| Objective:To compare the techniques of several MR sequences,quantifying the iron concentration of organs. Using the optimal magnetic resonance sequence, quantifying iron concentration of the liver, pancreas and myocardium of blood-transfusion-dependent patients. To explore the relationship between clinical parameters and organs' iron concentration. Methods:1. Superparamagnetic iron oxide nanoparticles(SPION) solution was used to establish the iron overload phantoms with different iron concentrations. 3.0T MR multi-echo fast low angled shot(FLASH) and 3D-VIBE-Dixon sequence were used to scan the phantoms. Measure the R2* values of phantoms, recorded for fR2* value(FLASH) and R2* values(3D-VIBE-Dixon). The relationship between fR2* value, R2* value and the actual iron concentration of phantoms was compared. The relationship of fR2* value and R2* value was also evaluated. The accuracy and characteristics of the two iron quantification sequences were analyzed.2. 12 patients with transfusion-dependent diseases, including 10 patients with chronic aplastic anemia(AA) and 2 Myelofibrosis patients(MF) underwent the liver and pancreas MR scan. The MR sequences included multi-echo FLASH, multi-echo 3D-VIBE-Dixon and MRS sequences(For pancreas,the MRS was excluded, for the single-voxel scanning). The correlations between the relative iron concentration using each sequence and the volume of iron intake were analyzed. Compare the different magnetic resonance techniques measuring the liver and pancreas.3. 35 transfusion-dependent patients(including myelodysplastic syndrome(MDS), AA and MF) and 35 healthy volunteers was divided into 4 groups, according to the amount of blood transfusion. They are no blood transfusion group(without any red cell transfusion history in three years, n = 6), a small amount of blood transfusion group(accumulative total blood transfusion 0-20 Units within 3 years, n = 14) and massive blood transfusion group(blood transfusion more than 20 Units within 3 years, n = 15).Using the optimal MR sequence according to part 2, to measure the relative concentration of iron in liver, myocardium and pancreas. Liver, pancreas and myocardium R2* value in different blood groups were compared. The correlation between R2* value of different organs was analyzed. The correlations of multi organs between R2* value and volume of blood transfusion, the correlation between serum ferritin and organ R2* value were analyzed. The relationships between liver, pancreas and heart R2* level and liver function, fasting blood-glucose(FBG), Left ventricular ejection fraction(LVEF) were evaluated to explore the characteristics of iron deposition in multiple organs among transfusion dependent patients.4. Some of the patients with iron adequately chelated for one year were followed up. Liver, pancreas, heart R2* value and SF value changes was compared. To analyze the effects on SF and multi organ iron concentration, after 1 year of iron chelation treatment. Results:1.(1) When concentration of SPION was 0-1.5 mg/ml, fR2* value and R2* value was significantly positive correlated with SPION(r=0.72, P<0.05;r =0.731,P<0.05).(2) The phantoms were divided into low concentration group and high concentration group. In low concentration group, the fR2* and the R2* values were all significantly correlated with the concentration of SPION(r=0.72,P<0.05;r =0.73,P<0.05); In high concentration group, the fR2* value had no significant correlation with the concentration of SPION, but the R2* values were significantly correlated with the concentration of SPION(r=0.51, P=0.09).(3)In low concentration group, fR2* value and R2* values were significantly positive correlation(r = 0.92, P = 0.01); fR2* values and R2 * value were consistency(kappa value of about 0.5, P < 0.05); But In high concentration group, fR2* value and R2* value had no significant correlation(r =-0.29, P > 0.05), kappa=0: two sequences have no consistency.2.(1) Liver fR2* value and transfusion iron intake had moderate positive correlation(r=0.64, P=0.002). Liver R2* values and liver R2 value were significantly correlate with transfusion iron in-take(r = 0.95, 0.97, P = 0.00, 0.00); Correlation between liver R2* value and iron in-take is higher than that of the fR2 * values and iron in-take. The pancreatic fR2* value and transfusion iron in-take had low correlation(r=0.29, P =0.00). The R2* value of pancreas was significantly associated with transfusion iron in-take(r=0.95, P < 0.05). 3D-VIBE-Dixon sequence is the best sequence for measurement of pancreas iron concentration.3.(1) For liver, pancreas, heart R2* values, there were statistically significant differences between the four different iron in-take groups; The R2* value of liver between control group and a small amount of blood transfusion group, normal control group and massive blood transfusion group, patients without transfusion group and a small amount of blood transfusion group, patients without blood transfusion group and massive transfusion group, a small amount of blood transfusion group and massive blood transfusion group, there were significant differences between these groups(P value = 0.00, 0.00, 0.032, 0.00, 0.00); And for the pancreas R2* value, normal control group and a small amount of blood transfusion group, normal control group and massive transfusion group and non-transfusion group and a small amount of blood transfusion group and non-transfusion group and large group, a small amount of blood transfusion and massive blood transfusion group, there were significant difference between these groups(P values= 0.00, 0.00, 0.003, 0.00, 0.00). For myocardium R2* value, between massive blood transfusion group and normal control group, massive blood transfusion group and patients without transfusion group, massive blood transfusion group and a small amount of blood transfusion group have statistical difference(P = 0.003, 0.002);(2) Pancreatic R2 * value and the myocardium R2* value had a significant correlation(r = 0.542, P = 0.017);(3) Liver R2 * values and serum ferritin concentrations were significantly correlated(r = 0.78, P = 0.00). Pancreatic R2* value and serum ferritin were significantly correlated(r=0.668, P=0.005), the myocardium R2* had no correlation with SF.(4) For the liver R2* value>555 s-1 group, direct bilirubin and total bilirubin increased significantly; 100s-1 group, myocardial R2* values, LVEF was significantly decreased.4. After 1 year of iron chelation treatment, 4 patients'(MDS 1 cases, AA 3 cases) mean SF were decreased and there's statistical significance. R2*value of liver and pancreas were decreased, but there was no significant difference.Conclusion:1. MRI can directly and reliably detect the levels of iron deposition in eachOrgans, and it is better than the clinical indicators such as SF.2. Through the comprehensive study of water model, multi-echo 3D-VIBE-Dixon sequence measuring iron concentration of liver and pancreas was more accuracy than that of MRS and multi echo FLASH sequence.3. For transfusion dependent patients, liver was first place that the iron deposited in, pancreas and myocardium are the next.4. After 1 year of the iron chelation therapy, SF can be significantly decreased, but the liver, pancreas and heart iron was not significantly decreased. |
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