Enhanced renal image contrast by ethanol fixation in phase-contrast X-ray computed tomography

J Synchrotron Radiat. 2014 Jul;21(Pt 4):795-800. doi: 10.1107/S1600577514010558. Epub 2014 Jun 12.

Abstract

Phase-contrast X-ray imaging using a crystal X-ray interferometer can depict the fine structures of biological objects without the use of a contrast agent. To obtain higher image contrast, fixation techniques have been examined with 100% ethanol and the commonly used 10% formalin, since ethanol causes increased density differences against background due to its physical properties and greater dehydration of soft tissue. Histological comparison was also performed. A phase-contrast X-ray system was used, fitted with a two-crystal X-ray interferometer at 35 keV X-ray energy. Fine structures, including cortex, tubules in the medulla, and the vessels of ethanol-fixed kidney could be visualized more clearly than that of formalin-fixed tissues. In the optical microscopic images, shrinkage of soft tissue and decreased luminal space were observed in ethanol-fixed kidney; and this change was significantly shown in the cortex and outer stripe of the outer medulla. The ethanol fixation technique enhances image contrast by approximately 2.7-3.2 times in the cortex and the outer stripe of the outer medulla; the effect of shrinkage and the physical effect of ethanol cause an increment of approximately 78% and 22%, respectively. Thus, the ethanol-fixation technique enables the image contrast to be enhanced in phase-contrast X-ray imaging.

Keywords: crystal X-ray interferometer; ethanol-fixation; kidney; phase shift; phase-contrast X-ray CT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ethanol / chemistry*
  • Fixatives / chemistry
  • Kidney / chemistry
  • Kidney / diagnostic imaging*
  • Male
  • Microscopy, Phase-Contrast / methods*
  • Radiographic Image Enhancement / methods*
  • Rats
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Specimen Handling / methods
  • Tissue Fixation / methods*
  • Tomography, X-Ray Computed / methods*

Substances

  • Fixatives
  • Ethanol