This table is used in the following articles:
This table does not include
uncommon and experimental sequences.
Group | Sequence | Abbr. | Physics | Main clinical distinctions | Example |
---|---|---|---|---|---|
Spin echo | T1 weighted | T1 | Measuring spin–lattice relaxation by using a short repetition time (TR) and echo time (TE). |
Standard foundation and comparison for other sequences |
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T2 weighted | T2 | Measuring spin–spin relaxation by using long TR and TE times |
Standard foundation and comparison for other sequences |
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Proton density weighted | PD | Long TR (to reduce T1) and short TE (to minimize T2). [4] |
Joint disease and injury.
[5]
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Gradient echo (GRE) | Steady-state free precession | SSFP | Maintenance of a steady, residual transverse magnetisation over successive cycles. [7] | Creation of cardiac MRI videos (pictured). [7] |
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Effective T2 or "T2-star" |
T2* | Spoiled gradient recalled echo (GRE) with a long echo time and small flip angle [8] | Low signal from hemosiderin deposits (pictured) and hemorrhages. [8] |
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Susceptibility-weighted | SWI | Spoiled gradient recalled echo (GRE), fully flow compensated, long echo time, combines phase image with magnitude image [9] | Detecting small amounts of hemorrhage ( diffuse axonal injury pictured) or calcium. [9] |
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Inversion recovery | Short tau inversion recovery | STIR | Fat suppression by setting an inversion time where the signal of fat is zero. [10] | High signal in edema, such as in more severe stress fracture. [11] Shin splints pictured: |
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Fluid-attenuated inversion recovery | FLAIR | Fluid suppression by setting an inversion time that nulls fluids | High signal in lacunar infarction, multiple sclerosis (MS) plaques, subarachnoid haemorrhage and meningitis (pictured). [12] |
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Double inversion recovery | DIR | Simultaneous suppression of cerebrospinal fluid and white matter by two inversion times. [13] | High signal of multiple sclerosis plaques (pictured). [13] |
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Diffusion weighted (DWI) | Conventional | DWI | Measure of Brownian motion of water molecules. [14] | High signal within minutes of cerebral infarction (pictured). [15] |
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Apparent diffusion coefficient | ADC | Reduced T2 weighting by taking multiple conventional DWI images with different DWI weighting, and the change corresponds to diffusion. [16] | Low signal minutes after cerebral infarction (pictured). [17] |
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Diffusion tensor | DTI | Mainly tractography (pictured) by an overall greater Brownian motion of water molecules in the directions of nerve fibers. [18] |
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Perfusion weighted (PWI) | Dynamic susceptibility contrast | DSC | Measures changes over time in susceptibility-induced signal loss due to gadolinium contrast injection. [20] |
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Arterial spin labelling | ASL | Magnetic labeling of arterial blood below the imaging slab, which subsequently enters the region of interest. [22] It does not need gadolinium contrast. [23] | |||
Dynamic contrast enhanced | DCE | Measures changes over time in the shortening of the spin–lattice relaxation (T1) induced by a gadolinium contrast bolus. [24] | Faster Gd contrast uptake along with other features is suggestive of malignancy (pictured). [25] |
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Functional MRI (fMRI) | Blood-oxygen-level dependent imaging | BOLD | Changes in oxygen saturation-dependent magnetism of hemoglobin reflects tissue activity. [26] | Localizing brain activity from performing an assigned task (e.g. talking, moving fingers) before surgery, also used in research of cognition. [27] |
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Magnetic resonance angiography (MRA) and venography | Time-of-flight | TOF | Blood entering the imaged area is not yet magnetically saturated, giving it a much higher signal when using short echo time and flow compensation. | Detection of aneurysm, stenosis, or dissection [28] |
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Phase-contrast magnetic resonance imaging | PC-MRA | Two gradients with equal magnitude, but opposite direction, are used to encode a phase shift, which is proportional to the velocity of spins. [29] | Detection of aneurysm, stenosis, or dissection (pictured). [28] |
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