Observation of a 1H double quantum filtered signal of water in biological tissues.

The observation of a 1H double quantum filtered (DQF) NMR signal of water in bovine sciatic nerve, bovine articular cartilage, rat tail tendon, and rat brain is reported. The origin of this signal in rat tail tendon was found to be a result of residual dipolar interaction between water protons and macromolecular protons. The dependence of the width of the 1H DQF spectra on the orientation indicated that in rat tail tendon the effective director of the residual dipolar interaction is parallel to the collagen fibers. 1H DQF NMR may be applied in imaging where the contrast obtained is related to the degree of order in the tissue.