[Study on identification of a calcium pyrophosphate dihydrate crystal using electron diffraction technique]

Abstract

Electron diffraction technique was used to identify a single crystal in synovial fluid and tissue obtained from patients with pseudogout. One hundred and ten kinds of reciprocal lattice planes of the triclinic calcium pyrophosphate dihydrate (CPPD) crystal were made from its crystallographical data. Electron diffraction patterns obtained from synthesized crystal closely fitted to the reciprocal lattice planes. Synovial fluid of ten patients who had chondrocalcinosis in the knee joint were examined. Diffraction patterns of a single rhomboid-shaped crystal fitted to the reciprocal lattice planes and these kinds of crystals were identified as triclinic CPPD crystals. A single triclinic crystal in the calcified meniscus prepared for transmission electron microscopy was identified in the same way as above. On the other hand, there weren't enough crystallographical data on the monoclinic CPPD crystal to construct the reciprocal lattice planes. Instead of comparing diffraction patterns with the reciprocal lattice planes, diffraction patterns of a single rod-like crystal were compared with those of a synthesized monoclinic CPPD crystal. This comparison combined with energy dispersive elemental analysis made it possible to identify a single rod-like crystal as a monoclinic CPPD crystal.