29:
767:
1472:
dual-echo PC-MRI (DEPC) method with dual velocity encoding in the same repetition time has been developed. The DEPC method does not only allow for proper velocity quantification, but also reduces the total acquisition time (especially when applied to 4D flow imaging) compared to a single-echo single-
1471:
will be application dependent and care must be exercised in the selection. In order to further allow for proper velocity quantification, especially in clinical applications where the velocity dynamic range of flow is high (e.g. blood flow velocities in vessels across the thoracoabdominal cavity), a
2936:
Displacement artifacts (also known as misregistration and oblique flow artifacts) occur when there is a time difference between the phase and frequency encoding. These artifacts are highest when the flow direction is within the slice plane (most prominent in the heart and aorta for biological
457:
2912:(vessel wall dilatations, at risk of rupture) or other abnormalities. MRA is often used to evaluate the arteries of the neck and brain, the thoracic and abdominal aorta, the renal arteries, and the legs (the latter exam is often referred to as a "run-off").
2888:(temporary image space) can be assigned accordingly to match-up with the timing of the heart beat and lung motion of the patient. This means that these scans are cardiac-averaged so the measured blood velocities are an average over multiple cardiac cycles.
558:
2850:
2731:
2612:
914:
If we take two different acquisitions with applied magnetic gradients that are the opposite of each other (bipolar gradients), we can add the results of the two acquisitions together to calculate a change in phase that is dependent on gradient:
300:
1438:(above the maximum velocity expected in the scan) will allow for the proper velocity quantification, but the larger dynamic range will obscure the smaller velocity features as well as decrease SNR. Therefore, the setting of
2096:
2009:
1922:
2106:
The balanced four-point method also includes four sets of encoding gradients. The first is the same as in the simple four-point method with negative gradients applied in all directions. The second has a negative moment in
28:
1330:
1586:
When each dimension of velocity is calculated based on acquisitions from oppositely applied gradients, this is known as a six-point method. However, more efficient methods are also used. Two are described here:
1405:(below the maximum velocity expected in the scan) will allow for better visualization of slower velocities (better SNR), but any higher velocities will alias to an incorrect value. Setting a ‘high’
2488:
2421:
2354:
1074:
852:
967:
357:
2930:
Intravoxel phase dispersion (when velocities within a pixel are heterogeneous or in areas of turbulent flow) can produce a resultant phase that does not resolve the flow features accurately.
762:{\displaystyle \phi =\gamma x_{0}\int _{0}^{t}G_{x}(\tau )d\tau +\gamma v_{x}\int _{0}^{t}G_{x}(\tau )\tau d\tau +\gamma {\frac {a_{x}}{2}}\int _{0}^{t}G_{x}(\tau )\tau ^{2}d\tau +\ldots }
2884:
signal is recorded throughout the imaging process. Similarly, the patient's respiratory patterns can be tracked throughout the scan. After the scan, the continuously collected data in
2927:
effects (when a voxel contains the boundary between static and moving materials) can overestimate phase leading to inaccurate velocities at the interface between materials or tissues.
1016:
3356:
Lotz, Joachim; Meier, Christian; Leppert, Andreas; Galanski, Michael (2002). "Cardiovascular Flow
Measurement with Phase-Contrast MR Imaging: Basic Facts and Implementation 1".
547:
518:
489:
206:
2737:
2618:
2499:
1133:
349:
214:
1572:
1536:
1503:
1469:
1436:
1403:
1243:
1206:
1169:
1110:
323:
175:
909:
882:
1245:
will be incorrectly calculated as moving in the opposite direction. However, there is a direct trade-off between the maximum velocity that can be encoded and the
1359:
2952:(VIPR) is a radially acquired MRI sequence which results in high-resolution MRA with significantly reduced scan times, and without the need for breath-holding.
2285:
2265:
2245:
2225:
2205:
2185:
2165:
2145:
2125:
1833:
1813:
1793:
1773:
1753:
1733:
1713:
1693:
1673:
1653:
1633:
1613:
3311:
Pelc, Norbert J.; Bernstein, Matt A.; Shimakawa, Ann; Glover, Gary H. (1991). "Encoding strategies for three‐direction phase‐contrast MR imaging of flow".
3266:
Pelc, Norbert J.; Bernstein, Matt A.; Shimakawa, Ann; Glover, Gary H. (1991). "Encoding strategies for three‐direction phase‐contrast MR imaging of flow".
2015:
1928:
1841:
3217:"Extending the dynamic range of phase contrast magnetic resonance velocity imaging using advanced higher-dimensional phase unwrapping algorithms"
3084:
Elkins, C.; Alley, M.T. (2007). "Magnetic resonance velocimetry: applications of magnetic resonance imaging in the measurement of fluid motion".
3221:
1255:
3039:
2885:
3469:
133:(RF) pulse to 'excite' the spins, changing the axis that the spins precess about. These spins can then be observed by receiver coils (
3447:
3166:
Ajala, Afis; Zhang, Jiming; Pednekar, Amol; Buko, Erick; Wang, Luning; Cheong, Benjamin; Hor, Pei-Herng; Muthupillai, Raja (2020).
