Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Non-Invasive High Resolution Detection of
Active Atherosclerotic Plaque in ApoE
Deficient Mice by Magnetic Resonance
Imagi...
A
B
l>Macrophages
infiltration
l>Extensive angiogenesis
and vasa vasorum
leakage
Plaque Morphology
vs.
Plaque Activity
Why do we need both?
The short answer is: because not all plaques with
similar morph...
Morphology vs. Activity Imaging
Inactive and
non-inflamed
plaque
Active and
inflamed
plaque
Appear Similar in
IVUS OCT MRI...
Current Methods for DetectionCurrent Methods for Detection
of Vulnerable Plaquesof Vulnerable Plaques
lOptical coherence
t...
Human Carotid Plaque
Courtesy of
Dr. Chun Yuan
University of Washington
We need MRI with vulnerable plaque
targeted contrast media that identifies:
1- Inflammation (macrophage infiltration),
2- ...
SuperparamagneticSuperparamagnetic
andand
Ultra-superparamagneticUltra-superparamagnetic
Iron OxideIron Oxide
lBlood pool ...
Particle Core Size Particle Size Blood
(nm) (nm) Half-life
Combidex 5-6 20-30 8h
Feridex 4-6 35-50 2.4±0.2h
DDM 43/34/102 ...
Current applications of SPIO in MR imaging:
-Detection of Hepatic Lesions
(primary and metastatic cancers)
-Experimental N...
USPIOs Enter the AtheroscleroticUSPIOs Enter the Atherosclerotic
Plaque ThroughPlaque Through
lMacrophages that engulfed
t...
In-vitro Study of Macrophage
SPIO Uptake
 In a series of in-vitro studies we have tested
the rate of SPIO uptake by human...
FL-labeled SPIO Incubated Macrophages 24hr
Double DAPI Staining with Fluorescence-labeled SPIO Macrophages
after 24hr Incubation
HypothesisHypothesis
Active macrophages residing inside
the inflamed vulnerable plaques can
be visualized following inject...
vasa vasorum
Over magnification is a major advantage of SPIO
Darkening property of SPIO in the white background of fat
and...
SPIO and T2 Effect
In-vitro study to show the effect of
macrophage SPIO uptake on their
T2 relaxation time
0
10
20
30
40
50
60
70
80
90
50 250 control
20 min
60 min
6 hours
24 hours
Macrophage Uptake of Feridex with Time
and Conc...
In-vivo distribution of SPIO in ApoE
deficient and wild type mice:
•For the initial study, we use the mouse model of
ather...
Pre and Post-SPIO Enhanced Magnetic
Resonance Imaging of ApoE K/O and Wild
Type Mice:
We used 4.7 tesla MRI unit (Universi...
•Tissues from different organs including liver,
kidneys, lung, heart, spleen and aorta
(including valve region ascending, ...
Histopathologic study of the Mouse injected
With SPIO (Thoracic Aorta)
ApoE KO mouse, Movat staining,
proximal aorta
Coron...
Histopathologic study of ApoE KO Mouse injected
With SPIO (Thoracic Aorta)
CD68 staining
(aortic plaque)
Iron Staining (ao...
Histopathologic study of ApoE KO Mouse
injected With SPIO (Abdominal Aorta)
H&E staining
Iron Staining CD 68 staining
Iron...
Histopathologic study of wild type Mouse
injected With SPIO (Thoracic Aorta)
H&E staining
CD68 stainingIron staining
Comparison of the Number of the Iron Particles (per
HPF) in ApoE KO Mice Plaque vs. Normal Wall
0
5
10
15
Atherosclerotic
...
MR Image of Abdominal Aorta After SPIO
Injection in ApoE and Control Mice
ApoE
deficien
t mouse
C57B1
(control)
mouse
Befo...
Typical in vivo MR images of a live mouse at the heart (left)
and renal level (right). Various vessels and aortic arch can...
We chose Watanabe Hereditary Hypercholesterolemic rabbits (WHHR) and
New Zealand White rabbits (NZW) for this study.
We in...
Histopathologic studies of Thoracic aorta in Watanabe
Hereditary Hypercholesterolemic rabbit after SPIO injection
H&E stai...
Histopathologic studies of Thoracic aorta in Watanabe
Hereditary Hypercholesterolemic rabbit after SPIO injection
H&E stai...
Plaque Cell Density vs SPIO
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70
Cell Denity in H&E staining
SPIOpositivecell-Iron
s...
MR Angiography 3D with Gadolinium-DTPA in
Watanabe Rabbit
Before SPIO injection After SPIO injection
Ex-vivo MR study of the thoracic aorta in Watanabe and
Wild type rabbit after SPIO injection compared to control.
3D MR An...
Ex-vivo MR study of the thoracic aorta in Watanabe and
Wild type rabbit after SPIO injection compared to control.
(Gradien...
Spio mri studies by dr naghavi
Upcoming SlideShare
Loading in …5
×

