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3025:) can be used to provide the static magnetic field. A permanent magnet that is powerful enough to be used in an MRI will be extremely large and bulky; they can weigh over 100 tonnes. Permanent magnet MRIs are very inexpensive to maintain; this cannot be said of the other types of MRI magnets, but there are significant drawbacks to using permanent magnets. They are only capable of achieving weak field strengths compared to other MRI magnets (usually less than 0.4 T) and they are of limited precision and stability. Permanent magnets also present special safety issues; since their magnetic fields cannot be "turned off," ferromagnetic objects are virtually impossible to remove from them once they come into direct contact. Permanent magnets also require special care when they are being brought to their site of installation.
2404:
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2007:(typically corresponding to a patient's head-to-toe direction and colored blue in diagram). Where negative-going gradient pulses are shown, they represent reversal of the gradient direction, i.e., right-to-left, back-to-front or toe-to-head. For human scanning, gradient strengths of 1–100 mT/m are employed: Higher gradient strengths permit better resolution and faster imaging. The pulse sequence shown here would produce a transverse (axial) image.
2433:
1906:
3086:, permitting higher resolution or faster scanning. However, higher field strengths require more costly magnets with higher maintenance costs, and have increased safety concerns. A field strength of 1.0–1.5 T is a good compromise between cost and performance for general medical use. However, for certain specialist uses (e.g., brain imaging) higher field strengths are desirable, with some hospitals now using 3.0 T scanners.
3320:
some of the spatial coding originating from the magnetic gradients with the spatial sensitivity of the different coil elements. However, the increased acceleration also reduces the signal-to-noise ratio and can create residual artifacts in the image reconstruction. Two frequently used parallel acquisition and reconstruction schemes are known as SENSE and GRAPPA. A detailed review of parallel imaging techniques can be found here:
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22:
3071:, also known as a coldhead, is used to recondense some helium vapor back into the liquid helium bath. Several manufacturers now offer 'cryogenless' scanners, where instead of being immersed in liquid helium the magnet wire is cooled directly by a cryocooler. Alternatively, the magnet may be cooled by carefully placing liquid helium in strategic spots, dramatically reducing the amount of liquid helium used, or,
3055:, losing resistance to flow of electric current. An electromagnet constructed with superconductors can have extremely high field strengths, with very high stability. The construction of such magnets is extremely costly, and the cryogenic helium is expensive and difficult to handle. However, despite their cost, helium cooled superconducting magnets are the most common type found in MRI scanners today.
1978:, the horizontal axis represents time. The vertical axis represents: (top row) amplitude of radio frequency pulses; (middle rows) amplitudes of the three orthogonal magnetic field gradient pulses; and (bottom row) receiver analog-to-digital converter (ADC). Radio frequencies are transmitted at the Larmor frequency of the nuclide to be imaged. For example, for H in a magnetic field of 1
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ramped on or off. Typical higher performance gradients have a slew rate of up to 100–200 T·m·s. The slew rate depends both on the gradient coil (it takes more time to ramp up or down a large coil than a small coil) and on the performance of the gradient amplifier (it takes a lot of voltage to overcome the inductance of the coil) and has significant influence on image quality.
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839:-weighted images. This provides high sensitivity for detection of vascular tissues (e.g., tumors) and permits assessment of brain perfusion (e.g., in stroke). There have been concerns raised recently regarding the toxicity of gadolinium-based contrast agents and their impact on persons with impaired kidney function. (See
1573:
3201:
Some important characteristics of gradient amplifiers and gradient coils are slew rate and gradient strength. As mentioned earlier, a gradient coil will create an additional, linearly varying magnetic field that adds or subtracts from the main magnetic field. This additional magnetic field will have
725:. Contrast in most MR images is actually a mixture of all these effects, but careful design of the imaging pulse sequence allows one contrast mechanism to be emphasized while the others are minimized. The ability to choose different contrast mechanisms gives MRI tremendous flexibility. In the brain,
167:
resonates depends on the strength of the local magnetic field around the proton or group of protons, a stronger field corresponds to a larger energy difference and higher frequency photons. By applying additional magnetic fields (gradients) that vary linearly over space, specific slices to be imaged
3315:
While it is possible to scan using the integrated coil for RF transmission and MR signal reception, if a small region is being imaged, then better image quality (i.e., higher signal-to-noise ratio) is obtained by using a close-fitting smaller coil. A variety of coils are available which fit closely
3012:
Just as important as the strength of the main magnet is its precision. The straightness of the magnetic lines within the center (or, as it is technically known, the iso-center) of the magnet needs to be near-perfect. This is known as homogeneity. Fluctuations (inhomogeneities in the field strength)
2938:
are: the main magnet, which polarizes the sample, the shim coils for correcting inhomogeneities in the main magnetic field, the gradient system which is used to localize the MR signal and the RF system, which excites the sample and detects the resulting NMR signal. The whole system is controlled by
4874:
This unrealistically assumes that the gradient is linear out to the end of the magnet bore. While this assumption is fine for pedagogical purposes, in most commercial MRI systems the gradient droops significantly after a much smaller distance; indeed, the decrease in the gradient field is the main
3319:
A recent development in MRI technology has been the development of sophisticated multi-element phased array coils which are capable of acquiring multiple channels of data in parallel. This 'parallel imaging' technique uses unique acquisition schemes that allow for accelerated imaging, by replacing
535:
variety of RF and gradient pulse sequences that gives MRI its versatility. Change of field gradient spreads the responding FID signal in the frequency domain, but this can be recovered and measured by a refocusing gradient (to create a so-called "gradient echo"), or by a radio frequency pulse (to
3307:
produced by nuclear relaxation inside the subject is true EM radiation (radio waves), and these leave the subject as RF radiation, but they are of such low power as to also not cause appreciable RF interference that can be picked up by nearby radio tuners (in addition, MRI scanners are generally
3231:
per centimeter or millitesla per meter (mT/m). High performance gradient coils used in MRI are typically capable of producing a gradient magnetic field of approximate 30 mT/m or higher for a 1.5 T MRI. The slew rate of a gradient system is a measure of how quickly the gradients can be
402:
is due to a tiny excess of protons in the lower energy state. This gives a net polarization that is parallel to the external field. Application of an RF pulse can tip this net polarization vector sideways (with, i.e., a so-called 90° pulse), or even reverse it (with a so-called 180° pulse). The
2018:
of longitudinal nuclear magnetization within a slab, or slice, creating transverse magnetization. The second part of the pulse sequence, PE, imparts a phase shift upon the slice-selected nuclear magnetization, varying with its location in the Y direction. The third part of the pulse sequence,
3197:
Scan speed is dependent on performance of the gradient system. Stronger gradients allow for faster imaging, or for higher resolution; similarly, gradient systems capable of faster switching can also permit faster scanning. However, gradient performance is limited by safety concerns over nerve
530:
coil to vary across the scanned region, so that different spatial locations become associated with different precession frequencies. Only those regions where the field is such that the precession frequencies match the RF frequency will experience excitation. Usually, these field gradients are
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oxygen in air) making, for example, the frontal lobes of the brain difficult to image. To restore field homogeneity a set of shim coils is included in the scanner. These are resistive coils, usually at room temperature, capable of producing field corrections distributed as several orders of
3032:
wound from copper wire is an alternative to a permanent magnet. An advantage is low initial cost, but field strength and stability are limited. The electromagnet requires considerable electrical energy during operation which can make it expensive to operate. This design is essentially
3194:-axis gradient is applied, the field strength may be 1.45 T at one end of a 1 m long bore and 1.55 T at the other). It is the magnetic gradients that determine the plane of imaging—because the orthogonal gradients can be combined freely, any plane can be selected for imaging.
3009:. Clinical magnets generally have a field strength in the range 0.1–3.0 T, with research systems available up to 9.4 T for human use and 21 T for animal systems. In the United States, field strengths up to 7 T have been approved by the FDA for clinical use.
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of the protons align to be either parallel or anti-parallel to the direction of the field. While each individual proton can only have one of two alignments, the collection of protons appear to behave as though they can have any alignment. Most protons align parallel to
2275:
Low signal for fat − Note that this only applies to standard Spin Echo (SE) sequences and not the more modern Fast Spin Echo (FSE) sequence (also referred to as Turbo Spin Echo, TSE), which is the most commonly used technique today. In FSE/TSE, fat will have a high
150:
pulse is then applied, which can excite protons from parallel to anti-parallel alignment, only the latter are relevant to the rest of the discussion. In response to the force bringing them back to their equilibrium orientation, the protons undergo a rotating motion
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When the MR scanner is placed in the hospital or clinic, its main magnetic field is far from being homogeneous enough to be used for scanning. That is why before doing fine tuning of the field using a sample, the magnetic field of the magnet must be measured and
1346:
decay, dephasing due to field inhomogeneity, flow, diffusion, etc. and any other phenomena that affect that amount of transverse magnetization available to induce signal in the RF probe or its phase with respect to the receiving coil' s electromagnetic field.
3256:. That coil is usually built into the body of the scanner. The power of the transmitter is variable, but high-end whole-body scanners may have a peak output power of up to 35 kW, and be capable of sustaining average power of 1 kW. Although these
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signal in the absence of field gradients. The FID from a poorly shimmed sample will show a complex decay envelope, often with many humps. Shim currents are then adjusted to produce a large amplitude exponentially decaying FID, indicating a homogeneous
1887:
666:
scanning or where images are needed very rapidly, is called echo-planar imaging (EPI): In this case, each RF excitation is followed by a train of gradient echoes with different spatial encoding. Multiplexed-EPI is even faster, e.g., for whole brain
3078:
Magnets are available in a variety of shapes. However, permanent magnets are most frequently C-shaped, and superconducting magnets most frequently cylindrical. C-shaped superconducting magnets and box-shaped permanent magnets have also been used.
1402:
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103:
are most often used to generate a detectable radio-frequency signal that is received by antennas close to the anatomy being examined. Hydrogen atoms are naturally abundant in people and other biological organisms, particularly in
1277:
587:
are a few tens of milliseconds. However, these values can vary widely between different tissues, as well as between different external magnetic fields. This behavior is one factor giving MRI its tremendous soft tissue contrast.
