The Effect of Iron Overload on the Mobilization of Peripheral Blood Hematopoietic Stem Cells in Pediatric Patients with Thalassemia Major.

INTRODUCTION: The purpose of this study was to examine the effect of iron overload on the mobilization of peripheral blood stem cells (PBSCs) in pediatric patients with ß-thalassemia major (TM). METHODS: We retrospectively reviewed the records of 226 patients with TM from whom PBSCs were collected. Iron overload was based on serum ferritin level, and liver and cardiac iron overload was measured by magnetic resonance imaging (MRI) T2*. RESULTS: The mean age of the TM patients was 7.35 ± 3.41 years. Of the patients, only 171 received MRI. Of the 171 patients, 35 had normal liver iron levels, 39 mild liver iron overload, 90 intermediate liver iron overload, and 7 severe liver iron overload. The intermediate + severe group was associated with significantly higher age and BMI and lower leukapheresis product white blood cell count and CD34+ cell levels (all, p < 0.05). CONCLUSION: Leukapheresis indices were similar between patients with different degrees of iron overload according to the ferritin level and cardiac iron overload, in which the later might be due to the small number of patients with cardiac overload. In patients with TM, the intermediate and severe liver iron overload was associated with poorer mobilization of PBSCs.

Optimal region-of-interest MRI R2* measurements for the assessment of hepatic iron content in thalassaemia major.

OBJECTIVES: To evaluate the performance of region-of-interest (ROI)-based MRI R2* measurements by using the first-moment noise-corrected model (M(1)NCM) to correct the non-central Chi noise in magnitude images from phased arrays for hepatic iron content (HIC) assessment. METHODS: R2* values were quantified using the M(1)NCM model. Three approaches were employed to determine the representative R2*: fitting of the ROI-averaged signal (average-then-fit, ATF); outputting the median and mean of R2*s from the pixel-wise fitting of decay signals within the ROI (denoted as PWFmed and PWFmea, respectively). The accuracy and precision of the three approaches were evaluated on synthesized data. The agreement among these approaches and their intra- and inter-observer reproducibility were assessed on 105 thalassaemia major patients. RESULTS: Simulations showed that ATF consistently yielded the highest accuracy and precision at varying noise levels. By contrast, PWFmed and PWFmea slightly and significantly overestimated high R2* at poor signal-to-noise ratios, respectively. Patient study showed that ATF agreed well with PWFmed, whereas PWFmea produced high R2* measurements for patients with severe HIC. No significant difference was observed in the reproducibility of the three approaches. CONCLUSIONS: PWFmea tends to overestimate high R2*, whereas ATF and PWFmed can produce more accurate R2* measurements for HIC assessment.

[Analysis of the risk factors for hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation for beta-thalassemia in children].

OBJECTIVE: To analyze the risk factors of hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation for beta-thalassemia in children. METHODS: The clinical records of 30 children with beta-thalassemia undergoing allogeneic hematopoietic stem cell transplantation between December, 2008 and November, 2009 were analyzed. RESULTS: Hemorrhagic cystitis occurred in 8 of the 33 patients with an incidence of 24.24%, including 1 with grade I, 6 with grade II and 1 with grade III hemorrhagic cystitis. The median time of hemorrhagic cystitis onset was 22.9 days (range 6-35 days) and the median duration was 11.9 days(range 3-27 days). Univariate analysis indicated that the different types of transplantation and acute graft-versus-host disease affect the occurrence of hemorrhagic cystitis. The children with Allo-PBSCT had higher incidence than those receiving Allo-PBSCT+Allo-UBT and Allo-BMT (P<0.05). The children at an age >or=6 years had obviously higher incidence of hemorrhagic cystitis than those at younger ages. CONCLUSION: Age is the major factor that affects the occurrence of hemorrhagic cystitis in children undergoing allogeneic hematopoietic stem cell transplantation for beta-thalassemia.