Numerical simulations of carotid MRI quantify the accuracy in measuring atherosclerotic plaque components in vivo.
OBJECTIVE
Atherosclerotic carotid plaques can be quantified in vivo by MRI. However, the accuracy in segmentation and quantification of components such as the thin fibrous cap (FC) and lipid-rich necrotic core (LRNC) remains unknown due to the lack of a submillimeter scale ground truth.


METHODS
A novel approach was taken by numerically simulating in vivo carotid MRI providing a ground truth comparison. Upon evaluation of a simulated clinical protocol, MR readers segmented simulated images of cross-sectional plaque geometries derived from histological data of 12 patients.


RESULTS
MR readers showed high correlation (R) and intraclass correlation (ICC) in measuring the luminal area (R = 0.996, ICC = 0.99), vessel wall area (R = 0.96, ICC = 0.94) and LRNC area (R = 0.95, ICC = 0.94). LRNC area was underestimated (mean error, -24%). Minimum FC thickness showed a mediocre correlation and intraclass correlation (R = 0.71, ICC = 0.69).


CONCLUSIONS
Current clinical MRI can quantify carotid plaques but shows limitations for thin FC thickness quantification. These limitations could influence the reliability of carotid MRI for assessing plaque rupture risk associated with FC thickness. Overall, MRI simulations provide a feasible methodology for assessing segmentation and quantification accuracy, as well as for improving scan protocol design.
Department of Biomedical Engineering, Erasmus Medical Center, Rotterdam, the Netherlands.
Harm A
HA
Nieuwstadt
Tom R
TR
Geraedts
Martine T B
MT
Truijman
M Eline
ME
Kooi
Aad
A
van der Lugt
Anton F W
AF
van der Steen
Jolanda J
JJ
Wentzel
Marcel
M
Breeuwer
Frank J H
FJ
Gijsen
D002340:Carotid Artery Diseases / Q000175:diagnosis*; D003198:Computer Simulation; D003287:Contrast Media; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008055:Lipids / Q000032:analysis; D018810:Magnetic Resonance Angiography / Q000379:methods*; D009336:Necrosis; D009942:Organometallic Compounds; D058226:Plaque, Atherosclerotic / Q000175:diagnosis*; D059629:Signal-To-Noise Ratio
D003287:Contrast Media; D008055:Lipids; D009942:Organometallic Compounds; C090600:gadobutrol
atherosclerosis; carotid MRI; component segmentation accuracy; fibrous cap thickness; numerical simulations; vulnerable plaque