关键词: 重型β-地中海贫血, 铁过载, 核磁共振功能成像, 脑组织T2*, 儿童

Abstract:
Objective
To analyze the application values of nuclear magnetic resonance functional imaging T2* in evaluation of iron overload in brain tissue in patients with severe beta thalassemia.
Methods
Totally 100 cases of patients with severe beta thalassemia receiving long-term high-volume transfusion who accepted treatments and were hospitalized in the Second People's Hospital of Shenzhen City of Department of Pediatrics from January 2009 to September 2016 were included as the observation group, and another 25 cases of healthy subjects who underwent magnetic resonance imaging (T2*) examination were selected as control group. According to serum ferritin level, the observation group were divided into two subgroups: mild group (1.0 to 2.5 g/L) of 57 cases, severe group (>2.5 g/L) of 43 cases. Then, the observation group and the control group underwent magnetic resonance imaging T2* examination, and the T2* values of different parts of brain tissue were compared between the two groups; the levels of T2* and CSF iron metabolism protein in brain tissue of mild group and severe group were compared and analyzed.
Results
The T2* values of different parts of brain tissue in the observation group were significantly lower than those of the control group, the difference being statistically significant (P<0.05). T2* values of different parts of brain tissue in the observation group were (from low to high):globus pallidus<corpora rubrum<lack substance<dorsal caudate putamen<corpora dentatum<caudate nucleus<gray matter<leukoencephalopathy<cerebella. The T2* value of brain tissue, transferrin, ferrous transporter membrane protein 1 and heme oxidase-1 in the severe group were significantly lower those in the mild group(P<0.05),and the ferritin, ceruloplasmin and hepcidin were significantly higher than the mild group(P<0.05).The transferrin, ferrous transporter membrane protein 1, heme oxidase-1 and T2* values showed positive correlation(r=0.309,0.617,0.326，P＜0.05),while the ferritin, ceruloplasmin and hepcidin showed negative correlation with T2*(r=-0.512,-0.474,-0.639，P＜0.05).
Conclusion
The nuclear magnetic resonance imaging T2* technology is helpful to evaluate the iron overload in brain tissue and assess the degree of disease in patients with beta-TM, thus it is worthy of being clinically promoted and applied.

Key words: Severe beta thalassemia, Iron overload, Nuclear magnetic resonance imaging, Brain tissue T2*, Children