MRI in Practice

MRI in Practice Index

motion artefact New Terminology with Regard to MRI and Implants and 435
time of flight MRA, 275–6 Devices (ASTM), 343–5
see also phase mismapping
NEX, see number of excitations
movement niche magnets, 319–20
of heart, 290, 291 nitrogen, mass number, 4
phase mismapping, 225–34, 260 NMV, see net magnetization vector
noise, 104, 420
MR active nuclei, 2–4, 419
MR conditional items, 344, 354 see also contrast to noise ratio; signal to noise ratio
noise (acoustic), 327, 350–1
pacemakers, 367–8 non-resonant power supplies, single shot imaging
MR microscopy, 410, 411
MR safe items, 344, 354 techniques, 189
MR signal, 15, 419 no phase wrap, 240, 420
nucleons, 2, 420
contrast, 22–3 nulling, 220–1
K space and, 94
K space lines, 91–3 breast implants, 218
noise vs, 104 see also gradient moment rephasing; saturation
spatial location, 59–79 null point, 420
MR spectroscopy, 407–10 STIR, 157
single voxel techniques, 407–8, 423 number of excitations (NEX), 95, 420
stimulated echo acquisition mode, 407–8, 424 anti-foldover, 240
MR unsafe items, 344, 345 bowel movement and, 233
MTC, see magnetization transfer contrast brain images, 121
multichannel head coils, 331 on scan time, 132
multidirectional flow, MRA, 280–2 signal to noise ratio vs, 114–5, 120
MultiHance, 378, 379, 380, 381 trade-offs, 136
multi-oblique images, heart, 291 Nyquist frequency, 77, 420
multiphase cardiac imaging, 300–4 Nyquist theorem, 74, 76, 420
multiple coils, 333–4 frequency wrap, 235
multiple overlapping thin section angiography
ocular implants, 364
(MOTSA), 271, 276, 419 Ohm’s law, 315–6, 420
multiple sclerosis, cervical spine, 181 open MRI systems, 314, 405–6
multi-shot (imaging), 419
multi-shot echo planar imaging, 189 high-field magnets, 319
multi-voxel techniques, 419 operator interfaces, 339
oral contrast agents, 384, 385
MR spectroscopy, 408, 409 orbits, temperature, 348
musculoskeletal imaging, STIR, 158 orthopedics
myelination, diffusion weighted imaging, 399
myocardial infarction implants, 365
niche magnets, 320
contrast-enhanced imaging, 392 otologic implants, 364
SPAMM, 304 outer lines, 420
out of phase, 420
National Radiological Protection Board (UK), on out of phase artefact, 244–9, 414
pregnant patients, 368 out of phase imaging, 221, 223, 259
time of flight MRA, 275
neck, MRA, 271 overlap, see multiple overlapping thin section
negative lines, K space, 81–2
neonates, diffusion weighted imaging, 399 angiography
neoplasms over-sampling (no phase wrap), 240, 420
oxygen, mass number, 4
infarcts vs, perfusion imaging, 403 oxygen tanks, 355
MR spectroscopy, 408 oxyhemoglobin, 404
nephrogenic systemic fibrosis, 382–3
nerve stimulation, 349–50 pacemakers, 367–8
net magnetic moment, 309 packing of molecules, 23
net magnetization vector (NMV), 7, 8, 11, 12, 18, 419 paired electrons, 309
cross-excitation, 253 paperclips, terminal velocity, 355
saturation, 33–4, 35, 36
neutrons, 2, 420

Index MRI in Practice

parallel alignment, 7 phase ghosting, 198
parallel imaging, 193–5, 336, 420 cervical spine, 228

acronyms, 196 phase gradients
coils, 193–5, 335 echo planar imaging, 187–8
K space filling, 98 spiral K space filling, 188
sensitivity encoding, 336 swapping with frequency encoding gradients,
paramagnetism, 310, 376 227–8
hemoglobin, 404
parotid gland, fat saturation, 215 phase images, 421
partial averaging, 101, 420 hypertrophic cardiomyopathy, 305
partial echo imaging, 99, 100, 420 phase contrast MRA, 282–3, 284
partial Fourier, 99–101
partial saturation, 420 phase matrices, 85, 86
partial voluming, 126, 420 brain images, 110, 111
parts per million K space, 81, 83
chemical shift, 243 reduction, 92
field strength inhomogeneities, 312 on scan time, 132
passive shielding, 321–2, 420 size, 95, 96
passive shimming, 322, 323, 420 trade-offs, 136
patches, transdermal, 344, 348 voxel geometry, 131

