Purpose
In clinical studies,
bright-blood magnetic resonance imaging (MRI) has been adopted for measuring myocardial T2* and for non-invasive longitudinal assessment of myocardial iron deposition [1].
A region of interest (ROI) of myocardium is drawn on a selected single short-axis image from a series of multi-gradient echo (MGE) acquisitions,
propagated through the series and fitted to a T2* equation to acquire myocardial transverse relaxation time [1].
A single short axis image is also selected in commercial software packages for T2* calculation,
for example the first or...
Methods and Materials
Two observers drew free-hand left ventricle epicard and endocard contours on a single image (method 1) and on a CNR-optimized composite image (method 2) derived from multi gradient echo T2* scans acquired with 8 TEs (2.59 - 18.20 ms,
2.23 ms increment) on 36 slices (7 apical,
29 mid or basal) from 21 patients (9 hematological and 12 suspected of cardiomyopathy).
Time delay of drawing between the two methods was more than one week.
Method 2 images were combinations of those three original images with...
Results
Method 2 showed significantly higher contour similarity between observers than method 1 with DSC value of 0.871 ± 0.016 vs.
0.829 ± 0.034,
P = 0.003.
Method 2 also showed higher segmental T2* reproducibility between observers on the septum than method 1 with narrower limit of agreement (n = 65,
LoA of ± 4.20 vs.
± 4.97),
also in case of myocardial iron accumulation define as T2* < 20ms (n = 7,
± 2.69 vs.
± 3.85) as shown in table 1.
Pearson correlation shows...
Conclusion
Inter-observer consistency on myocardial T2* assessment as a measure of iron deposition is improved using more consistent myocardial contours on images generated by the CNR-optimized composite method.
References
[1] Nilesh R,
et al.
Improved R2* measurements in myocardial iron overload.
J of Magn Reson Imaging 2006; 23:9–16
[2] Meloni A,
et al.
Preferential patterns of myocardial iron overload by multislice multiecho T*2 CMR in thalassemia major patients.
Magn Reson Med 2010; 64(1):211-219
[3] CMRTools : ThalassaemiaTools workflow.
Cardiovascular Imaging Solutions Ltd,
London,
UK. http://www.cmrtools.com/cmrweb/ThalassaemiaToolsWorkflow.htm.
Published 2008.
Accessed July 4,
2013
[4] He T,
et al.
Black-blood T2* technique for myocardial iron measurement in thalassemia.
J Magn Reson Imaging 2007; 25(6):1205-1209.
[5] Petitjean C,...
