Utility of USPIO-enhanced MR imaging to identify inflammation and the fibrous cap: A comparison of symptomatic and asymptomatic individuals

Howarth, S. P. S., Tang, T. Y., Trivedi, R., Weerakkody, R., U-King-Im, J., Gaunt, M. E., Boyle, J. R., Li, Z. Y., Miller, S. R., Graves, M. J., & Gillard, J. H. (2009) Utility of USPIO-enhanced MR imaging to identify inflammation and the fibrous cap: A comparison of symptomatic and asymptomatic individuals. European Journal of Radiology, 70(3), pp. 555-560.

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Background and purpose:

Inflammation is a risk factor the vulnerable atheromatous plaque. This can be detected in vivo on high-resolution magnetic resonance (MR) imaging using a contrast agent, Sinerem™, an ultra-small super-paramagnetic iron oxide (USPIO). The aim of this study was to explore whether there is a difference in the degree of MR defined inflammation using USPIO particles, between symptomatic and asymptomatic carotid plaques. We report further on its T1 effect of enhancing the fibrous cap, which may allow dual contrast resolution of carotid atheroma.


Twenty patients with carotid stenosis (10 symptomatic and 10 asymptomatic) underwent multi-sequence MR imaging before and 36 h post-USPIO infusion. Images were manually segmented into quadrants and signal change in each quadrant was calculated following USPIO administration. Mean signal change across all quadrants were compared between the two groups. Results: Symptomatic patients had significantly more quadrants with a signal drop than asymptomatic individuals (75% vs. 32%, p < 0.01). Asymptomatic plaques had more quadrants with signal enhancement than symptomatic ones (68% vs. 25%, p < 0.05); their mean signal change was also higher (46% vs. 15%, p < 0.01) and this appeared to correlate with a thicker fibrous cap on histology.


Symptomatic patients had more quadrants with signal drop suggesting larger inflammatory infiltrates. Asymptomatic individuals showed significantly more enhancement possibly suggesting greater stability as a result of thicker fibrous caps. However, some asymptomatic plaques also had focal areas of signal drop, suggesting an occult macrophage burden. If validated by larger studies, USPIO may be a useful dual contrast agent able to improve risk stratification of patients with carotid stenosis and inform selection for intervention.

Impact and interest:

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ID Code: 90337
Item Type: Journal Article
Refereed: No
Keywords: Atherosclerosis, Carotid stenosis, Inflammation, MRI, Plaque vulnerability, USPIO
DOI: 10.1016/j.ejrad.2008.01.047
ISSN: 1872-7727
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute of Health and Biomedical Innovation
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2008 Elsevier Ireland Ltd
Deposited On: 16 Nov 2015 05:17
Last Modified: 02 Dec 2015 05:39

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