Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Department of Pediatrics, Division of Pediatric Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
J Magn Reson Imaging. 2019 Feb;49(2):466-477. doi: 10.1002/jmri.26213. Epub 2018 Oct 15.
Blood transfusions are administered to children and adults with sickle cell anemia (SCA) for secondary stroke prevention, or as treatment for recurrent pain crises or acute anemia, but transfusion effects on cerebral hemodynamics and metabolism are not well-characterized.
To compare blood transfusion-induced changes in hemometabolic parameters, including oxygen extraction fraction (OEF) and cerebral blood flow (CBF), within and between adults and children with SCA.
Prospective, longitudinal study.
Adults with SCA (n = 16) receiving simple (n = 7) or exchange (n = 9) transfusions and children with SCA (n = 11) receiving exchange transfusions were scanned once when hematocrit was near nadir and again within 7 days of transfusion. Adult controls without SCA or sickle trait (n = 7) were scanned twice on separate days.
FIELD STRENGTH/SEQUENCE: 3.0T T -weighted, T -weighted, and T -relaxation-under-spin-tagging (TRUST) imaging, and phase contrast angiography.
Global OEF was computed as the relative difference between venous oxygenation (from TRUST) and arterial oxygenation (from pulse oximetry). Global CBF was computed as total blood flow to the brain normalized by intracranial tissue volume.
Hemometabolic variables were compared using two-sided Wilcoxon signed-rank tests; associations were analyzed using two-sided Spearman's correlation testing.
In adults with SCA, posttransfusion OEF = 0.38 ± 0.05 was lower (P = 0.001) than pretransfusion OEF = 0.45 ± 0.09. A change in OEF was correlated with increases in hematocrit (P = 0.02; rho = -0.62) and with pretransfusion hematocrit (P = 0.02; rho = 0.65). OEF changes after transfusion were greater (P = 0.002) in adults receiving simple versus exchange transfusions. Posttransfusion CBF = 77.7 ± 26.4 ml/100g/min was not different (P = 0.27) from pretransfusion CBF = 82.3 ± 30.2 ml/100g/min. In children with SCA, both posttransfusion OEF = 0.28 ± 0.04 and CBF = 76.4 ± 26.4 were lower than pretransfusion OEF = 0.36 ± 0.06 (P = 0.004) and CBF = 96.4 ± 16.5 (P = 0.004).
Cerebral OEF reduces following transfusions in adults and children with SCA. CBF reduces following transfusions more often in children compared to adults, indicating that vascular reserve capacity may remain near exhaustion posttransfusion in many adults.
2 Technical Efficacy Stage 5 J. Magn. Reson. Imaging 2019;49:466-477.
镰状细胞贫血（SCA）患儿和成人接受输血治疗，目的是预防二次中风，或治疗复发性疼痛危象或急性贫血，但输血对脑血流动力学和代谢的影响尚未得到很好的描述。
比较 SCA 成人和儿童输血诱导的血液代谢参数变化，包括氧提取分数（OEF）和脑血流量（CBF）。
前瞻性、纵向研究。
接受单纯输血（n=7）或交换输血（n=9）的 SCA 成人患者和接受交换输血的 SCA 儿童患者（n=11），在血球比容接近最低点时进行扫描，输血后 7 天内再次扫描。无 SCA 或镰状细胞特征的成人对照（n=7）在不同的日子进行两次扫描。
磁场强度/序列：3.0T T1-加权、T2-加权和 T2-透过自旋标记（TRUST）成像及相位对比血管造影。
全球 OEF 计算为静脉血氧饱和度（来自 TRUST）与动脉血氧饱和度（来自脉搏血氧仪）之间的相对差异。全球 CBF 计算为脑总血流量除以颅内组织体积。
使用双侧 Wilcoxon 符号秩检验比较血液代谢变量；使用双侧 Spearman 相关检验分析相关性。
SCA 成人患者输血后 OEF=0.38±0.05，低于输血前的 OEF=0.45±0.09（P=0.001）。OEF 的变化与血球比容的增加相关（P=0.02；rho=-0.62），与输血前的血球比容相关（P=0.02；rho=0.65）。与接受单纯输血的患者相比，接受交换输血的患者 OEF 变化更大（P=0.002）。输血后 CBF=77.7±26.4ml/100g/min，与输血前 CBF=82.3±30.2ml/100g/min（P=0.27）无差异。SCA 儿童患者输血后 OEF=0.28±0.04和 CBF=76.4±26.4 均低于输血前的 OEF=0.36±0.06（P=0.004）和 CBF=96.4±16.5（P=0.004）。
SCA 患儿和成人输血后大脑 OEF 降低。与成人相比，儿童输血后 CBF 降低更为常见，这表明许多成人在输血后血管储备能力可能接近耗尽。
2 技术效果阶段 5 J. 磁共振成像 2019；49:466-477.
