RESUMO
PURPOSE: To assess the performance and results of R(2) relaxometry using a fat-suppressed (FS) multiecho sequence and compare these to conventional R(2) relaxometry in estimating tissue iron overload. MATERIALS AND METHODS: Relaxation rate values (R(2)=1/T2) of the liver, spleen, pancreas and vertebral bone marrow (VBM) were estimated in 21 patients with ß-thalassemia major, using a respiratory-triggered 16-echo Carr-Purcell-Meiboom-Gill (CPMG) spin-echo sequence before (R(2)) and after (R(2) FS) the application of chemically selective fat suppression. RESULTS: Hepatic and splenic R(2) FS values correlated with respective R(2) values (r=0.98 and r=0.96, P<.001), whereas correlations between R(2) FS and R(2) values for pancreas and VBM were not statistically significant. Bland-Altman plots show disagreement between R(2) and R(2) FS values, particularly for pancreas and VBM. Hepatic, pancreatic and VBM R(2) FS values correlated with serum ferritin (r=0.88, P<.001; r=0.51, P<.003; and r=0.75, P<.002, respectively). Hepatic R(2) FS values correlated with splenic R(2) FS (r=0.77, P<.03), pancreatic R(2) FS (r=0.61, P<.006) and VBM R(2) FS values (r=0.70, P<.001), whereas pancreatic R(2) FS values correlated also with VMB R(2) FS values. On the contrary, among the R(2) values of the above tissues, obtained without fat suppression, only hepatic R(2) values correlated with serum ferritin, whereas no correlation was documented between hepatic and pancreatic or VBM R(2) values. The application of fat suppression did not improve breathing or flow artifacts. CONCLUSION: Application of fat suppression in the standard CPMG sequence improved the capability of MRI in noninvasive quantification of iron, particularly in lipid-rich tissues, such as vertebral bone marrow (VBM) and pancreas.
