Very few phantoms for rodent cardiac MRI have been published Li

Very few phantoms for rodent cardiac MRI have been published. Li et al. [12] developed a static doughnut-shaped digital phantom for their work on myocardium imaging. Riegler et al. [13] described a phantom consisting of a heart extracted from

a rat within which was inserted a balloon that was inflated to PD0325901 different volumes for calibration. Extending this to cyclic inflation would produce very realistic MRI data but with the disadvantage of requiring sacrifice of an animal, having a limited lifespan, involving biological tissues and not being easily reproducible by other labs. To date, there appears to be no reported work describing the design of a rodent phantom manufactured from readily available materials and not involving excised tissues or ex vivo preparations. The aim of this work was to close this gap by developing cardiac

phantoms suitable for rodent MRI. The phantoms were designed to provide realistic MRI data sets mimicking LV geometry and motion in the short-axis view. The main criterion was to mimic the dynamic behavior of the heart in the short-axis (“cross-sectional”) view of the left ventricle at midventricular level. The phantoms should produce plausible MRI images, be of the same general dimensions as mouse and rat left ventricles, and undergo similar distension and change in wall thickness. It was not the intention to model complex rotation and shortening movements

or to mimic ventricular blood flow patterns. Previous studies have used a number of materials to construct cardiac phantoms, IWR-1 including agarose [6], latex [14], silicone [7], [11] and [15] and PVA Cryogel [10]. The latter material is a gel, which has been used in the construction of ultrasound and MRI-compatible phantoms [16], [17], [18] and [19]. Celecoxib The gel is converted into an elastic solid by undergoing a number of freeze–thaw cycles. The elastic modulus and relaxation times T1 and T2 are controlled by the number of cycles, typically ranging between 2 and 10. PVA Cryogel was chosen for construction of the cardiac phantoms in this study because of the ability to readily control the characteristics of the material. For cyclic distension of the phantom, two approaches were considered, namely, local activation and remote activation. Remote activation has been used in previous studies involving connection of the chamber to a remote pump via stiff tubing [9] and [11]. The potential disadvantage of this technique is loss of pulsatility due to some unavoidable elasticity of the tubing. Local activation could involve generation of a force close to the phantom. Possibilities might include use of the scanner’s B0 magnetic field itself [20]. Though local activation would have been a technically elegant solution, a remote method was chosen as it is simple to implement and has worked in previous published studies.

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