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Tolga Çukur¹, Michael Lustig¹, Dwight Georger Nishimura¹

¹Stanford University, Stanford, California , USA

Flow-independent angiography offers the ability to produce vessel images without contrast agents. 3D magnetization-prepared balanced SSFP can be used to acquire these angiograms, where the phase encodes are interleaved and preparation is repeated prior to the start of each interleave. However, frequent repetition of the preparation significantly reduces the scan efficiency. The sparsity of the angiograms allows for the use of compressed sensing to undersample the phase encodes and save scan time. These savings can be allotted for preparing the magnetization more often, or alternatively, improving resolution.

Andrew Nicholas Priest¹, Martin John Graves¹, Pauline Wong¹, David John Lomas¹

¹Addenbrooke's Hospital and University of Cambridge, Cambridge, UK

Preparation modules containing ‘diffusion weighting’ or motion-sensitising gradients have recently been used to suppress the blood signal in images of the vessel wall. Since the blood suppression can be selectively applied, it is possible to produce subtraction images which selectively depict the vascular anatomy while suppressing the signal from static tissues. Furthermore, by acquiring images with different degrees of suppression, images which selectively depict either arteries or veins can be produced. This work demonstrates high-resolution 3D vascular images in the lower leg in healthy volunteers, and might be applied to clinical situations which currently require contrast agent administration.

Michael Langham¹, Tom Floyd¹, Jeremy Magland¹, Emile Mohler, III¹, Felix W. Wehrli¹

¹University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA

We demonstrate MR susceptometry-based oximetric quantification of reactive hyperemia in response to cuff-induced ischemia by making direct time-course measurement of oxygen saturation level in the femoral artery and vein of both normal subjects and patients with peripheral arterial disease (PAD). The washout time and the upslope were significantly longer and less, respectively, for PAD patients compared to normal. The washout time refers to the time required to observe oxygen depleted venous blood that is washed out of the capillary bed during the reactive hyperemia and the upslope correspond to the reoxygenation rate in the vein after the washout.

Pauline Wong¹, Martin John Graves¹, David John Lomas¹

¹University of Cambridge and Addenbrooke's Hospital, Cambridge, UK

Fresh Blood Imaging, a non-contrast enhanced 3D MRA technique, has been implemented for the real-time imaging environment and demonstrated in healthy volunteers.  As the technique is directly related to the pulsatility of the vessel flow, a time consuming prep scan is typically used to calculate the systole and diastole trigger delays.  We have implemented a 2D version in real-time and used a rapid flow measurement as the prep scan for calculating trigger delays.  Localisation, navigation, flow measurement and FBI angiography were performed in a single scan/sequence.  Results in peripheral vessels are shown with T_acq~0.5-1min (8 averages).

Jian Xu¹, Peter Weale¹, Laub Gerhard¹, Peter Schmitt², Jaeseok Park², Bernd Stoeckel¹, Qun Chen³, Ruth P. Lim³, Andrew Hardie³, Pippa Storey³, Elizabeth Hecht³, Kellyanne Mcgorty³, Vivian S. Lee³

¹Siemens Medical Solutions USA Inc., Malvern, Pennsylvania, USA; ²Siemens Medical Solutions, Erlangen, Germany; ³New  York University, New York, New York, USA

A Novel Non-contrast MRA Technique using Triggered 3D SPACE for Improved Spatial Resolution and Speed is developed, which uses selective RF excitation, non selective RF refocusing pulses and variable flip angles for contrast manipulation.  SPACE helps achieve lower SAR and shorter ETS, resulting in total acquisition windows of around 100ms, a slice turbo factor in 3D direction can speed up the acquisition. We performed a comparison between the SPACE and the TSE based approaches in terms of spatial resolution and reduced blurring and small vessel conspicuity.