3131:
52:(lower). Laminar flow is present in the true lumen (closed arrow) and helical flow is present in the false lumen (open arrow).
3397:
2897:
2427:
2360:
2293:
87:
83:
3313:
3268:
1027:
782:
452:{\displaystyle \mathbf {r} (\tau )=\mathbf {r} _{0}+\mathbf {v} _{r}\tau +{\frac {1}{2}}\mathbf {a} _{r}\tau ^{2}+\ldots }
138:
921:
3129:
Taylor, Charles A.; Draney, Mary T. (2004). "Experimental and computational methods in cardiovascular fluid mechanics".
1835:. Then, the velocities can be solved based on the phase information from the corresponding phase encodes as follows:
2933:
Assuming that acceleration and higher orders of motion are negligible can be inaccurate depending on the flow field.
145:
respond to the added energy in different ways, and imaging parameters can be adjusted to highlight desired tissues.
75:
49:
2924:
2900:(MRA). This is used to generate images of arteries (and less commonly veins) in order to evaluate them for
552:
If we only consider static spins and spins in the x-direction, we can rewrite equation for phase shift as:
975:
3086:
1362:
1246:
2845:{\displaystyle {\hat {v}}_{z}={\frac {-\phi _{1}-\phi _{2}+\phi _{3}+\phi _{4}}{2\gamma \Delta M_{1}}}}
2726:{\displaystyle {\hat {v}}_{y}={\frac {-\phi _{1}+\phi _{2}-\phi _{3}+\phi _{4}}{2\gamma \Delta M_{1}}}}
2607:{\displaystyle {\hat {v}}_{x}={\frac {-\phi _{1}+\phi _{2}+\phi _{3}-\phi _{4}}{2\gamma \Delta M_{1}}}}
523:
494:
465:
3215:
Salfitya, M.F.; Huntleya, J.M.; Gravesb, M.J.; Marklundc, O.; Cusackd, R.; Beauregardd, D.A. (2006).
3140:
3095:
180:
41:
1595:
Four sets of encoding gradients are used. The first is a reference and applies a negative moment in
1575:
134:
90:. Since modern PC-MRI is typically time-resolved, it provides a means of 4D imaging (three spatial
1115:
332:
295:{\displaystyle \phi =\gamma \int _{0}^{t}B_{0}+\mathbf {G} (\tau )\cdot \mathbf {r} (\tau )d\tau }
3338:
3293:
3111:
2905:
326:
3392:
2864:, in order to get highly resolved scans in 3D space and time without motion artifacts from the
3443:
3433:
3416:
3391:
Petersson, Sven; Dyverfeldt, Petter; Gårdhagen, Roland; Karlsson, Matts; Ebbers, Tino (2010).
3373:
3330:
3285:
3248:
3197:
3066:
3010:
2992:
3033:
Stankovic, Zoran; Allen, Bradley D.; Garcia, Julio; Jarvis, Kelly B.; Markl, Michael (2014).
1544:
1508:
1475:
1441:
1408:
1375:
1215:
1178:
1141:
1082:
1021:
The phase shift is measured and converted to a velocity according to the following equation:
308:
154:
3406:
3365:
3322:
3277:
3238:
3230:
3187:
3179:
3148:
3103:
3056:
3048:
3000:
2982:
142:
3168:"Mitral Valve Flow and Myocardial Motion Assessed with Dual-Echo Dual-Velocity Cardiac MRI"
3152:
887:
860:
129:
proportional to the strength of that field. Then, energy is added to the system through a
3369:
2920:
In particular, a few limitations of PC-MRI are of importance for the measured velocities:
2861:
130:
3440:
Advanced MR Imaging in
Clinical Practice, An Issue of Radiologic Clinics of North America
1338:
3144:
3099:
3052:
3243:
3216:
3192:
3167:
3061:
3034:
3005:
2970:
2270:
2250:
2230:
2210:
2190:
2170:
2150:
2130:
2110:
1818:
1798:
1778:
1758:
1738:
1718:
1698:
1678:
1658:
1638:
1618:
1598:
114:
3463:
3115:
1172:
117:, some of these spins align with the axis of the external field, which causes a net '
45:
3342:
3297:
773:
37:
2091:{\displaystyle {\hat {v}}_{z}={\frac {\phi _{z}-\phi _{0}}{\gamma \Delta M_{1}}}}
2004:{\displaystyle {\hat {v}}_{y}={\frac {\phi _{y}-\phi _{0}}{\gamma \Delta M_{1}}}}
1917:{\displaystyle {\hat {v}}_{x}={\frac {\phi _{x}-\phi _{0}}{\gamma \Delta M_{1}}}}
2877:
149:
776:
and higher order terms are negligible to simplify the expression for phase to:
3107:
3020:
79:
2996:
3326:
3281:
3183:
2987:
2909:
126:
118:
91:
3420:
3377:
3252:
3234:
3201:
3070:
3014:
148:
All of these spins have a phase that is dependent on the atom's velocity.
