Qin Qin^1,2, Guanshu Liu^1,2, Ye Qiao¹, and Dexiang Liu^1,2,3
1Radiology, Johns Hopkins University, Baltimore, MD, United States, ²F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, ³Radiology, Panyu District Central Hospital, Guangzhou, China, People's Republic of

Time-resolved non-contrast-enhanced MR angiography (NCE-MRA), by providing hemodynamic flow patterns, is promising for many vascular disorders. Conventional techniques remove tissue background using various arterial spin labeling (ASL) approaches with paired subtraction of control and label scans. Here a new multi-phase MRA method is introduced that achieves background suppresstion by applying a tissue mask, which is derived from thresholding a velocity-selective MRA (VSMRA) obtained at the end of the cycle. The feasibility of this new single-scan dynamic approach was demonstrated on extracranial and intracranial vasculatures of healthy volunteers at 3T. 

Ioannis Koktzoglou^1,2, Matthew T Walker^1,2, Joel R Meyer^1,2, Ian G Murphy^1,3, and Robert R Edelman^1,3
1Radiology, NorthShore University HealthSystem, Evanston, IL, United States, ²University of Chicago Pritzker School of Medicine, Chicago, IL, United States, ³Northwestern University Feinberg School of Medicine, Chicago, IL, United States

Nonenhanced hybridized arterial spin labeling (hASL) magnetic resonance angiography (MRA) using a fast low-angle shot (FLASH) readout was used to image the extracranial carotid arteries at 3 Tesla. Comparisons were made with 2D time-of-flight (TOF) MRA and contrast-enhanced MRA. Image quality obtained hASL FLASH MRA was found to be superior to that 2D TOF, with the method also providing improved inter-rater agreement, quantification of arterial cross-sectional area, and vessel sharpness.

Chengcheng Zhu¹, Bing Tian², Florent Seguro¹, Joe Leach¹, Qi Liu², Jianping Lu², Luguang Chen², Michael Hope¹, and David Saloner^1
1Radiology, University of California, San Francisco, San Francisco, CA, United States, ²Radiology, Changhai Hospital, Shanghai, China, People's Republic of

Computed Tomography angiography (CTA) is the gold standard for abdominal aortic aneurysm (AAA) imaging, but requires radiation and iodinated contrast. We previously developed an isotropic 3D black blood technique (DANTE-SPACE) for AAA imaging. In this study we validated 3D MRI against CTA for AAA diameter and volume measurement, and found excellent accuracy and reproducibility. Features of intra-luminal thrombus (ILT) composition that are possibly related to faster AAA growth can be identified on 3D MRI but not on CTA. 3D black blood MRI can be used as a non-invasive tool for AAA serial monitoring and ILT evaluation and has the potential to improve patient risk stratification. 

Chengcheng Zhu¹, Thomas Hope¹, Henrik Haraldsson¹, Farshid Faraji¹, David Saloner¹, and Michael Hope^1
1Radiology, University of California, San Francisco, San Francisco, CA, United States

Abdominal aortic aneurysms (AAAs) with focal inflammation (identified by USPIO uptake) have been reported to predict faster growth. Previous 2D T2* mapping method is limited by spatial resolution. This study evaluated 3D high-resolution techniques (up to 1.3mm isotropic) for inflammation imaging of AAAs. Experiments were preformed using both USPIO phantoms and in vivo patient studies. We found the signal characteristics of 3D DANTE-SPACE images had good agreement with T2* value drop, and it provided higher resolution and possible information on USPIO concentration. Therefore, 3D high resolution methods may help risk stratify patients with AAA disease by characterizing and quantifying inflammation.

Jessica AM Bastiaansen¹, Davide Piccini^1,2, Ruud B van Heeswijk^1,3, and Matthias Stuber^1,3
1Department of Radiology, University hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, ²Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland, ³Center for Biomedical Imaging, Lausanne, Switzerland

Large volume fat suppression is increasingly challenging at high magnetic field strengths due to B₀ and B₁ inhomogeneities. In this study, we developed a novel lipid-insensitive binomial off-resonant (LIBRE) radiofrequency excitation pulse to achieve near-complete fat suppression in large 3D volumes and applied it to whole-heart coronary imaging at 3T. In 6 healthy volunteers, we performed free-breathing self-navigated whole-heart 3D radial coronary MRA, and quantitatively compared the results to more commonly used methods for lipid nulling. We show that LIBRE significantly improves the signal nulling of lipid resonances resulting in both improved blood pool delineation for self-navigation and increased vessel conspicuity in the final images.