Takayuki Masui¹, Motoyuki Katayama¹, Kimihiko Sato¹, Hidekazu Seo¹, Hiroki Ikuma¹, Akihiko Kutsuna¹, Masayoshi Sugimura¹, Kazuhiko Ito¹, Mitsuaharu Miyoshi², Tetsuji Tsukamoto²

¹Seirei Hamamatsu General Hospital, Hamamatsu, Japan; ²GEYMS, Hino, Japan

In the evaluation of 63 patients with suspected renal tumor, respiratory triggered ECG gated non-contrast (NC) MRA using FIESTA with Flow-Preparation pulse  and contrast dynamic (C) MRA were performed. With successfully triggered ECG, identical information of the middle to proximal renal arteries and entire abdominal aorta could be obtained with NC and C-MRA. Peripheral portions of the renal arteries were better depicted on NC MRA than C MRA without overlap of the other structures. Consequently, in case of contraindication to use of MR contrast agents, NC MRA can give anatomical information of renal arteries, preoperatively.

Robert R. Edelman¹, Ioannis Koktzoglou¹

¹Evanston Northwestern Healthcare, Evanston, Illinois, USA

STARBURST (Selectively Targeted Angiographic Rendering using Blood’s Unique Relaxation properties and Subtraction Technique) was used to create flow-independent peripheral MR venograms.   The method involves the acquisition of two image sets (with one set being tagged by a spatially non-selective radiofrequency pulse) that are subtracted to render an angiogram.  Extensive lengths of the veins were shown including submillimeter branch vessels; the arteries were almost completely suppressed with the application of spatially selective pre-inversion.  The results demonstrate the feasibility of high resolution MR venography of the lower extremities with suppression of arterial signal and without the need for contrast administration.

Kevin Michael Johnson¹, Darren Lum¹, Chistopher J. Francois¹, Scott B. Reeder¹, Reede F. Busse², Tom M. Grist¹, Oliver Wieben¹

¹University of Wisconsin - Madison, Madison, Wisconsin, USA; ²MR Applied Science Lab, GE Healthcare, Madison, Wisconsin, USA

This study investigates the use of a modified phase contrast VIPR sequence for volumetric 3D velocity imaging of the renal arteries without a contrast agent. With the addition of adaptive respiratory gating, high quality angiograms were obtained in volunteers and patients. This approach provides an excellent alternative for patients that are excluded from contrast enhanced MRA otherwise. This includes subjects with compromised kidney function due to potential nephrogenic systemic fibrosis issues and kidney transplant patients for regular follow-ups.

Jinnan Wang¹, Vasily L. Yarnykh¹, Baocheng Chu¹, Jerry Molitor², Richard Nash, Fei Liu¹, Stephen Schwartz¹, Chun Yuan¹

¹University of Washington, Seattle, Washington, USA; ²University of Minnesota, Minneapolis, Minnesota, USA

In this study, we report the initial experience in high resolution MR angiography of scleroderma digital vasculature imaging. Micro MR angiography sequence was optimized for finger vessel imaging. Based on the angiography images, significant differences were found on arterial lumen size, number of visible veins and vascular scores, between scleroderma patients and normal volunteers. These quantitative variables can be potentially used as prospective biomarkers for scleroderma disease evaluation.

Marco Piccirelli¹, Nicola DeZanche¹, Jurek Nordmeyer-Massner¹, Michaela Soellinger¹, Michael Wyss¹, Gérard Crelier¹, Klaas Paul Pruessmann¹, Sebastian Kozerke¹

¹University and ETH Zurich, Zurich, Switzerland

Shape, blood flow, and wall shear stress of the carotid artery are associated with its function. The determination of related parameters relies on accurate angiographic and velocity data. We present a dedicated 7T receive-only, two-element surface coil for carotid imaging. The coil geometry was tailored to the neck and jaw anatomy. Comparison of the surface coil with a standard T/R-volume head coil showed a drastic SNR improvement making high-quality phase-contrast imaging possible. Particle traces in small branches of the carotid blood flow demonstrate the excellent SNR performance of the coil.