TY - JOUR
T1 - Magnetization transfer magnetic resonance of human atherosclerotic plaques ex vivo detects areas of high protein density
AU - Qiao, Ye
AU - Hallock, Kevin J.
AU - Hamilton, James A.
N1 - Funding Information:
The authors would like to thank Drs. Alkystis Phinikaridou and Stephan Anderson for helpful comments and technical assistance with this work. Support for this work was provided by NIH (P50HL083801 to JAH).
PY - 2011
Y1 - 2011
N2 - Background: Proteins are major plaque components, and their degradation is related to the plaque instability. We sought to assess the feasibility of magnetization transfer (MT) magnetic resonance (MR) for identifying fibrin and collagen in carotid atherosclerotic plaques ex vivo. Methods. Human carotid artery specimens (n = 34) were obtained after resection from patients undergoing endarterectomy. MR was completed within 12 hr after surgery on an 11.7T MR microscope prior to fixation. Two sets of T1W spoiled gradient echo images were acquired with and without the application of a saturation pulse set to 10 kHz off resonance. The magnetization transfer ratio (MTR) was calculated, and the degree of MT contrast was correlated with histology. Results: MT with appropriate calibration clearly detected regions with high protein density, which showed a higher MTR (thick fibers (collagen type I) (54 8%)) compared to regions with a low amount of protein including lipid (46 8%) (p = 0.05), thin fibers (collagen type III) (11 6%) (p = 0.03), and calcification (6.8 4%) (p = 0.02). Intraplaque hemorrhage (IPH) with different protein density demonstrated different MT effects. Old (rich in protein debris) and recent IPH (rich in fibrin) had a much higher MTR 69 6% and 55 9%, respectively, compared to fresh IPH (rich in intact red blood cells)(9 3%). Conclusions: MT MR enhances plaque tissue contrast and identifies the protein-rich regions of carotid artery specimens. The additional information from MTR of IPH may provide important insight into the role of IPH on plaque stability, evolution, and the risk for future ischemic events.
AB - Background: Proteins are major plaque components, and their degradation is related to the plaque instability. We sought to assess the feasibility of magnetization transfer (MT) magnetic resonance (MR) for identifying fibrin and collagen in carotid atherosclerotic plaques ex vivo. Methods. Human carotid artery specimens (n = 34) were obtained after resection from patients undergoing endarterectomy. MR was completed within 12 hr after surgery on an 11.7T MR microscope prior to fixation. Two sets of T1W spoiled gradient echo images were acquired with and without the application of a saturation pulse set to 10 kHz off resonance. The magnetization transfer ratio (MTR) was calculated, and the degree of MT contrast was correlated with histology. Results: MT with appropriate calibration clearly detected regions with high protein density, which showed a higher MTR (thick fibers (collagen type I) (54 8%)) compared to regions with a low amount of protein including lipid (46 8%) (p = 0.05), thin fibers (collagen type III) (11 6%) (p = 0.03), and calcification (6.8 4%) (p = 0.02). Intraplaque hemorrhage (IPH) with different protein density demonstrated different MT effects. Old (rich in protein debris) and recent IPH (rich in fibrin) had a much higher MTR 69 6% and 55 9%, respectively, compared to fresh IPH (rich in intact red blood cells)(9 3%). Conclusions: MT MR enhances plaque tissue contrast and identifies the protein-rich regions of carotid artery specimens. The additional information from MTR of IPH may provide important insight into the role of IPH on plaque stability, evolution, and the risk for future ischemic events.
UR - http://www.scopus.com/inward/record.url?scp=84860560643&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84860560643&partnerID=8YFLogxK
U2 - 10.1186/1532-429X-13-73
DO - 10.1186/1532-429X-13-73
M3 - Article
C2 - 22107813
AN - SCOPUS:84860560643
SN - 1097-6647
VL - 13
JO - Journal of Cardiovascular Magnetic Resonance
JF - Journal of Cardiovascular Magnetic Resonance
IS - 1
M1 - 73
ER -