84:, and cardiac pacemakers nowadays may also have an MRI in spite of effects of the strong magnetic fields. This does not apply on older devices, and details for medical professionals are provided by the device's manufacturer.
3122:
boundaries within that sample, causing signal dropout (regions showing no signal) and spatial distortions in acquired images. For humans or animals the effect is particularly pronounced at air-tissue boundaries such as the
3227:) is useful for imaging. Along any given axis, the gradient will add to the magnetic field on one side of the zero position and subtract from it on the other side. Since the additional field is a gradient, it has units of
2019:
another slice selection (of the same slice) uses another shaped pulse to cause a 180° rotation of transverse nuclear magnetization within the slice. This transverse magnetisation refocuses to form a spin echo at a time
651:(2DFT) technique with slice selection, or by the three-dimensional Fourier transform (3DFT) technique. Another name for 2DFT is spin-warp. What follows here is a description of the 2DFT technique with slice selection.
3189:
which permit rapid and precise adjustments to their field strength and direction. Typical gradient systems are capable of producing gradients from 20 to 100 mT/m (i.e., in a 1.5 T magnet, when a maximal
2112:-space data, a two-dimensional inverse Fourier transform is performed to provide the familiar MR image. Either the magnitude or phase of the Fourier transform can be taken, the former being far more common.
2026:. During the spin echo, a frequency-encoding (FE) or readout gradient is applied, making the resonant frequency of the nuclear magnetization vary with its location in the X direction. The signal is sampled
3169:
Gradient coils are used to spatially encode the positions of protons by varying the magnetic field linearly across the imaging volume. The Larmor frequency will then vary as a function of position in the
1178:{\displaystyle S(t)={\tilde {\rho }}_{\mathrm {eff} }\left({\vec {k}}(t)\right)\equiv \int _{-\infty }^{\infty }\mathrm {d} {\vec {x}}\ \rho ({\vec {x}})\cdot e^{2\pi i\ {\vec {k}}(t)\cdot {\vec {x}}}}
3620:
Weissleder R, Elizondo G, Wittenberg J, Rabito CA, Bengele HH, Josephson L (May 1990). "Ultrasmall superparamagnetic iron oxide: characterization of a new class of contrast agents for MR imaging".
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1586:, in particular) to understand the role of phase encoding (the so-called spin-warp method). In a standard spin echo or gradient echo scan, where the readout (or view) gradient is constant (e.g.,
463:
When the radio frequency pulse is turned off, the transverse vector component produces an oscillating magnetic field which induces a small current in the receiver coil. This signal is called the
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is created by differences in the strength of the NMR signal recovered from different locations within the sample. This depends upon the relative density of excited nuclei (usually
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1330:
966:
4887:
Imaging
Systems for Medical Diagnostics: Fundamentals, Technical Solutions and Applications for Systems Applying Ionizing Radiation, Nuclear Magnetic Resonance and Ultrasound
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component (such as all conventional radio wave transmissions have). Thus, the high-powered electromagnetic field produced in the MRI transmitter coil does not produce much
1390:
2901:
1766:
1737:
5013:
Griswold MA, Jakob PM, Heidemann RM, Nittka M, Jellus V, Wang J, Kiefer B, Haase A (June 2002). "Generalized autocalibrating partially parallel acquisitions (GRAPPA)".
3005:
The magnet is the largest and most expensive component of the scanner, and the remainder of the scanner is built around it. The strength of the magnet is measured in
1568:{\displaystyle I\left({\vec {x}}\right)=\int _{-\infty }^{\infty }\mathrm {d} {\vec {k}}\ S\left({\vec {k}}(t)\right)\cdot e^{-2\pi i\ {\vec {k}}(t)\cdot {\vec {x}}}}
1631:-space are scanned in opposite directions, this must be taken into account in the reconstruction. Multi-shot EPI and fast spin echo techniques acquire only part of
1776:-space determines the field of view of the image (maximum frequency that is correctly sampled) and the maximum value of k sampled determines the resolution; i.e.,
359:
2907:
190:
on the current flowing in the gradient coils, the gradient coils will try to move producing loud knocking sounds, for which patients require hearing protection.
3429:
Poustchi-Amin M, Mirowitz SA, Brown JJ, McKinstry RC, Li T (2000). "Principles and applications of echo-planar imaging: a review for the general radiologist".
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axis. When a non-zero phase-encoding pulse is added in between the RF excitation and the commencement of the readout gradient, this line moves up or down in
1194:
647:
Although each of these schemes is occasionally used in specialist applications, the majority of MR Images today are created either by the two-dimensional
4749:
4724:
Obasih KM, Mruzek (1996). "Thermal design and analysis of a cryogenless superconducting magnet for interventional MRI therapy". In
Timmerhaus KD (ed.).
4622:
3812:
3276:, there is very little RF interference produced by the MRI machine. The reason for this is that the MRI is not a radio transmitter. The RF frequency
2738:
Magnetic labeling of arterial blood below the imaging slab, which subsequently enters the region of interest. It does not need gadolinium contrast.
2108:
After the two-dimensional matrix (typical dimension between 128 × 128 and 512 × 512) has been acquired, producing the so-called
80:
and is, therefore, a safe procedure suitable for diagnosis in children and repeated runs. Patients with specific non-ferromagnetic metal implants,
4320:
Chua TC, Wen W, Slavin MJ, Sachdev PS (February 2008). "Diffusion tensor imaging in mild cognitive impairment and
Alzheimer's disease: a review".
4242:"Signal evolution and infarction risk for apparent diffusion coefficient lesions in acute ischemic stroke are both time- and perfusion-dependent"
5122:
2808:
Localizing brain activity from performing an assigned task (e.g. talking, moving fingers) before surgery, also used in research of cognition.
3292:
at its RF frequency, and the power is confined to the coil space and not radiated as "radio waves." Thus, the transmitting coil is a good EM
918:-space formalism, a technique that proved invaluable in unifying different MR imaging techniques. They showed that the demodulated MR signal
4702:
3690:
Twieg DB (1983). "The k-trajectory formulation of the NMR imaging process with applications in analysis and synthesis of imaging methods".
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imaging, whereas proton-density-weighted imaging provides little contrast in healthy subjects. Additionally, functional parameters such as
926:) generated by the interaction between an ensemble of freely precessing nuclear spins in the presence of a linear magnetic field gradient
877:
tissue retains the agent, but abnormal areas (e.g., scars, tumors) do not. They can also be taken orally, to improve visualization of the
3067:, ambient heat causes the helium to slowly boil off. Such magnets, therefore, require regular topping-up with liquid helium. Generally a
654:
The 3DFT technique is rather similar except that there is no slice selection and phase-encoding is performed in two separate directions.
3523:
Weinmann HJ, Brasch RC, Press WR, Wesbey GE (March 1984). "Characteristics of gadolinium-DTPA complex: a potential NMR contrast agent".
722:
4765:"Japan makes progress toward realization of MRI magnets using high temperature superconducting wire materials | NextBigFuture.com"
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Two gradients with equal magnitude, but opposite direction, are used to encode a phase shift, which is proportional to the velocity of
2609:
Reduced T2 weighting by taking multiple conventional DWI images with different DWI weighting, and the change corresponds to diffusion.
4983:
2057:
times, but with the phase-encoding gradient incremented (indicated by the horizontal hatching in the green gradient block). Typically
1672:-space in determining image contrast can be exploited in more advanced imaging techniques. One such technique is spiral acquisition—a
4685:
2868:
3585:
Widder DJ, Greif WL, Widder KJ, Edelman RR, Brady TJ (February 1987). "Magnetite albumin microspheres: a new MR contrast material".
3748:
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163:, which yields a changing voltage in the receiver coils to give a signal. The frequency at which a proton or group of protons in a
2403:
3464:
Feinberg DA, Moeller S, Smith SM, Auerbach E, Ramanna S, Gunther M, Glasser MF, Miller KL, Ugurbil K, Yacoub E (December 2010).
112:. For this reason, most MRI scans essentially map the location of water and fat in the body. Pulses of radio waves excite the
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Most superconducting magnets have their coils of superconductive wire immersed in liquid helium, inside a vessel called a
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155:), much like a spun wheel under the effect of gravity. The protons will return to the low energy state by the process of
2421:
Spoiled gradient recalled echo (GRE), fully flow compensated, long echo time, combines phase image with magnitude image
2365:
844:
618:
A number of schemes have been devised for combining field gradients and radio frequency excitation to create an image:
4764:
1953:
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1935:
1627:-space is scanned in a single shot, following either a sinusoidal or zig-zag trajectory. Since alternating lines of
3013:
within the scan region should be less than three parts per million (3 ppm). Three types of magnets have been used:
1635:-space per excitation. In each shot, a different interleaved segment is acquired, and the shots are repeated until
5273:
Spatially
Resolved Magnetic Resonance: Methods, Materials, Medicine, Biology, Rheology, Geology, Ecology, Hardware
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Pruessmann KP, Weiger M, Scheidegger MB, Boesiger P (November 1999). "SENSE: sensitivity encoding for fast MRI".
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particles, whenever the spin of a single proton is measured it can only have one of two results commonly called
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energy transition, and magnetic field gradients localize the signal in space. By varying the parameters of the
4525:
Turnbull LW (January 2009). "Dynamic contrast-enhanced MRI in the diagnosis and management of breast cancer".
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Magnetic field strength is an important factor in determining image quality. Higher magnetic fields increase
2947:
969:
1582:-space formalism, a number of seemingly complex ideas became simple. For example, it becomes very easy (for
4075:
2798:
2786:
2550:
2666:
1882:{\displaystyle {\rm {FOV}}\propto {\frac {1}{\Delta k}}\qquad \mathrm {Resolution} \propto |k_{\max }|\ .}
5254:
Magnetic
Resonance Microscopy: Methods and Applications in Materials Science, Agriculture and Biomedicine
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Permanent magnet: Conventional magnets made from ferromagnetic materials (e.g., steel alloys containing
2010:
The first part of the pulse sequence, SS, achieves "slice selection". A shaped pulse (shown here with a
1707:(CNR) when compared to conventional zig-zag acquisitions, especially in the presence of rapid movement.
509:. At the same time, the longitudinal magnetization starts to recover exponentially with a time constant
4102:
3558:
Laniado M, Weinmann HJ, Schörner W, Felix R, Speck U (1984). "First use of GdDTPA/dimeglumine in man".