3334:
3289:
2901:
2880:
compensation are employed. Beginning with cardiac gating, the patient's
1209:
110:
1578:(phase unwrapping) can be used to increase both dynamic range and SNR.
1325:{\displaystyle SNR_{v}={\frac {\pi }{\sqrt {2}}}{\frac {v}{v_{enc}}}SNR}
2873:
122:
113:
have a randomly aligned angular spin momentum. When placed in a strong
3411:
2971:"Magnetic resonance angiography: current status and future directions"
1365:
of the image (which depends on the magnetic field of the scanner, the
2969:
Hartung, Michael P; Grist, Thomas M; François, Christopher J (2011).
106:
2869:
2865:
1366:
102:
2944:
Vastly undersampled
Isotropic Projection Reconstruction (VIPR)
2881:
34:
Vastly undersampled
Isotropic Projection Reconstruction (VIPR)
1249:
of the velocity measurements. This can be described by:
2950:
Vastly undersampled
Isotropic Projection Reconstruction
2483:{\displaystyle \phi _{4}-\phi _{1}=\phi _{y}+\phi _{z}}
2416:{\displaystyle \phi _{3}-\phi _{1}=\phi _{x}+\phi _{z}}
2349:{\displaystyle \phi _{2}-\phi _{1}=\phi _{x}+\phi _{y}}
16:
Magnetic resonance imaging to determine flow velocities
2896:
Phase contrast MRI is one of the main techniques for
2740:
2621:
2502:
2430:
2363:
2296:
2273:
2253:
2233:
2213:
2193:
2173:
2153:
2133:
2113:
2018:
1931:
1844:
1821:
1801:
1781:
1761:
1741:
1721:
1701:
1681:
1661:
1641:
1621:
1601:
1547:
1511:
1478:
1444:
1411:
1378:
1341:
1258:
1218:
1181:
1144:
1118:
1085:
1069:{\displaystyle v={\frac {v_{enc}}{\pi }}\Delta \phi }
1030:
978:
924:
890:
863:
785:
561:
526:
497:
468:
360:
335:
311:
217:
183:
157:
3393:"Simulation of phase contrast MRI of turbulent flow"
1208:
below the maximum velocity in the slice will induce
847:{\displaystyle \phi =\gamma (x_{0}M_{0}+v_{x}M_{1})}
2287:. This gives us the following system of equations:
1171:
defines range of velocities visible, known as the ‘
962:{\displaystyle \Delta \phi =v(\gamma \Delta M_{1})}
57:
21:
2844:
2725:
2606:
2482:
2415:
2348:
2279:
2259:
2239:
2219:
2199:
2179:
2159:
2139:
2119:
2090:
2003:
1916:
1827:
1807:
1787:
1767:
1747:
1727:
1707:
1687:
1667:
1647:
1627:
1607:
1566:
1530:
1497:
1463:
1430:
1397:
1353:
1324:
1237:
1200:
1163:
1127:
1104:
1068:
1010:
961:
903:
876:
846:
761:
541:
512:
483:
451:
343:
317:
294:
200:
169:
1112:is the maximum velocity that can be recorded and
1212:in the image where a velocity just greater than
1505:PC-MRI acquisition carried out at two separate
1369:volume, and the acquisition time of the scan).
177:of a spin is a function of the gradient field
8:
2975:Journal of Cardiovascular Magnetic Resonance
2856:Retrospective Cardiac and Respiratory Gating
1775:. And the last applies a positive moment in
1541:To allow for more flexibility in selecting
884:is the zeroth moment of the x-gradient and
3442:. Vol. 53. Elsevier Health Sciences.
125:about the axis of the external field at a
27:
3410:
3242:
3191:
3060:
3004:
2986:
2833:
2812:
2799:
2786:
2773:
2763:
2754:
2743:
2742:
2739:
2714:
2693:
2680:
2667:
2654:
2644:
2635:
2624:
2623:
2620:
2595:
2574:
2561:
2548:
2535:
2525:
2516:
2505:
2504:
2501:
2474:
2461:
2448:
2435:
2429:
2407:
2394:
2381:
2368:
2362:
2340:
2327:
2314:
2301:
2295:
2272:
2252:
2232:
2212:
2192:
2172:
2152:
2132:
2112:
2079:
2061:
2048:
2041:
2032:
2021:
2020:
2017:
1992:
1974:
1961:
1954:
1945:
1934:
1933:
1930:
1905:
1887:
1874:
1867:
1858:
1847:
1846:
1843:
1820:
1800:
1780:
1760:
1740:
1720:
1715:. The third applies a positive moment in
1700:
1680:
1660:
1640:
1620:
1600:
1552:
1546:
1516:
1510:
1483:
1477:
1449:
1443:
1416:
1410:
1383:
1377:
1340:
1299:
1290:
1278:
1269:
1257:
1223:
1217:
1186:
1180:
1149:
1143:
1117:
1090:
1084:
1043:
1037:
1029:
1002:
986:
977:
950:
923:
895:
889:
868:
862:
835:
825:
812:
802:
784:
741:
722:
712:
707:
692:
686:
656:
646:
641:
631:
600:
590:
585:
575:
560:
533:
528:
525:
504:
499:
496:
475:
470:
467:
437:
427:
422:
411:
399:
394:
384:
379:
361:
359:
336:
334:
310:
272:
255:
246:
236:
231:
216:
184:
182:
156:
68:Phase contrast magnetic resonance imaging
22:Phase contrast magnetic resonance imaging
2493:Then, the velocities can be calculated:
1655:. The next applies a positive moment in
2961:
911:is the first moment of the x gradient.
