Brismar T B, Karlsson M, Li T, Ringertz H
Department of Radiology, Karolinska MR Research Centre, Karolinska Hospital, Box 60 500, S-171 76 Stockholm, Sweden.
Eur Radiol. 1999;9(1):141-4. doi: 10.1007/s003300050645.
The aim of this study was to investigate whether MR imaging of trabecular bone structure using magnetic inhomogeneity measurements is related to the amount of bone mineral in human vertebrae. Weight, bone mineral content (BMCDXA), bone mineral per area (BMADXA) and bone mineral density (BMDCT) were determined in 12 defatted human lumbar vertebrae (L2-L4) by weighing, dual X-ray absorptiometry (DXA) and CT. Inhomogeneity caused by susceptibility differences between trabecular bone and surrounding water was studied with MR imaging at 1.5 T using the GESFIDE sequence. The pulse sequence determines the transverse relaxation rate R2(*) and its two components, the non-reversible transverse relaxation rate (R2) and the reversible transverse relaxation rate (R2'; i. e. relaxation rate due to magnetic susceptibility) in a single scan. Voxel size was 0.9 x 1.9 x 5.0 mm. Positive significant correlations between R2' and weight, BMCDXA, BMADXA and BMDCT were observed (r > 0.61 and p < 0.05 for all). Unexpectedly, R2 was also positively correlated with weight, BMCDXA and BMDCT (r > 0.66 and p < 0.05 for all), but not with BMADXA. Thus, R2' measurements are related to the amount of bone mineral, but they also provide information which is not obtainable from bone mineral measurements.
本研究的目的是调查利用磁不均匀性测量对小梁骨结构进行磁共振成像是否与人体椎骨中的骨矿物质含量相关。通过称重、双能X线吸收法（DXA）和CT对12个脱脂人体腰椎（L2-L4）的重量、骨矿物质含量（BMCDXA）、单位面积骨矿物质（BMADXA）和骨矿物质密度（BMDCT）进行了测定。利用GESFIDE序列在1.5T场强下通过磁共振成像研究了小梁骨与周围水之间的磁化率差异所引起的不均匀性。该脉冲序列在单次扫描中可测定横向弛豫率R2(*)及其两个分量，即不可逆横向弛豫率（R2）和可逆横向弛豫率（R2'；即由磁化率引起的弛豫率）。体素大小为0.9×1.9×5.0mm。观察到R2'与重量、BMCDXA、BMADXA和BMDCT之间存在显著正相关（所有r>0.61且p<0.05）。出乎意料的是，R2也与重量、BMCDXA和BMDCT呈正相关（所有r>0.66且p<0.05），但与BMADXA不相关。因此，R2'测量与骨矿物质含量相关，但它们也提供了从骨矿物质测量中无法获得的信息。