436 patellar tendon, magic angle, 257–8 phase mismapping, 225–34, 260
see also ghosting
pathology weighting, 421
inversion recovery, 154 phase over-sampling (no phase wrap), 240, 420
phase wrap, 236–42, 421
patients Philips, acronyms for rapid imaging techniques,
preparation, 370–1
screening, 360–1 196
Phong’s formula, 276
patient transportation systems, 337 phosphenes, 350
pellets (ammunition), 365 phosphorus, mass number, 4
pelvis, fast spin echo, 149 piano keyboard analogy, 67, 68
penile implants, 364
perfluorocarbon, 384 fast Fourier transform, 86
perfusion imaging, 373, 387, 400–4 pituitary gland, 386
periodicity, chemical misregistration and, 247, 249 pixel area, 105–6
peripheral gating, cardiac, 233, 298, 299–300
peripheral nerve stimulation, 349–50 spatial resolution vs, 127
permanent magnets, 311, 312–4, 321 pixel shift, 244, 245
personnel planes

levels, 360 cardiac imaging, 290–1
pregnancy, 369 see also axes; coronal plane; longitudinal plane;
qualified to inject, 379
screening, 360–1 transverse plane
phase, 418, 421 planning, architectural, 357, 358
chemical shift artefact, single shot imaging point resolved spectroscopy spin echo (PRESS), 407–8,

techniques, 191–2 421
fast Fourier transform, 87 polarity, magnetic field gradients, 47, 421
frequency vs, watch analogy, 13–14 ‘pop-out’ windows, 353
magnetic moments, 13, 325 ports, vascular access, 363
see also intra-voxel dephasing positive lines, K space, 81–2
phase contrast MRA (PC-MRA), 276–86, 421 power injectors, contrast enhanced MRA, 288
phased array coils, 333–4 power supplies
signal to noise ratio, 123
phase encoding, 62, 69–71, 72, 73, 421 high-speed gradient systems, 328–9
axes, 74 single shot imaging techniques, 189
cardiac imaging, 294 precession, 8–10, 421
fast spin echo, 143, 145, 146 precessional frequency, 8, 9–10, 421
gradient changes per TR, 82, 83, 88 field strength inhomogeneities, 34
K space traversal and, 97 magnetic field gradients, 48
voxel geometry, 127 magnetic moments, 325
position on gradient, 60–1
see also tumbling rates
precessional path, 8, 9, 421
pregnancy, 368–9
pre-magnetization, fast gradient echo, 185

MRI in Practice Index

pre-saturation, 224 radiofrequency coils, 330–6 437
chemical, 214 in tables, 337
for phase mismapping, 228–9
vascular imaging, 265, 266–7, 268 radiofrequency pulses, 11, 141, 330–7, 338,
see also spatial pre-saturation 422