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1594:-space is scanned per RF excitation. When the phase encoding gradient is zero, the line scanned is the
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3889:"A Current Review of the Meniscus Imaging: Proposition of a Useful Tool for Its Radiologic Analysis"
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is 'shimmed' by adjusting currents in the shim coils. Field homogeneity is measured by examining an
1970:
Simplified timing diagram for two-dimensional-Fourier-transform (2DFT) Spin Echo (SE) pulse sequence
540:"), or in digital post-processing of the spread signal. The whole process can be repeated when some
48:
in order to investigate the anatomy and physiology of the body, and to detect pathologies including
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2264:
2000:(typically corresponding to a patient's front-to-back direction and colored green in diagram), and
1916:
1357:
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199:
1619:-space formalism also makes it very easy to compare different scanning techniques. In single-shot
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appears dark. The contrast of white matter, gray matter and cerebrospinal fluid is reversed using
60:, disorders of muscles and joints, and abnormalities in the heart and blood vessels among others.
5314:
4750:"Philips Helium-Free MRI System Combines Productivity with High Quality Imaging | Medgadget"
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around parts of the body such as the head, knee, wrist, breast, or internally, e.g., the rectum.
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of the trajectory proportional to the vector of the applied magnetic field gradient. By the term
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3974:"Principles, techniques, and applications of T2*-based MR imaging and its special applications"
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In some situations it is not possible to generate enough image contrast to adequately show the
333:
can be used to describe the behaviour of an ensemble of protons adequately. As with other spin
253:
135:
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3406:
How does MRI work?: An
Introduction to the Physics and Function of Magnetic Resonance Imaging
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1993:(typically corresponding to a patient's left-to-right direction and colored red in diagram),
622:
329:
Quantum mechanics is required to accurately model the behaviour of a single proton. However,
315:): one low-energy and one high-energy, which are separated by a very small splitting energy.
4293:
3466:"Multiplexed echo planar imaging for sub-second whole brain FMRI and fast diffusion imaging"
2764:
Faster Gd contrast uptake along with other features is suggestive of malignancy (pictured).
1699:
decay the signal is greatest at the start of the acquisition, hence acquiring the center of
881:, and to prevent water in the gastrointestinal tract from obscuring other organs (e.g., the
490:, which shortens the FID. The time constant for the observed decay of the FID is called the
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3664:
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464:
421:
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Ljunggren S (1983). "A simple graphical representation of
Fourier-based imaging methods".
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721:) of those nuclei after the pulse sequence, and often on other parameters discussed under
8:
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105:
65:
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4917:, Edelstein WA, Hayes CE, Souza SP, Mueller OM (November 1990). "The NMR phased array".
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of that proton which is a linear combination of the parallel and anti-parallel states.
77:
5151:
3303:
The receiver consists of the coil, pre-amplifier and signal processing system. The RF
832:
compound) is given. Gadolinium-enhanced tissues and fluids appear extremely bright on
387:. The static fields used most commonly in MRI cause precession which corresponds to a
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4393:"Magnetic resonance diffusion-perfusion mismatch in acute ischemic stroke: An update"
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times by the ADC during this period, as represented by the vertical lines. Typically
1272:{\displaystyle {\vec {k}}(t)\equiv \int _{0}^{t}{\vec {G}}(\tau )\ \mathrm {d} \tau }
772:
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of the spin system, or the number of nuclei with parallel versus anti-parallel spin.
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The longitudinal magnetisation is then allowed to recover somewhat and after a time
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4827:"Automatic, localized in vivo adjustment of all first- and second-order shim coils"
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After a sample is placed into the scanner, the main magnetic field is distorted by
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2842:, giving it a much higher signal when using short echo time and flow compensation.
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Maintenance of a steady, residual transverse magnetisation over successive cycles.
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2088:(the spin echo maximum), phase only encodes spatial location in the Y direction.
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37:
2986:
A short extract of a 20-minute scanning session, recorded outside the above unit
930:
and a receiver-coil equals the
Fourier transform of the effective spin density,
3375:
3285:
3063:. Despite thermal insulation, sometimes including a second cryostat containing
2496:
2452:
2392:
Spoiled gradient recalled echo (GRE) with a long echo time and small flip angle
1768:
are conjugate variables (with respect to the
Fourier transform) we can use the
890:
527:
479:
388:
362:
300:
269:
229:
203:
117:
113:
96:
88:
4783:"High-temperature superconducting coils tested for future NMR magnet - MagLab"
3808:
2300:
431:. The loss of phase coherence in the transverse plane is called transverse or
5395:
3273:
3185:
Gradient coils are usually resistive electromagnets powered by sophisticated
3048:
2674:
2345:
2280:
2230:
1704:
909:
672:
366:
312:
307:
around an axis along the direction of the field. Protons align in two energy
180:
173:
160:
100:
5066:
Blaimer M, Breuer F, Mueller M, Heidemann RM, Griswold MA, Jakob PM (2004).
1966:
471:
experiment, the FID decays approximately exponentially with a time constant
5175:
5094:
5044:
4991:
4930:
4845:
4546:
4428:
4341:
4275:
4007:
3924:
3905:
3509:
3450:
3309:
3228:
3214:; however, only the component along the magnetic field (usually called the
3128:
3006:
2637:
2536:
2467:
2209:
2148:
2121:
1979:
886:
858:
825:
733:
365:. When we discuss the state of a proton or protons we are referring to the
53:
26:
5159:
4938:
4853:
3719:
3641:
3606:
3598:
3571:
3544:
3536:
2515:
598:(III) work by altering (shortening) the relaxation parameters, especially
5294:
Principles of
Magnetic Resonance Imaging: A Signal Processing Perspective
4984:
10.1002/(SICI)1522-2594(199911)42:5<952::AID-MRM16>3.0.CO;2-S
4655:
4597:
4503:
4475:
4409:
4369:
4298:
4192:
4164:
4136:
4052:
3989:
3947:
3865:
3245:
3044:
2396:
2321:
1643:-space represent lower spatial frequencies than the data at the edges of
1282:
In other words, as time progresses the signal traces out a trajectory in
741:
559:
531:
modulated to sweep across the region to be scanned, and it is the almost
4875:
delimiter of the useful field of view of a modern commercial MRI system.
3101:
FID signal from a well shimmed sample, showing a pure exponential decay.
2694:
Measures changes over time in susceptibility-induced signal loss due to
2474:
5216:
NMR Imaging in Biomedicine: Supplement 2 Advances in Magnetic Resonance
3887:
Lefevre N, Naouri JF, Herman S, Gerometta A, Klouche S, Bohu Y (2016).
3186:
3097:
3068:
2995:
2802:
2508:
2217:
2205:
855:
829:
820:, taken orally, for imaging the stomach and small bowel. However, most
812:
of interest by adjusting the imaging parameters alone, in which case a
595:
555:(TR) is the time between two successive excitations of the same slice.
304:
249:
152:
5036:
4215:
3089:
824:
are selected for their specific magnetic properties. Most commonly, a
68:
or into a joint to enhance the image and facilitate diagnosis. Unlike
5271:
Blümer P (1998). Blümler P, Blümich B, Botto RE, Fukushima E (eds.).
4890:
4538:
3711:
3261:
3022:
2930:
Schematic of construction of a cylindrical superconducting MR scanner
2315:
2213:
2188:
2164:
1983:
1639:-space is sufficiently well-covered. Since the data at the center of
1583:
809:
537:
410:
The recovery of longitudinal magnetization is called longitudinal or
41:
1905:
1354:-space formula, it follows immediately that we reconstruct an image
120:, different contrasts may be generated between tissues based on the
5197:
Magnetic resonance imaging: Physical principles and sequence design
4959:
4705:(Press release). U.S. Food and Drug Administration. 12 October 2017
3428:
3060:
3029:
2890:
2886:
2850:
2846:
2657:
2015:
882:
532:
446:
257:
233:
49:
3619:
2245:
482:
at different spatial locations ("inhomogeneities") that cause the
5374:
Electromagnetic Analysis and Design in Magnetic Resonance Imaging
2768:
2714:
have decreased perfusion and delayed contrast arrival (pictured).
805:
457:
293:
289:
237:
69:
5336:
Magnetic Resonance Imaging: Physical Principles and Applications
2492:
Fluid suppression by setting an inversion time that nulls fluids
21:
5177:
Magnetic Resonance Imaging: Principles, Methods, and Techniques
2952:
737:
478:. However, in practical MRI there are small differences in the
392:
285:
245:
241:
57:
5068:"SMASH, SENSE, PILS, GRAPPA: How to Choose the Optimal Method"
3093:
FID signal from a badly shimmed sample has a complex envelope.
873:-weighted images and may be used for liver imaging, as normal
5194:
5065:
3972:
Chavhan GB, Babyn PS, Thomas B, Shroff MM, Haacke EM (2009).
2459:
2201:
2197:
874:
817:
688:
663:
164:
109:
73:
5012:
3886:
3557:
3463:
2812:
2126:
168:
can be selected, and an image is obtained by taking the 2-D
4648:
4100:
2011:
4240:
An H, Ford AL, Vo K, Powers WJ, Lee JM, Lin W (May 2011).
3835:
Principles and Applications of Radiological Physics E-Book
2860:
914:
In 1983, Ljunggren and Twieg independently introduced the
861:, have become available. These agents appear very dark on
678:
4913:
4677:
Schepkin, Victor D.; Grant, Samuel C.; Cross, Timothy A.
3522:
3336:
Independent (newspaper) obituary of R Edward 20 July 2001
3272:) at powers usually exceeding the highest powers used by
2224:
1986:
would be employed. The three field gradients are labeled
1680:-space to spiral out from the center to the edge. Due to
383:
determined by the particle's gyro-magnetic ratio and the
4726:
Proceedings of the 1995 cryogenic engineering conference
3971:
3779:"Basic proton MR imaging. Tissue Signal Characteristics"
3584:
3403:
1892:(These relationships apply to each axis independently.)
4703:"FDA clears first 7T magnetic resonance imaging device"
2287:
Standard foundation and comparison for other sequences
2240:
Standard foundation and comparison for other sequences
643:
Gradients in the RF field rather than the static field.
