Ultrasmall Superparamagnetic Particles of Iron Oxide in Patients with Acute Myocardial Infarction: Early Clinical Experience

Shirjel R Alam, Anoop S V Shah, Jennifer Richards, Ninian N Lang, Gareth Barnes, Nikhil Joshi, Tom Macgillivray, Graham McKillop, Saeed Mirsadraee, John Payne, Keith A A Fox, Peter Henriksen, David E Newby, Scott I K Semple

Research output: Contribution to journalArticlepeer-review

Abstract

Background
Inflammation following acute myocardial infarction (MI) has detrimental effects on reperfusion, myocardial remodelling, and ventricular function. Magnetic resonance imaging using ultrasmall superparamagnetic particles of iron oxide can detect cellular inflammation in tissues, and we therefore explored their role in acute MI in humans.

Methods and Results
Sixteen patients with acute ST-segment elevation MI were recruited to undergo 3 sequential magnetic resonance scans within 5 days of admission at baseline, 24 and 48 hours following no infusion (controls; n=6) or intravenous infusion of ultrasmall superparamagnetic particles of iron oxide (n=10; 4 mg/kg). T2*-weighted multigradient-echo sequences were acquired and R2* values were calculated for specific regions of interest. In the control group, R2* values remained constant in all tissues across all scans with excellent repeatability (bias of −0.208 s−1, coefficient of repeatability of 26.96 s−1; intraclass coefficient 0.989). Consistent with uptake by the reticuloendothelial system, R2* value increased in the liver (84±49.5 to 319±70.0 s−1; P<0.001) but was unchanged in skeletal muscle (54±8.4 to 67.0±9.5 s−1; P>0.05) 24 hours after administration of ultrasmall superparamagnetic particles of iron oxide. In the myocardial infarct, R2* value increased from 41.0±12.0 s−1 (baseline) to 155±45.0 s−1 (P<0.001) and 124±35.0 s−1 (P<0.05) at 24 and 48 hours, respectively. A similar but lower magnitude response was seen in the remote myocardium, where it increased from 39±3.2 s−1 (baseline) to 80±14.9 s−1 (P<0.001) and 67.0±15.7 s−1 (P<0.05) at 24 and 48 hours, respectively.

Conclusions
Following acute MI, uptake of ultrasmall superparamagnetic particles of iron oxide occurs with the infarcted and remote myocardium. This technique holds major promise as a potential method for assessing cellular myocardial inflammation and left ventricular remodelling, which may have a range of applications in patients with MI and other inflammatory cardiac conditions.

Clinical Trial Registration
URL: http://www.clinicaltrials.gov. Unique identifier: NCT01323296.

Original languageEnglish
Pages (from-to)559-565
Number of pages7
JournalCirculation: Cardiovascular Imaging
Volume5
Issue number5
DOIs
Publication statusPublished - Sept 2012

Keywords / Materials (for Non-textual outputs)

  • myocardial infarction
  • inflammation
  • magnetic resonance imaging
  • ultrasmall superparamagnetic particles of iron oxide

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