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An MRI pulse sequence in magnetic resonance imaging (MRI) is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance. A multiparametric MRI is a combination of two or more sequences, and/or including other specialized MRI configurations such as spectroscopy.
An MRI sequence is a particular setting of radiofrequency pulses and gradients, resulting in a particular image appearance. The T1 and T2 weighting can also be described as MRI sequences. Overview table. This table does not include uncommon and experimental sequences.
- Overview
- Terminology
- T1 Weighted Sequences
- T2 Weighted Sequences
- Proton Density Weighted Sequences
- Diffusion Weighted Sequences
- Flow Sensitive Sequences
- Miscellaneous Sequences
The simplest way to think about the multitude of sequences available on modern scanners is to divide them according to the dominant influence on the appearance of tissues. This leads to a division of all sequences into proton density (PD) weighted, T1 weighted, T2 weighted, diffusion weighted, flow sensitiveand 'miscellaneous'. A number of 'optiona...
When describing most MRI sequences we refer to the shade of grey of tissues or fluid with the word intensity, leading to the following absolute terms: 1. high signal intensity = white 2. intermediate signal intensity = grey 3. low signal intensity = black Often we refer to the appearance by relative terms: 1. hyperintense = brighter than the thing ...
T1 weighted (T1W) sequences are part of almost all MRI protocols and are best thought of as the most 'anatomical' of images (historically the T1W sequence was known as the anatomical sequence), resulting in images that most closely approximate the appearances of tissues macroscopically, although even this is a gross simplification. The dominant sig...
T2 weighted (T2W) sequences are part of almost all MRI protocols. Without modification the dominant signal intensities of different tissues are: 1. fluid (e.g. urine, CSF): high signal intensity (white) 2. muscle: intermediate signal intensity (grey) 3. fat: high signal intensity (white) 4. brain 4.1. grey matter: intermediate signal intensity (gre...
Given that nuclear magnetic resonance of protons (hydrogen ions) forms the major basis of MRI, it is not surprising that signal can be weighted to reflect the actual density of protons; an intermediate sequence sharing some features of both T1 and T2. Proton density images were extensively used for brain imaging, however they have largely been repl...
Diffusion weighted imaging assess the ease with which water molecules move around within a tissue (mostly representing fluid within the extracellular space) and gives insight into cellularity (e.g. tumors), cell swelling (e.g. ischemia) and edema. The dominant signal intensities of different tissues are: 1. fluid (e.g. urine, CSF): no restriction t...
One of the great advantages of MRI is its ability to image physiological flow of fluids (e.g. blood flow) often without the need for intravenous contrast. This allows for the imaging of arteries, veins and CSF flow. Read more about MR angiography. Read more about MR venography. Read more about CSF flow studies.
In addition to the aforementioned sequences, novel applications have been developed over the years, largely beyond the scope of this introductory article. Different compounds interact with the magnetic field of MRI scanners slightly differently and the amounts of these compounds can be detected in a quantifiable way in a prescribed region of tissue...
Nov 29, 2021 · An MRI pulse sequence is a programmed set of changing magnetic gradients. Each sequence will have a number of parameters, and multiple sequences grouped together into an MRI protocol. Parameters. A pulse sequence is generally defined by multiple parameters, including: time to echo (TE) time to repetition (TR) flip angle.
In MRI, a pulse sequence refers to the specific timing and duration of the electromagnetic pulses and radio frequency (RF) signals used to create an image. Each pulse sequence is designed to produce a specific type of contrast between different types of tissues in the body.
Sequences introduction. MRI is the imaging technique that has most benefited from technological innovation. The many advances have led to improvements in quality and acquisition speed. Each sequence is a subtle combination of radiofrequency pulses and gradients.
Dec 18, 2018 · Sequence Abbr. Main clinical distinctions Example Spin echo: T1 weighted: T1: Lower signal for more water content, as in edema, tumor, infarction, inflammation, infection, hyperacute or chronic hemorrhage ; High signal for fat; High signal for paramagnetic substances, such as MRI contrast agents