198:
The MRI scanner was developed from 1975 to 1977 at the
5316:
Echo-Planar Imaging: Theory, Technique and Application
5195:
Haacke EM, Brown RF, Thompson M, Venkatesan R (1999).
4073:
3051:
to 4 K (−269 °C, −452 °F) it becomes a
2951:
A mobile MRI unit visiting Glebefields Health Centre,
2644:
of water molecules in the directions of nerve fibers.
662:
Another scheme which is sometimes used, especially in
5312:
3837:(6 ed.). Elsevier Health Sciences. p. 292.
1785:
1745:
1716:
1405:
1360:
1300:
1197:
981:
936:
801:
and so can be encoded with suitable pulse sequences.
339:
4365:"Dynamic susceptibility contrast (DSC) MR perfusion"
4319:
2753:
Measures changes over time in the shortening of the
526:
In MRI, the static magnetic field is augmented by a
4094:
3967:
3965:
3560:
Physiological Chemistry and Physics and Medical NMR
3348:
Principles of Nuclear Magnetic Resonance Microscopy
5291:
4287:
4285:
3280:produced in the "transmitting coil" is a magnetic
1881:
1760:
1731:
1567:
1384:
1324:
1271:
1177:
960:
640:Building the image point-by-point or line-by-line.
353:
3880:
3832:
551:of the spins has been more or less restored. The
460:of the system, or the number of nuclei in phase.
299:When these spins are placed in a strong external
5393:
4045:
3962:
3735:
3733:
3731:
3729:
3308:situated in metal mesh lined rooms which act as
1863:
893:have also been studied for potential use in the
4282:
4179:
1676:gradient is applied, causing the trajectory in
5289:
4676:
4499:"Dynamic contrast enhanced (DCE) MR perfusion"
4239:
4185:
3296:transmitter at radio frequency, but a poor EM
1895:
816:may be administered. This can be as simple as
4129:
3726:
3139:After placing the sample in the scanner, the
2921:
2649:Evaluating white matter deformation by tumors
2115:
2064:of between 128 and 512 repetitions are made.
692:
210:. The full body scanner was created in 1978.
4728:. New York: Plenum Press. pp. 305–312.
4723:
4518:
4471:"Arterial spin labelling (ASL) MR perfusion"
4023:
3940:
3801:
3404:Weishaupt D, Koechli VD, Marincek B (2013).
2098:is between 5 ms and 100 ms, while
968:. Fundamentally, the signal is derived from
502:relaxation time, and is always shorter than
407:with the RF pulse and therefore each other.
379:, the protons will appear to precess at the
5251:
4313:
3858:
3833:Graham D, Cloke P, Vosper M (31 May 2011).
3457:
2196:Lower signal for more water content, as in
1934:. Unsourced material may be challenged and
732:-weighting causes the nerve connections of
318:
4617:
4615:
4590:
4561:
4233:
4074:Berger F, de Jonge M, Smithuis R, Maas M.
3826:
3772:
3770:
3768:
3766:
2838:Blood entering the imaged area is not yet
2040:of between 128 and 512 samples are taken.
736:to appear white, and the congregations of
292:or protons, and no net spin; however, the
206:FRS FRSE following from his research into
172:of the spatial frequencies of the signal (
124:properties of the hydrogen atoms therein.
5313:Schmitt F, Stehling MK, Turner R (1998).
5237:. Springer Science & Business Media.
5232:
5213:
5026:
4973:
4795:
4418:
4408:
4265:
4216:"MRI Physics: Diffusion-Weighted Imaging"
3997:
3936:
3934:
3914:
3904:
3654:
3499:
3489:
3408:. Springer Science & Business Media.
3345:
3235:
3161:field. The process is usually automated.
2869:Phase-contrast magnetic resonance imaging
2105:is between 100 ms and 2000 ms.
1954:Learn how and when to remove this message
456:on the other hand is associated with the
5333:
4824:
4798:Biomedical Magnetic Resonance Technology
4524:
4384:
4125:
4123:
4039:
3852:
3096:
3088:
2946:
2925:
1965:
20:
5352:
5173:
4612:
4291:
4103:"Fluid attenuation inversion recoveryg"
3763:
2424:Detecting small amounts of hemorrhage (
679:Image contrast and contrast enhancement
372:In the presence of the magnetic field,
252:, have a non–zero spin and therefore a
5394:
5270:
5235:NMR in Biomedicine: The Physical Basis
5120:
4884:
4623:"Magnetic Resonance Angiography (MRA)"
4390:
4207:
4082:. Radiology Society of the Netherlands
4067:
4019:
4017:
3931:
3587:AJR. American Journal of Roentgenology
3525:AJR. American Journal of Roentgenology
3422:
3248:system consists of an RF synthesizer,
657:
486:to vary across the body. This creates
398:The net longitudinal magnetization in
4570:"Milestone 19: (1990) Functional MRI"
4157:
4120:
3689:
3443:10.1148/radiographics.21.3.g01ma23767
3284:with very little associated changing
3202:components in all 3 directions, viz.
5075:Topics in Magnetic Resonance Imaging
4762:
4649:Keshavamurthy J, Ballinger R et al.
4584:
4496:
4468:
4362:
4132:"Double inversion recovery sequence"
4101:Hacking C, Taghi Niknejad M, et al.
2399:deposits (pictured) and hemorrhages.
2272:Higher signal for more water content
2081:are imposed to ensure that, at time
1932:adding citations to reliable sources
1899:
213:
5371:
4679:"In vivo MR Imaging at 21.1 T"
4490:
4462:
4435:
4356:
4151:
4014:
3776:
2703:Provides measurements of blood flow
2483:Fluid-attenuated inversion recovery
2134:uncommon and experimental sequences
146:as this is a lower energy state. A
13:
5113:
5087:10.1097/01.rmr.0000136558.09801.dd
4213:
3943:"Steady-state free precession MRI"
2960:
1846:
1843:
1840:
1837:
1834:
1831:
1828:
1825:
1822:
1819:
1808:
1794:
1791:
1788:
1451:
1445:
1440:
1262:
1077:
1071:
1066:
1018:
1015:
1012:
613:
95:energy when placed in an external
56:, neurological conditions such as
14:
5413:
5199:. New York: J. Wiley & Sons.
5152:10.1038/scientificamerican0582-78
4026:"Susceptibility weighted imaging"
2640:(pictured) by an overall greater
2455:where the signal of fat is zero.
1325:{\displaystyle \rho ({\vec {x}})}
961:{\displaystyle \rho ({\vec {x}})}
771:, cerebral blood volume (CBV) or
547:-relaxation has occurred and the
4567:
3300:transmitter at radio frequency.
3073:high temperature superconductors
2994:Problems playing this file? See
2976:
2900:
2859:
2811:
2767:
2719:
2665:
2619:
2590:
2549:
2514:
2473:
2431:
2402:
2371:
2336:
2291:
2244:
1904:
1668:The importance of the center of
897:, but are less frequently used.
127:When inside the magnetic field (
99:. In clinical and research MRI,
5290:Liang ZP, Lauterbur PC (1999).
5059:
5006:
4953:
4907:
4878:
4868:
4818:
4789:
4775:
4756:
4742:
4717:
4695:
4670:
4642:
3893:Radiology Research and Practice
3809:"MRI Questions, Fast Spin Echo"
3683:
3648:
3634:10.1148/radiology.175.2.2326474
3613:
3260:are in the RF range of tens of
2685:Dynamic susceptibility contrast
2501:multiple sclerosis (MS) plaques
2050:the whole sequence is repeated
1817:
1605:-space, i.e., we scan the line
256:. In the case of the so-called
5319:. Springer Berlin Heidelberg.
5180:. Medical Physics Publishing.
5015:Magnetic Resonance in Medicine
4962:Magnetic Resonance in Medicine
4919:Magnetic Resonance in Medicine
4834:Magnetic Resonance in Medicine
4763:Wang, Brian (8 January 2017).
4048:"Short tau inversion recovery"
3578:
3551:
3516:
3393:
3368:
3339:
3330:
2916:
2821:Magnetic resonance angiography
2600:Apparent diffusion coefficient
2583:High signal within minutes of
2451:Fat suppression by setting an
2267:by using long TR and TE times
1982:, a frequency of 42.5781
1869:
1854:
1752:
1723:
1658:-space determines the image's
1557:
1545:
1539:
1533:
1496:
1490:
1484:
1461:
1419:
1379:
1373:
1364:
1319:
1313:
1304:
1294:we mean the true spin density
1255:
1249:
1243:
1216:
1210:
1204:
1167:
1155:
1149:
1143:
1114:
1108:
1099:
1087:
1047:
1041:
1035:
1004:
991:
985:
955:
949:
940:
1:
3657:Journal of Magnetic Resonance
3323:
3037:Superconducting electromagnet
2710:, the infarcted core and the
1385:{\displaystyle I({\vec {x}})}
1332:corrected for the effects of
224:Subatomic particles have the
4391:Chen F, Ni YC (March 2012).
4334:10.1097/WCO.0b013e3282f4594b
4322:Current Opinion in Neurology
4258:10.1161/STROKEAHA.110.610501
4160:"Diffusion weighted imaging"
4046:Sharma R, Taghi Niknejad M.
3741:"Magnetic Resonance Imaging"
3677:10.1016/0022-2364(83)90060-4
3491:10.1371/journal.pone.0015710
3380:Questions and Answers in MRI
3164:
2787:Blood-oxygen-level dependent
2531:Simultaneous suppression of
2443:Short tau inversion recovery
2352:Steady-state free precession
2132:This table does not include
2067:The negative-going lobes in
691:protons), on differences in
445:is thus associated with the
91:are able to absorb and emit
7:
3028:Resistive electromagnet: A
2934:The major components of an
1896:Example of a pulse sequence
822:contrast agents used in MRI
594:, such as those containing
568:is around one second while
276:, sometimes referred to as
272:, such as H, there are two
10:
5418:
5402:Magnetic resonance imaging
5252:Blümich B, Kuhn W (1992).
4796:Chen CN, Hoult DH (1989).
4397:World Journal of Radiology
4294:"Diffusion tensor imaging"
4186:Weerakkody Y, Gaillard F.
3861:"MRI sequences (overview)"
2922:Construction and operation
2805:reflects tissue activity.
