BACKGROUND The diagnostic utility of cardiovascular magnetic resonance (CMR) is limited during the early stages of myocarditis. This study examined whether ferumoxytol-enhanced CMR (FE-CMR) could detect an earlier stage of acute myocarditis compared to gadolinium-enhanced CMR. METHODS Lewis rats were induced to develop autoimmune myocarditis. CMR (3 T, GE Signa) was performed at the early- (day 14, n = 7) and the peak-phase (day 21, n = 8) of myocardial inflammation. FE-CMR was evaluated as % myocardial dephasing signal loss on gradient echo images at 6 and 24 h (6 h- & 24 h-FE-CMR) following the administration of ferumoxytol (300μmolFe/kg). Pre- and post-contrast T2* mapping was also performed. Early (EGE) and late (LGE) gadolinium enhancement was obtained after the administration of gadolinium-DTPA (0.5 mmol/kg) on day 14 and 21. Healthy rats were used as control (n = 6). RESULTS Left ventricular ejection fraction (LVEF) was preserved at day 14 with inflammatory cells but no fibrosis seen on histology. EGE and LGE at day 14 both showed limited myocardial enhancement (EGE: 11.7 ± 15.5%; LGE: 8.7 ± 8.7%; both p = ns vs. controls). In contrast, 6 h-FE-CMR detected extensive myocardial signal loss (33.2 ± 15.0%, p = 0.02 vs. EGE and p < 0.01 vs. LGE). At day 21, LVEF became significantly decreased (47.4 ± 16.4% vs control: 66.2 ± 6.1%, p < 0.01) with now extensive myocardial involvement detected on EGE, LGE, and 6 h-FE-CMR (41.6 ± 18.2% of LV). T2* mapping also detected myocardial uptake of ferumoxytol both at day 14 (6 h R2* = 299 ± 112 s- 1vs control: 125 ± 26 s- 1, p < 0.01) and day 21 (564 ± 562 s- 1, p < 0.01 vs control). Notably, the myocardium at peak-phase myocarditis also showed significantly higher pre-contrast T2* (27 ± 5 ms vs control: 16 ± 1 ms, p < 0.001), and the extent of myocardial necrosis had a strong positive correlation with T2* (r = 0.86, p < 0.001). CONCLUSIONS FE-CMR acquired at 6 h enhance detection of early stages of myocarditis before development of necrosis or fibrosis, which could potentially enable appropriate therapeutic intervention.

中文翻译：

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Ferumoxytol 增强心血管磁共振检测早期急性心肌炎。


背景技术心血管磁共振(CMR)的诊断效用在心肌炎的早期阶段是有限的。本研究检验了与钆增强 CMR 相比，ferumoxytol 增强 CMR (FE-CMR) 是否可以检测到急性心肌炎的早期阶段。方法 诱导Lewis大鼠发生自身免疫性心肌炎。 CMR（3 T，GE Signa）在心肌炎症的早期（第 14 天，n = 7）和高峰期（第 21 天，n = 8）进行。 FE-CMR 被评估为施用 ferumoxytol (300μmolFe/kg) 后 6 小时和 24 小时（6 小时和 24 小时-FE-CMR）梯度回波图像上的心肌相移信号损失百分比。还进行了对比前和对比后 T2* 映射。第 14 天和第 21 天给予钆-DTPA (0.5 mmol/kg) 后，获得早期 (EGE) 和晚期 (LGE) 钆增强。健康大鼠用作对照 (n = 6)。结果 第 14 天左心室射血分数 (LVEF) 保持不变，且有炎症细胞，但组织学上未见纤维化。第 14 天的 EGE 和 LGE 均显示有限的心肌增强（EGE：11.7 ± 15.5%；LGE：8.7 ± 8.7%；与对照组相比，p = ns）。相反，6 h-FE-CMR 检测到广泛的心肌信号丢失（33.2 ± 15.0%，p = 0.02 与 EGE 相比，p < 0.01 与 LGE 相比）。第 21 天时，LVEF 显着下降（47.4 ± 16.4% 与对照：66.2 ± 6.1%，p < 0.01），现在 EGE、LGE 和 6 h-FE-CMR 检测到广泛的心肌受累（LV 的 41.6 ± 18.2%） ）。 T2* 绘图还检测到第 14 天（6 小时 R2* = 299 ± 112 s- 1 对比对照：125 ± 26 s- 1，p < 0.01）和第 21 天（564 ± 562 s- 1，p）心肌对阿莫西托的摄取< 0.01 与对照相比）。值得注意的是，心肌炎高峰期的心肌也表现出显着较高的对比前 T2*（27 ± 5 ms 与对照：16 ± 1 ms，p < 0。001），心肌坏死程度与T2*呈强正相关（r = 0.86，p < 0.001）。结论 6 小时时获得的 FE-CMR 增强了心肌炎发生坏死或纤维化之前早期阶段的检测，这可能有助于适当的治疗干预。