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1. ME/BIO 481 23 Sept 2009Magnetic Resonance Imaging --Basics Curtis Johnson, PhD candidate
Mechanical Science & Engineering Dept.
University of Illinois U-C
2. 2 Outline Background:
MRI Physics
Relaxation phenomena and kinetics
Space encoding
In Vivo Applications:
Bone and muscle
Human calf in dorsiflexion
Brain elastography
3. 3
4. 4 MRI Today
5. 5 MRI Guided-Coronary Balloon Angioplasty
6. 6 NMR signal …predominantly from protons
7. 7
8. 8
9. 9
10. 10
11. 11
12. 12
13. 13
14. 14 Proton Relaxation in Solution
15. 15
16. 16
17. 17
18. 18
19. 19
20. 20 Nuclear spins in a B Gradient
21. 21
22. 22
23. 23 2-D Images with MRI
24. 24 MRI Guided-Coronary Balloon Angioplasty
25. 25 MRI Scanner
26. 26 Scanner Overview
27. 27 Superconducting Magnet
28. 28 Other Magnet Types
29. 29 Shimming
30. 30 Other Magnet Types
31. 31
32. 32 MRI Guided-Coronary Balloon Angioplasty
33. 33 Knee
34. 34 MRI Measures of Muscle & Bone
35. 35 Orientation dependent diffusion
36. 36 Displacement-Weighted MRI
37. 37 Displacement-Weighted MRI
38. 38 Displacement-Weighted MRI
39. 39 Displacement-Weighted MRI
40. 40 Calf Muscles
41. 41 Soleus Anatomy
42. 42 Fiber orientation maps
43. 43 High Resolution (SOL, LG, MG)
44. 44 6 Slices (SOL, LG, MG)
45. 45 Muscle fiber superstructure: intramuscular connective tissue ? lateral force transmission We analyzed the structural features of the perimysium collagen network in bovine Flexor carpi radialis muscle using various sample
preparation methods and microscopy techniques. We Wrst observed by scanning electron microscopy that perimysium formed a regular
network of collagen Wbers with three hierarchical levels including (i) a loose lattice of large interwoven Wbers ramiWed in (ii) numerous collagen
plexi attaching together adjacent myoWbers at the level of (iii) speciWc structures that we call perimysial junctional plates. Second,
we looked more closely at the intracellular organization underneath each plate using transmission electron microscopy, immunohistochemistry,
and a three-dimensional reconstruction from serial sections. We observed the accumulation of myonuclei arranged in clusters
surrounded by a high density of subsarcolemmal mitochondria and the proximity of capillary branches. Third, we analyzed the distribution
of these perimysial junctional plates, subsarcolemmal mitochondria, and myonuclei clusters along the myofibers using a statistical
analysis of the distances between these structures. This revealed a global colocalization and the existence of adhesion domains between
endomysium and perimysium. Taken together, our observations give a better description of the perimysium organization in skeletal
muscle, and provide evidence that perimysial junctional plates with associated intracellular subdomains may participate in the lateral
transmission of contractile forces as well as mechanosensing.
The perimysium collagen network and junctional plates. Electron micrographs (SEM) of skeletal muscle Wbers prepared according to the NaOH
digestion technique (6N at 18 °C) revealed (A) on lateral and (B) front views the overall lattice of collagen interwoven Wbers, (C) the distribution of plexi at
the surface of myoWber (noted p), and (D) plexi adhering to the surface of adjacent myoWbers. Note the collagen Wbers crossing myoWbers at an angle of
approximately 60°. Electron micrographs of skeletal muscle Wbers prepared according to the fracture technique show in greaster detail (E) the attachment
of perimysium plexi to myoWbers at the level of a particular structure that we call “the perimysial junctional plate” (PJP). PJP are approximately 150–
200 m in length. High magniWcation (F) shows the merging of the perimysium with the endomysium (noted e) at the extremities of two branches of the
same plexus, which seems to connect with the outer surface of the sarcolemma at and between costameric structures.
Model of perimysium organization in skeletal bovine muscle. The
top panel represents a longitudinal view of a skeletal muscle covering
1mm in length. We show the perimysium as a loose network of interwoven
collagen Wbers as observed by SEM. At the angles of these interwoven
Wbers, plexi branches originate and adhere to the surface of adjacent myo-
Wbers. This illustration in the second panel shows its branches as well as its
association with a myonuclei cluster and the accumulation of subsarcolemmal
mitochondria in the intracellular subdomain. The bottom panel is
a simpliWed drawing of the attachment region that we called the perimysial
junctional plate (200 m long) with several adhesion points on and
between the costameric structures, as well as associated membrane densiWcations
as indicated in SEM and TEM views. A sarcomere has been
depicted on the bottom left to give an idea of the scale.
