Fukuzaki M, Shioya S, Haida M
Department of Communication Engineering, Tokai University Junior College, Tokyo, Japan.
Tokai J Exp Clin Med. 1997 May;22(2):53-7.
The water content of lung, brain, and muscle tissue was measured by nuclear magnetic resonance (NMR) and compared with gravimetric determinations. The NMR signal intensity of water was measured by a single 90 degree pulse and by a spin-echo sequence. The absolute water content was determined by the difference in the sample's weight before and after desiccation. The NMR detectable water in each tissue was expressed as a percentage of the signal intensity for an equal weight of distilled water. Using the single pulse measurement, 67% of the gravimetrically-measured water was detected in collapsed lung samples (consisting of about 47% retained air), in contrast to 96% for brain and 98% for muscle. For degassed lung samples, the NMR detectability of water increased to 87% with the single pulse measurement and to 90% with the spin-echo measurement, but the values remained significantly less than those of brain or muscle. Factors that caused the NMR signal loss of 33% in collapsed lung samples were: air-tissue interfaces (20%), microscopic field inhomogeneity (3%), and a water component with an extremely short magnetization decay time constant (10%).
通过核磁共振（NMR）测量肺、脑和肌肉组织的含水量，并与重量法测定结果进行比较。水的NMR信号强度通过单个90度脉冲和自旋回波序列进行测量。绝对含水量通过干燥前后样品重量的差值来确定。每个组织中NMR可检测到的水以等重量蒸馏水信号强度的百分比表示。使用单脉冲测量时，在塌陷肺样本（约47%为残留空气）中，重量法测量的水中有67%可被检测到，相比之下，脑为96%，肌肉为98%。对于脱气肺样本，单脉冲测量时水的NMR可检测性提高到87%，自旋回波测量时提高到90%，但这些值仍显著低于脑或肌肉的值。导致塌陷肺样本中NMR信号损失33%的因素包括：气-组织界面（20%）、微观场不均匀性（3%）以及具有极短磁化衰减时间常数的水成分（10%）。