pre-term infants, diffusion weighted imaging, bandwidth, 65, 66
399 signal to noise ratio vs, 122
see also receive bandwidth
projectiles, 355
propeller K space filling, 188–9 echo formation, 167–8
ramped, time of flight MRA, 275
bowel movement and, 233 respiratory gating, 231
prospective gating, 292, 293 safety, 346–8
prostate shape, 252, 255
sources, 307–8
intra-cavity coils, 333 radiofrequency shielding, 336–7
MR spectroscopy, 409 radiofrequency spoiling, 172–3, 422
prostheses, 361–8 radiography, intra-ocular foreign bodies, 364–5
see also implants ramped RF pulses, time of flight MRA, 275
protium, 4–8 ramping up, 318
protocols, 103, 339 ramp sampling, 329, 422
decision making, 134–7 readout gradient, 69, 75, 422
proton density, 22, 421 echo planar imaging, 187
signal to noise ratio vs, 105 spiral K space filling, 188
proton density contrast, 27 receive bandwidth, 77, 80, 115–23, 422
proton density weighting, 27, 30–1, 421 chemical shift artefact and, 122–3, 243–4,
cardiac imaging, 293
fast spin echo, 148 246
gradient echo pulse sequences, 52, 54, 56, 57, 58, echo time, frequency matrices and, 78–9
magnetic susceptibility artefact and, 251–2
164, 165 reduced, 122–3
heat analogy, 33 trade-offs, 136, 137
images, 34 receiver coils, 331–4
inversion recovery, 152, 154, 157 recovery, 16, 422
pulse sequences, 42–3 rectangular field of view, 127, 130, 131, 422
single shot imaging techniques, 190 chest of drawers analogy, 131, 132
spatial pre-saturation and, 213 K space filling, 98, 131
protons, 2, 421 synonyms, 196
bound vs free, 125 rectum
pseudo-frequencies, 87, 88, 89, 421 air, 384
pseudo-gating, 300 intra-cavity coils, 333
public areas, 359, 360–1 red blood cells, sickled, 353
pulsatile flow, 210, 262 reduction factor, 422
gating for, 299–300 scan time in parallel imaging, 195
pulse control units, 338–9, 421 see also acceleration factor
pulse programmers, 338 refocusing angle, single shot fast spin echo, 150
pulse sequences, 19–20, 34–9, 140–97, 421 relaxation, 16, 23–5, 422
diffusion weighted imaging, 398–9 contrast agents on, 373
flow-sensitive, 203 at steady state, 167
K space traversal and, 96 relaxivity, 378, 422
T1 contrast and, 25–6 renal artery stenosis, 404
see also gradient echo pulse sequences; spin echo renal excretion, gadolinium chelates, 382
repetition time (TR), 94, 95, 96, 103, 422
quadrature coils, 332 balanced gradient echo, 179
signal to noise ratio, 123 brain images, 116, 117
bright blood imaging, 267
quantum theory, populations of nuclei, 6 ciné acquisition, cardiac imaging, 301–2
quenching, 319, 353–4, 421 contrast enhanced MRA, 288
questionnaires, personnel screening, 361 effective, R to R interval, 292–3, 297, 304
quiet systems, 327, 350 entry slice phenomenon vs, 204
fast spin echo, 148
racing analogy, see Larmor Grand Prix (analogy)
radiofrequency amplifiers, 422

Index MRI in Practice

repetition time (TR), continued safety, 341–71
gradient echo pulse sequences, 50–1, 52, 56, 165 cardiac gating, 298–9
spin echo vs, 57 coils, 336
image formation, 84–5, 88 gadolinium, 380–3
inversion recovery, 154 helium, 319, 353–4
pulse sequences, 20 policy, 369–70
gas oven analogy, 31, 32, 33 terminology, 343–5
image weighting, 29–30
respiratory gating and, 231 sagittal plane, 74
on scan time, 132 phase encoding gradients, 71
signal to noise ratio vs, 109 spatial encoding, 68
single shot imaging techniques, 190
spatial pre-saturation and, 213 sagittal sinus thrombosis, imaging for, 284–5
steady state and, 166 sampling, 73–9, 329–30
time of flight MRA, 270, 271, 274
trade-offs, 136 ramp sampling, 329, 422
values, 43 sampling frequencies, 75–7, 423
see also SAT TR sampling intervals, 76, 423
sampling times, 423
rephasing, 39, 40
fast spin echo, 143 see also acquisition windows
SAR, see specific absorption rate
438 magnetic field gradients, 49–50 SAT TR, 218, 423
saturation, 215–9, 417, 423
pulse sequence categories, 141
steady state free precession, 175, 176 avoidance in balanced gradient echo, 179
reporting, adverse events, 370 blood flow suppression, 271, 272
residual transverse magnetization, 167, 422 entry slice phenomenon and, 203, 204
radiofrequency spoiling and, 173 fat, 215, 216, 217, 219, 220–1, 222, 416
resistive magnets, 316–7, 321, 422 net magnetization vector, 33–4, 35, 36
resolution, 126, 135 water, 215–9, 426
echo time vs, 133 see also spatial pre-saturation
K space lines, 91, 92–3 scan time, 131–2, 133, 134, 135
signal to noise ratio vs, 106–7, 334 contrast enhanced MRA, 288–9
temporal vs spatial, 288 fast spin echo, 143, 144
volume imaging, 138–9 gradient moment rephasing, 210
see also spatial resolution parallel imaging, 195
resonance, 11–15, 422 signal to noise ratio vs, 95–6, 115
resonant power supplies, 329 square vs rectangular field of view, 127
single shot imaging techniques, 189 steady state free precession, 178
respiratory compensation, 229–33, 422 volume imaging, 138
fast spin echo, 146 screening, personnel, 360–1
K space filling, 98, 230–1 security doors, 358
synonyms, 196 sensitivity encoding, see parallel imaging
respiratory gating, 231, 422 sensitivity profiles, surface coils, 332–3
respiratory navigator echoes, 231–3, 422 sequential acquisitions, 101, 102, 423
RESTORE, see driven equilibrium Fourier transform patient movement, 132
resuscitation, crash carts, 369 shaded surface display (SSD), MRA, 276
retrospective gating, 292 shading artefact, 256, 260
reverse flip angle excitation pulse, 151 shielding
rewinders, 50, 422 magnetic, 321–2
coherent gradient echo, 169–70 radiofrequency, 336–7
steady state free precession, 175 shimming, 322–3, 423
right-hand thumb rule, 315 short axis view, heart, 291
rise times (gradient speeds), 133, 326–7, 423 short tau inversion recovery (STIR), 157–9, 160, 219,
FDA limits, 350
rotational force (torque), 354–5, 362 222
R to R interval lumbar spine, 161
ECG, 292–3, 423 shrapnel, 365
effective repetition time, 292–3, 297, 304 sickle cell crisis, 353
R wave, ECG, 292 Siemens, acronyms for rapid imaging techniques,