We analyzed the structural features of the perimysium collagen network in bovine Flexor carpi radialis muscle using various sample
preparation methods and microscopy techniques. We Wrst observed by scanning electron microscopy that perimysium formed a regular
network of collagen Wbers with three hierarchical levels including (i) a loose lattice of large interwoven Wbers ramiWed in (ii) numerous collagen
plexi attaching together adjacent myoWbers at the level of (iii) speciWc structures that we call perimysial junctional plates. Second,
we looked more closely at the intracellular organization underneath each plate using transmission electron microscopy, immunohistochemistry,
and a three-dimensional reconstruction from serial sections. We observed the accumulation of myonuclei arranged in clusters
surrounded by a high density of subsarcolemmal mitochondria and the proximity of capillary branches. Third, we analyzed the distribution
of these perimysial junctional plates, subsarcolemmal mitochondria, and myonuclei clusters along the myofibers using a statistical
analysis of the distances between these structures. This revealed a global colocalization and the existence of adhesion domains between
endomysium and perimysium. Taken together, our observations give a better description of the perimysium organization in skeletal
muscle, and provide evidence that perimysial junctional plates with associated intracellular subdomains may participate in the lateral
transmission of contractile forces as well as mechanosensing.
The perimysium collagen network and junctional plates. Electron micrographs (SEM) of skeletal muscle Wbers prepared according to the NaOH
digestion technique (6N at 18 °C) revealed (A) on lateral and (B) front views the overall lattice of collagen interwoven Wbers, (C) the distribution of plexi at
the surface of myoWber (noted p), and (D) plexi adhering to the surface of adjacent myoWbers. Note the collagen Wbers crossing myoWbers at an angle of
approximately 60°. Electron micrographs of skeletal muscle Wbers prepared according to the fracture technique show in greaster detail (E) the attachment
of perimysium plexi to myoWbers at the level of a particular structure that we call “the perimysial junctional plate” (PJP). PJP are approximately 150–
200 m in length. High magniWcation (F) shows the merging of the perimysium with the endomysium (noted e) at the extremities of two branches of the
same plexus, which seems to connect with the outer surface of the sarcolemma at and between costameric structures.
Model of perimysium organization in skeletal bovine muscle. The
top panel represents a longitudinal view of a skeletal muscle covering
1mm in length. We show the perimysium as a loose network of interwoven
collagen Wbers as observed by SEM. At the angles of these interwoven
Wbers, plexi branches originate and adhere to the surface of adjacent myo-
Wbers. This illustration in the second panel shows its branches as well as its
association with a myonuclei cluster and the accumulation of subsarcolemmal
mitochondria in the intracellular subdomain. The bottom panel is
a simpliWed drawing of the attachment region that we called the perimysial
junctional plate (200 m long) with several adhesion points on and
between the costameric structures, as well as associated membrane densiWcations
as indicated in SEM and TEM views. A sarcomere has been
depicted on the bottom left to give an idea of the scale.
46. 46 Biomechanical implications
47. 47 Foot Dorsiflexion
48. 48 Passive dorsiflexion: NIRS
49. 49 Skeletal muscle microstructure: Composite medium model of myocytes Two main compartments contribute to the diffusion properties of the composite medium: the intracellular space (within the muscle fiber) and he extracellular space (endomysium) that surrounds the muscle fibers)
Two main compartments contribute to the diffusion properties of the composite medium: the intracellular space (within the muscle fiber) and he extracellular space (endomysium) that surrounds the muscle fibers)
50. 50 MRI Guided-Coronary Balloon Angioplasty
51. 51 MR Elastography Setup
52. 52 MR Elastography – Agar Gel
53. 53 Incompressibility ?
54. 54 Incompressibility ?
55. 55 MRE in brain phantom
56. 56 MRE in gel with brain tissue
57. 57 MRE in Human Brain Add one of your brain videos here…
58. 58 Sources RW Cox “(f)MRI Physics with Hardly Any Math” 2001
RR Ernst, G Bodenhausen, A. Wokaum “Principles of NMR in 1 & 2 Dimensions” 1987
A Abragam “The principles of Magnetic Resonance” 1980
F Wehrli, J MacFall, T Newton “Parameters determining the appearance of NMR images” GE 1984