ISMRM 24th Annual Meeting & Exhibition 07-13 May 2016 Singapore

Combined Educational & Scientific Session: The Singapore Flyer of Vascular Imaging

Skill Level: Intermediate to Advanced

Organizers: Martin J. Graves, Ph.D. & Jeanette Schulz-Menger, M.D.

Thursday 12 May 2016

This session will provide an overview of cutting-edge techniques in both contrast and non-contrast enhanced magnetic resonance angiography (MRA) and also demonstrate the use of quantitative flow imaging techniques for assessing how abnormal blood flow impacts on cardiovascular disease. Invited presentations will be interleaved with cutting-edge scientific developments.

Target Audience
Clinicians, scientists and engineers who wish to gain an in-depth perspective on the technical foundations and clinical applications of state-of-the-art magnetic resonance angiograpy and flow imaging techniques.

Educational Objectives
Upon completion of this course, participants should be able to:

  • Critically appraise recent developments in MRA and investigate how they could be applied clinically;
  • Evaluate the role of flow imaging techniques as hemodynamic biomarkers of disease; and
  • Review and integrate the latest scientific developments in the field into their own practice.

Moderators: Martin Graves, Konstantin Nikolaou
Advanced Techniques for  MRA - Permission Withheld
Gabriele Krombach
Contrast enhanced and non-contrast enhanced MR angiography represent the two main methods for delineation of vessels. In contrast enhanced MRA, classically spatial resolution and temporal resolution have to be balanced against each other. View sharing and central read out of k-space have been introduced for subsecond acquisition of high resolution dynamics. This technique has a broad spectrum of clinical applications. In non-contrast MRA the classical approaches time-of-flight and phase contrast angiography suffered from long acquisition time and were prone to flow artifacts in regions with non-laminar flow. Application of balanced steady state free precession with flow sensitive dephasing allows for selective delineation of arteries with high signal intensity and high spatial resolution without flow related artefacts. This technique has already been demonstrated to be of high clinical impact in many vessel territories including the upper and lower extremities.  

Feasibility of Time-Resolved Subtractionless Contrast Enhanced Dixon MRA of the lower legs on 1.5T
Marc Kouwenhoven1, Silke Hey1, Christine Nabuurs1, Alan Huang1, Adri Duijndam1, Elwin de Weerdt1, Holger Eggers2, Niels Blanken3, and Tim Leiner3
1Philips, Best, Netherlands, 2Philips Research, Hamburg, Germany, 3Radiology Dept., University Medical Center, Utrecht, Netherlands
In this work, the feasibility is explored for subtractionless first-pass time-resolved contrast enhanced MRA of the lower legs on 1.5T using Dixon, viewsharing and parallel imaging with high acceleration factors. Results in seven consecutive patients are analyzed and compared with the conventional subtraction method.  It is demonstrated that with the subtractionless method, bulk motion artifacts are eliminated, and SNR is significantly increased.

Clinical Performance of a Non-contrast MR Angiography Protocol in the Pre-Transplant Evaluation of the Liver Vasculature
Jeremy Collins1, Eric Keller2, Edouard Semaan3, Riad Salem2, Maria Carr2, Michael Markl2, and James C Carr2
1Radiology, Northwestern University, Chicago, IL, United States, 2Northwestern University, Chicago, IL, United States, 3Chicago, IL, United States
Assessment of the hepatic vasculature is critical as part of the pre-liver transplant evaluation. The prevalence of renal insufficiency and concerns regarding gadolinium administration in this cohort has created a need for a non-contrast alternative for vascular assessment. We evaluated the clinical performance of a non-contrast MRA (NCMRA) protocol at 3T in the assessment of the hepatic vasculature in patients with cirrhosis, with contrast-enhanced MRA (CEMRA) as the reference standard. The NCMRA protocol was diagnostic in 94% of subjects, identifying all relevant variant anatomy. Clinically available NCMRA techniques when combined into a comprehensive protocol enable assessment of the hepatic vasculature. 

Advanced Techniques for Flow Imaging
Michael Hope1
We will focus on the emerging applications of multidimensional MR flow imaging (4D Flow). The techniques and hemodynamic biomarkers that we will discuss can be applied broadly throughout the cardiovascular system. Two key issues must be addressed when considering these applications: 1) clear advantages over ultrasound/echocardiography and 2) matching advanced imaging capabilities with clinical questions that change the management of patients with cardiovascular disease. The goal is to provide a unique understanding of how abnormal flow promotes or exacerbates disease. This understanding, in turn, could allow patients to be risk-stratified based on flow, guide medical therapy, and identify new pathways to target with drug therapy and patients that may benefit from early intervention. The outline of the talk is 1) review of two current clinical applications for MRI flow imaging and 2) discussion of four emerging applications for 4D Flow. 

Impact of Bicuspid Aortic Valve Fusion Phenotype and Valve Stenosis on Aortic 3D Hemodynamics: New Insights from a Large Cohort 4D Flow MRI Study in 312 subjects
Alex J Barker1, Pim van Ooij2, Emilie Bollache1, David Guzzardi3, S. Chris Malaisrie4, Patrick M McCarthy4, Jeremy D Collins1, James Carr1, Paul WM Fedak3, and Michael Markl1,5
1Radiology, Northwestern Univeristy, Chicago, IL, United States, 2Academic Medical Center, Amsterdam, Netherlands, 3University of Calgary, Calgary, AB, Canada, 4Cardiac Surgery, Northwestern Univeristy, Chicago, IL, United States, 5Bioengineering, Northwestern University, Chicago, IL, United States
Bicuspid aortic valve (BAV) morphology will alter transvalvular blood flow patterns and vessel wall shear stress (WSS). These hemodynamic changes have been associated with the regional expression of BAV aortopathy. However, the presence of aortic stenosis can confound the regional expression of WSS. The purpose of this study was to use aortic WSS atlases to understand the role of aortic valve morphology and stenosis on the expression of WSS in the ascending aorta of a large control and BAV patient cohort (n=312).

MRI assessment of aortic flow in patients with pulmonary hypertension in response to exercise
Jacob Macdonald1, Omid Forouzan2, Naomi Chesler2, Christopher Francois3, and Oliver Wieben1,3
1Medical Physics, University of Wisconsin - Madison, Madison, WI, United States, 2Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States, 3Radiology, University of Wisconsin - Madison, Madison, WI, United States
Cardiopulmonary exercise testing is gaining increased recognition as a useful tool for assessing pulmonary hypertension (PH). Using an MRI-compatible exercise device that allows subjects to exercise in the bore of the magnet, we investigated the effects of exercise stress on blood flow in the ascending aorta in healthy controls and patients with PH. The measurements we obtained demonstrated a decreased exercise capacity in PH subjects and in older controls. Some parameters, such as cardiac output, demonstrated statistically significant changes between rest and stress, while others were unclear due to the relatively low exercise power tolerated by the PH patients.

Adjournment & Meet the Teachers

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
Continuing Medical Education to provide continuing medical education for physicians.