Principles, Benefits and Challenges of Whole-Body 3T MRI

Targeted CE per ARRT’s Discipline, Category, and Subcategory classification:
[Note: Discipline-specific Targeted CE credits may be less than the total Category A credits approved for this course.]

Magnetic Resonance Imaging: 2.75
Safety: 0.25
MRI Screening and Safety: 0.25
Image Production: 1.00
Physical Principles of Image Formation: 0.50
Sequence Parameters and Options: 0.50
Procedures: 1.50
Neurological: 1.50

Outline

1. Introduction
2. Physical Effects of Higher Magnetic Field Strengths
   1. Signal-to-Noise Ratio
   2. Larmor Frequency and Chemical Shift
   3. Relaxation Times
   4. Contrast-enhanced MR Imaging
   5. Susceptibility
   6. RF Deposition and Specific Absorption Rate
   7. Dielectric Effects
3. How to Deal with High-Field-Strength-Related Difficulties
   1. Deal with Increased Chemical Shift
   2. Compensate for Altered Relaxation Times
   3. Avoid Susceptibility Effects
   4. Cope with Increased RF Deposition
   5. Correct Dielectric Effects
   6. Patient Safety Issues
4. Clinical Applications
   1. Structural Brain Imaging
   2. DWI and Diffusion-Tensor Imaging
   3. Susceptibility-based and Perfusion Imaging
   4. MR Angiography
5. Conclusion

Objectives

Upon completion of this course, students will:

1. identify terminology used to measure magnetic field strength at system isocenter
2. learn the basic methods used to compensate for the artifacts and physical effects of higher field strength imaging
3. identify the measure of quality in MR imaging, as SNR relates to magnetic field strength
4. define and describe signal to noise ratio
5. define spatial resolution, the measure of detail in MR imaging
6. establish the advantage of shorter in-phase times realized with 3.0T systems as compared to 1.5T
7. define the cause of safety concerns of higher field MR systems
8. identify factors that increase RF absorption
9. establish FDA limits for whole body SAR
10. define and establish clinical limitations to B1 inhomogeneity
11. define chemical shift as it relates to magnetic field strength
12. identify the type and location of chemical shift artifacts
13. identify advantages of chemical shift at higher field strengths
14. learn the impact of gray matter-to-white matter contrast at 3T
15. establish 3T’s effect on tissues’ T1 and T2 relaxation times, compared to 1.5T
16. identify the function of gadolinium as an intravenous contrast agent used in MRI imaging
17. define magnetic susceptibility
18. identify the sequences most prone to the effects of magnetic susceptibility
19. learn the fundamental sequences that exploit the advantages of increased susceptibility effects at 3.0T
20. identify threshold limitations for RF deposition limiting heating of human tissue
21. establish the factor adjustments that lead to increases in RF deposition
22. compare low SAR with fast MRI pulse sequences and the clinical impact on patient care
23. define B1 inhomogeneity and describe its effect on an image
24. identify dielectric effects in MRI imaging
25. establish the clinical application of the predominant phase when dielectric effects occur
26. identify the most common corrective measure in compensating for chemical shift artifacts
27. establish the advantages of employing a wide receiver bandwidth
28. identify the common corrective measures for altered relaxation times at 3.0T
29. establish the impact of receiver bandwidth changes on the SNR
30. establish the impact of TR in T1 weighted images
31. identify susceptibility artifacts
32. identify corrective measures in avoiding susceptibility effects
33. identify the two main methods of coping with RF deposition at high field strengths
34. identify the application of parallel imaging in dealing with RF deposition
35. define the value and impact of flip angle modulation techniques when managing RF deposition in patients
36. identify the anatomic region least prone to artifacts, SAR limitations, and RF penetration uniformity
37. identify 3T’s impact on cerebral lesions crossing the blood brain barrier with contrast enhanced T1 weighted images
38. identify the main corrective measure for reduction of susceptibility effects in diffusion weighted imaging
39. define perfusion and establish its clinical value
40. establish the clinical advantages of time resolved MR angiography