Spio mri studies by dr naghavi

85 views

Published on

SHAPE Society

Published in: Health & Medicine
  • Be the first to comment

  • Be the first to like this

Spio mri studies by dr naghavi

  1. 1. Non-Invasive High Resolution Detection of Active Atherosclerotic Plaque in ApoE Deficient Mice by Magnetic Resonance Imaging after Injection of Super Paramagnetic Iron Oxide (SPIO) Center for Vulnerable Plaque Research University of Texas at Houston Texas Heart Institute
  2. 2. A B
  3. 3. l>Macrophages infiltration l>Extensive angiogenesis and vasa vasorum leakage
  4. 4. Plaque Morphology vs. Plaque Activity Why do we need both? The short answer is: because not all plaques with similar morphology would result in similar outcome.
  5. 5. Morphology vs. Activity Imaging Inactive and non-inflamed plaque Active and inflamed plaque Appear Similar in IVUS OCT MRI w/o CM Morphology Show Different Activity Thermography, Spectroscopy, immunoscintigraphy, MRI with targeted contrast media…
  6. 6. Current Methods for DetectionCurrent Methods for Detection of Vulnerable Plaquesof Vulnerable Plaques lOptical coherence tomography lRadioscintigraph lThermography lNear infrared spectroscopy lMagnetic resonance imaging
  7. 7. Human Carotid Plaque Courtesy of Dr. Chun Yuan University of Washington
  8. 8. We need MRI with vulnerable plaque targeted contrast media that identifies: 1- Inflammation (macrophage infiltration), 2- Fissured/Permeable Cap, 3- Leaking Angiogenesis and 4- Intra-Plaque Hemorrhage 5- …
  9. 9. SuperparamagneticSuperparamagnetic andand Ultra-superparamagneticUltra-superparamagnetic Iron OxideIron Oxide lBlood pool Magnetic resonance (MR) imaging contrast media with a central core of iron oxide generally coated by a polysaccharide layer lShortening MR relaxation time lEngulfed by and accumulated in cells with phagocytic activity
  10. 10. Particle Core Size Particle Size Blood (nm) (nm) Half-life Combidex 5-6 20-30 8h Feridex 4-6 35-50 2.4±0.2h DDM 43/34/102 6.4 20-30 6h Clariscan MION 4-6 17 varies Feruglose --- --- --- --- Examples of commercially available SPIOs
  11. 11. Current applications of SPIO in MR imaging: -Detection of Hepatic Lesions (primary and metastatic cancers) -Experimental Nephritic syndrome in Laboratory animals -Monitoring rejection of transplanted heart or kidney in the animal model of allograft transplantation. -Experimental detection of CNS lesions in laboratory animals.
  12. 12. USPIOs Enter the AtheroscleroticUSPIOs Enter the Atherosclerotic Plaque ThroughPlaque Through lMacrophages that engulfed them lFissured or thin cap l Extensive angiogenesis l vasa vasorum leakage l Intra plaque hemorrhage
  13. 13. In-vitro Study of Macrophage SPIO Uptake  In a series of in-vitro studies we have tested the rate of SPIO uptake by human activated monocytes in different conditions regarding incubation time and concentration of SPIO. All SPIO were labeled by a fluorescent dye (DCFA).
  14. 14. FL-labeled SPIO Incubated Macrophages 24hr
  15. 15. Double DAPI Staining with Fluorescence-labeled SPIO Macrophages after 24hr Incubation
  16. 16. HypothesisHypothesis Active macrophages residing inside the inflamed vulnerable plaques can be visualized following injection of SPIO or USPIOs into the systemic circulation by virtue of a decrease in the magnetic resonance signal intensity of the plaque,and correlate with histopathologic characteristics of vulnerability to rupture.
  17. 17. vasa vasorum Over magnification is a major advantage of SPIO Darkening property of SPIO in the white background of fat and water of plaque is another advantage
  18. 18. SPIO and T2 Effect In-vitro study to show the effect of macrophage SPIO uptake on their T2 relaxation time
  19. 19. 0 10 20 30 40 50 60 70 80 90 50 250 control 20 min 60 min 6 hours 24 hours Macrophage Uptake of Feridex with Time and Concentration Shown by T2 Reduction Concentration µmol/ml
  20. 20. In-vivo distribution of SPIO in ApoE deficient and wild type mice: •For the initial study, we use the mouse model of atherosclerosis. • •ApoE deficient mouse has similar atherosclerotic lesions to human and the lesions are more common in the aortic arch and thoracic aorta. • We used ApoE deficient mice and normal variant (C57BL mice) as control. •The SPIO that we used was Feridex (Berlex) injectable solution. •Animals were sacrificed on day 3 and 5 after injection.
