Fast Low Angle Shot (FLASH) is a gradient echo technique and can be used for rapid imaging of relatively short T2 material, however, it is heavily T2* weighted, which limits the signal to noise ratio

achievable [12]. Single Point Imaging (SPI) is a pure phase encode technique that can be implemented with very short dephasing times and is therefore well suited to imaging short T2 and T2* materials. However, relatively long acquisition times are required, even with fast SPI techniques such as SPRITE [9]. Slice selection with pure phase encoding is also a challenge so it is commonly used for three dimensional rather than two dimensional acquisitions, further increasing the acquisition time. Other techniques commonly used for short T2 and T2* materials are sweep imaging with Fourier transformation (SWIFT) [13] and zero echo time (ZTE) [14], however R428 concentration these are also not slice selective. UTE potentially provides a method for rapidly imaging heterogeneous material with slice selection. The acquisition time for UTE images may still be too long for studying evolving systems such as fluidized beds. Recently, CS has been introduced to reduce the acquisition time of MRI experiments by up to an order of magnitude [3], [15] and [16]. CS works by exploiting the natural structure of MR images to reconstruct images accurately from partially sampled k-space data. CS has been applied to many systems [17],

[18], [19], [20] and [21] and pulse sequences but to the authors knowledge, has not yet been used with UTE. One of the challenges associated with implementing selleckchem UTE is ensuring that the gradient shape is generated accurately. It is well known that the gradient shape produced by the gradient amplifiers and coil does not match the input gradient perfectly. The error in gradient shape is typically corrected through the gradient pre-emphasis. However, the pre-emphasis may not produce the exact input gradient especially when short ramp times are used as in UTE. In most imaging sequences the remaining error is small enough that it does affect the final image.

UTE is sensitive to the shape of the slice selection gradient, therefore it is desirable to ensure the gradient shape is accurate. A recently published technique by Goora et al. [22] introduces the idea of gradient Morin Hydrate pre-equalization as a technique to correct for the induced errors in gradient shape when using a short ramp. Their approach is applicable on almost any hardware platform and therefore is appealing for UTE imaging applications in material science and chemical engineering. In this paper, common artifacts associated with the slice selection in UTE are illustrated using simulations of the Bloch equation. Experimental measurements are then used to demonstrate the implementation of accurate slice selection using UTE. In order to ensure accurate slice selection, the shape of the slice selection gradient was optimized by introducing the gradient pre-equalization of Goora et al. [22].