82:. PC-MRI can be considered a method of
61:method of magnetic resonance angiograph
3222:Journal of the Royal Society Interface
3153:10.1146/annurev.fluid.36.050802.121944
18:
3370:10.1148/radiographics.22.3.g02ma11651
3314:Journal of Magnetic Resonance Imaging
3269:Journal of Magnetic Resonance Imaging
2167:. The third has a negative moment in
491:is the initial position of the spin,
7:
3040:Cardiovascular Diagnosis and Therapy
2227:. The last has a negative moment in
3053:10.3978/j.issn.2223-3652.2014.01.02
1011:{\displaystyle \Delta M_{1}=2M_{1}}
2826:
2707:
2588:
2072:
1985:
1898:
1119:
1060:
979:
943:
925:
14:
3172:Radiology: Cardiothoracic Imaging
78:used primarily to determine flow
3132:Annual Review of Fluid Mechanics
1372:For an example, setting a ‘low’
542:{\displaystyle \mathbf {a} _{r}}
529:
513:{\displaystyle \mathbf {v} _{r}}
500:
484:{\displaystyle \mathbf {r} _{0}}
471:
423:
395:
380:
362:
337:
273:
256:
185:
201:{\displaystyle \mathbf {G} (t)}
86:. It also provides a method of
3398:Magnetic Resonance in Medicine
2898:magnetic resonance angiography
2748:
2629:
2510:
2026:
1939:
1852:
956:
937:
841:
795:
734:
728:
668:
662:
612:
606:
372:
366:
283:
277:
266:
260:
195:
189:
164:
158:
88:magnetic resonance angiography
84:Magnetic Resonance Velocimetry
1:
1135:is the recorded phase shift.
121:' magnetization. These spins
1128:{\displaystyle \Delta \phi }
344:{\displaystyle \mathbf {r} }
2187:, and a positive moment in
2127:, and a positive moment in
1795:, and a negative moment in
1735:, and a negative moment in
1675:, and a negative moment in
40:of a 56-year-old male with
3486:
3470:Magnetic resonance imaging
3035:"4D flow imaging with MRI"
2102:Balanced Four-Point Method
549:is the spin acceleration.
520:is the spin velocity, and
139:Faraday's law of induction
76:magnetic resonance imaging
50:superior mesenteric artery
3438:Hersh Chandarana (2015).
3108:10.1007/s00348-007-0383-2
2247:and a positive moment in
36:of a phase contrast (PC)
33:
26:
1591:Simple Four-point Method
74:) is a specific type of
3327:10.1002/jmri.1880010404
3282:10.1002/jmri.1880010404
3184:10.1148/ryct.2020190126
2988:10.1186/1532-429X-13-19
1567:{\displaystyle v_{enc}}
1531:{\displaystyle v_{enc}}
1498:{\displaystyle v_{enc}}
1464:{\displaystyle v_{enc}}
1431:{\displaystyle v_{enc}}
1398:{\displaystyle v_{enc}}
1238:{\displaystyle v_{enc}}
1201:{\displaystyle v_{enc}}
1164:{\displaystyle v_{enc}}
1105:{\displaystyle v_{enc}}
318:{\displaystyle \gamma }
170:{\displaystyle (\phi )}
3235:10.1098/rsif.2005.0096
2904:(abnormal narrowing),
2846:
2727:
2608:
2484:
2417:
2350:
2281:
2261:
2241:
2221:
2201:
2181:
2161:
2141:
2121:
2092:
2005:
1918:
1829:
1809:
1789:
1769:
1749:
1729:
1709:
1689:
1669:
1649:
1629:
1609:
1568:
1532:
1499:
1465:
1432:
1399:
1355:
1326:
1239:
1202:
1165:
1129:
1106:
1070:
1012:
963:
905:
878:
848:
763:
543:
514:
485:
453:
345:
319:
296:
202:
171:
105:with an odd number of
3087:Experiments in Fluids
2847:
2728:
2609:
2485:
2418:
2351:
2282:
2262:
2242:
2222:
2202:
2182:
2162:
2142:
2122:
2093:
2006:
1919:
1830:
1810:
1790:
1770:
1750:
1730:
1710:
1690:
1670:
1650:
1630:
1610:
1569:
1533:
1500:
1466:
1433:
1400:
1363:signal-to-noise ratio
1356:
