Microvascular Imaging Using Compressed Sensing at 7T MRI: A Preliminary Study

The aim of this study was to obtain high-resolution images with a short acquisition time using a compressed sensing (CS) technique for microvascular imaging, especially of the lenticulostriate arteries (LSAs), with 7T magnetic resonance imaging (MRI). Initially, two different radio frequency (RF) coils, birdcage and multi-channel phased array, were tested to compare images of micro-vessels acquired using the CS technique with those acquired using conventional magnetic resonance angiography (MRA) at 7T MRI. High-resolution CS MRA as well as low- and high-resolution conventional time-of-flight MRA images obtained with a multi-channel RF coil was compared to evaluate the feasibility of the CS technique for microvascular imaging. Signal intensities were then used to quantitatively estimate vessel sizes. Compared to low-resolution MRA, the CS technique improved the depiction of the LSAs and provided a substantially reduced partial volume effect of the vessels. Despite the short acquisition time of the CS technique, it clearly depicted the LSA morphology almost as well as the high-resolution MRA. The measured size difference between micro-vessels that were analyzed using the CS technique and those analyzed using high-resolution MRA was about 20 %; however, the difference between the high-resolution and the low-resolution MRA was as high as 100 %. This study evaluated the feasibility of the CS technique for microvascular imaging with 7T MRI. A CS technique that combines high-resolution imaging with a short acquisition time would be a very effective method for microvascular imaging in both research and clinical studies.