Distribution of cardiac iron measured by magnetic resonance imaging (MRI)-R*2

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Hematology

Background:

• Iron overload diseases, such as β-thalassemia major, lead to dangerous iron accumulation in the heart.
• Accurate assessment of cardiac iron is crucial for predicting and preventing heart failure.
• Magnetic resonance imaging (MRI) R(2)* is a promising technique for quantifying tissue iron concentration.

Purpose of the Study:

• To evaluate the regional distribution of cardiac iron using MRI-R(2)* in patients with iron overload conditions.
• To determine the most reliable region within the heart for MRI-R(2)* measurements to assess iron overload.

Main Methods:

• Breathhold electrocardiogram (ECG)-gated 1.5 T MRI was performed on 32 patients (11-79 years) with iron overload.
• Transverse relaxation rates (R(2)*) were measured in specific cardiac wall quadrants (septal, anterior, lateral, posterior).
• Region of interest (ROI)-based signal intensities were analyzed across 12 echo times (TE).

Main Results:

• Significant correlations in R(2)* values were observed between the septal quadrant and all other quadrants.
• In patients with normal R(2)* (< 50 s(-1)), other quadrants showed significantly higher normalized median rates (126%-174%) than the septum.
• Boundary effects from surrounding tissues and organs complicated the separation of segmental iron distribution.

Conclusions:

• Measuring MRI-R(2)* in the interventricular septum is the most robust method for detecting cardiac iron overload.
• Septal R(2)* measurements are least affected by boundary artifacts, improving the detection of patients at risk of heart failure.