Department of Radiology, The First Affiliated Hospital of China Medical University, Shenyang, China; Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California.
Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California.
JACC Cardiovasc Imaging. 2019 Apr;12(4):693-703. doi: 10.1016/j.jcmg.2018.01.018. Epub 2018 Apr 18.
This study sought to determine whether T cardiac magnetic resonance (CMR) can stage both hemorrhagic and nonhemorrhagic myocardial infarctions (MIs).
CMR-based staging of MI with or without contrast agents relies on the resolution of T elevations in the chronic phase, but whether this approach can be used to stage both hemorrhagic and nonhemorrhagic MIs is unclear.
Hemorrhagic (n = 15) and nonhemorrhagic (n = 9) MIs were created in dogs. Multiparametric noncontrast mapping (T, T, and T*) and late gadolinium enhancement (LGE) were performed at 1.5- and 3.0-T at 5 days (acute) and 8 weeks (chronic) post-MI. CMR relaxation values and LGE intensities of hemorrhagic, peri-hemorrhagic, nonhemorrhagic, and remote territories were measured. Histopathology was performed to elucidate CMR findings.
T of nonhemorrhagic MIs was significantly elevated in the acute phase relative to remote territories (1.5-T: 39.8 ± 12.8%; 3.0-T: 27.9 ± 16.5%; p < 0.0001 for both) but resolved to remote values by week 8 (1.5-T: -0.0 ± 3.2%; p = 0.678; 3.0-T: -0.5 ± 5.9%; p = 0.601). In hemorrhagic MI, T of hemorrhage core was significantly elevated in the acute phase (1.5-T: 17.7 ± 10.0%; 3.0-T: 8.6 ± 8.2%; p < 0.0001 for both) but decreased below remote values by week 8 (1.5-T: -8.2 ± 3.9%; 3.0-T: -5.6 ± 6.0%; p < 0.0001 for both). In contrast, T of the periphery of hemorrhage within the MI zone was significantly elevated in the acute phase relative to remote territories (1.5-T: 35.0 ± 16.1%; 3.0-T: 24.2 ± 10.4%; p < 0.0001 for both) and remained elevated at 8 weeks post-MI (1.5-T: 8.6 ± 5.1%; 3.0-T: 6.0 ± 3.3%; p < 0.0001 for both). The observed elevation of T in the peri-hemorrhagic zone of MIs and the absence of T elevation in nonhemorrhagic MIs were consistent with ongoing or absence of histological evidence of inflammation, respectively.
Hemorrhagic MIs are associated with persisting myocardial inflammation and edema, which can confound staging of hemorrhagic MIs when T elevations alone are used to discriminate between acute and chronic MI. Moreover, given the poor prognosis in patients with hemorrhagic MI, CMR evidence for myocardial hemorrhage with persistent edema may evolve as a risk marker in patients after acute MI.
本研究旨在确定 T 心脏磁共振（CMR）是否可用于分期出血性和非出血性心肌梗死（MI）。
基于对比剂的 MI 分期依赖于慢性期 T 抬高的分辨率，但尚不清楚该方法是否可用于分期出血性和非出血性 MI。
在犬中创建出血性（n=15）和非出血性（n=9）MI。在 1.5 和 3.0-T 上，于 MI 后 5 天（急性期）和 8 周（慢性期）进行多参数非对比映射（T、T 和 T*）和晚期钆增强（LGE）。测量出血性、出血周围、非出血性和远隔区域的 CMR 弛豫值和 LGE 强度。进行组织病理学检查以阐明 CMR 结果。
非出血性 MI 的 T 在急性期明显高于远隔区域（1.5-T：39.8±12.8%；3.0-T：27.9±16.5%；p<0.0001），但在第 8 周恢复至远隔区域值（1.5-T：-0.0±3.2%；p=0.678；3.0-T：-0.5±5.9%；p=0.601）。在出血性 MI 中，出血核心的 T 在急性期明显升高（1.5-T：17.7±10.0%；3.0-T：8.6±8.2%；p<0.0001），但在第 8 周低于远隔区域值（1.5-T：-8.2±3.9%；3.0-T：-5.6±6.0%；p<0.0001）。相比之下，MI 区域内出血周围的 T 在急性期明显高于远隔区域（1.5-T：35.0±16.1%；3.0-T：24.2±10.4%；p<0.0001），且在 MI 后 8 周仍升高（1.5-T：8.6±5.1%；3.0-T：6.0±3.3%；p<0.0001）。在 MI 出血周围区域观察到的 T 升高和非出血性 MI 中缺乏 T 升高与分别存在或不存在炎症的组织学证据一致。
出血性 MI 与持续的心肌炎症和水肿有关，当单独使用 T 抬高来区分急性和慢性 MI 时，这可能会混淆出血性 MI 的分期。此外，鉴于出血性 MI 患者的预后较差，急性 MI 后存在持续水肿的心肌出血的 CMR 证据可能会作为风险标志物出现。
