Improved visualization of diffusion-prepared MR neurography (SHINKEI) in the lumbosacral plexus combining high-intensity reduction (HIRE) technique.

PURPOSE: This study attempted to improve visualization of the pelvic nervous system using the high-intensity reduction (HIRE)-nerve-SHeath signal increased with INKed rest-tissue RARE Imaging (SHINKEI) technique that involves subtracting signals of 3D heavily T2W images from SHINKEI images. We identified the optimum TE value for 3D heavily T2W images and assessed the usefulness of the HIRE-SHINKEI technique. MATERIALS AND METHODS: Coronal lumbosacral plexus images were acquired from six healthy volunteers at 3 T. We optimized the TE of the 3D heavily T2-weighted (T2W) images in HIRE-SHINKEI and compared HIRE-SHINKEI images with conventional SHINKEI images with respect to nerve depiction, and vein, bladder, and cerebrospinal fluid (CSF) signal suppression using a 5-point scale. RESULTS: In 3D heavily T2W images optimized by HIRE-SHINKEI technique, the signal corresponding to nerves became significantly lower at TE = 400 ms (p < 0.0005), while that of veins occurred at TE = 400 ms and 600 ms (p < 0.05). The suppression of bladder signals was significant at TE = 400, 600, and 800 ms (p < 0.05); however, there was no difference in signal inhibition from CSF at all TEs tested. Based on these results, an optimal TE of 600 ms was identified for 3D heavily T2W images; these images corresponded to the minimal loss of nerve signal and simultaneous maximum subtraction of signals from the bladder, vein, and CSF with dissimilar T2 values. Compared with SHINKEI images, the optimized HIRE-SHINKEI images selectively delineated nerves in greater detail, and along with significant signal suppression of the bladder (p < 0.0001) and veins (p < 0.05). CONCLUSION: HIRE-SHINKEI can be used to better visualize the lumbosacral plexus with higher signal suppression of other pelvic structures. Such detailed Magnetic resonance neurography and selective depiction of nerves are useful for the diagnosis of peripheral nerve disorders.

[Evaluation of the right internal iliac artery which is anastomosed to transplant renal artery using non-contrast enhanced MR angiography with electrocardiography-gated and 3D True SSFP time-spatial labeling inversion pulse sequence].

To evaluate whether electrocardiography-gated is useful in non-contrast-enhanced MRA with time-spatial labeling inversion pulse (Time-SLIP) in renal transplantation patients compared with respiration-triggered free-breathing. Simulation-based analyses of black blood time interval (BBTI) values for spatial selective inversion-recovery pulse and electrocardiography rates were performed, and confirmed on human subjects using a three-dimensional (3D) coherent steady-state free precession (SSFP) sequence on a 1.5 tesla Toshiba MRI scanner. Signal acquisition interval and BBTI values in which signal of a water tissue becomes the null point showed a strong correlation, and successfully suppressed signals from the background and provided better contrast between the arteries and the background. Because electrocardiography-gated non-contrast MRA does not depend on the respiration interval, providing a contrast stable, it was suggested to be an effective screening tool for evaluation of pelvic arteries.

[Optimal imaging parameters and the advantage of cerebrospinal fluid flow image using time-spatial labeling inversion pulse at 3 tesla magnetic resonance imaging: comparison of image quality for 1.5 tesla magnetic resonance imaging].

Cerebrospinal fluid (CSF) imaging by time-spatial labeling inversion pulse (Time-SLIP) technique is labeled by CSF with a selective inversion recovery (IR) pulse as internal tracer, thus making it possible to visualize CSF dynamics non-invasively. The purpose of this study was to clarify labeled CSF signals during various black blood time to inversion (BBTI) values at 3 tesla (T) and 1.5 T magnetic resonance imaging (MRI) and to determine appropriate CSF imaging parameters at 3 T MRI in 10 healthy volunteers. To calculate optimal BBTI values, ROIs were set in untagged cerebral parenchyma and CSF on the image of the CSF flow from the aqueduct to the fourth ventricle in 1.5 T and 3 T MRI. Visual evaluation of CSF flow also was assessed with changes of matrix and echo time (TE) at 3 T MRI. The mean BBTI value at null point of untagged CSF in 3 T MRI was longer than that of 1.5 T. The MR conditions of the highest visual evaluation were FOV, 14 cm×14 cm; Matrix, 192×192; and TE, 117 ms. CSF imaging using Time-SLIP at 3 T MRI is expected visualization of CSF flow and clarification of CSF dynamics in more detail by setting the optimal conditions because 3 T MRI has the advantage of high contrast and high signal-to-noise ratio.