What is the role of imaging studies in the workup of transfusion-induced iron overload?

Updated: May 07, 2021
  • Author: Geneva E Guarin, MD, MBA; Chief Editor: Emmanuel C Besa, MD  more...
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Computed tomography (CT) scanning has a limited sensitivity (63%) for the assessment of hepatic iron overload. [52] An elevated hepatic CT density associated with an elevated serum ferritin indicates iron overload; however, a normal hepatic CT density does not exclude iron overload. [53] CT scanning is not sensitive when serum ferritin is less than 1000 mcg/L. [54]

Superconducting quantum interference device (SQUID) magnetic measurements of liver iron in patients with iron overload are quantitatively equivalent to biochemical determinations on tissue obtained by biopsy. [55] SQUID can also measure spleen iron content and can be used for monitoring the clinical response to chelation therapy. [56] However, the complexity, cost, and technical demands of the liquid helium–cooled superconducting instruments required at present necessitate restricted clinical access to this method. [57] The latest generation SQUID can be used at room temperature. [58]

Magnetic resonance imaging (MRI) is the noninvasive means of imaging choice and can detect iron deposition in the liver, heart, [59] joints, and pituitary. MRI assessment of myocardial iron loading with the use of gradient echo T2* measurements has reliable reproducibility and has been validated in multiple centers. [60] Quantitative R2* MRI using the transverse magnetic relaxation rate is useful for the measurement of hepatic iron content at facilities with experienced personnel and the proper equipment.58 Liver iron content estimated by MRI was found to be strongly correlated to that measured by liver biopsy in many studies. [61]

MRI is useful to assess pituitary iron overload in patients with transfusional hemochromatosis and secondary hypogonadism by detection of a significant decreased signal intensity of the anterior lobe of the pituitary gland on T2-weighted images. [62] The degree of reduction of the pituitary-to-fat signal intensity ratio correlates with the presence of hypogonadotropic hypogonadism, with a sensitivity of 90%, a specificity of 89%, and an overall accuracy of 89%. [63]

In addition, MRI can be used for the accurate detection of hemochromatosis in the joints of thalassemia patients receiving multiple transfusions. [64] However, iron deposition in the pancreas cannot be reliably predicted by MRI. [65] MRI mapping accurately estimates hepatic iron concentration in patients with transfusion-dependent thalassemia and sickle cell disease. [66] MRI is rapid, noninvasive, and cost effective, and could limit the use of liver biopsy to assess liver iron content. [67]

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