Ultrafast 3D spin-echo acquisition improves Gadolinium-enhanced MRI signal contrast enhancement

Abstract

Long scan times of 3D volumetric MR acquisitions usually necessitate ultrafast in vivo gradient-echo acquisitions, which are intrinsically susceptible to magnetic field inhomogeneities. This is especially problematic for contrast-enhanced (CE)-MRI applications, where non-negligible T2* effect of contrast agent deteriorates the positive signal contrast and limits the available range of MR acquisition parameters and injection doses. To overcome these shortcomings without degrading temporal resolution, ultrafast spin-echo acquisitions were implemented. Specifically, a multiplicative acceleration factor from multiple spin echoes (×32) and compressed sensing (CS) sampling (×8) allowed highly-accelerated 3D Multiple-Modulation-Multiple-Echo (MMME) acquisition. At the same time, the CE-MRI of kidney with Gd-DOTA showed significantly improved signal enhancement for CS-MMME acquisitions (×7) over that of corresponding FLASH acquisitions (×2). Increased positive contrast enhancement and highly accelerated acquisition of extended volume with reduced RF irradiations will be beneficial for oncological and nephrological applications, in which the accurate in vivo 3D quantification of contrast agent concentration is necessary with high temporal resolution.

A new ultrafast 3D gradient echo‐based imaging method using quadratic‐phase encoding

“…However, the quantification of Gd concentration is challenging not only because signal sensitivity relies on the injection dose, being limited by T 2 * effects, but also because inflow effects cannot be avoided with 2D acquisition in a limited slice coverage, especially for AIF measurements covering the entire tissue of interest . Although 2D spin echo fast imaging sequences combined with compressed‐sensing techniques further reduce the unwanted T 2 * effects with a desirable degree of temporal resolution, they may incur high SAR and low SNR problems as well as inflow effects mentioned above. In contrast, RASE provides more accurate estimation of the expected Gd concentration even at high doses (Figure ) because it is less sensitive to T 2 * effects.…”

Compressed‐Sensing MP2RAGE sequence: Application to the detection of brain metastases in mice at 7T

“…In parallel, the CS technique can also be used to increase the spatial resolution without majorly lengthening acquisition duration. This approach has already been used for DCE imaging in rats . In our case, the spatial resolution of the images was increased to facilitate the detection of early growing metastases that have small diameters and to more accurately measure their volumes.…”

Investigating the stability of fast iterative shrinkage thresholding algorithm for MR imaging reconstruction using compressed sensing

“…In clinic applications, the choice of appropriate MR imaging parameters among different scanning sequences depends on the specific application of interest [12]. And increasing the CS acceleration factor reduces the scanning time but led to induce more artifacts in the reconstructions.…”

“…Due to its excellent temporal resolution and satisfactory temporal resolution, compressed sensing has become a research hotspot in the field of medical imaging gradually. [12][13][14].…”