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MR imaging of the brain: comparison of gradient-echo and spin-echo pulse sequences
Objective:
Gradient-echo pulse sequences can reduce imaging time and decrease motion artifacts. If gradient-echo pulse sequences are shown to be comparable to spin-echo sequences in MR imaging of the brain, then gradient-echo imaging can be valuable for examining critically ill, anxious, or uncooperative patients and can increase patient throughput. The purpose of this study was to prospectively compare one fast multiplanar spoiled gradient-recalled acquisition in the steady state (GRASS) (FMPSPGR) sequence with one conventional T1-weighted spin-echo sequence to determine the reliability of the FMPSPGR sequence for detecting cerebral lesions.
Subjects And Methods:
Fifty-one patients with 142 cranial lesions, including brain tumors, infarction, infection, and noninflammatory lesions, were examined. Forty-two unenhanced and 39 contrast-enhanced FMPSPGR (113-240/2.6-3.6/90 degrees/4 [TR/TE/flip angle/acquisitions]) and spin-echo T1-weighted (400-579/11-12/90 degrees/2) MR images of the head were obtained with a 1.5-T system. The visibility, margination, and extent of the lesions; image quality; contrast; and artifacts were qualitatively and quantitatively compared.
Results:
Supratentorial lesions were more conspicuous on the unenhanced FMPSPGR images because of the higher signal-to-noise ratio of the normal brain resulting in higher lesion contrast. The higher contrast-to-noise ratio of neoplasms on the contrast-enhanced spin-echo images was not found to be significant in the independent qualitative analysis. The conspicuity and extent of other lesions evaluated with the two pulse sequences were not significantly different for either the unenhanced or the contrast-enhanced studies. Vascular pulsation artifacts were significantly reduced on the contrast-enhanced FMPSPGR images. Susceptibility and chemical-shift phase-cancellation artifacts were more pronounced on the FMPSPGR images.
Conclusion:
The FMPSPGR sequence provides high-quality images with fewer vascular pulsation artifacts three to four times faster than the spin-echo sequence. The FMPSPGR sequence can reliably show intracranial lesions and can substitute for the T1-weighted spin-echo sequence in routine brain imaging.
Insights
Fast multiplanar spoiled gradient-recalled acquisition in the steady state (GRASS) (FMPSPGR) MRI sequences reliably detect brain lesions and are faster than spin-echo sequences. FMPSPGR imaging can substitute for conventional spin-echo in routine brain scans.
Area of Science:
- Neuroradiology
- Magnetic Resonance Imaging (MRI)
Background:
- Gradient-echo (GRE) sequences offer reduced imaging time and fewer motion artifacts compared to spin-echo (SE) sequences.
- GRE sequences may enhance patient throughput and utility in imaging critically ill or uncooperative patients.
Purpose of the Study:
- To prospectively compare a fast multiplanar spoiled gradient-recalled acquisition in the steady state (FMPSPGR) sequence with a conventional T1-weighted spin-echo (SE) sequence.
- To determine the reliability of the FMPSPGR sequence for detecting cerebral lesions.
Main Methods:
- Fifty-one patients with 142 cranial lesions underwent unenhanced and contrast-enhanced MRI using both FMPSPGR and T1-weighted SE sequences on a 1.5-T system.
- Lesion visibility, margination, extent, image quality, contrast, and artifacts were qualitatively and quantitatively assessed.
Main Results:
- Unenhanced FMPSPGR images showed more conspicuous supratentorial lesions due to higher lesion contrast.
- No significant difference in conspicuity or extent for other lesions between sequences.
- FMPSPGR demonstrated significantly reduced vascular pulsation artifacts, though with more pronounced susceptibility artifacts.
Conclusions:
- The FMPSPGR sequence provides high-quality brain images with fewer vascular artifacts, 3-4 times faster than SE.
- FMPSPGR reliably detects intracranial lesions and can replace T1-weighted SE in routine brain imaging.