1327:
1247:signal-to-noise ratio
1240:
1203:
1166:
1130:
1107:
1071:
1013:
964:
906:
904:{\displaystyle M_{1}}
879:
877:{\displaystyle M_{0}}
849:
764:
544:
515:
486:
454:
346:
320:
297:
203:
172:
2738:
2619:
2500:
2428:
2361:
2294:
2271:
2251:
2231:
2211:
2191:
2171:
2151:
2131:
2111:
2016:
1929:
1842:
1819:
1799:
1779:
1759:
1739:
1719:
1699:
1679:
1659:
1639:
1619:
1599:
1545:
1509:
1476:
1442:
1409:
1376:
1339:
1256:
1216:
1179:
1142:
1116:
1083:
1028:
976:
922:
888:
861:
783:
772:We then assume that
559:
524:
495:
466:
358:
333:
309:
215:
181:
155:
135:Radiofrequency coils
3145:2004AnRFM..36..197T
3100:2007ExFl...43..823E
1576:instantaneous phase
1354:{\displaystyle SNR}
717:
651:
595:
241:
2842:
2723:
2604:
2480:
2413:
2346:
2277:
2257:
2237:
2217:
2197:
2177:
2157:
2137:
2117:
2088:
2001:
1914:
1825:
1805:
1785:
1765:
1745:
1725:
1705:
1685:
1665:
1645:
1625:
1605:
1564:
1528:
1495:
1461:
1428:
1395:
1351:
1322:
1235:
1198:
1161:
1125:
1102:
1066:
1008:
959:
901:
874:
844:
759:
703:
637:
581:
539:
510:
481:
449:
341:
327:Gyromagnetic ratio
315:
292:
227:
198:
167:
3412:10.1002/mrm.22494
2840:
2751:
2721:
2632:
2602:
2513:
2280:{\displaystyle y}
2260:{\displaystyle x}
2240:{\displaystyle z}
2220:{\displaystyle z}
2200:{\displaystyle x}
2180:{\displaystyle y}
2160:{\displaystyle z}
2140:{\displaystyle y}
2120:{\displaystyle x}
2086:
2029:
1999:
1942:
1912:
1855:
1828:{\displaystyle y}
1808:{\displaystyle x}
1788:{\displaystyle z}
1768:{\displaystyle z}
1748:{\displaystyle x}
1728:{\displaystyle y}
1708:{\displaystyle z}
1688:{\displaystyle y}
1668:{\displaystyle x}
1648:{\displaystyle z}
1628:{\displaystyle y}
1608:{\displaystyle x}
1311:
1288:
1287:
1058:
701:
419:
65:
64:
3477:
3454:
3453:
3431:
3425:
3424:
3414:
3405:(4): 1039–1046.
3388:
3382:
3381:
3353:
3347:
3346:
3308:
3302:
3301:
3263:
3257:
3256:
3246:
3212:
3206:
3205:
3195:
3163:
3157:
3156:
3126:
3120:
3119:
3081:
3075:
3074:
3064:
3030:
3024:
3018:
3008:
2990:
2966:
2872:, retrospective
2851:
2849:
2848:
2843:
2841:
2839:
2838:
2837:
2818:
2817:
2816:
2804:
2803:
2791:
2790:
2778:
2777:
2764:
2759:
2758:
2753:
2752:
2744:
2732:
2730:
2729:
2724:
2722:
2720:
2719:
2718:
2699:
2698:
2697:
2685:
2684:
2672:
2671:
2659:
2658:
2645:
2640:
2639:
2634:
2633:
2625:
2613:
2611:
2610:
2605:
2603:
2601:
2600:
2599:
2580:
2579:
2578:
2566:
2565:
2553:
2552:
2540:
2539:
2526:
2521:
2520:
2515:
2514:
2506:
2489:
2487:
2486:
2481:
2479:
2478:
2466:
2465:
2453:
2452:
2440:
2439:
2422:
2420:
2419:
2414:
2412:
2411:
2399:
2398:
2386:
2385:
2373:
2372:
2355:
2353:
2352:
2347:
2345:
2344:
2332:
2331:
2319:
2318:
2306:
2305:
2286:
2284:
2283:
2278:
2266:
2264:
2263:
2258:
2246:
2244:
2243:
2238:
2226:
2224:
2223:
2218:
2206:
2204:
2203:
2198:
2186:
2184:
2183:
2178:
2166:
2164:
2163:
2158:
2146:
2144:
2143:
2138:
2126:
2124:
2123:
2118:
2097:
2095:
2094:
2089:
2087:
2085:
2084:
2083:
2067:
2066:
2065:
2053:
2052:
2042:
2037:
2036:
2031:
2030:
2022:
2010:
2008:
2007:
2002:
2000:
1998:
1997:
1996:
1980:
1979:
1978:
1966:
1965:
1955:
1950:
1949:
1944:
1943:
1935:
1923:
1921:
1920:
1915:
1913:
1911:
1910:
1909:
1893:
1892:
1891:
1879:
1878:
1868:
1863:
1862:
1857:
1856:
1848:
1834:
1832:
1831:
1826:
1814:
1812:
