Ferumoxytol-enhanced magnetic resonance imaging assessing inflammation after myocardial infarction

Figures

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  Figure 1. (A) Duration and distribution of USPIO enhancement after single-dose administration in the first week after MI. (B) Repeated myocardial uptake of USPIO following MI. MI, myocardial infarction; USPIO, ultrasmall superparamagnetic particles of iron oxide.

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  Figure 2. Histology section of trucut biopsy from infarcted myocardium. (A) Haematoxylin and eosin (×5 magnification) stain displaying a thin region of viable healthy myocardium (strip of dark pink) surrounded by infarcted myocardium (lighter pink). (D) Infarcted myocardium shows an abundance of inflammatory cells and early granulation formation. (B) Prussian blue (×5) staining revealing intracellular iron (E, ×20 and G, ×50), not seen in the region of healthy myocardium. (C) CD68 (×5) staining revealing macrophages within the infarcted myocardium (F, ×20 and H, ×50), again not seen in healthy myocardium. G+H show colocalisation of iron within macrophages.

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  Figure 3. (A) USPIO uptake in myocardium after MI with repeated USPIO administration. (B) R2* 24 hours following USPIO (without subtraction of baseline values). Time course variation in USPIO uptake was seen in the infarct zone peaking at days 2 and 3. No variation of USPIO uptake was seen in peri-infarct and remote myocardium. Compared with remote myocardium, increased USPIO uptake was seen in the infarct zone until days 10–16 post MI. (****p<0.0001, ***p<0.001, **p<0.01, *p<0.05). Compared with remote myocardium, greater post-USPIO R2* was seen in the infarct zone until days 10–16 post MI. (***p<0.001, **p<0.01, *p<0.05). A+B: n = 11 (days 2–3, 4–7 and 17–25), 10 (days 10–16) and 10 (days 78–99). MI, myocardial infarction; USPIO, ultrasmall superparamagnetic particles of iron oxide.

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  Figure 4. Examples of myocardial oedema and USPIO enhancement in the infarct zone after MI. Three examples of MI (1—anteroseptal, 2—lateral and 3—inferior) illustrating LGE, USPIO enhancement (R2* map) and oedema (T2 map) at early (up to 10 days) and late (3 months) time points. Early inflammation and oedema seen on R2* (dark region) and T2 maps (light region), respectively, have improved or resolved by 3 months. LGE, late gadolinium enhancement; MI, myocardial infarction; USPIO, ultrasmall superparamagnetic particles of iron oxide.

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  Figure 5. T2 value in the myocardium after MI. Time course variation in infarct and peri-infarct T2 was seen in the 3-month period following MI, both peaking at days 3–9. Compared with remote myocardium, higher T2 was seen in the infarct zone throughout the duration of the study and in the peri-infarct zone until days 17–24 (****p<0.0001, ***p<0.001, **p<0.01, *p<0.05); n = 15 (days 1–2), 14 (days 3–9 and 77–98), 8 (days 10–16) and 10 (days 17–24). MI, myocardial infarction.

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  Figure 6. USPIO enhancement after single-dose administration in the first week following MI. Following single-dose administration, USPIO enhancement was detected in all myocardial regions at 24 hours. USPIO was detected in bone marrow until 4–9 days, and spleen and liver until 13–21 days (****p<0.0001, ***p<0.001, *p<0.05); n = 21 (baseline, 24 hours), 11 (days 4–9), 15 (days 13–21) and 5 (days 78–99). MI, myocardial infarction; USPIO, ultrasmall superparamagnetic particles of iron oxide.