Multisite trial of MR flow measurement: Phantom and protocol design

Abstract

Purpose: To describe a portable, easily assembled phantom with well-defined bore geometry together with a series of tests that will form the basis of a standardized quality assurance protocol in a multicenter trial of flow measurement by the MR phase mapping technique. Materials and Methods:The phantom consists of silicone polymer layers containing parallel straight and stenosed flow channels in one layer and a U-bend in a second layer, separated by hermetically sealed agarose slabs. The phantom is constructed by casting low melting-point metal in an aluminum mold precisely milled to the desired geometry, and then using the low melting-point metal core as a negative around which the silicone is allowed to set. By melting out the metal, the flow channels are established. The milled aluminum mold is reusable, ensuring faithful reproduction of the flow geometry for all phantoms thus produced. The agarose layers provide additional loading and static background signal for background correction. With the use of the described phantom, one can evaluate flow measurement accuracy and repeatability, as well as the influence of several imaging geometry factors: slice offset, in-plane position, and slice-flow obliquity. Results:The new phantom is compact and portable, and is well suited for reassembly. We were able to demonstrate its facility in a battery of tests of interest in evaluating MR flow measurements. Conclusion:The phantom is a robust standardized test object for use in a multicenter trial. Such a trial, to investigate the performance of MR flow measurement using the phantom and the tests we describe, has been initiated.

Importance of initial stress for abdominal aortic aneurysm wall motion: Dynamic MRI validated finite element analysis

“…Dynamic threedimensional balanced turbo field echo (3D B-TFE) and 2D B-TFE images were acquired in 15 phases of the cardiac cycle (VCG triggered). The proximal boundary of the AAA model was determined from the 2D quantitative flow (Qflow, Summers et al, 2005) imaging plane, which was placed perpendicular to the vessel wall (directly below the renal arteries). A static recording of the AAA was made with a black blood (BB) protocol.…”

Integrated physiological flow simulator and pulse sequence monitoring system for MRI

“…The phantom can range from a simple tube to a dedicated anthropomorphic model [13]. Most pumps described in the literature have been either based on a motor-controlled gear pump design [5,7,10,11] or have used a commercial flow system (Shelley Medical Imaging Technologies, Ontario, Canada) [2,14]. Additional components (e.g.…”

Hemodynamic evaluation in patients with transposition of the great arteries after the arterial switch operation: 4D flow and 2D phase contrast cardiovascular magnetic resonance compared with Doppler echocardiography

“…Previous studies [ 9 – 13 ] have demonstrated excellent flow parameter agreement and improved volumetric velocity analysis when using 4D flow CMR compared to 2D PC CMR. In addition, several studies [ 14 – 16 ] have been performed to assess the reliability of flow measurements. However, to the best of our knowledge, no study has focused on the evaluation of peak velocity measured by 4D flow CMR in patients with TGA.…”