1811:
1806:
1794:
1792:
1791:
1786:
1774:
1772:
1771:
1766:
1754:
1752:
1751:
1746:
1734:
1732:
1731:
1726:
1714:
1712:
1711:
1706:
1694:
1692:
1691:
1686:
1674:
1672:
1671:
1666:
1654:
1652:
1651:
1646:
1634:
1632:
1631:
1626:
1614:
1612:
1611:
1606:
1582:Encoding Methods
1573:
1571:
1570:
1565:
1563:
1562:
1537:
1535:
1534:
1529:
1527:
1526:
1504:
1502:
1501:
1496:
1494:
1493:
1470:
1468:
1467:
1462:
1460:
1459:
1437:
1435:
1434:
1429:
1427:
1426:
1404:
1402:
1401:
1396:
1394:
1393:
1360:
1358:
1357:
1352:
1331:
1329:
1328:
1323:
1312:
1310:
1309:
1291:
1289:
1283:
1279:
1274:
1273:
1244:
1242:
1241:
1236:
1234:
1233:
1207:
1205:
1204:
1199:
1197:
1196:
1170:
1168:
1167:
1162:
1160:
1159:
1134:
1132:
1131:
1126:
1111:
1109:
1108:
1103:
1101:
1100:
1075:
1073:
1072:
1067:
1059:
1054:
1053:
1038:
1017:
1015:
1014:
1009:
1007:
1006:
991:
990:
968:
966:
965:
960:
955:
954:
910:
908:
907:
902:
900:
899:
883:
881:
880:
875:
873:
872:
853:
851:
850:
845:
840:
839:
830:
829:
817:
816:
807:
806:
768:
766:
765:
760:
746:
745:
727:
726:
716:
711:
702:
697:
696:
687:
661:
660:
650:
645:
636:
635:
605:
604:
594:
589:
580:
579:
548:
546:
545:
540:
538:
537:
532:
519:
517:
516:
511:
509:
508:
503:
490:
488:
487:
482:
480:
479:
474:
458:
456:
455:
450:
442:
441:
432:
431:
426:
420:
412:
404:
403:
398:
389:
388:
383:
365:
350:
348:
347:
342:
340:
324:
322:
321:
316:
301:
299:
298:
293:
276:
259:
251:
250:
240:
235:
207:
205:
204:
199:
188:
176:
174:
173:
168:
48:(upper) and the
31:
19:
3485:
3484:
3480:
3479:
3478:
3476:
3475:
3474:
3460:
3459:
3458:
3457:
3450:
3437:
3432:
3428:
3390:
3389:
3385:
3355:
3354:
3350:
3310:
3309:
3305:
3265:
3264:
3260:
3214:
3213:
3209:
3165:
3164:
3160:
3128:
3127:
3123:
3083:
3082:
3078:
3032:
3031:
3027:
2968:
2967:
2963:
2958:
2946:
2918:
2894:
2862:medical imaging
2858:
2829:
2819:
2808:
2795:
2782:
2769:
2765:
2741:
2736:
2735:
2710:
2700:
2689:
2676:
2663:
2650:
2646:
2622:
2617:
2616:
2591:
2581:
2570:
2557:
2544:
2531:
2527:
2503:
2498:
2497:
2470:
2457:
2444:
2431:
2426:
2425:
2403:
2390:
2377:
2364:
2359:
2358:
2336:
2323:
2310:
2297:
2292:
2291:
2269:
2268:
2249:
2248:
2229:
2228:
2209:
2208:
2189:
2188:
2169:
2168:
2149:
2148:
2129:
2128:
2109:
2108:
2104:
2075:
2068:
2057:
2044:
2043:
2019:
2014:
2013:
1988:
1981:
1970:
1957:
1956:
1932:
1927:
1926:
1901:
1894:
1883:
1870:
1869:
1845:
1840:
1839:
1817:
1816:
1797:
1796:
1777:
1776:
1757:
1756:
1737:
1736:
1717:
1716:
1697:
1696:
1677:
1676:
1657:
1656:
1637:
1636:
1617:
1616:
1597:
1596:
1593:
1584:
1548:
1543:
1542:
1512:
1507:
1506:
1479:
1474:
1473:
1445:
1440:
1439:
1412:
1407:
1406:
1379:
1374:
1373:
1337:
1336:
1295:
1265:
1254:
1253:
1219:
1214:
1213:
1182:
1177:
1176:
1175:’. A choice of
1145:
1140:
1139:
1114:
1113:
1086:
1081:
1080:
1039:
1026:
1025:
998:
982:
974:
973:
946:
920:
919:
891:
886:
885:
864:
859:
858:
831:
821:
808:
798:
781:
780:
737:
718:
688:
652:
627:
596:
571:
557:
556:
527:
522:
521:
498:
493:
492:
469:
464:
463:
433:
421:
393:
378:
356:
355:
351:is defined as:
331:
330:
307:
306:
242:
213:
212:
179:
178:
153:
152:
131:Radio frequency
100:
53:
17:
12:
11:
5:
3483:
3481:
3473:
3472:
3462:
3461:
3456:
3455:
3448:
3426:
3383:
3364:(3): 651–671.
