Shuji Nagata1, Hiroshi Nishimura2, Kimberly K Amrami3, Kazutaka Nashiki1, Tatsuyuki Tonan1, Uchiyama Yusuke1, Kiminori Fujimoto1, and Toshi Abe1
1Kurume University Hospital, Kurume, Japan, 2Saiseikai Futsukaichi Hospital, Chikushino, Japan, 3Mayo Clinic, Rochester, MN, United States
Synopsis
A high-resolution MR
neurography using 3D fat
suppression T2-weighted Cube combined
with double inversion
recovery (3D FS DIR Cube) was evaluated
the feasibility of brachial plexus assessment. 15 normal
volunteers were scanned 3D FS
DIR Cube, 3D FS T2-weighted Cube
(3D FS T2 Cube), and 2D IDEAL water
on a 3T MRI scanner using a GEM
NV coil. The 3D FS
DIR Cube can provide excellent contrast between brachial
plexus branch and surrounding tissues and increase the conspicuity of the
nerves delineation with uniformed fat suppression and vessels
signal suppression compared with 3D FS T2 Cube and 2D IDEAL water.Introduction
With advances in both
software (optimal coil and sequences) and hardware high-resolution MR imaging
for brachial plexus will become more common. Although 3D fast
spin-echo (FSE) T2-weighted image and IDEAL
water image result in good fat suppression and delineation of peripheral nerves
owing to increased dynamic range of contrast, the imaging is frequently limited
by suboptimal signal-to-noise ratio and conspicuous vascular signal, which
limits the selective evaluation of smaller peripheral nerves within their
neurovascular bundles. Most of the
applications of double
inversion recovery (DIR) technique have
been especially for detection of multiple sclerosis lesions of the cerebral
cortex [1] and carotid vessel wall imaging [2]. In this study, we propose a new scheme to acquire high-resolution and
volumetric neurographic images using 3D fat suppression T2-weighted Cube combined with DIR (3D FS DIR Cube). It
employs both inversion recovery technique and frequency-selective fat
saturation to obtain more robust homogeneous fat suppression. Moreover, Cube,
variable reforcus flip angle FSE can be generated with excellent vascular
suppression because of sufficient blood flow masking effect [3].
Purpose
The aim was to evaluate
the feasibility of brachial plexus assessment using
3D FS DIR Cube and to compare it with 3D FS T2-weighted Cube (3D FS T2 Cube) and 2D IDEAL water.
Materials
Experiment – 15 normal volunteers (10 men and 5 women; 23-51 years, mean
35.1) were imaged on a 3T MRI scanner (Discovery 750w, GE Healthcare, Waukesha,
WI, USA) using a GEM NV coil. 3D FS DIR
Cube, 3D FS
T2 Cube, and 2D IDEAL water were acquired. The scan
parameters for the 3D FS DIR Cube were as follows: TR/TE
5100/60, IR1/IR2 2200/220, +50 kHz BW, 2.0mm slice thickness, 320 × 224 matrix,
ETL 120, 1 NEX, 34 cm FOV, and scan time 4 mm 18 seconds. Scan parameters for 3D FS T2 Cube were as follows: TR/TE 3200/maximum, 50 kHz BW, 2 mm slice thickness,
320 × 224 matrix, ETL 96, 1 NEX, 34 cm FOV, and scan time 3 minutes 58 seconds.
And scan parameters for 2D
IDEAL were as follows: TR/TE 4901/68, +83.33 kHz BW, 3
mm slice thickness, 320 × 224 matrix, ETL 13, 2 NEX, 34 cm FOV, and scan time 4
minutes 10 seconds. Image Evaluation - Two musculoskeletal
radiologists evaluated all images in consensus. The images were assessed for nerve-to-fat
signal ratio (nerve signal/fat signal), nerve-to-muscle signal ratio (nerve
signal/muscle signal), nerve-to-cerebrospinal fluid (CSF) signal ratio (nerve
signal/CSF signal), nerve-to-disc signal ratio (nerve signal/intervertebral
disc signal), and nerve-to-artery signal ratio (nerve signal/subclavian artery
signal). Nerves were measured to calculate the means of four different regions
(bilateral C6 and C7 nerve roots). Intervertebral disc was measured at the
level of C6/7. The conspicuity of brachial plexus branch, homogeneity of fat
suppression, vessels signal suppression, and quality of maximum intensity projection
(MIP) image were qualitatively assessed. The Kruskal-Wallis test and the Mann-Whitney U test with Bonferroni
correction were used to compare the mean values obtained from each
sequence. A value of p < 0.05 was considered significant.
Result
3D
FS DIR Cube had the highest nerve-to-fat signal ratio
and nerve-to-CSF signal ratio that was significantly higher than 3D FS T2 Cube and 2D IDEAL
water. 3D FS DIR Cube had also the highest nerve-to-artery signal ratio that was significantly
higher than 2D IDEAL water (Fig. 1). In qualitative assessment, the conspicuity of
brachial plexus branch, homogeneity of fat suppression, vessels signal
suppression, and quality of MIP was best on 3D FS DIR Cube (Fig. 2, 3).
Conclusion
The 3D FS
DIR Cube can provide excellent contrast between brachial
plexus and surrounding tissues and increase the conspicuity of the nerves
delineation with uniformed fat suppression and vessels
signal suppression compared to 3D FS T2 Cube and 2D IDEAL water.
Acknowledgements
No acknowledgement found.References
[1] Kolber et al. J Neural 2015;262:1473-82. [2] Bonanno et al. Invest
Radiol 2015;50:135-43. [3] Inoue et al. Japanese Journal of Radiology
Technology 2012;261:880-8.