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Myocardial iron quantification using T2-prepared SSFP parametric images at 3 Tesla

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Journal of Cardiovascular Magnetic Resonance201315 (Suppl 1) :P138

https://doi.org/10.1186/1532-429X-15-S1-P138

  • Published:

Keywords

  • Iron Overload
  • Hemochromatosis
  • Chelate Therapy
  • Diagnostic Image Quality
  • Iron Chelate Therapy

Background

Quantification of myocardial iron overload is critical for the management of patients with hemochromatosis. The effects of excess iron over T2 and T2* relaxation times are well known and both measures strongly correlate with iron concentration. Due to its lower sensitivity to B0 inhomogeneities, T2 has theoretical advantages over T2*, but the latter became the clinical standard as it can be easily obtained in a fast one breath-hold ECG gated multi-echo GRE sequence. T2* is especially challenging at 3T due to greater B0 inhomogeneities at higher field strengths. We aimed to validate a recently developed T2-prepared SSFP sequence that quantifies myocardial T2 times at 3T, compared to standard GRE based multi-echo T2* times at 1.5T.

Methods

A total of 15 normal volunteers and 7 chronic anemia patients (with a myocardial T2* measure <20 ms in the last 2 years, five of these on iron chelating therapy) were prospectively enrolled. Myocardial T2* and T2 times were quantified in the same day, the former using a breath-hold multi-echo GRE sequence at 1.5T (Symphony, Siemens, Erlangen, Germany) and the latter using a recently developed T2 mapping technique based on a breath-hold T2-prepared SSFP sequence at 3T (Verio, Siemens, Erlangen, Germany). All ROIs were placed at mid-interventricular septum, carefully avoiding the blood pool (Figure 1). All analyses were blinded.
Figure 1
Figure 1

T2 map at 3T of a patient with iron overload showing reduced T2 time within the interventricular septum (32.2 ms), in agreement with a significantly reduced T2* time at 1.5T (8.5 ms - not shown).

Results

All patients had regular heart rhythm and all MRI exams showed diagnostic image quality. Volunteers and patients had significantly different mean myocardial T2* (27.2 ms +/- 3.9 vs. 15.4 ms +/- 6.3 p<0.05 respectively) and T2 times (44.9 ms +/- 2.2 vs. 37.9 ms +/- 6.6 p<0.05 respectively). 3T T2 times strongly correlated with 1.5T T2* times (r=0.91 and Figure 2). C-statistic of 3T T2 times for the prediction of a 1.5T T2* <20 ms was 0.97. Using the 3T T2 cut-off of 40 ms and the standard 1.5T T2* of 20 ms, sensitivity and specificity for 3T T2 were 80% and 100% respectively.
Figure 2
Figure 2

Correlation curve between T2 at 3T and T2* at 1.5T. The whole data were best fitted by a quadratic curve with r=0.91. Red lines delimitate true positives (TP), true negatives (TN), false positives (FP) and false negatives (FN) based on a T2 cut-off of 40 ms for the prediction of a T2* < 20 ms.

Conclusions

Our results show that myocardial T2 values obtained with a T2-prepared SSFP parametric sequence can potentially serve as a valuable tool for quantification of iron overload at 3T.

Funding

Internal.

Authors’ Affiliations

(1)
CDPI - Clínica de Diagnóstico por Imagem, Rio de Janeiro, Brazil
(2)
Laboratory of Cardiac Energetics, National Institutes of Health, Bethesda, MD, USA
(3)
Siemens LTDA, São Paulo, Brazil
(4)
Siemens Healthcare, Erlangen, Germany
(5)
Medicine/Cardiology, Johns Hopkins University, Baltimore, MD, USA

Copyright

© Camargo et al; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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