Korean J Radiol.  2012 Feb;13(1):44-52. 10.3348/kjr.2012.13.1.44.

MR Imaging of the Spine at 3.0T with T2-Weighted IDEAL Fast Recovery Fast Spin-Echo Technique

• Ren AJ
• Guo Y
• Tian SP
• Shi LJ
• Huang MH

• KMID: 1058792
• DOI: http://doi.org/10.3348/kjr.2012.13.1.44

Abstract

OBJECTIVE
To compare the iterative decomposition of water and fat with echo asymmetry and the least-squares estimation (IDEAL) method with a fat-saturated T2-weighted (T2W) fast recovery fast spin-echo (FRFSE) imaging of the spine.
MATERIALS AND METHODS
Images acquired at 3.0 Tesla (T) in 35 patients with different spine lesions using fat-saturated T2W FRFSE imaging were compared with T2W IDEAL FRFSE images. Signal-to-noise ratio (SNR)-efficiencies measurements were made in the vertebral bodies and spinal cord in the mid-sagittal plane or nearest to the mid-sagittal plane. Images were scored with the consensus of two experienced radiologists on a four-point grading scale for fat suppression and overall image quality. Statistical analysis of SNR-efficiency, fat suppression and image quality scores was performed with a paired Student's t test and Wilcoxon's signed rank test.
RESULTS
Signal-to-noise ratio-efficiency for both vertebral body and spinal cord was higher with T2W IDEAL FRFSE imaging (p < 0.05) than with T2W FRFSE imaging. T2W IDEAL FRFSE demonstrated superior fat suppression (p < 0.01) and image quality (p < 0.01) compared to fat-saturated T2W FRFSE.
CONCLUSION
As compared with fat-saturated T2W FRFSE, IDEAL can provide a higher image quality, higher SNR-efficiency, and consistent, robust and uniform fat suppression. T2W IDEAL FRFSE is a promising technique for MR imaging of the spine at 3.0T.

Keyword

Spine; Magnetic resonance imaging; Fat suppression; Water-fat separation; Fast recovery fast spin-echo

MeSH Terms

Adult
Aged
Aged, 80 and over
Female
Humans
Image Interpretation, Computer-Assisted
Magnetic Resonance Imaging/*methods
Male
Middle Aged
Signal-To-Noise Ratio
Spinal Diseases/*diagnosis/pathology
Statistics, Nonparametric

Figure

• 

  Fig. 1 41-year-old woman with lower back pain. A. Sagittal T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) fast recovery fast spin-echo (FRFSE) water-only image. B. Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) fat-only image. C. Recombined iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) in-phase image. D. Recombined iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) out-of-phase image. Separate water (A) and fat (B) images demonstrate uniform separation of water and fat. Correction of chemical shift artifacts is shown in recombined in-phase image (C).

• 

  Fig. 2 26-year-old man with history of surgery after traffic accident. A. Sagittal T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) fast recovery fast spin-echo (FRFSE) water-only image. B. Sagittal fat-saturated T2-weighted fast recovery fast spin-echo (FRFSE) image. Failed fat-saturation and susceptibility artifacts due to B0 field inhomogeneities generated from metallic hardware in several thoracic vertebral bodies that obscured large portion of spinal cord and vertebral body (arrows). Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) image demonstrated very uniform fat separation despite presence of metallic hardware (A).

• 

  Fig. 3 56-year-old man with neck pain. A. Sagittal T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) fast recovery fast spin-echo (FRFSE) water-only image. B. Sagittal fat-saturated T2-weighted fast recovery fast spin-echo (FRFSE) image. Note failure of fat suppression in areas with air-tissue interfaces, and unfavorable geometry on fat-saturated fast recovery fast spin-echo (FRFSE) image (arrows), but uniformity of water-fat separation on water-only image was demonstrated (A).

• 

  Fig. 4 76-year-old woman with history of trauma. A. Sagittal T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) fast recovery fast spin-echo (FRFSE) water-only image. B. Sagittal fat-saturated T2-weighted fast recovery fast spin-echo (FRFSE) image. Compression of T11 vertebral body is seen (arrows). Poor fat suppression on fat-saturated fast recovery fast spin-echo (FRFSE) image in areas near top margin of field of view is seen mimicking T5 vertebral body marrow edema (dashed arrow), but superior fat-water separation and signal-to-noise ratio performance in corresponding iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) water-only image show that this is artifact caused by poor fat saturation (A).

• 

  Fig. 5 56-year-old man with 12-year history of lung adenocarcinoma. A, B. Sagittal T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) fast recovery fast spin-echo (FRFSE) water-only images. C, D. Corresponding fat-saturated T2-weighted fast recovery fast spin-echo (FRFSE) images. This patient has multiple metastases in spine. Fat-saturated T2-weighted fast recovery fast spin-echo (FRFSE) images demonstrate unreliable fat suppression in superior regions of images due to off-isocenter B0 inhomogeneities (arrows), which obscured lesion in left spinal facet joint at T9/T10 (dashed arrow). All lesions are distinctly visualized on iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) water-only images because of uniform and reliable fat suppression (arrowheads).

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