3348:
3321:(4): 405–413.
3303:
3276:(4): 405–413.
3258:
3229:(8): 415–427.
3207:
3178:(2): e190126.
3158:
3121:
3076:
3047:(2): 173–192.
3025:
2960:
2959:
2957:
2954:
2945:
2942:
2939:
2938:
2934:
2931:
2928:
2925:Partial volume
2917:
2914:
2893:
2890:
2857:
2854:
2853:
2852:
2836:
2832:
2828:
2825:
2822:
2815:
2811:
2807:
2802:
2798:
2794:
2789:
2785:
2781:
2776:
2772:
2768:
2762:
2757:
2750:
2747:
2733:
2717:
2713:
2709:
2706:
2703:
2696:
2692:
2688:
2683:
2679:
2675:
2670:
2666:
2662:
2657:
2653:
2649:
2643:
2638:
2631:
2628:
2614:
2598:
2594:
2590:
2587:
2584:
2577:
2573:
2569:
2564:
2560:
2556:
2551:
2547:
2543:
2538:
2534:
2530:
2524:
2519:
2512:
2509:
2491:
2490:
2477:
2473:
2469:
2464:
2460:
2456:
2451:
2447:
2443:
2438:
2434:
2423:
2410:
2406:
2402:
2397:
2393:
2389:
2384:
2380:
2376:
2371:
2367:
2356:
2343:
2339:
2335:
2330:
2326:
2322:
2317:
2313:
2309:
2304:
2300:
2276:
2256:
2236:
2216:
2196:
2176:
2156:
2136:
2116:
2103:
2100:
2099:
2098:
2082:
2078:
2074:
2071:
2064:
2060:
2056:
2051:
2047:
2040:
2035:
2028:
2025:
2011:
1995:
1991:
1987:
1984:
1977:
1973:
1969:
1964:
1960:
1953:
1948:
1941:
1938:
1924:
1908:
1904:
1900:
1897:
1890:
1886:
1882:
1877:
1873:
1866:
1861:
1854:
1851:
1824:
1804:
1784:
1764:
1744:
1724:
1704:
1684:
1664:
1644:
1624:
1604:
1592:
1589:
1583:
1580:
1561:
1558:
1555:
1551:
1525:
1522:
1519:
1515:
1492:
1489:
1486:
1482:
1458:
1455:
1452:
1448:
1425:
1422:
1419:
1415:
1392:
1389:
1386:
1382:
1350:
1347:
1344:
1333:
1332:
1321:
1318:
1315:
1308:
1305:
1302:
1298:
1294:
1286:
1282:
1277:
1272:
1268:
1264:
1261:
1232:
1229:
1226:
1222:
1195:
1192:
1189:
1185:
1158:
1155:
1152:
1148:
1138:The choice of
1124:
1121:
1099:
1096:
1093:
1089:
1077:
1076:
1065:
1062:
1057:
1052:
1049:
1046:
1042:
1036:
1033:
1005:
1001:
997:
994:
989:
985:
981:
970:
969:
958:
953:
949:
945:
942:
939:
936:
933:
930:
927:
898:
894:
871:
867:
855:
854:
843:
838:
834:
828:
824:
820:
815:
811:
805:
801:
797:
794:
791:
788:
770:
769:
758:
755:
752:
749:
744:
740:
736:
733:
730:
725:
721:
715:
710:
706:
700:
695:
691:
685:
682:
679:
676:
673:
670:
667:
664:
659:
655:
649:
644:
640:
634:
630:
626:
623:
620:
617:
614:
611:
608:
603:
599:
593:
588:
584:
578:
574:
570:
567:
564:
536:
531:
507:
502:
478:
473:
461:
460:
448:
445:
440:
436:
430:
425:
418:
415:
410:
407:
402:
397:
392:
387:
382:
377:
374:
371:
368:
364:
339:
314:
303:
302:
291:
288:
285:
282:
279:
275:
271:
268:
265:
262:
258:
254:
249:
245:
239:
234:
230:
226:
223:
220:
197:
194:
191:
187:
166:
163:
160:
115:magnetic field
99:
96:
63:
62:
59:
55:
54:
32:
24:
23:
15:
13:
10:
9:
6:
4:
3:
2:
3482:
3471:
3468:
3467:
3465:
3451:
3449:9780323376181
3445:
3441:
3435:
3430:
3427:
3422:
3418:
3413:
3408:
3404:
3400:
3399:
3394:
3387:
3384:
3379:
3375:
3371:
3367:
3363:
3359:
3358:Radiographics
3352:
3349:
3344:
3340:
3336:
3332:
3328:
3324:
3320:
3316:
3315:
3307:
3304:
3299:
3295:
3291:
3287:
3283:
3279:
3275:
3271:
3270:
3262:
3259:
3254:
3250:
3245:
3240:
3236:
3232:
3228:
3224:
3223:
3218:
3211:
3208:
3203:
3199:
3194:
3189:
