BACKGROUND:Disc functional magnetic resonance imaging studies are mostly carried out under lying and a non-load state, and do not reflect the changes in morphology and function of the upright human body under disc load conditions. Therefore, we need to study characteristics of disc functional magnetic resonance imaging in the upright state. OBJECTIVE: To analyze the effect of axial load on apparent diffusion coefficient and T2 of intervertebral discs. METHODS:The study consisted of 17 patients with low back pain aged 34-65 years. Before and after axial load, T2 weighted MR imaging, T1 weighted MR imaging, diffusion tensor imaging, and T2-mapping imaging of the lumbar spine were performed. Load quality was 40%-50% body weight. At 10 minutes after axial load, another diffusion tensor imaging was performed. After 15-minute load, another T2-mapping sequence was scanned. Diffusion tensor imaging scan parameters: single echo-planar imaging, repetition time 2 500 ms, echo time 89 ms, six diffusion directions, b value of 400 s/mm2, sweep time 4:10 minutes. Raw data of diffusion tensor imaging were used to construct apparent diffusion coefficient map and b0 map. Apparent diffusion coefficient value of intervertebral discs was calculated before and after loading. T2 map was automaticaly constructed using T2-mapping sequence to measure apparent diffusion coefficient and T2 values in the whole intervertebral disc of nucleus pulposus, and the changes of them were analyzed under short-time axial load. RESULTS AND CONCLUSION:Pfirrmann grading results in 17 patients with 85 discs were obtained as folows: 0 in Grade I, 26 in Grade II, 19 in Grade III, 30 in Grade IV, and 10 in Grade V. Al 85 disc T2 relaxation time mapping and 84 disc apparent diffusion coefficient mapping were accepted. Under short-time axial load in 84 discs, apparent diffusion coefficient reduced in the whole disc (reduced 38×10-3 mm2/s,Z=2.567,P < 0.05) and nucleus pulposus (reduced 62×10-3mm2/s,Z=3.461,P < 0.05). Apparent diffusion coefficient changes mainly affected Grade Pfirrmann III discs (reduced 55×10-3mm2/s,Z=2.556,P < 0.05). T2 changes mainly affected normal intervertebral discs (Pfirrmann grade II). Under the load, T2 value of intervertebral discs diminished (reduced 3.17 ms,Z=2.967,P < 0.05). No significant difference in apparent diffusion coefficient and T2 value was detected under the load in other grades of the intervertebral discs (P > 0.05). These results suggest that changes in apparent diffusion coefficient and T2 values were different due to different Pfirrmann grades under short-time axial load. To evaluate magnetic resonance imaging function of intervertebral discs, we should choose different evaluation method according to different degeneration degrees.

Objective:To explore the clinical characteristics of Diamond-Blackfan anemia (DBA) in children caused by RPL5 gene mutation, thus improving the understanding of the etiology of DBA.Methods:The clinical data and sequencing results of a child with DBA caused by RPL5 gene mutation treated in the Children′s Hospital of Fudan University were analyzed.In addition, through literature review of reported DBA cases at domestic and home, summarized the clinical features of DBA.Results:The patient was an 8-year-old male child.Bone marrow puncture examination of the child showed DBA, and a heterozygous mutation of RPL5 gene c. 657C>G, p.Y219X was identified for the first time in the DBA case.A total of 47 cases of DBA were retrieved from the online databases plus the one reported in this study (48 cases in total), and their clinical features were summarized as follows: the incidence of DBA was similar in men and women.The number of DBA patients in Asia was lower than that in Europe and the United States.DBA was mainly a sporadic disease.Among the exon mutations in European and American cases of DBA, 43.0% of them had mutations in Exon3.The malformation rate of DBA patients with RPL5 mutation was 81.3% (39/48 cases, excluding short stature cases), which was higher than that of patients with other mutation types.The response rate of glucocorticoid therapy for DBA was 46.0%, which was lower than that of the overall response rate.Conclusions:chr1: 93303142(c.657 C>G, p.Y219X) is a newly detected mutation of RPL5 gene in the DBA case, which expands the pathogenic gene spectrum of DBA.Patients with RPL5 mutation have higher rates of teratogenicity and multiple teratogenicity, and a lower response rate to hormone therapy.