A segmental, multislice, multi-echo T-2* MRI approach could be useful in heart iron-overloaded patients to account for heterogeneous iron distribution, demonstrated by histological studies. However, segmental T-2* assessment in heart can be affected by the presence of geometrical and susceptibility artefacts, which can act on different segments in different ways. The aim of this study was to assess T-2* value distribution in the left ventricle and to develop a correction procedure to compensate for artefactual variations in segmental analysis. MRI was performed in four groups of 22 subjects each: healthy subjects (I), controls (II) (thalassemia intermedia patients without iron overload), thalassemia major patients with mild (III) and heavy (IV) iron overload. Three short-axis views (basal, median, and apical) of the left ventricle were obtained and analyzed using custom-written, previously validated software. The myocardium was automatically segmented into a 16-segment standardized heart model, and the mean T-2* value for each segment was calculated. Punctual distribution of T-2* over the myocardium was assessed, and T-2* inhomogeneity maps for the three slices were obtained. In group I, no significant variation in the mean T-2* among slices was found. T-2* showed a characteristic circumferential variation in all three slices. The effect of susceptibility differences induced by cardiac veins was evident, together with low-scale variations induced by geometrical artefacts. Using the mean segmental deviations as correction factors, an artefact correction map was developed and used to normalize segmental data. The correction procedure was validated on group II. Group IV showed no significant presence of segmental artefacts, confirming the hypothesis that susceptibility artefacts are additive in nature and become negligible for high levels of iron overload. Group III showed a greater variability with respect to normal subjects. The correction map failed to compensate for these variations if both additive and percentage-based corrections were applied. This may reinforce the hypothesis that true inhornogeneity in iron deposition exists. Copyright (c) 2007 John Wiley & Sons, Ltd.
|Autori:||Positano V; Pepe A; Santarelli MF; Scattini B; De Marchi D; Ramazzotti A; Forni G; Borgna-Pignatti C; Lai ME; Midiri M; Maggio A; Lombardi M; Landini L|
|Titolo:||Standardized T-2* map of normal human heart in vivo to correct T-2(*) segmental artefacts RID A-6953-2008|
|Anno del prodotto:||2007|
|Digital Object Identifier (DOI):||10.1002/nbm.1121|
|Appare nelle tipologie:||1.1 Articolo in rivista|