3185:
3181:
3177:
3173:
3169:
3162:
3159:
3154:
3150:
3146:
3142:
3138:
3134:
3133:
3125:
3122:
3117:
3113:
3109:
3105:
3101:
3097:
3093:
3089:
3088:
3080:
3077:
3072:
3068:
3063:
3058:
3054:
3050:
3046:
3042:
3041:
3036:
3029:
3026:
3022:
3016:
3012:
3007:
3002:
2998:
2994:
2989:
2984:
2980:
2976:
2972:
2965:
2962:
2955:
2953:
2951:
2943:
2941:
2935:
2932:
2929:
2926:
2923:
2922:
2921:
2915:
2913:
2911:
2907:
2903:
2899:
2891:
2889:
2887:
2883:
2879:
2875:
2871:
2867:
2863:
2855:
2834:
2830:
2823:
2820:
2813:
2809:
2805:
2800:
2796:
2792:
2787:
2783:
2779:
2774:
2770:
2766:
2760:
2755:
2745:
2734:
2715:
2711:
2704:
2701:
2694:
2690:
2686:
2681:
2677:
2673:
2668:
2664:
2660:
2655:
2651:
2647:
2641:
2636:
2626:
2615:
2596:
2592:
2585:
2582:
2575:
2571:
2567:
2562:
2558:
2554:
2549:
2545:
2541:
2536:
2532:
2528:
2522:
2517:
2507:
2496:
2495:
2494:
2475:
2471:
2467:
2462:
2458:
2454:
2449:
2445:
2441:
2436:
2432:
2424:
2408:
2404:
2400:
2395:
2391:
2387:
2382:
2378:
2374:
2369:
2365:
2357:
2341:
2337:
2333:
2328:
2324:
2320:
2315:
2311:
2307:
2302:
2298:
2290:
2289:
2288:
2274:
2254:
2234:
2214:
2194:
2174:
2154:
2134:
2114:
2101:
2080:
2076:
2069:
2062:
2058:
2054:
2049:
2045:
2038:
2033:
2023:
2012:
1993:
1989:
1982:
1975:
1971:
1967:
1962:
1958:
1951:
1946:
1936:
1925:
1906:
1902:
1895:
1888:
1884:
1880:
1875:
1871:
1864:
1859:
1849:
1838:
1837:
1836:
1822:
1802:
1782:
1762:
1742:
1722:
1702:
1682:
1662:
1642:
1622:
1602:
1590:
1588:
1581:
1579:
1577:
1559:
1556:
1553:
1549:
1539:
1523:
1520:
1517:
1513:
1490:
1487:
1484:
1480:
1456:
1453:
1450:
1446:
1423:
1420:
1417:
1413:
1390:
1387:
1384:
1380:
1370:
1368:
1364:
1348:
1345:
1342:
1319:
1316:
1313:
1306:
1303:
1300:
1296:
1292:
1284:
1280:
1275:
1270:
1266:
1262:
1259:
1252:
1251:
1250:
1248:
1230:
1227:
1224:
1220:
1211:
1193:
1190:
1187:
1183:
1174:
1173:dynamic range
1156:
1153:
1150:
1146:
1136:
1122:
1097:
1094:
1091:
1087:
1063:
1055:
1050:
1047:
1044:
1040:
1034:
1031:
1024:
1023:
1022:
1019:
1003:
999:
995:
992:
987:
983:
951:
947:
940:
934:
931:
928:
918:
917:
916:
912:
896:
892:
869:
865:
836:
832:
826:
822:
818:
813:
809:
803:
799:
792:
789:
786:
779:
778:
777:
775:
756:
753:
750:
747:
742:
738:
731:
723:
719:
713:
708:
704:
698:
693:
689:
683:
680:
677:
674:
671:
665:
657:
653:
647:
642:
638:
632:
628:
624:
621:
618:
615:
609:
601:
597:
591:
586:
582:
576:
572:
568:
565:
562:
555:
554:
553:
550:
534:
505:
476:
446:
443:
438:
434:
428:
416:
413:
408:
405:
400:
390:
385:
375:
369:
354:
353:
352:
328:
312:
289:
286:
280:
269:
263:
252:
247:
243:
237:
232:
228:
224:
221:
218:
211:
210:
209:
192:
161:
151:
146:
144:
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2916:Limitations
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2876:gating and
150:Phase shift
42:dissections
3094:(6): 823.
2956:References
2906:occlusions
92:dimensions
80:velocities
3116:121958168
3021:CC-BY-2.0
2997:1532-429X
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2910:aneurysms
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