Cong Sun1,2, Kiarash Ghassaban3,4, Jiaguang Song5, Yufan Chen1, Chao Zhang1, Feifei Qu6, Jinxia Zhu7, Guangbin Wang8, E Mark Haacke9,10. 1. Department of Radiology, Shandong Provincial Hospital, Shandong University, Jinan, China. 2. Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, People's Republic of China. 3. Department of Radiology, Wayne State University, Detroit, MI, USA. 4. SpinTech MRI Inc., Bingham Farms, MI, USA. 5. Department of Ultrasound, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China. 6. MR Collaboration, Siemens Healthineers Ltd., Shanghai, China. 7. MR Collaboration, Siemens Healthineers Ltd., Beijing, China. 8. Department of Radiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, 324, Jingwu Road, Jinan, 250021, Shandong, China. wgb7932596@hotmail.com. 9. Department of Radiology, Wayne State University, Detroit, MI, USA. nmrimaging@aol.com. 10. SpinTech MRI Inc., Bingham Farms, MI, USA. nmrimaging@aol.com.
Abstract
OBJECTIVES: To evaluate calcium deposition in the fetal spine in vivo during the second and third trimesters using quantitative susceptibility mapping (QSM). METHODS: Fifty-four pregnant women in their second and third trimesters underwent a 2D multi-echo STrategically Acquired Gradient Echo (STAGE) MR imaging protocol at 3T covering the fetal spine. The first echo data was used for QSM processing. A linear regression model was used to assess the correlation between magnetic susceptibility and gestational age (GA). A paired sample t-test was used to compare the consistency of QSM measurements from each sequence. RESULTS: The magnetic susceptibility of the fetal spine decreased linearly with advancing GA, with a slope of -52.3 parts per billion (ppb)/week and a Pearson correlation coefficient (r) of 0.83 (p < 0.001). In 37 subjects for whom the STAGE local QSM data were available from both flip angles, the average magnetic susceptibility values were -1111 ± 278 ppb and -1081 ± 262 ppb for FA = 8° and FA = 40°, respectively. These means were not statistically different according to a paired sample t-test (p = 0.156). CONCLUSIONS: QSM is a reliable technique for evaluating calcium deposition and bone mineral density of fetal vertebrae. Our results demonstrate an increase in fetal calcium levels as a function of GA. These measures might be able to provide reference values for calcium content in the fetal spine during the second and third trimesters. KEY POINTS: • Calcium deposition and mineralization in the fetal spine, evaluated by vertebral magnetic susceptibility, increased with advancing gestational age. • Our results provide reference values for calcium content in the fetal spine during the second and third trimesters.
OBJECTIVES: To evaluate calcium deposition in the fetal spine in vivo during the second and third trimesters using quantitative susceptibility mapping (QSM). METHODS: Fifty-four pregnant women in their second and third trimesters underwent a 2D multi-echo STrategically Acquired Gradient Echo (STAGE) MR imaging protocol at 3T covering the fetal spine. The first echo data was used for QSM processing. A linear regression model was used to assess the correlation between magnetic susceptibility and gestational age (GA). A paired sample t-test was used to compare the consistency of QSM measurements from each sequence. RESULTS: The magnetic susceptibility of the fetal spine decreased linearly with advancing GA, with a slope of -52.3 parts per billion (ppb)/week and a Pearson correlation coefficient (r) of 0.83 (p < 0.001). In 37 subjects for whom the STAGE local QSM data were available from both flip angles, the average magnetic susceptibility values were -1111 ± 278 ppb and -1081 ± 262 ppb for FA = 8° and FA = 40°, respectively. These means were not statistically different according to a paired sample t-test (p = 0.156). CONCLUSIONS: QSM is a reliable technique for evaluating calcium deposition and bone mineral density of fetal vertebrae. Our results demonstrate an increase in fetal calcium levels as a function of GA. These measures might be able to provide reference values for calcium content in the fetal spine during the second and third trimesters. KEY POINTS: • Calcium deposition and mineralization in the fetal spine, evaluated by vertebral magnetic susceptibility, increased with advancing gestational age. • Our results provide reference values for calcium content in the fetal spine during the second and third trimesters.