2156:Main clinical distinctions
2119:
2116:Overview of main sequences
1761:{\displaystyle {\vec {k}}}
1732:{\displaystyle {\vec {x}}}
1396:of the sampled data, viz.
970:Faraday's law of induction
907:
900:
828:contrast agent (usually a
608:
516:which is much larger than
469:nuclear magnetic resonance
363:parallel and anti-parallel
322:
220:Nuclear magnetic resonance
217:
208:nuclear magnetic resonance
193:
34:Magnetic resonance imaging
5123:"NMR Imaging in Medicine"
4130:Di Muzio B, Abd Rabou A.
3305:electromagnetic radiation
3290:electromagnetic radiation
2942:
2819:
2766:
2763:
2744:Dynamic contrast enhanced
2718:
2700:
2673:
2612:Low signal minutes after
2557:
2523:Double inversion recovery
2462:, such as in more severe
2439:
2344:
2314:(to reduce T1) and short
2163:
2014:modulation) causes a 90°
1394:inverse Fourier transform
769:cerebral blood flow (CBF)
746:cerebrospinal fluid (CSF)
400:thermodynamic equilibrium
232:. Certain nuclei such as
40:technique mostly used in
5355:NMR Imaging of Materials
5121:Pykett IL (1 May 1982).
4825:Gruetter R (June 1993).
4651:"Phase contrast imaging"
4443:"Arterial spin labeling"
4024:Di Muzio B, Gaillard F.
3941:Luijkx T, Weerakkody Y.
3270:electromagnetic spectrum
3105:
2801:-dependent magnetism of
2539:by two inversion times.
2505:subarachnoid haemorrhage
2216:, hyperacute or chronic
1654:value for the center of
488:destructive interference
319:Resonance and relaxation
200:University of Nottingham
3859:du Plessis V, Jones J.
3745:University of Wisconsin
3352:Oxford University Press
2939:one or more computers.
2755:spin–lattice relaxation
2729:Arterial spin labelling
2412:Susceptibility-weighted
2301:Proton density weighted
2181:spin–lattice relaxation
1772:to show that a step in
1705:contrast to noise ratio
1674:rotating magnetic field
1612: = constant.
854:contrast agents, e.g.,
467:(FID). In an idealized
403:protons will come into
179:). Due to the magnetic
157:spin-lattice relaxation
4931:10.1002/mrm.1910160203
4846:10.1002/mrm.1910290613
4628:Johns Hopkins Hospital
4591:Luijkx T, Gaillard F.
4448:University of Michigan
3783:Harvard Medical School
3258:electromagnetic fields
3236:Radio frequency system
3102:
3094:
3002:
2965:
2931:
2840:magnetically saturated
2428:pictured) or calcium.
1971:
1883:
1762:
1733:
1703:-space first improves
1569:
1386:
1326:
1292:effective spin density
1273:
1179:
962:
895:gastrointestinal tract
879:gastrointestinal tract
744:to appear gray, while
355:
134:) of the scanner, the
30:
3599:10.2214/ajr.148.2.399
3537:10.2214/ajr.142.3.619
3278:electromagnetic field
3218:-axis, hence denoted
3100:
3092:
3084:signal-to-noise ratio
3075:may be used instead.
2964:
2950:
2929:
2654:fractional anisotropy
2426:diffuse axonal injury
1969:
1884:
1763:
1734:
1570:
1387:
1327:
1274:
1180:
963:
669:functional MRI (fMRI)
480:static magnetic field
424:with a time constant
385:strength of the field
356:
29:clinical MRI scanner.
24:
5233:Fukushima E (1989).
5214:Mansfield P (1982).
4802:Taylor & Francis
4800:. Medical Sciences.
4752:. 12 September 2018.
4410:10.4329/wjr.v4.i3.63
3990:10.1148/rg.295095034
3906:10.1155/2016/8329296
3376:"Quantum philosophy"
3346:Callaghan P (1994).
2580:of water molecules.
2546:plaques (pictured).
2265:spin–spin relaxation
2233:substances, such as
1928:improve this section
1783:
1743:
1714:
1590:), a single line of
1403:
1358:
1298:
1195:
979:
934:
723:specialized MR scans
629:reconstruction from
536:create a so-called "
465:free induction decay
337:
159:. This appears as a
5357:. Clarendon Press.
5334:Kuperman V (2000).
5144:1982SciAm.246e..78P
5131:Scientific American
4292:Smith D, Bashir U.
4080:Radiology Assistant
3704:1983MedPh..10..610T
3669:1983JMagR..54..338L
3482:2010PLoSO...515710F
3134:spherical harmonics
3047:alloy is cooled by
3019:rare-earth elements
2759:gadolinium contrast
2708:cerebral infarction
2696:gadolinium contrast
2614:cerebral infarction
2585:cerebral infarction
2533:cerebrospinal fluid
2440:Inversion recovery
2235:MRI contrast agents
1449:
1236:
1075:
658:Echo-planar imaging
635:computed tomography
592:MRI contrast agents
549:thermal equilibrium
354:{\displaystyle 1/2}
331:classical mechanics
5353:Blümich B (2000).
5338:. Academic Press.
5174:Sprawls P (2000).
4527:NMR in Biomedicine
4188:"Ischaemic stroke"
4076:"Stress fractures"
3103:
3095:
3003:
2966:
2932:
2757:(T1) induced by a
2675:Perfusion weighted
2559:Diffusion weighted
2544:multiple sclerosis
2497:lacunar infarction
2368:videos (pictured).
2318:(to minimize T2).
1972:
1879:
1758:
1729:
1565:
1432:
1382:
1322:
1269:
1222:
1175:
1058:
958:
351:
226:quantum mechanical
78:ionizing radiation
31:
5383:978-0-8493-9693-9
5364:978-0-19-850683-6
5345:978-0-08-053570-8
5326:978-3-540-63194-1
5305:978-0-7803-4723-6
5282:978-3-527-29637-8
5263:978-3-527-28403-0
5244:978-0-88318-609-1
5225:978-0-323-15406-2
5206:978-0-471-35128-3
5187:978-0-944838-97-6
5169:on 10 March 2016.
5037:10.1002/mrm.10171
4900:978-3-89578-226-8
4885:Oppelt A (2006).
4811:978-0-85274-118-4
4735:978-0-306-45300-7
4691:on 24 April 2008.
4158:Lee M, Bashir U.
3844:978-0-7020-4614-8
3415:978-3-662-07805-1
3361:978-0-19-853997-1
3254:transmitting coil
2981:
2914:
2913:
2799:oxygen saturation
2327:High signal from
2183:by using a short
1964:
1963:
1956:
1875:
1815:
1755:
1726:
1560:
1536:
1526:
1487:
1469:
1464:
1422:
1376:
1316:
1260:
1246:
1207:
1170:
1146:
1136:
1111:
1095:
1090:
1038:
1007:
952:
852:superparamagnetic
773:blood oxygenation
649:Fourier transform
288:have no unpaired
284:. Nuclei such as
214:Nuclear magnetism
170:Fourier transform
82:cochlear implants
5409:
5387:
5368:
5349:
5330:
5309:
5297:
5286:
5267:
5248:
5229:
5210:
5191:
5170:
5168:
5162:. Archived from
5127:
5107:
5106:
5072:
5063:
5057:
5056:
5030:
5010:
5004:
5003:
4977:
4957:
4951:
4950:
4911:
4905:
4904:
4882:
4876:
4872:
4866:
4865:
4831:
4822:
4816:
4815:
4793:
4787:
4786:
4779:
4773:
4772:
4760:
4754:
4753:
4746:
4740:
4739:
4721:
4715:
4714:
4712:
4710:
4699:
4693:
4692:
4690:
4684:. Archived from
4683:
4674:
4668:
4667:
4665:
4663:
4646:
4640:
4639:
4637:
4635:
4619:
4610:
4609:
4607:
4605:
4593:"Functional MRI"
4588:
4582:
4581:
4579:
4577:
4565:
4559:
4558:
4539:10.1002/nbm.1273
4522:
4516:
4515:
4513:
4511:
4494:
4488:
4487:
4485:
4483:
4466:
4460:
4459:
4457:
4455:
4439:
4433:
4432:
4422:
4412:
4388:
4382:
4381:
4379:
4377:
4360:
4354:
4353:
4317:
4311:
4310:
4308:
4306:
4289:
4280:
4279:
4269:
4237:
4231:
4230:
4228:
4226:
4211:
4205:
4204:
4202:
4200:
4183:
4177:
4176:
4174:
4172:
4155:
4149:
4148:
4146:
4144:
4127:
4118:
4117:
4115:
4113:
4098:
4092:
4091:
4089:
4087:
4071:
4065:
4064:
4062:
4060:
4043:
4037:
4036:
4034:
4032:
4021:
4012:
4011:
4001:
3969:
3960:
3959:
3957:
3955:
3938:
3929:
3928:
3918:
3908:
3884:
3878:
3877:
3875:
3873:
3856:
3850:
3848:
3830:
3824:
3823:
3821:
3819:
3813:MRIQuestions.com
3805:
3799:
3798:
3796:
3794:
3785:. Archived from
3774:
3761:
3760:
3758:
3756:
3747:. Archived from
3737:
3724:
3723:
3712:10.1118/1.595331
3687:
3681:
3680:
3652:
3646:
3645:
3617:
3611:
3610:
3582:
3576:
3575:
3555:
3549:
3548:
3520:
3514:
3513:
3503:
3493:
3461:
3455:
3454:
3426:
3420:
3419:
3397:
3391:
3390:
3388:
3386:
3372:
3366:
3365:
3343:
3337:
3334:
3041:niobium-titanium
2983:
2982:
2963:
2904:
2863:
2827:) and venography
2815:
2771:
2723:
2669:
2628:Diffusion tensor
2623:
2594:
2553:
2518:
2477:
2435:
2406:
2395:Low signal from
2375:
2340:
2295:
2248:
2229:High signal for
2223:High signal for
2139:
2138:
2130:
1959:
1952:
1948:
1945:
1939:
1908:
1900:
1888:
1886:
1885:
1880:
1873:
1872:
1867:
1866:
1857:
1849:
1816:
1814:
1803:
1798:
1797:
1767:
1765:
1764:
1759:
1757:
1756:
1748:
1738:
1736:
1735:
1730:
1728:
1727:
1719:
1698:
1697:
1574:
1572:
1571:
1566:
1564:
1563:
1562:
1561:
1553:
1538:
1537:
1529:
1524:
1503:
1499:
1489:
1488:
1480:
1467:
1466:
1465:
1457:
1454:
1448:
1443:
1428:
1424:
1423:
1415:
1391:
1389:
1388:
1383:
1378:
1377:
1369:
1331:
1329:
1328:
1323:
1318:
1317:
1309:
1286:-space with the
1278:
1276:
1275:
1270:
1265:
1258:
1248:
1247:
1239:
1235:
1230:
1209:
1208:
1200:
1184:
1182:
1181:
1176:
1174:
1173:
1172:
1171:
1163:
1148:
1147:
1139:
1134:
1113:
1112:
1104:
1093:
1092:
1091:
1083:
1080:
1074:
1069:
1054:
1050:
1040:
1039:
1031:
1023:
1022:
1021:
1009:
1008:
1000:
967:
965:
964:
959:
954:
953:
945:
872:
871:
800:
799:
766:
765:
720:
719:
693:relaxation times
586:
585:
501:
500:
484:Larmor frequency
381:Larmor frequency
360:
358:
357:
352:
347:
325:Relaxation (NMR)
267:
266:
262:
136:magnetic moments
64:may be injected
46:nuclear medicine
16:Overview article
5417:
5416:
5412:
5411:
5410:
5408:
5407:
5406:
5392:
5391:
5390:
5384:
5365:
5346:
5327:
5306:
5283:
5264:
5245:
5226:
5207:
5188:
5166:
5125:
5116:
5114:Further reading
5111:
5110:
5070:
5064:
5060:
5028:10.1.1.462.3159
5011:
5007:
4975:10.1.1.139.3032
4958:
4954:
4912:
4908:
4901:
4893:. p. 566.
