Rapid High Resolution MR Neurography with a Diffusion-weighted Pre-pulse

Abstract

Purpose: To introduce, optimize, and assess the feasibility of a new scheme to rapidly acquire high-resolution volumetric neurographic images using a three-dimensional turbo spin-echo sequence combined with a diŠusion-weighted pre-pulse called improved motionsensitized driven equilibrium (iMSDE): DiŠusion-prepared MR Neurography (D-prep MRN).Methods: In order to optimize the signal suppression of blood vessels and muscle at Dprep MRN, coronal lumbosacral plexus images were acquired inˆve volunteers at 3T, and the following parameters were examined: iMSDE gradient-strength (b-value) of 0, 2 and 10 s/mm 2 (with the aim to suppress blood vessels) and iMSDE preparation duration (iMSDE prep-time ) of 18, 50 and 100 ms (with the aim to suppress muscle signal). Subsequently, the feasibility of the optimized D-prep MRN sequence in visualizing the brachial plexus, lumbosacral plexus, and cranial nerves was evaluated in 5 healthy volunteers.Results: A higher b-value of 10 s/mm 2 was better in signal suppression of blood vessels, whereas an intermediate iMSDE prep-time of 50 ms provided the best compromise between suppression of muscle signal and minimization of signal loss of nerves. With these parameters, the normal nerve structures showed high signal intensity, while the blood vessels and muscles were eŠectively suppressed. The optimized D-prep MRN sequence clearly showed the three-dimensional trajectory of the brachial plexus, lumbosacral plexus, and cranial nerves.Conclusion: D-prep MRN was introduced and optimized, and clearly showed detailed anatomy of the brachial plexus, lumbosacral plexus, and cranial nerves. These results suggest that the D-prep MRN can be used for fast, high-resolution, volumetric imaging of the peripheral nervous system.

High Isotropic Resolution T2 Mapping of the Lumbosacral Plexus with T2-Prepared 3D Turbo Spin Echo

“…Finally, the present T2 preparation did not use flow or diffusion encoding gradients, thus giving rise to potential signal contamination by surrounding CSF and vessels. The T2 preparation modules with flow or diffusion encoding gradients could be used in the future to remove CSF and vessel signal contamination [5,7,21].…”

“…In this context, 3D turbo spin echo (TSE) or 3D fast spin echo (FSE) are most commonly used for achieving isotropic high-resolution T2-weighted nerve imaging in or near a plexus [2][3][4]. Furthermore, fat-suppressed 3D TSE imaging has recently been combined with the improved motion sensitized driven equilibrium (iMSDE) preparation to suppress vessel signal and improve plexus nerve delineation [5][6][7].…”

Recent advances in magnetic resonance neuroimaging of lumbar nerve to clinical applications: A review of clinical studies utilizing Dffusion Tensor Imaging and Diffusion-weighted magnetic resonance neurography

“…We excluded reviews, spinal cord studies and animal or in vivo studies. Our review identified a total of 35 articles: 24 DTI studies and 11 diffusionweighted MR neurography studies [31][32][33][34][35][36][37][38][39][40][41] . The number of lumbar nerve DTI studies has sharply increased in recent years ( Fig.…”

Imaging of the lumbar plexus: Optimized refocusing flip angle train design for 3D TSE

“…Echo spacing = 4 msec, maximum flip angles = [100°, 125°], six start‐up echoes, field of view (FOV) = 400 × 400 × 80 mm 3 , acquisition voxel = 1.25 × 1.25 × 1.4 mm 3 , reconstruction voxel = 0.63 × 0.63 × 0.7 mm 3 , TR/TE = 2000/330 msec, echo train length = 150, duration of each 3D TSE scan = 4 minutes 26 seconds, reference tissue relaxation times T 1 = 1010 msec and T 2 = 90 msec, parallel imaging with reduction factor R = 2.5, no partial Fourier, fat suppression using spectral inversion recovery. Similar to current work in MR neurography with 3D TSE, a T 2 preparation module with two refocusing pulses and with four bipolar velocity encoding gradients was placed before readout to increase nerve–muscle contrast and to reduce vessel signal. The module was employed with TE prep = 29 msec and encoding velocities = 1 cm/s along all three gradient axes.…”