Giulia Ginami¹, Davide Piccini^1,2, Pierre Monney³, Pier Giorgio Masci³, and Matthias Stuber^1,4
1University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, ²Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland, ³Division of Cardiology and Cardiac MR Center, University Hospital of Lausanne (CHUV), Lausanne, Switzerland, ⁴Center for Biomedical Imaging (CIBM), Lausanne, Switzerland

The performance of Self-Navigation (SN) for respiratory motion compensation in 3T whole-heart coronary MRA may be compromised by contrast variations secondary to slow-infusion of a contrast agent. In this study, we quantitatively and successfully tested the hypothesis that an Iterative approach to SN (IT-SN) leads to improved performance during slow infusion.

Mark L. Schiebler¹, Michael D. Repplinger², Christopher Lindholm³, John Harringa², Christopher J. François¹, Karl K. Vigen¹, Azita G. Hamedani², Thomas M. Grist^1,4,5, Scott B. Reeder^1,2,4,6, and Scott K. Nagle^1,5,7
1Radiology, UW-Madison, Madison, WI, United States, ²Emergency Medicine, UW-Madison, Madison, WI, United States, ³UW Madison School of Medicine, UW-Madison, Madison, WI, United States, ⁴Biomedical Engineering, UW-Madison, Madison, WI, United States, ⁵Medical Physics, UW-Madison, Madison, WI, United States, ⁶Medicine, UW-Madison, Madison, WI, United States, ⁷Pediatrics, UW-Madison, Madison, WI, United States

The aim of this study was to determine the effectiveness of pulmonary magnetic resonance angiography (PE-MRA) for the primary diagnosis of pulmonary embolism (PE). We retrospectively reviewed the electronic medical records of 675 consecutive patients who underwent PE-MRA. Adverse events (venous thromboembolism (VTE), bleeding or death) that were potentially related either to  over or under treatment of PE during the subsequent 6 months  were extracted from the electronic medical record. The negative predictive value for this test was found to be 97%. Based upon these outcomes, PE-MRA performs similarly to CTA as a primary test to exclude clinically significant pulmonary embolism in patients presenting acutely with dyspnea.

Salvatore Saporito¹, Ingeborg H.F. Herold ^1,2, Patrick Houthuizen³, Jacques A. den Boer¹, Harrie C.M. van den Bosch⁴, Hendrikus H.M. Korsten ^1,2, Hans C. van Assen¹, and Massimo Mischi^1
1Department of Electrical Engineering, Eindhoven University of technology, Eindhoven, Netherlands, ²Department of Anesthesiology and Intensive Care, Catharina Hospital Eindhoven, Eindhoven, Netherlands,³Department of Cardiology, Catharina Hospital Eindhoven, Eindhoven, Netherlands, ⁴Department of Radiology, Catharina Hospital Eindhoven, Eindhoven, Netherlands

Objective measures to assess pulmonary circulation status would improve heart failure patient care. We propose a method for the characterization of the transpulmonary circulation by DCE-MRI. Parametric deconvolution was performed between contrast agent first passage time-enhancement curves derived from the right and left ventricular blood pool. The transpulmonary circulation was characterized as a linear system with impulse response modelled as local density random walk model. We tested the method on 32 heart failure patients and 19 healthy volunteers; patients presented longer transpulmonary transit times and more skewed transpulmonary impulse responses.

Jeffrey H Maki¹ and Gregory J Wilson^1
1Radiology, University of Washington, Seattle, WA, United States

Gadolinium contrast for CE-MRA is typically injected at a fixed, relatively fast (1.5 – 2.0 mL/s) rate.  This results in a peaked bolus profile such that vascular signal intensity (SI) decays during latter k-space acquisition, leading to blurring and ringing artifacts.  A “tailored” test bolus-based predictive algorithm was developed to determine a patient-individualized multi-phase injection to achieve any arbitrary arterial SI “plateau” duration.  This technique was tested on 10 patients and compared to 10 patients receiving a fixed 1.6 mL/s contrast injection.  The tailored bolus plateau duration was 24 vs. 9 s (p < 0.01) with only a 20% SI loss.

Fei Han¹, Ziwu Zhou¹, Takegawa Yoshida¹, Kim-Lien Nguyen^1,2, Paul J Finn¹, and Peng Hu^1
1Radiology, University of California, Los Angeles, Los Angeles, CA, United States, ²Division of Cardiology, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, United States

We proposed a cardiac and respiratory self-gated, 4D multi-phase steady-state imaging with contrast (MUSIC) technique for detailed evaluation of cardiovascular anatomies. A rotating cartesian k-space sampling pattern was designed that integrates frequently sampled k-space centerline as self-gating signal and allows retrospective data-binning based on derived motion signal. Phantom and in-vivo results on 7 clinical indicated pediatric CHD patients show that the proposed self-gated MUSIC could potentially eliminates the need of external physiological signal for motion gating, has increased scan efficiency while maintaining or exceeding the image quality of the original MUSIC.