Johnston D L, Rice L, Vick G W, Hedrick T D, Rokey R
Department of Medicine, Baylor College of Medicine, Houston, Texas.
Am J Med. 1989 Jul;87(1):40-7. doi: 10.1016/s0002-9343(89)80481-4.
The ability of stored intracellular iron to enhance magnetic susceptibility forms the basis by which tissue iron can be detected by nuclear magnetic resonance (NMR) imaging. We used this technique to assess myocardial, spleen, and liver iron content in patients with known or suspected iron overload disorders.
Spin echo NMR images were obtained in 30 patients; 20 had chronic anemias treated by multiple blood transfusions, five had idiopathic hemochromatosis, and five had non-hemochromatotic liver disease with elevated serum ferritin levels and no stainable iron on liver biopsy. The acquisition of oblique images through the short axis of the left ventricle permitted assessment of left ventricular function, while demonstrating the liver and spleen on the same image. Iron content was assessed using a signal intensity ratio of organ (spleen, liver, or myocardium) to skeletal muscle.
In patients with multiple blood transfusions, iron content was highest in liver, followed by the spleen. Significant iron overload was detected in the myocardium of only one patient. Left ventricular systolic wall thickening was normal in patients receiving multiple blood transfusions. Two patients with treated idiopathic hemochromatosis had normal signal intensity ratios, and three untreated patients had evidence of significant deposits of iron in the liver and spleen as indicated by a reduction in signal intensity ratios (0.2 +/- 0.01 and 0.9 +/- 0.01, respectively). Five patients with non-hemochromatotic liver disease and high serum ferritin levels had normal signal intensity ratios by NMR imaging.
NMR imaging is a useful method of detecting tissue iron and distinguishing disease due to iron overload. Myocardial iron deposition is a late event, occurring after accumulation of iron in the spleen and liver.
储存的细胞内铁增强磁化率的能力构成了通过核磁共振（NMR）成像检测组织铁的基础。我们使用该技术评估已知或疑似铁过载疾病患者的心肌、脾脏和肝脏铁含量。
对30例患者进行了自旋回波NMR成像；20例为接受多次输血治疗的慢性贫血患者，5例为特发性血色素沉着症患者，5例为非血色素沉着性肝病患者，其血清铁蛋白水平升高，但肝活检未发现可染色铁。通过左心室短轴获取斜位图像可评估左心室功能，同时在同一图像上显示肝脏和脾脏。使用器官（脾脏、肝脏或心肌）与骨骼肌的信号强度比评估铁含量。
在多次输血的患者中，肝脏铁含量最高，其次是脾脏。仅1例患者的心肌检测到明显的铁过载。接受多次输血的患者左心室收缩期室壁增厚正常。2例接受治疗的特发性血色素沉着症患者信号强度比正常，3例未接受治疗的患者肝脏和脾脏有明显铁沉积的证据，表现为信号强度比降低（分别为0.2±0.01和0.9±0.01）。5例非血色素沉着性肝病且血清铁蛋白水平高的患者通过NMR成像信号强度比正常。
NMR成像是检测组织铁并区分铁过载所致疾病的有用方法。心肌铁沉积是晚期事件，发生在铁在脾脏和肝脏蓄积之后。
