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T2 relaxation time study of iron overload in b-thalassemia
S I Mavrogeni1, E D Gotsis, V Markussis
1Onassis Cardiac Surgery Center, Athens, Greece. som@aias.net.gr
Insights
Myocardial iron overload in b-thalassemia major patients can be assessed using MRI. The heart/skeletal muscle signal intensity ratio is a sensitive and reliable MRI index for measuring cardiac iron in these patients.
Area of Science:
- Cardiology
- Radiology
- Medical Imaging
Background:
- Myocardial iron deposition is a common complication in patients with b-thalassemia major due to frequent blood transfusions.
- Excess iron in the heart can lead to severe cardiac dysfunction and complications.
- Accurate assessment of myocardial iron levels is crucial for managing these patients.
Purpose of the Study:
- To evaluate the effectiveness of two Magnetic Resonance Imaging (MRI) indices in assessing myocardial iron deposition in adult patients with b-thalassemia major.
- To compare the T2 relaxation time and the heart/skeletal muscle signal intensity ratio as indicators of cardiac iron overload.
Main Methods:
- ECG-gated spin echo MRI images were acquired from 54 adult b-thalassemia major patients and 9 healthy controls using a 1.5 T system.
- T2 relaxation time and heart/skeletal muscle signal intensity ratio were measured.
- Patients were stratified into two groups based on serum ferritin levels (<2000 ng/mL and >2000 ng/mL).
Main Results:
- Heart T2 relaxation time was significantly lower in both patient groups compared to controls (P < 0.001 and P < 0.01).
- The heart/skeletal muscle signal intensity ratio was significantly lower in patients compared to controls (P < 0.001).
- The heart/skeletal muscle signal intensity ratio showed an inverse relationship with serum ferritin levels (r = -0.52, P < 0.01) and was measurable in 94% of patients.
Conclusions:
- The heart/skeletal muscle signal intensity ratio is a sensitive MRI index for assessing myocardial iron overload in b-thalassemia major.
- This ratio offers an advantage over T2 relaxation time due to its higher measurability across different iron concentrations.
Abstract:
Myocardial iron deposition occurs as a result of blood transfusion therapy in b-thalassemia major patients. Since this deposition causes various cardiac complications, it is of interest to assess the iron content of the myocardium in relation to the clinical picture of the patients. Two different MRI indices were used to achieve this purpose: the T2 relaxation time and the heart/skeletal muscle signal intensity ratio. ECG gated spin echo images were obtained from 54 adult thalassemic patients, with a mean age of 26 (18-44) years, at TE = 22 ms and 60 ms, using a 1.5 T system. Patients were divided into 2 groups (A and B), according to their serum ferritin levels (> or < 2000 ng ml(-1)). Results were compared with nine controls, with a mean age of 25 (18-43) years. Heart T2 relaxation time in controls (44.3 +/- 3.5 ms) was higher than in group A (29.9 +/- 5.7 ms, P < 0.001) and group B (33.4 +/- 6.8 ms, P < 0.01). T2 was measurable in 66% of group A and 83% of group B patients. The heart/muscle signal intensity ratio in group A (0.45 +/- 0.27) was lower than in group B (0.82 +/- 0.33, P < 0.001) and the controls (1.15 +/- 0.20, P < 0.001). The heart/muscle signal intensity ratio was measurable in 94% of the patients and demonstrated an inverse relationship with the serum ferritin levels (r = -0.52, P < 0.01). This study indicates that the heart/muscle ratio is a sensitive index of iron overload and it can be measured in the majority of patients, irrespective of tissue iron concentration, thereby offering an advantage over the use of T2 relaxation time.