  21. 21. Pre and Post-SPIO Enhanced Magnetic Resonance Imaging of ApoE K/O and Wild Type Mice: We used 4.7 tesla MRI unit (University of Texas, Galveston MRI Unit, Galveston, TX) in our study. After baseline MR imaging with respiratory gating, we injected 1mMolFe/kg super paramagnetic iron oxide to six ApoE deficient and two C57bl mice through the tail vein. Post-contrast MR imaging were performed in day 5 with the same parameters (TR=2.5 sec, TE=0.012 sec, FOV=6.6 cm, slice thickness=2.0mm, flip angle (orient)=trans, and matrices=256x256). We selected the aorta at the level of kidney for comparison of the baseline and post-contrast images.
  22. 22. •Tissues from different organs including liver, kidneys, lung, heart, spleen and aorta (including valve region ascending, descending and abdominal) was obtained and stained. • We used Hematoxyline and Eosin (H&E), Iron, CD68 and Movat staining. • After Iron staining, aortic wall of the ApoE deficient mice and normal variant were compared based on the number of Iron particle. • Also different doses of Feridex and The timing between injection and tissue obtaining was considered.
  23. 23. Histopathologic study of the Mouse injected With SPIO (Thoracic Aorta) ApoE KO mouse, Movat staining, proximal aorta Coronary Cross section Atherosclerosis plaque
  24. 24. Histopathologic study of ApoE KO Mouse injected With SPIO (Thoracic Aorta) CD68 staining (aortic plaque) Iron Staining (aortic plaque) Iron Staining (coronary section) Iron particles Iron particles
  25. 25. Histopathologic study of ApoE KO Mouse injected With SPIO (Abdominal Aorta) H&E staining Iron Staining CD 68 staining Iron particles
  26. 26. Histopathologic study of wild type Mouse injected With SPIO (Thoracic Aorta) H&E staining CD68 stainingIron staining
  27. 27. Comparison of the Number of the Iron Particles (per HPF) in ApoE KO Mice Plaque vs. Normal Wall 0 5 10 15 Atherosclerotic Aorta Average number of iron particles per sample P <0.001
  28. 28. MR Image of Abdominal Aorta After SPIO Injection in ApoE and Control Mice ApoE deficien t mouse C57B1 (control) mouse Before Injection After Injection (5 Days ) Dark (negatively enhanced) aortic wall, full of iron particles Bright aortic lumen and wall without negative enhancement and no significant number of iron particles
  29. 29. Typical in vivo MR images of a live mouse at the heart (left) and renal level (right). Various vessels and aortic arch can easily e seen in these images. The slice thickness is 0.5 mm and the in-plane resolution is 50 µm (7.1 T MR system).
  30. 30. We chose Watanabe Hereditary Hypercholesterolemic rabbits (WHHR) and New Zealand White rabbits (NZW) for this study. We injected them with SPIO (Feridex) 1 mMol Fe/kg and obtained baseline as well as 5-day post-SPIO injection MR images of the aorta (1.5 Tesla MRI system at the University of Texas, MD Anderson,Houston,Texas). Then we compared the images in hypercholesterolemic rabbits with the normal,wild type NZW rabbits. Rabbit ex-vivo MRI studies: After the in-vivo MR images, we sacrificed the animals and excised the aorta. Then we put the isolated aorta in a gel medium, clamped both ends and any side branches and injected gadolinium inside the lumen. We did the same procedure for all rabbits. We also used 2 more rabbits, one WHHR and one NZW that were not injected with SPIO, as control, in the ex-vivo MR study. SPIO-Enhanced MRI study in rabbits
  31. 31. Histopathologic studies of Thoracic aorta in Watanabe Hereditary Hypercholesterolemic rabbit after SPIO injection H&E staining Iron staining Iron staining
  32. 32. Histopathologic studies of Thoracic aorta in Watanabe Hereditary Hypercholesterolemic rabbit after SPIO injection H&E staining Iron staining Iron staining Iron particles
  33. 33. Plaque Cell Density vs SPIO 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 Cell Denity in H&E staining SPIOpositivecell-Iron staining Series1 R=0.956 Correlation between Iron positive cells in Iron staining and cell density in H&E staining in rabbit atherosclerotic aorta.
  34. 34. MR Angiography 3D with Gadolinium-DTPA in Watanabe Rabbit Before SPIO injection After SPIO injection
  35. 35. Ex-vivo MR study of the thoracic aorta in Watanabe and Wild type rabbit after SPIO injection compared to control. 3D MR Angiography with Gadolinium-DTPA Watanabe rabbit Post-SPIO Watanabe rabbit control NZW rabbit control NZW rabbit Post-SPIO
  36. 36. Ex-vivo MR study of the thoracic aorta in Watanabe and Wild type rabbit after SPIO injection compared to control. (Gradient echo) Watanabe rabbit Post-SPIO Watanabe rabbit control NZW rabbit Post-SPIO NZW rabbit control

×