Determine the myocardial T2* cut-off value in thalassemia using gaussian mixtures models

Background 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).