title: Reduced transverse relaxation rate (RR2) for improved sensitivity in monitoring myocardial iron in thalassemia.
abstract: OBJECTIVE
  To evaluate the reduced transverse relaxation rate (RR2), a new relaxation index which has been shown recently to be primarily sensitive to intracellular ferritin iron, as a means of detecting short-term changes in myocardial storage iron produced by iron-chelating therapy in transfusion-dependent thalassemia patients.
  
  
  METHODS
  A single-breathhold multi-echo fast spin-echo sequence was implemented at 3 Tesla (T) to estimate RR2 by acquiring signal decays with interecho times of 5, 9 and 13 ms. Transfusion-dependent thalassemia patients (N = 8) were examined immediately before suspending iron-chelating therapy for 1 week (Day 0), after a 1-week suspension of chelation (Day 7), and after a 1-week resumption of chelation (Day 14).
  
  
  RESULTS
  The mean percent changes in RR2, R2, and R2* off chelation (between Day 0 and 7) were 11.9 ± 8.9%, 5.4 ± 7.7% and -4.4 ± 25.0%; and, after resuming chelation (between Day 7 and 14), -10.6 ± 13.9%, -8.9 ± 8.0% and -8.5 ± 24.3%, respectively. Significant differences in R2 and RR2 were observed between Day 0 and 7, and between Day 7 and 14, with the greatest proportional changes in RR2. No significant differences in R2* were found.
  
  
  CONCLUSIONS
  These initial results demonstrate that significant differences in RR2 are detectable after a single week of changes in iron-chelating therapy, likely as a result of superior sensitivity to soluble ferritin iron, which is in close equilibrium with the chelatable cytosolic iron pool. RR2 measurement may provide a new means of monitoring the short-term effectiveness of iron-chelating agents in patients with myocardial iron overload.
authors: Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors: Jerry S
authors: JS
authors: Cheung
authors: Wing-Yan
authors: WY
authors: Au
authors: Shau-Yin
authors: SY
authors: Ha
authors: Daniel
authors: D
authors: Kim
authors: Jens H
authors: JH
authors: Jensen
authors: Iris Y
authors: IY
authors: Zhou
authors: Matthew M
authors: MM
authors: Cheung
authors: Yin
authors: Y
authors: Wu
authors: Hua
authors: H
authors: Guo
authors: Pek-Lan
authors: PL
authors: Khong
authors: Truman R
authors: TR
authors: Brown
authors: Gary M
authors: GM
authors: Brittenham
authors: Ed X
authors: EX
authors: Wu
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