- Oral presentation
- Open Access
Determine the myocardial T2* cut-off value in thalassemia using gaussian mixtures models
© He et al; licensee BioMed Central Ltd. 2012
- Published: 1 February 2012
- Cardiovascular Magnetic Resonance
- Iron Overload
- Gaussian Mixture Model
- Thalassemia Major
Cardiovascular magnetic resonance (CMR) can provide a non-invasive means of measuring the amount of tissue iron. The iron results in shortening of proton relaxation times and both CMR T2* and T2 have been validated as non-invasive means for assessment of myocardial iron overload. (1,2,3,4). We have reported that a T2* value below 20ms represents iron overload in the heart (5). This cut-off value, though proven very useful in clinical practice, was based on 15 normal volunteers in our initial report (5). There is currently little data to confirm this important cut-off value which has been widely accepted for early diagnosis of myocardial iron in patients with thalassemia major (TM).
A mixture model corresponds to the mixture distribution that represents the probability distribution of observations in the overall population. We believe myocardial T2* and T2 data may contain an intrinsic pattern which can be explored for clinical diagnosis. The current study, therefore, aimed at clustering patients automatically into normal and abnormal groups by using Gaussian mixture models (6).
In total 236 TM patients (age 28±20 years old, 119 males) were studied on a 1.5T MRI scanner All patients were scanned using the black blood T2* (3) and T2 (4) sequences, each within a breath-hold. A single mid-ventricular short axis slice was imaged with T2* and T2 measured in the left ventricular septum. The clustering algorithm using Gaussian mixture models was developed in Matlab.
This study confirms that T2* is a reliable tool for screening patients with iron overload. There appears an intrinsic pattern in myocardial T2* and T2 data in patients with thalassemia patients; Gaussian mixture model can automatically cluster the 2-dimensional data and the results agree well with that using a T2* cut-off value of 20ms. There are a few mismatched samples and a further study is needed to clarify and explain this phenomimen in order to provide improved myocardial tissue characterization for patients with TM.
This study was supported by the UK NIHR Cardiovascular Biomedical Research Unit of Royal Brompton Hospital and Imperial College, London. Dr He was supported by Wellcome Trust Value In People (VIP) award and now holds a British Heart Foundation (BHF) Intermediate Basic Science Fellowship (FS/08/26225).
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.