4883:
4879:
4873:
4869:
4829:
4823:
4819:
4812:
4794:
4790:
4781:
4780:
4776:
4769:Next Big Future
4761:
4757:
4748:
4747:
4743:
4736:
4722:
4718:
4708:
4706:
4701:
4700:
4696:
4688:
4681:
4675:
4671:
4661:
4659:
4647:
4643:
4633:
4631:
4621:
4620:
4613:
4603:
4601:
4589:
4585:
4575:
4573:
4566:
4562:
4523:
4519:
4509:
4507:
4495:
4491:
4481:
4479:
4467:
4463:
4453:
4451:
4441:
4440:
4436:
4389:
4385:
4375:
4373:
4361:
4357:
4318:
4314:
4304:
4302:
4290:
4283:
4238:
4234:
4224:
4222:
4212:
4208:
4198:
4196:
4184:
4180:
4170:
4168:
4156:
4152:
4142:
4140:
4128:
4121:
4111:
4109:
4107:radiopaedia.org
4099:
4095:
4085:
4083:
4072:
4068:
4058:
4056:
4044:
4040:
4030:
4028:
4022:
4015:
3970:
3963:
3953:
3951:
3939:
3932:
3885:
3881:
3871:
3869:
3857:
3853:
3845:
3831:
3827:
3817:
3815:
3807:
3806:
3802:
3792:
3790:
3789:on 5 March 2016
3775:
3764:
3754:
3752:
3739:
3738:
3727:
3692:Medical Physics
3688:
3684:
3653:
3649:
3618:
3614:
3583:
3579:
3556:
3552:
3521:
3517:
3462:
3458:
3427:
3423:
3416:
3398:
3394:
3384:
3382:
3374:
3373:
3369:
3362:
3344:
3340:
3335:
3331:
3326:
3268:portion of the
3266:shortwave radio
3250:power amplifier
3242:radio frequency
3238:
3226:
3167:
3160:
3146:
3108:
3065:liquid nitrogen
3001:
3000:
2992:
2990:
2989:
2988:
2987:
2984:
2977:
2974:
2972:Audio recording
2967:
2961:
2956:
2945:
2924:
2919:
2905:
2642:Brownian motion
2578:Brownian motion
2542:High signal of
2495:High signal in
2464:stress fracture
2458:High signal in
2382:
2279:Low signal for
2185:repetition time
2131:
2124:
2118:
2104:
2097:
2087:
2080:
2073:
2063:
2056:
2049:
2039:
2032:
2025:
2006:
1999:
1992:
1960:
1949:
1943:
1940:
1925:
1909:
1898:
1868:
1862:
1858:
1853:
1818:
1807:
1802:
1787:
1786:
1784:
1781:
1780:
1770:Nyquist theorem
1747:
1746:
1744:
1741:
1740:
1718:
1717:
1715:
1712:
1711:
1696:
1693:
1692:
1691:
1686:
1664:
1653:
1611:
1600:
1552:
1551:
1528:
1527:
1511:
1507:
1479:
1478:
1477:
1473:
1456:
1455:
1450:
1444:
1436:
1414:
1413:
1409:
1404:
1401:
1400:
1368:
1367:
1359:
1356:
1355:
1350:From the basic
1345:
1338:
1308:
1307:
1299:
1296:
1295:
1288:velocity vector
1261:
1238:
1237:
1231:
1226:
1199:
1198:
1196:
1193:
1192:
1162:
1161:
1138:
1137:
1124:
1120:
1103:
1102:
1082:
1081:
1076:
1070:
1062:
1030:
1029:
1028:
1024:
1011:
1010:
999:
998:
997:
980:
977:
976:
944:
943:
935:
932:
931:
912:
906:
889:agents such as
870:
867:
866:
865:
850:More recently,
845:Contrast agents
838:
798:
795:
794:
793:
788:
781:
764:
761:
760:
759:
754:
731:
718:
715:
714:
713:
708:
701:
681:
660:
616:
614:Imaging schemes
611:
604:
584:
581:
580:
579:
574:
567:
553:repetition time
546:
522:
515:
508:
499:
496:
495:
494:
477:
455:
444:
437:
430:
416:
378:
343:
338:
335:
334:
327:
321:
264:
260:
259:
254:magnetic moment
222:
216:
196:
189:
148:radio frequency
145:
133:
93:radio frequency
62:Contrast agents
38:medical imaging
17:
12:
11:
5:
5415:
5405:
5404:
5389:
5388:
5382:
5372:Jin J (1998).
5369:
5363:
5350:
5344:
5331:
5325:
5310:
5304:
5287:
5281:
5268:
5262:
5249:
5243:
5230:
5224:
5211:
5205:
5192:
5186:
5171:
5117:
5115:
5112:
5109:
5108:
5081:(4): 223–236.
5058:
5021:(6): 1202–10.
5005:
4952:
4925:(2): 192–225.
4906:
4899:
4877:
4867:
4817:
4810:
4788:
4774:
4755:
4741:
4734:
4716:
4694:
4669:
4641:
4611:
4583:
4560:
4517:
4489:
4461:
4434:
4383:
4355:
4312:
4281:
4252:(5): 1276–81.
4232:
4206:
4178:
4150:
4119:
4093:
4066:
4038:
4013:
3984:(5): 1433–49.
3961:
3930:
3879:
3851:
3843:
3825:
3800:
3762:
3751:on 10 May 2017
3725:
3682:
3663:(2): 338–343.
3647:
3612:
3593:(2): 399–404.
3577:
3550:
3515:
3476:(12): e15710.
3456:
3421:
3414:
3392:
3367:
3360:
3338:
3328:
3327:
3325:
3322:
3286:electric field
3264:(often in the
3237:
3234:
3222:
3166:
3163:
3158:
3144:
3120:susceptibility
3107:
3104:
3057:
3056:
3053:superconductor
3034:
3026:
2991:
2985:
2975:
2970:
2969:
2968:
2959:
2958:
2957:
2944:
2941:
2923:
2920:
2918:
2915:
2912:
2911:
2898:
2883:
2876:
2871:
2865:
2864:
2857:
2843:
2836:
2831:
2830:Time-of-flight
2828:
2817:
2816:
2809:
2806:
2795:
2790:
2784:
2777:Functional MRI
2773:
2772:
2765:
2762:
2751:
2746:
2740:
2739:
2736:
2731:
2725:
2724:
2717:
2716:
2715:
2704:
2699:
2692:
2687:
2682:
2671:
2670:
2663:
2662:
2661:
2650:
2645:
2634:
2629:
2625:
2624:
2617:
2610:
2607:
2602:
2596:
2595:
2588:
2581:
2574:
2569:
2566:
2555:
2554:
2547:
2540:
2529:
2524:
2520:
2519:
2512:
2493:
2490:
2485:
2479:
2478:
2471:
2456:
2453:inversion time
2449:
2444:
2441:
2437:
2436:
2429:
2422:
2419:
2414:
2408:
2407:
2400:
2393:
2390:
2385:
2377:
2376:
2369:
2362:
2359:
2354:
2349:
2342:
2341:
2334:
2333:
2332:
2329:meniscus tears
2319:
2308:
2303:
2297:
2296:
2289:
2285:
2284:
2277:
2273:
2268:
2261:
2256:
2250:
2249:
2242:
2238:
2237:
2227:
2221:
2192:
2177:
2172:
2167:
2161:
2160:
2157:
2154:
2151:
2146:
2143:
2120:Main article:
2117:
2114:
2102:
2095:
2085:
2078:
2071:
2061:
2054:
2047:
2037:
2030:
2023:
2004:
1997:
1990:
1976:timing diagram
1962:
1961:
1944:September 2009
1912:
1910:
1903:
1897:
1894:
1890:
1889:
1878:
1871:
1865:
1861:
1856:
1852:
1848:
1845:
1842:
1839:
1836:
1833:
1830:
1827:
1824:
1821:
1813:
1810:
1806:
1801:
1796:
1793:
1790:
1754:
1751:
1725:
1722:
1694:
1684:
1662:
1651:
1609:
1598:
1576:
1575:
1559:
1556:
1550:
1547:
1544:
1541:
1535:
1532:
1523:
1520:
1517:
1514:
1510:
1506:
1502:
1498:
1495:
1492:
1486:
1483:
1476:
1472:
1463:
1460:
1453:
1447:
1442:
1439:
1435:
1431:
1427:
1421:
1418:
1412:
1408:
1392:by taking the
1381:
1375:
1372:
1366:
1363:
1343:
1336:
1321:
1315:
1312:
1306:
1303:
1280:
1279:
1268:
1264:
1257:
1254:
1251:
1245:
1242:
1234:
1229:
1225:
1221:
1218:
1215:
1212:
1206:
1203:
1186:
1185:
1169:
1166:
1160:
1157:
1154:
1151:
1145:
1142:
1133:
1130:
1127:
1123:
1119:
1116:
1110:
1107:
1101:
1098:
1089:
1086:
1079:
1073:
1068:
1065:
1061:
1057:
1053:
1049:
1046:
1043:
1037:
1034:
1027:
1020:
1017:
1014:
1006:
1003:
996:
993:
990:
987:
984:
957:
951:
948:
942:
939:
908:Main article:
905:
899:
891:barium sulfate
868:
836:
814:contrast agent
796:
786:
779:
762:
752:
729:
716:
706:
699:
680:
677:
659:
656:
645:
644:
641:
638:
615:
612:
610:
607:
602:
582:
572:
565:
558:Typically, in
544:
528:field gradient
520:
513:
506:
497:
475:
453:
442:
435:
428:
414:
389:radiofrequency
376:
350:
346:
342:
323:Main article:
320:
317:
301:magnetic field
218:Main article:
215:
212:
204:Raymond Andrew
195:
192:
187:
143:
131:
118:pulse sequence
101:hydrogen atoms
97:magnetic field
76:, MRI uses no
15:
9:
6:
4:
3:
2:
5414:
5403:
5400:
5399:
5397:
5385:
5379:
5376:. CRC Press.