196
signal, see MR signal
signal averaging, acronyms, 196

MRI in Practice Index

signal decay curves, perfusion imaging, 402–3 spin-down electrons, 309 439
signal to noise ratio (SNR), 104–23, 133–4, 135, 137, spin-down nuclei, 6, 104, 424
spine
332, 334
gradient coils, 123, 124 contrast-enhanced imaging, 388–90
scan time vs, 95–6, 115 phased array coils, 333, 334
ultra-high-field systems, 354 spin echo, 39, 167–9, 424
silicone implants multiphase cardiac imaging, 300–1
breast, nulling, 218 pulse sequences, 141–63, 424
single shot fast spin echo, 150, 423
diffusion weighted imaging, 399 diffusion weighted imaging, 398–9
metal objects, 251 duty cycle, 327
single shot imaging techniques, 186–93, 197 K space filling, 82, 84
single voxel techniques, MR spectroscopy, 407–8, 423 metal objects, 251, 253
sinusoidal sampling, 329, 330 signal to noise ratio, 107
siting, 357–9 slice select gradient, 65
shielding considerations, 322 time of flight phenomenon, 200–1
skin, nephrogenic systemic fibrosis, 383 timing parameters, 40–3, 57
skin patches, 344, 348 using one echo, 40–2, 142
skin staples, 366 using two echoes, 42–3, 142
sleep, cardiac imaging, 296 vascular imaging, 262, 263–5
slew rates, 326, 327, 423 see also fast spin echo
slice acquisition, cardiac imaging, 294 spin echo EPI, 189–90, 197
slice encoding, 102, 138, 423 abdomen, 194
slice select gradient, axes, 74 spin lattice relaxation, 16, 424
slice selection, 62–3, 64, 65, 67, 71, 423 spin–spin relaxation, 23, 424
in repetition time, 84–5 spin tagged perfusion, 387
slice thickness, 65, 66, 133, 202 spin-up electrons, 309
brain images, 108 spin-up nuclei, 6, 104, 424
entry slice phenomenon vs, 204 SPIR (spatial inversion recovery), 219–20, 222
spatial resolution vs, 126 spiral flow, 199, 200
three-dimensional volumetric acquisitions, 137 spiral K space filling, 188–9
trade-offs, 136 spoiled gradient echo, see incoherent gradient echo
on voxel volume, 106 spoilers, 49, 424
Society of Magnetic Resonance Imaging Safety, on sprinter analogy, sampling, 76
square field of view, 127, 128, 129, 131
pregnant patients, 368 squaring, RF pulses, 255
sodium, mass number, 4 SSFP, see steady state free precession
solenoid electromagnets, 315–6, 423 SS-FSE, see single shot fast spin echo
space, see siting stability, gadolinium chelates, 382
SPAMM, 304–6, 424 stacks of slices, entry slice phenomenon and, 203–4
spatial encoding, 60–79, 423 staples, 366
spatial inversion recovery (SPIR), 219–20, 222 steady state, 166–9, 178–9, 424
spatial location of signal, 59–79 steady state free precession (SSFP), 175–9, 182
spatial modulation of magnetization (SPAMM), 304–6, acronyms, 196
vascular imaging, 267, 269
424 stenosis, vortex flow, 199, 200
spatial pre-saturation, 210–23, 224 stimulated echo acquisition mode (STEAM), MR

