Chung H W, Wehrli F W, Williams J L, Kugelmass S D, Wehrli S L
MRI/S Laboratory, Academia Sinica, Taipei, Taiwan, R.O.C.
J Bone Miner Res. 1995 May;10(5):803-11. doi: 10.1002/jbmr.5650100518.
A new approach for the quantitative analysis of trabecular microstructure, based on high-field proton nuclear magnetic resonance (NMR) imaging, is presented. NMR is ideal because it provides high contrast between the marrow proton signal and the bone, which appears with background intensity. Images from 1 cm3 defatted specimens of trabecular bone, suspended in water doped with 1 mM Gd(DTPA) to shorten T1 to about 300 ms, can be obtained at a resolution on the order of 30-50 microns and slice thickness of 150 microns, in 10 minutes at 400 MHz proton frequency. Digital image processing algorithms were designed and evaluated for the measurement of bone area fraction, perimeter length, mean trabecular thickness, and separation. Bone area fraction derived from the NMR images was found to be in excellent agreement with bone volume fraction measured independently (slope = 0.96, r2 = 0.924, p < 0.0001). Errors in the mean trabecular thickness and separation were < 6%. The effects of finite imaging slice thickness and signal-to-noise ratio (SNR) were also evaluated. The data suggest a resolution of 50 x 50 x 200 microns 3 and an SNR on the order of 10 to provide safe margins for precise and accurate structural analysis by means of the algorithms presented in this paper. The method allows simultaneous measurement at multiple locations within the specimen volume without the need for physical sectioning.
本文提出了一种基于高场质子核磁共振（NMR）成像的小梁微观结构定量分析新方法。NMR非常理想，因为它能在骨髓质子信号和呈现背景强度的骨骼之间提供高对比度。对于悬浮在掺杂1 mM Gd（DTPA）以将T1缩短至约300 ms的水中的1 cm³脱脂小梁骨标本，在400 MHz质子频率下10分钟内即可获得分辨率约为30 - 50微米、切片厚度为150微米的图像。设计并评估了用于测量骨面积分数、周长、平均小梁厚度和间距的数字图像处理算法。发现从NMR图像得出的骨面积分数与独立测量的骨体积分数高度吻合（斜率 = 0.96，r² = 0.924，p < 0.0001）。平均小梁厚度和间距的误差 < 6%。还评估了有限成像切片厚度和信噪比（SNR）的影响。数据表明，分辨率为50×50×200微米³且SNR约为10时，可为本文提出的算法进行精确准确的结构分析提供安全余量。该方法允许在标本体积内的多个位置同时进行测量，而无需进行物理切片。