5375:
5370:
5366:
5360:
5356:
5351:
5347:
5341:
5337:
5332:
5328:
5322:
5318:
5317:
5311:
5307:
5301:
5296:
5295:
5288:
5284:
5278:
5275:. Wiley-VCH.
5274:
5269:
5265:
5259:
5255:
5250:
5246:
5240:
5236:
5231:
5227:
5221:
5217:
5212:
5208:
5202:
5198:
5193:
5189:
5183:
5179:
5178:
5172:
5165:
5161:
5157:
5153:
5149:
5145:
5141:
5137:
5133:
5132:
5124:
5119:
5118:
5104:
5100:
5096:
5092:
5088:
5084:
5080:
5076:
5069:
5062:
5054:
5050:
5046:
5042:
5038:
5034:
5029:
5024:
5020:
5016:
5009:
5001:
4997:
4993:
4989:
4985:
4981:
4976:
4971:
4968:(5): 952–62.
4967:
4963:
4956:
4948:
4944:
4940:
4936:
4932:
4928:
4924:
4920:
4916:
4910:
4902:
4896:
4892:
4888:
4881:
4871:
4863:
4859:
4855:
4851:
4847:
4843:
4840:(6): 804–11.
4839:
4835:
4828:
4821:
4813:
4807:
4803:
4799:
4792:
4784:
4778:
4770:
4766:
4759:
4751:
4745:
4737:
4731:
4727:
4720:
4704:
4698:
4687:
4680:
4673:
4658:
4657:
4652:
4645:
4630:
4629:
4624:
4618:
4616:
4600:
4599:
4594:
4587:
4571:
4564:
4556:
4552:
4548:
4544:
4540:
4536:
4532:
4528:
4521:
4506:
4505:
4500:
4493:
4478:
4477:
4472:
4465:
4450:
4449:
4444:
4438:
4430:
4426:
4421:
4416:
4411:
4406:
4402:
4398:
4394:
4387:
4372:
4371:
4366:
4359:
4351:
4347:
4343:
4339:
4335:
4331:
4327:
4323:
4316:
4301:
4300:
4295:
4288:
4286:
4277:
4273:
4268:
4263:
4259:
4255:
4251:
4247:
4243:
4236:
4221:
4217:
4210:
4195:
4194:
4189:
4182:
4167:
4166:
4161:
4154:
4139:
4138:
4133:
4126:
4124:
4108:
4104:
4097:
4081:
4077:
4070:
4055:
4054:
4049:
4042:
4027:
4020:
4018:
4009:
4005:
4000:
3995:
3991:
3987:
3983:
3979:
3978:Radiographics
3975:
3968:
3966:
3950:
3949:
3944:
3937:
3935:
3926:
3922:
3917:
3912:
3907:
3902:
3898:
3894:
3890:
3883:
3868:
3867:
3862:
3855:
3846:
3840:
3836:
3829:
3814:
3810:
3804:
3788:
3784:
3780:
3773:
3771:
3769:
3767:
3750:
3746:
3742:
3736:
3734:
3732:
3730:
3721:
3717:
3713:
3709:
3705:
3701:
3698:(5): 610–21.
3697:
3693:
3686:
3678:
3674:
3670:
3666:
3662:
3658:
3651:
3643:
3639:
3635:
3631:
3628:(2): 489–93.
3627:
3623:
3616:
3608:
3604:
3600:
3596:
3592:
3588:
3581:
3573:
3569:
3566:(2): 157–65.
3565:
3561:
3554:
3546:
3542:
3538:
3534:
3531:(3): 619–24.
3530:
3526:
3519:
3511:
3507:
3502:
3497:
3492:
3487:
3483:
3479:
3475:
3471:
3467:
3460:
3452:
3448:
3444:
3440:
3437:(3): 767–79.
3436:
3432:
3431:Radiographics
3425:
3417:
3411:
3407:
3401:
3396:
3381:
3377:
3371:
3363:
3357:
3353:
3349:
3342:
3333:
3329:
3321:
3317:
3313:
3311:
3310:Faraday cages
3306:
3301:
3299:
3295:
3291:
3287:
3283:
3279:
3275:
3274:amateur radio
3271:
3267:
3263:
3259:
3255:
3251:
3247:
3243:
3233:
3230:
3225:
3221:
3217:
3213:
3209:
3205:
3199:
3198:stimulation.
3195:
3193:
3188:
3183:
3181:
3177:
3173:
3162:
3157:
3152:
3148:
3143:
3137:
3135:
3130:
3126:
3121:
3116:
3114:
3099:
3091:
3087:
3085:
3080:
3076:
3074:
3070:
3066:
3062:
3054:
3050:
3049:liquid helium
3046:
3042:
3038:
3035:
3031:
3027:
3024:
3020:
3016:
3015:
3014:
3010:
3008:
2999:
2997:
2973:
2954:
2949:
2940:
2937:
2928:
2909:
2903:
2899:
2896:
2892:
2888:
2885:Detection of
2884:
2881:
2877:
2875:
2872:
2870:
2867:
2866:
2862:
2858:
2856:
2852:
2848:
2845:Detection of
2844:
2841:
2837:
2835:
2832:
2829:
2826:
2822:
2818:
2814:
2810:
2807:
2804:
2800:
2796:
2794:
2791:
2788:
2785:
2782:
2778:
2775:
2774:
2770:
2760:
2756:
2752:
2750:
2747:
2745:
2742:
2741:
2737:
2735:
2732:
2730:
2727:
2726:
2722:
2713:
2709:
2705:
2702:
2701:
2697:
2693:
2691:
2688:
2686:
2683:
2680:
2676:
2672:
2668:
2664:
2659:
2656:may indicate
2655:
2651:
2648:
2647:
2646:
2643:
2639:
2635:
2633:
2630:
2627:
2626:
2622:
2618:
2615:
2611:
2608:
2606:
2603:
2601:
2598:
2597:
2593:
2589:
2586:
2582:
2579:
2575:
2573:
2570:
2567:
2564:
2560:
2556:
2552:
2548:
2545:
2541:
2538:
2534:
2530:
2528:
2525:
2522:
2521:
2517:
2513:
2510:
2506:
2502:
2498:
2494:
2491:
2489:
2486:
2484:
2481:
2480:
2476:
2472:
2469:
2465:
2461:
2457:
2454:
2450:
2448:
2445:
2442:
2438:
2434:
2430:
2427:
2423:
2420:
2418:
2415:
2413:
2410:
2409:
2405:
2401:
2398:
2394:
2391:
2389:
2386:
2384:
2381:Effective T2
2379:
2378:
2374:
2370:
2367:
2363:
2360:
2358:
2355:
2353:
2350:
2347:
2346:Gradient echo
2343:
2339:
2335:
2330:
2326:
2325:
2323:
2322:Joint disease
2320:
2317:
2313:
2309:
2307:
2304:
2302:
2299:
2298:
2294:
2290:
2288:
2282:
2278:
2274:
2271:
2270:
2269:
2266:
2262:
2260:
2257:
2255:
2252:
2251:
2247:
2243:
2241:
2236:
2232:
2228:
2226:
2222:
2219:
2215:
2211:
2207:
2203:
2199:
2195:
2194:
2193:
2190:
2186:
2182:
2178:
2176:
2173:
2171:
2168:
2166:
2162:
2158:
2155:
2152:
2150:
2147:
2144:
2141:
2140:
2137:
2135:
2129:
2123:
2113:
2111:
2106:
2101:
2094:
2089:
2084:
2077:
2070:
2065:
2060:
2053:
2046:
2041:
2036:
2029:
2022:
2017:
2013:
2008:
2003:
1996:
1989:
1985:
1981:
1977:
1968:
1958:
1955:
1947:
1937:
1933:
1929:
1923:
1922:
1918:
1913:This section
1911:
1907:
1902:
1901:
1893:
1876:
1859:
1850:
1811:
1804:
1799:
1779:
1778:
1777:
1775:
1771:
1749:
1720:
1708:
1706:
1702:
1690:
1683:
1679:
1675:
1671:
1666:
1661:
1657:
1650:
1646:
1642:
1638:
1634:
1630:
1626:
1622:
1618:
1613:
1608:
1604:
1597:
1593:
1589:
1585:
1581:
1554:
1548:
1542:
1530:
1521:
1518:
1515:
1512:
1508:
1504:
1500:
1493:
1481:
1474:
1470:
1458:
1437:
1433:
1429:
1425:
1416:
1410:
1406:
1399:
1398:
1397:
1395:
1370:
1361:
1353:
1348:
1342:
1339:preparation,
1335:
1310:
1301:
1293:
1289:
1285:
1266:
1252:
1240:
1232:
1227:
1223:
1219:
1213:
1201:
1191:
1190:
1189:
1164:
1158:
1152:
1140:
1131:
1128:
1125:
1121:
1117:
1105:
1096:
1084:
1063:
1059:
1055:
1051:
1044:
1032:
1025:
1001:
994:
988:
982:
975:
974:
973:
971:
946:
937:
929:
925:
921:
917:
911:
910:K-space (MRI)
903:
898:
896:
892:
888:
884:
880:
876:
864:
860:
859:nanoparticles
857:
853:
848:
846:
842:
835:
831:
827:
823:
819:
815:
811:
807:
802:
792:
785:
778:
774:
770:
758:
751:
747:
743:
739:
735:
728:
724:
712:
705:
698:
694:
690:
686:
676:
674:
673:diffusion MRI
670:
665:
655:
652:
650:
642:
639:
636:
633:, such as in
632:
628:
624:
621:
620:
619:
606:
601:
597:
593:
589:
578:
571:
564:
561:
556:
554:
550:
543:
539:
534:
529:
524:
523:(see below).
