFA with hip and knee flexion. Volume coregistration between two different image acquisitions was performed using the femur geometry as a reference. We found that the proximal part of the SFA moved more inferiorly than the distal segment, which contributed to shortening of the SFA.
Comparison of 3D-TRICKS and 3D Bolus Chase MR
Angiography for Evaluation of Infra-Popliteal Arteries
Xiaoming Zhang1, Honglei Zhang2, Hsien Wang3, Yi Wang2, Martin R. Prince2
1Shandong University Qilu Hospital, Jinan, People's Republic of China; 2Weill Medical College of Cornell University, New York, New York, USA; 3Columbia College, New York, New York, USA
To compare the utility of 3D time resolved MRA and 3D bolus chase MRA for evaluating infra-popliteal arteries, data from 113 patients were reviewed retrospectively. The image quality was determined. Among all of the factors(age, gender, weight, ulcer/gangrene/cellulitis, diabetes, hypertension, CHF and arterial phase duration), only U/G/C and arterial phase duration had statistically significant partial effects indicating TRICKS provides more information in calves with fast flow due to ulceration, gangrene or cellulitis. In patients with slower flow and longer arterial phase with late venous enhancement, TRICKS is unnecessary and may be eliminated to reduce the total Gd dose.
Comparison of HYPR Stack-Of-Stars and HYPR VIPR to
TRICKS in Peripheral CE MRA
Yan Wu1, Kevin Johnson1, Oliver Wieben1, Julia velikina1, Andres Carrillo2, Steven Kecskemeti1, Charles A. Mistretta1, Frank R. Korosec1
1University of Wisconsin-Madison, Madison, Wisconsin, USA; 2GE Healthcare, Evanston, Illinois, USA
HYPR is a reconstruction algorithm that enables rapid frame update rates while providing high SNR and temporal accuracy. In this study, three time-resolved imaging methods were compared, the stack-of-stars acquisition with HYPR reconstruction, the VIPR acquisition with HYPR reconstruction, and 3D Cartesian TRICKs method. The three methods were used to acquire contrast-enhanced MR angiograms of the peripheral vessels in healthy human volunteers. It has been demonstrated that both HYPR methods provide better spatial and temporal resolution than TRICKs; in comparing the HYPR methods, VIPR permits higher undersampling factors (better spatial or temporal resolution), whereas HYPR stack-of-stars is more geometrically suited.
Optimizing Peripheral Contrast-Enhanced MRA Using
A-Priori Knowledge of Bolus Kinetics Through the Optimal Choice of
Imaging Parameters and Acquisition Time<
Jeffrey Harold Maki1, 2, Silke Potthast2, David J. Glickerman1, Cecil E. Hayes2, Maisie E. Wang2, Gregory J. Wilson3
1Puget Sound VAHCS, Seattle, Washington, USA; 2University of Washington, Seattle, Washington, USA; 3Philips Medical, Cleveland, Ohio, USA
Through the a-priori knowledge of individual patient bolus kinetics, optimal timing for single-injection moving table peripheral CE-MRA can be determined to avoid venous enhancement. Knowing this, system specific parameter choices (2D SENSE factor, bandwidth, flip angle, TR and TE) can be uniquely determined to maximize SNR for any given patient at the desired acquisition time. We describe the theory behind these choices, show how to construct protocols to achieve maximal SNR with minimal venous enhancement, and demonstrate clinical examples (MRA vs DSA).
Clinical Experience of HYPR FLOW
YiJing Wu1, Kevin M. Johnson1, Julia Velikina1, Patrick Turski2, Charles A. Mistretta2
1University of Wisconsin, Madison, Wisconsin, USA; 2University of Wisconsin Medical School, Madison, Wisconsin, USA
Phase Contrast (PC) HYPR FLOW employs PC VIPR images as the composite and reconstructs the first pass Time Resolved Contrast Enhanced (TR-CE) VIPR acquisition using HYPR LR technique. HYPR FLOW decouples the temporal resolution, which is defined by TR-CE VIPR acquisition, from the spatial resolution and SNR, which depend on the PC VIPR acquisition, resulting in both high temporal resolution and isotropic spatial resolution with preserved SNR from the PC images. In addition, the phase contrast scan will add flow information to the CE-MRA time frames and provide velocity information suitable for the calculation of hemodynamic parameters such as pressure map and wall shear stress (WSS) which are potentially beneficial for understanding of the physiologic conditions behind diseases such as arterio-venous malformation (AVM). This abstract presents our clinical experience with HYPR FLOW including the contrast waveform fidelity, spatial resolution, SNR improvement over the VIPR method, and the physiological information beyond the contrast enhanced angiography.
|7-Tesla Time-Resolved Contrast-Enhanced 3D MRA
(TWIST) of the Intracranial Vessels
Stefan Maderwald1, 2, Jens M. Theysohn1, 2, Oliver Kraff1, 2, Susanne C. Ladd1, 2, Karsten Wicklow3, Peter Schmitt3, Mark E. Ladd1, 2, Harald H. Quick1, 2
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany; 2Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen, Germany; 3Siemens Medical Solutions, Erlangen, Germany
Three dimensional contrast-enhanced magnetic resonance angiography (CE-MRA) is a well established, reliable, and accurate technique for the evaluation of vascular pathologies of the intracranial vessels at 1.5T. When performing time-resolved 3D MRA of the intracranial vessels, the signal-to-noise ratio (SNR) achievable at 1.5T can be a limiting factor in simultaneously supporting the desired spatial and temporal resolution. In this study we evaluated the potential of 7-Tesla MRA for time-resolved high-resolution 3D CE-MRA of the intracranial vessels using the TWIST (Time-resolved angiography WIth Stochastic Trajectories) technique.
Influence of the Injection Rate on Vessel Signal and
Image Quality in First Pass Imaging with Gadofosveset (Vasovist®)
Henrik Jakob Michaely1, Ulrike I. Attenberger2, Christian Fink1, Maximilian F. Reiser2, Stefan O. Schoenberg1
1University Hosptial Mannheim, Mannheim, Germany; 2University of Munich, Munich, Germany
This study investigates the influence of the injection rate of gadofosvest on the image quality and the vessel enhancement during the steady state. In 21 healthy volunteers three different injection rates (1ml/s, 2ml/s, 4ml/s) were applied. No significant differences could be found in peak signal intensity in the thoracic and abdominal aorta as well as in the kidneys. With a slow injection rate of 1ml/s a significantly longer purely arterial imaging window was achieved.