With the rapid increase of MRI systems in hospitals in China,national multi-sectoral strategies have been put forward to clarify requirements for improving image quality of MRI systems and preventing application risks in clinic.Quality control of MRI systems becomes an important task for regulators as well as hospital radiology departments.The tools used for quality control include imaging performance phantom and specialized function phantom,which can realize detection or calibration for parameters such as high contrast resolution,image uniformity and relaxation time.This article mainly reviews the research progress of the operation principles,common types and clinical applications for these two types of phantoms mentioned above.

Purpose To explore the feasibility and practical value of using National Institute of Metrology(NIM)calorimetry method to measure whole-body specific absorption rate(SAR)values of in-service MRI equipment.Materials and Methods A NIM calorimetry device for measuring whole-body SAR values was developed,SAR values of different MRI devices were measured by NIM calorimetry,and compared with National Electrical Manufacturers Association(NEMA)calorimetry and pulse-energy method to verify the measurement accuracy and applicability of the NIM calorimetry method.Results The NIM calorimetry device developed in this study had reliable performance,and the experimental results indicated the difference in measurement results between NIM calorimetry(1.63 W/kg)and NEMA calorimetry(1.80 W/kg)was within 10%.The difference between the SAR measurement results of multiple MRI devices based on NIM calorimetry(0.46,0.93,0.61 W/kg)and the pulse energy method(0.42,0.89,0.56 W/kg)was within 10%.Conclusion The NIM calorimetry method in this study can accurately measure whole-body SAR values and has applicability.

With the rapid increase of MRI systems in hospitals in China,national multi-sectoral strategies have been put forward to clarify requirements for improving image quality of MRI systems and preventing application risks in clinic.Quality control of MRI systems becomes an important task for regulators as well as hospital radiology departments.The tools used for quality control include imaging performance phantom and specialized function phantom,which can realize detection or calibration for parameters such as high contrast resolution,image uniformity and relaxation time.This article mainly reviews the research progress of the operation principles,common types and clinical applications for these two types of phantoms mentioned above.

Purpose To explore the feasibility and practical value of using National Institute of Metrology(NIM)calorimetry method to measure whole-body specific absorption rate(SAR)values of in-service MRI equipment.Materials and Methods A NIM calorimetry device for measuring whole-body SAR values was developed,SAR values of different MRI devices were measured by NIM calorimetry,and compared with National Electrical Manufacturers Association(NEMA)calorimetry and pulse-energy method to verify the measurement accuracy and applicability of the NIM calorimetry method.Results The NIM calorimetry device developed in this study had reliable performance,and the experimental results indicated the difference in measurement results between NIM calorimetry(1.63 W/kg)and NEMA calorimetry(1.80 W/kg)was within 10%.The difference between the SAR measurement results of multiple MRI devices based on NIM calorimetry(0.46,0.93,0.61 W/kg)and the pulse energy method(0.42,0.89,0.56 W/kg)was within 10%.Conclusion The NIM calorimetry method in this study can accurately measure whole-body SAR values and has applicability.

Background::Heterotaxy (HTX) is a thoracoabdominal organ anomaly syndrome and commonly accompanied by congenital heart disease (CHD). The aim of this study was to analyze rare copy number variations (CNVs) in a HTX/CHD cohort and to examine the potential mechanisms contributing to HTX/CHD.Methods::Chromosome microarray analysis was used to identify rare CNVs in a cohort of 120 unrelated HTX/CHD patients, and available samples from parents were used to confirm the inheritance pattern. Potential candidate genes in CNVs region were prioritized via the DECIPHER database, and PNPLA4 was identified as the leading candidate gene. To validate, we generated PNPLA4-overexpressing human induced pluripotent stem cell lines as well as pnpla4-overexpressing zebrafish model, followed by a series of transcriptomic, biochemical and cellular analyses. Results::Seventeen rare CNVs were identified in 15 of the 120 HTX/CHD patients (12.5%). Xp22.31 duplication was one of the inherited CNVs identified in this HTX/CHD cohort, and PNPLA4 in the Xp22.31 was a candidate gene associated with HTX/CHD. PNPLA4 is expressed in the lateral plate mesoderm, which is known to be critical for left/right embryonic patterning as well as cardiomyocyte differentiation, and in the neural crest cell lineage. Through a series of in vivo and in vitro analyses at the molecular and cellular levels, we revealed that the biological function of PNPLA4 is importantly involved in the primary cilia formation and function via its regulation of energy metabolism and mitochondria-mediated ATP production. Conclusions::Our findings demonstrated a significant association between CNVs and HTX/CHD. Our data strongly suggested that an increased genetic dose of PNPLA4 due to Xp22.31 duplication is a disease-causing risk factor for HTX/CHD.

ObjectiveTo investigate the therapeutic effects of the conditioning regimen with or without total body irradiation on allogeneic hematopoietic stem cell transplantation in acute leukemia.Methods We retrospectively evaluated clinical outcomes in 287 allo-HSCT recipients with acute leukemia (ALL- 105,AML-129,and AUL-53) who received myeloablative conditioning regimen with or without total body irradiation from January 2002 to August 2011.Two hundred and six patients obtained complete remission (CR) and 81 non-remission (NR) before transplantation.One hundred and ninety-nine patients received conditioning with total body irradiation (TBI+ Cy group,9 Gy given over 2 days),and 88 patients received busulfan (BuCy group,3.2 mg·kg-1 ·d-1 ),both followed by cyclophosphamide.ResultsThere were no statistically significant differences in hematopoietic reconstitution,regimen-related toxicity (RRT),graft-versus-host disease (GVHD) and relapse between two groups.For patients with AML and AUL,there was no significant difference in the 5-year survival between the two regimens (P＞ 0.05),while for ALL-CR patients,the TBI + Cy regimen had a higher over survival rate (52.0％ vs.31.3％,LogRank=4.249,P＜0.05) and DFS (50.4％ vs.27.8％,LogRank =4.445,P＜0.05) than BuCy.In TBI + Cy group and BuCy group,the proportion of CD19+ B cells at the first month after HSCT was (4.04 ± 1.86)％ and (1.47 ±0.99) ％ (P＜0.05),that of NK cells at 12th month after HSCT was (23.38 ± 12.19) ％ and (13.11± 7.99) ％ (P＜0.05),and that of CD4+ CD45RO+ cells at 9th month after HSCT was (14.63 ±6.17)％ and (9.07 ± 3.12)％ (P＜0.01),respectively.ConclusionUsing TBI-containing regimen was more effective for treating ALL-CR patients than busulphan-containing regimen,but no difference was found for long-term outcomes in patients with AML and AUL between the two regimens.The 9 Gy TBI-based regimens may not affect recipients' thymic function,T-cells reconstitution and immune tolerance,coming out a non-increase of GVHD.