519:
512:
505:
493:
489:
485:
481:
474:
470:
466:
461:
459:
452:
448:
441:
434:
427:
423:
422:exponentially
419:
413:
408:
406:
401:
396:
394:
390:
386:
382:
375:
370:
368:
367:wave function
364:
348:
344:
340:
332:
326:
316:
314:
313:Zeeman effect
310:
306:
302:
297:
295:
291:
287:
283:
279:
275:
271:
268:
255:
251:
247:
243:
239:
235:
231:
227:
221:
211:
209:
205:
201:
191:
186:
182:
181:Lorentz force
178:
176:
171:
166:
162:
161:magnetic flux
158:
154:
149:
142:
137:
130:
125:
123:
119:
115:
111:
107:
102:
98:
94:
90:
89:atomic nuclei
85:
83:
79:
75:
71:
67:
66:intravenously
63:
59:
55:
51:
47:
43:
39:
35:
28:
23:
19:
5373:
5354:
5335:
5315:
5293:
5272:
5253:
5234:
5218:. Elsevier.
5215:
5196:
5176:
5164:the original
5138:(5): 78–88.
5135:
5129:
5078:
5074:
5061:
5018:
5014:
5008:
4965:
4961:
4955:
4922:
4918:
4909:
4886:
4880:
4870:
4837:
4833:
4820:
4797:
4791:
4777:
4768:
4758:
4744:
4725:
4719:
4707:. Retrieved
4697:
4686:the original
4672:
4660:. Retrieved
4654:
4644:
4632:. Retrieved
4626:
4602:. Retrieved
4596:
4586:
4574:. Retrieved
4563:
4533:(1): 28–39.
4530:
4526:
4520:
4508:. Retrieved
4502:
4497:Gaillard F.
4492:
4480:. Retrieved
4474:
4469:Gaillard F.
4464:
4452:. Retrieved
4446:
4437:
4403:(3): 63–74.
4400:
4396:
4386:
4374:. Retrieved
4368:
4363:Gaillard F.
4358:
4328:(1): 83–92.
4325:
4321:
4315:
4303:. Retrieved
4297:
4249:
4245:
4235:
4223:. Retrieved
4219:
4209:
4197:. Retrieved
4191:
4181:
4169:. Retrieved
4163:
4153:
4141:. Retrieved
4135:
4110:. Retrieved
4106:
4096:
4084:. Retrieved
4079:
4069:
4057:. Retrieved
4051:
4041:
4029:. Retrieved
3981:
3977:
3952:. Retrieved
3946:
3896:
3892:
3882:
3870:. Retrieved
3864:
3854:
3834:
3828:
3816:. Retrieved
3803:
3791:. Retrieved
3787:the original
3777:Johnson KA.
3753:. Retrieved
3749:the original
3695:
3691:
3685:
3660:
3656:
3650:
3625:
3621:
3615:
3590:
3586:
3580:
3563:
3559:
3553:
3528:
3524:
3518:
3473:
3469:
3459:
3434:
3430:
3424:
3405:
3395:
3383:. Retrieved
3379:
3370:
3347:
3341:
3332:
3318:
3314:
3302:
3297:
3293:
3246:transmission
3239:
3223:
3219:
3215:
3211:
3207:
3203:
3200:
3196:
3191:
3184:
3179:
3175:
3171:
3168:
3155:
3141:
3138:
3129:paramagnetic
3117:
3109:
3081:
3077:
3058:
3011:
3004:
2993:
2935:
2933:
2897:(pictured).
2873:
2833:
2824:
2792:
2780:
2748:
2733:
2689:
2678:
2638:tractography
2631:
2616:(pictured).
2604:
2587:(pictured).
2571:
2568:Conventional
2562:
2537:white matter
2526:
2487:
2468:Shin splints
2446:
2416:
2387:
2383:or "T2-star"
2364:Creation of
2356:
2331:. (pictured)
2324:and injury.
2305:
2286:
2281:paramagnetic
2258:
2239:
2231:paramagnetic
2210:inflammation
2174:
2125:
2122:MRI sequence
2109:
2107:
2099:
2092:
2090:
2082:
2075:
2068:
2066:
2058:
2051:
2044:
2042:
2034:
2027:
2020:
2009:
2001:
1994:
1987:
1973:
1950:
1941:
1926:Please help
1914:
1891:
1773:
1709:
1700:
1688:
1681:
1677:
1669:
1667:
1659:
1655:
1648:
1647:-space, the
1644:
1640:
1636:
1632:
1628:
1624:
1616:
1614:
1606:
1602:
1595:
1591:
1587:
1579:
1577:
1351:
1349:
1340:
1333:
1291:
1283:
1281:
1187:
927:
923:
919:
915:
913:
901:
862:
849:
840:
833:
826:paramagnetic
803:
790:
783:
776:
756:
749:
734:white matter
726:
710:
703:
696:
682:
661:
653:
646:
617:
599:
590:
576:
569:
562:
560:soft tissues
557:
552:
541:
525:
517:
510:
503:
491:
472:
462:
450:
439:
438:relaxation.
432:
425:
411:
409:
397:
373:
371:
328:
298:
281:
277:
228:property of
223:
197:
184:
174:
140:
128:
126:
114:nuclear spin
86:
54:inflammation
32:
18:
4656:Radiopaedia
4598:Radiopaedia
4504:Radiopaedia
4476:Radiopaedia
4370:Radiopaedia
4299:Radiopaedia
4220:XRayPhysics
4193:Radiopaedia
4165:Radiopaedia
4137:Radiopaedia
4053:Radiopaedia
3948:Radiopaedia
3899:: 8329296.
3866:Radiopaedia
3045:niobium-tin
2936:MRI scanner
2917:MRI scanner
2797:Changes in
2698:injection.
2576:Measure of
2511:(pictured).
2397:hemosiderin
2366:cardiac MRI
2254:T2 weighted
2170:T1 weighted
887:Diamagnetic
775:can affect
742:gray matter
631:projections
420:and occurs
309:eigenstates
274:spin states
36:(MRI) is a
4709:7 December
4662:15 October
4634:15 October
4604:16 October
4510:15 October
4482:15 October
4454:27 October
4376:14 October
4305:13 October
4225:15 October
4214:Hammer M.
4199:15 October
4171:13 October
4143:13 October
4112:3 December
4086:13 October
4059:13 October
4031:15 October
3954:13 October
3872:13 January
3324:References
3282:near-field
3187:amplifiers
3069:cryocooler
3007:teslas (T)
2996:media help
2895:dissection
2855:dissection
2803:hemoglobin
2509:meningitis
2283:substances
2263:Measuring
2218:hemorrhage
2206:infarction
2179:Measuring
2091:Typically
1665:contrast.
1584:physicists
1578:Using the
856:iron oxide
830:gadolinium
596:Gadolinium
418:relaxation
153:precession
122:relaxation
5298:. Wiley.
5256:. Wiley.
5023:CiteSeerX
4970:CiteSeerX
4915:Roemer PB
4891:Wiley-VCH
4568:Chou Ih.
3622:Radiology
3298:radiation
3262:megahertz
3165:Gradients
3039:: When a
3033:obsolete.
3023:neodymium
2955:, England
2470:pictured:
2214:infection
2189:echo time
2187:(TR) and
2165:Spin echo
1915:does not
1851:∝
1809:Δ
1800:∝
1753:→
1724:→
1623:, all of
1558:→
1549:⋅
1534:→
1519:π
1513:−
1505:⋅
1485:→
1462:→
1446:∞
1441:∞
1438:−
1434:∫
1420:→
1374:→
1314:→
1302:ρ
1267:τ
1253:τ
1244:→
1224:∫
1220:≡
1205:→
1168:→
1159:⋅
1144:→
1129:π
1118:⋅
1109:→
1097:ρ
1088:→
1072:∞
1067:∞
1064:−
1060:∫
1056:≡
1036:→
1005:~
1002:ρ
950:→
938:ρ
810:pathology
538:spin-echo
42:radiology
25:Modern 3
5396:Category
5095:15548953
5053:14724155
5045:12111967
5000:16046989
4992:10542355
4862:41112243
4576:9 August
4572:. Nature
4547:18654999
4429:22468186
4350:24731783
4342:18180656
4276:21454821
4008:19755604
3925:27057352
3793:14 March
3755:14 March
3510:21187930
3470:PLOS ONE
3451:11353123
3127:(due to
3061:cryostat
3030:solenoid
3021:such as
2891:stenosis
2887:aneurysm
2851:stenosis
2847:aneurysm
2712:penumbra
2658:dementia
2652:Reduced
2159:Example
2145:Sequence
2016:nutation
883:pancreas
847:below.)
685:contrast
533:infinite
447:enthalpy
296:C does.
290:neutrons
202:by Prof
87:Certain
5160:7079720
5140:Bibcode
4947:9482029
4939:2266841
4854:8350724
4555:5305422
4420:3314930
4267:3384724
3999:2799958
3916:4766355
3720:6646065
3700:Bibcode
3665:Bibcode
3642:2326474
3607:3492120
3572:6505042
3545:6607655
3501:3004955
3478:Bibcode
3400:Page 26
3182:-axes.
3125:sinuses
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