acronyms, 196 spectroscopy, 407–8, 424
vascular imaging, 263, 266 stimulated echoes, 168, 178–9, 424
spatial resolution, 126, 134, 424
temporal resolution vs, 288 steady state free precession, 175, 177
specific absorption rate (SAR), 347 see also spin echo
single shot fast spin echo, 150 STIR, see short tau inversion recovery
vascular imaging, 266 storage, images, 339–40
spectra stray fields, see fringe fields
electromagnetic, 11 strictures, vortex flow, 199, 200
MR spectroscopy, 407–10 stroke, diffusion weighted imaging, 399
spin subtraction, MRA, 269, 270, 289
nuclear, 2 subway trains, 357
see also angular momentum superconducting electromagnets, 317–9, 321, 424

Index MRI in Practice

superior sagittal sinus, MRA, 284–5, 286 T2* decay, 31–4, 37, 38, 425
superparamagnetism, 311, 376 gadolinium on, 373
surface coils, 332–3
T2* dephasing, gradient echo pulse sequence, 46
signal to noise ratio, 123 T2* weighted images, cervical spine, 177–8, 180
surgical clips, 366 T2* weighting
surgical instruments, 355, 356
susceptibility, 309 ciné acquisition, cardiac imaging, 301–2
gradient echo pulse sequences, 52, 53, 54, 55, 57,
see also magnetic susceptibility
susceptibility weighting, 404 164, 165
sutures, metallic, 366 true T2 weighting vs, 177–8
swallowing, phase mismapping, 228–9 tables (patient transportation systems), 337
swapping axes, 227–8 tagging, perfusion imaging, 401, 403
symmetry of data, K space, 90–1 tattoos, 348, 370
synthesizers, RF pulses, 331 TAU time, 40, 42, 425
see also time from inversion
440 T1 contrast, 25–6, 27 temperature
T1 enhancement agents, 376–7, 383, 384, 424 on contrast parameters, 373
T1 recovery, 16, 17, 22–3, 424 patient, 347, 348
sensitivity of magnets, 314
fat, 23–4, 33–4 tumor ablation, 407
gadolinium on, 373 temporal vs spatial resolution, 288
water, 25, 33–4 terminology, MRI safety, 343–5
T1 relaxation times, 16, 424 Tesla (unit), 8, 312
brain, 28, 167 Teslascan (manganese), 376, 383
gadolinium on, 373 test boluses, MRA, 289
relaxivity vs, 378 testicles, temperature, 348
at steady state, 167 thermal energy, 7
T1 weighted images, 26, 142, 424 thermal equilibrium, 7, 425
brain, see under brain thermal injuries, see burns
fast spin echo, 147, 148 three-dimensional volumetric acquisitions, 101–2,
heart, 293
pulse sequences, 40–2 137–9, 425
spatial pre-saturation and, 213 phase contrast MRA, 283
T1 weighting, 29–30, 44–5 time of flight MRA, 270, 271, 275, 276
gradient echo pulse sequences, 52, 53, 55, 58, 165 three-terminal gradient coils, 323–5
inversion recovery, 152, 154, 156 time from inversion (TI), 152, 425
T2 contrast, 27, 28 FLAIR, 160
T2 decay, 16, 17, 23, 425 STIR, 157–8
fat, 25, 26 vascular imaging, 265
temperature and B0 on, 373 time intensity curves, perfusion imaging, 403, 425
water, 25, 26 time of flight, 425
T2 enhancement agents, 377–8, 425 time of flight MRA, 270–6, 425
T2 recovery, 22–3 time of flight phenomenon, 200–3
bound vs free protons, 125 time of flight signal loss, 263
gadolinium on, 373 time varied magnetic field (TMVF) effects, 327, 345,
T2 relaxation time
gadolinium on, 373, 425 349–50, 351
relaxivity vs, 378 timing parameters, pulse sequences, 19–20, 40–3, 57,
at steady state, 167
T2 shine through, 399, 425 58
T2 weighted images, 27, 142, 372, 425 tissues
brain, 46, 374
contrast to noise ratio, 125 contrast, 22–3
fast spin echo, 148 isotropic vs anisotropic, 398
heart, 293 torque, 354–5, 362
pulse sequences, 42–3 trace images, 399
T2 weighting, 30, 44–5 trade-offs, 134, 136–7, 247
single shot imaging techniques, 190 gradient moment rephasing, vascular imaging, 267
steady state free precession, 175, 176–7 time of flight MRA, 271
training, safety, 358, 360
trains, subways, 357
trains of echoes, see echo trains
transceivers, 332, 425

