Presentations

Abstract

Introduction:

Iron-Dextran is a commonly used form of iron replacement therapy for anemic patients. Iron is superparamagnetic and can therefore cause shortening of T1 and T2 on magnetic resonance imaging (MRI) and blooming on gradient sequences.

Case Information:

The patient is a 71-year-old woman with a past medical history of metastatic leiomyosarcoma and chronic gastrointestinal (GI) bleeding of unknown source, receiving chemotherapy and iron-dextran injections. Two days after an iron-dextran injection, she underwent head MRI for concerns of worsening metastatic disease in the setting of increasing lightheadedness, which revealed diffusely abnormal, hypointense susceptibility weighted imaging signal throughout the supratentorial and infratentorial subarachnoid space and increased signal on precontrast T1 images in the vasculature and nasal mucosa. These unexpected findings were due to IV iron supplementation.

Discussion:

Iron-Dextran is an effective iron-replacement therapy for anemic patients. The iron component of iron-dextran is known to be paramagnetic and can cause shortening of T1 and T2, presenting as increased signal on T1 weighted images.1 Field inhomogeneities from the iron result in quicker dephasing from transverse magnetization and hypointensities on gradient echo. Iron dextran is removed from the plasma by reticuloendothelial macrophages (RES) and is digested into iron and dextran, meaning that duration of iron effect has variation due to deviance of RES and digestive enzymes on a patient-to-patient basis.2 It has been cited that the effects of iron-dextrose on MRI can last anywhere between 7 days and 3 months.2 These effects on MRI are under documented and underrecognized, which can confound image interpretation and lead to delays in diagnosis or even misdiagnosis.1 It is therefore recommended that MRI precede iron infusions when feasible. If not feasible, ensuring that the interpreting radiologist is aware of the recent infusion will help avoid confusion from this confounding variable.

Conclusion:

The limited awareness of the impact of iron-dextran on MRI findings contributes to confusion and image misinterpretation. Limiting the use of iron-dextran in patients who require impending MRI, utilizing alternate forms of imaging when appropriate, and increasing radiologist awareness of iron effects on MRI will all likely improve instance of accurate MRI readings in iron-dependent patients.