Ferumoxytol-enhanced magnetic resonance imaging in acute myocarditis

Abstract

ObjectivesUltrasmall superparamagnetic particles of iron oxide (USPIO)-enhanced MRI can detect tissue-resident macrophage activity and identify cellular inflammation within tissues. We hypothesised that USPIO-enhanced MRI would provide a non-invasive imaging technique that would improve the diagnosis and management of patients with acute myocarditis.MethodsTen volunteers and 14 patients with suspected acute myocarditis underwent T2, T2* and late gadolinium enhancement (LGE) 3T MRI, with further T2* imaging at 24 hours after USPIO (ferumoxytol, 4 mg/kg) infusion, at baseline and 3 months. Myocardial oedema and USPIO enhancement were determined within areas of LGE as well as throughout the myocardium.ResultsMyocarditis was confirmed in nine of the 14 suspected cases of myocarditis. There was greater myocardial oedema in regions of LGE in patients with myocarditis when compared with healthy volunteer myocardium (T2 value, 57.1±5.3 vs 46.7±1.6 ms, p<0.0001). There was no demonstrable difference in USPIO enhancement between patients and volunteers even within regions displaying LGE (change in R2*, 35.0±15.0 vs 37.2±9.6 s−1, p>0.05). Imaging after 3 months in patients with myocarditis revealed a reduction in volume of LGE, a reduction in oedema measures within regions displaying LGE and improvement in ejection fraction (mean −19.7 mL, 95% CI (−0.5 to −40.0)), −5.8 ms (−0.9 to −10.7) and +6% (0.5% to 11.5%), respectively, p<0.05 for all).ConclusionIn patients with acute myocarditis, USPIO-enhanced MRI does not provide additional clinically relevant information to LGE and T2 mapping MRI. This suggests that tissue-resident macrophages do not provide a substantial contribution to the myocardial inflammation in this condition.Clinical trial registration NCT02319278; Results.

Myocardial and Systemic Inflammation in Acute Stress-Induced (Takotsubo) Cardiomyopathy

“…It is therefore most likely that the cellular protagonists responsible for the organ-specific inflammatory response observed herein (USPIO uptake in the myocardium) are macrophages. This is in contrast to other types of acute heart failure presentations, such as acute myocarditis, where our group have previously shown that USPIO-enhanced magnetic resonance imaging was not able to detect a myocardial macrophage infiltrate, as the inflammatory cells involved in acute myocarditis are predominantly lymphocytes28. Moreover, our ex-vivo macrophage culture data suggest that the increase in USPIO uptake in the myocardium of patients with takotsubo cardiomyopathy was not attributable to an increased efficiency of USPIO uptake but to a large increase in tissue-resident myocardial macrophages.…”

Cardiovascular magnetic resonance native T2 and T2* quantitative values for cardiomyopathies and heart transplantations: a systematic review and meta-analysis

“…5). At 3 T, these were 63.8 ± 8.0 ms in myocarditis patients and 53.3 ± 3.3 ms in controls [186,187] (Table 1, Fig. 6).…”

“…Most included studies in this metaanalysis therefore acquired multiple SAx slices [51, 54-56, 61, 63, 65], however some studies acquired only one [60] or three [49] SAx slices at the level of the infarcted area, which is more prone to missing the infarct core. In the studies with myocarditis patients mapping acquisition was generally also performed over multiple SAx covering the whole myocardium [38, 171-173, 175-180, 182, 183, 185], however in some studies the T 2 values were only acquired from a LGE hyperintense based ROI [25,174,181,184,187]. Also, studies including MI, often distinguish between the infarct region or core and use remote myocardium as the healthy control tissue.…”

Heartbeat: Transcatheter procedures for secondary mitral regurgitation?

“…In this issue of Heart , Stirrat and colleagues3 tested the hypothesis that using ultrasmall superparamagnetic particles of iron oxide (USPIO)-enhanced CMR to detect myocardial macrophage activity provide additive diagnostic value in patients with suspected acute myocarditis. Compared with 10 normal volunteers, 14 patients with suspected myocarditis showed great myocardial oedema associated with late-gadolinium enhancement, as expected, but there was no difference in USPIO enhancement (figure 2).…”