MRI in Practice Index

transdermal patches, 344, 348 velocity encoding techniques, phase contrast MRA, 441
transducers, respiratory compensation, 230 285–6
translational forces, 355, 356
transmit bandwidth, 65, 66 velocity-induced phase shifts, phase contrast MRA,
transmitters, RF pulses, 330–1, 423 276–7
transverse plane, 425
velocity of flow
decay in, 16 entry slice phenomenon vs, 204
flip angle relative to, 11–12, 19 time of flight phenomenon, 201–3
magnetization vs signal, 24
trigger delay, cardiac imaging, 297, 425 Venetian blind artefact, 271
triggering ventricles (cardiac), 290
MRA, 289 visual disturbances, 350
T waves, 352 volume arrays, 333
see also respiratory gating volume coils, 331, 332, 426
trigger window, cardiac imaging, 294–7 volume imaging, see three-dimensional volumetric
triple IR prep, 163, 265
trucks, mobile MR units, 358 acquisitions
truncation artefact, 249–50, 425 vortex flow, 199, 200
TSE, see fast spin echo voxels
tumbling rates, 23, 373–5, 376
tumors isotropic, 418
ablation, 407 volume imaging, 138–9
MR spectroscopy, 408
tuning, coils, 336 shape, 127
tuning fork analogy, slice selection, 63, 64 volume, 105–7
turbo factor, 144, 147, 148
see also echo trains, length contrast enhanced MRA, 288
turbo spin echo, see fast spin echo spatial resolution vs, 126–7
turbulent flow, 199, 200 time of flight MRA, 275
intra-voxel dephasing, 207
TVMF (time varied magnetic field) effects, 327, 345, warm bore, 322
‘warm zone’, 356
349–50, 351 warning signs, 361
T waves, triggering, 352 watch analogy
two-chamber view, heart, 291
two-dimensional volumetric acquisitions, 101, 102, 426 chemical misregistration, 246, 248
field strength inhomogeneities, 34
phase contrast MRA, 283–6 phase vs frequency, 13–14
time of flight MRA, 270–1, 274, 275 spatial encoding, 72–3

ultra-high-field systems, 317 phase encoding, 70
pregnancy and, 368 water, 1–2, 23, 25, 26
safety aspects, 354
shielding, 322 driven equilibrium Fourier transform, 151
molecular tumbling, 373–5
ultra-low field scanners, 320 saturation, 215–9, 426
uncertainty principle (Heisenberg), 2 T1 and T2 relaxation times, brain, 28, 167
under-sampling, truncation artefact, 249–50 T1 recovery, 25, 33–4
unpaired electrons, 310 T1 vs T2 weighted images, 44–5
TR vs contrast, 29, 30
gadolinium, 376 Water’s view, intra-ocular foreign bodies, 365
user interface, 337–40 websites
on implants, 361
valves (heart valve prostheses), 363–4 MRI safety, 343
vascular access ports, 363 screening forms from, 361
vascular imaging, 261–90 weight
vascularity, T2 weighted images, 142 magnets, 314
vectors shielding, 322
weight (body), gadolinium dose vs, 379
magnetic moment as, 4 weighting, 29–31, 44–5
net magnetization vector as, 18 diffusion weighted imaging as, 398
velocity encoding gradients (VENC), 277, 279–80, 281, fast spin echo, 144–5
in gradient echo, 51–6
282 see also T1 weighted images; T2 weighted images
white matter (brain)
diffusion tensor imaging, 399, 402, 415
diffusion weighted imaging, 398

Index MRI in Practice

white matter (brain) continued wires
suppression, FLAIR, 160, 163 pacemakers, 367
T1 and T2 relaxation times, 28, 167 see also cables

White Paper on MRI Safety wrap
American College of Radiology, 342–3, 369–70 moiré artefact, 256
on contrast injection, 380 see also aliasing
warning signs, 361
Z-axis, 61
whole body imaging, 410 zipper artefact, 255–6, 259
windows, ‘pop-out’, 353 zones
window settings, 339, 426
MRI safety, 356, 358–9
see also acquisition windows

442

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