Computed tomographic (CT) analysis of the internal architectures of lumbar discs in normal subjects using measure set technique
10.3348/jkrs.1984.20.1.152
- Author:
Yong Whee BAHK
;
Jae Mun LEE
- Publication Type:Original Article
- MeSH:
Bias (Epidemiology);
Calibration;
Clothing;
Gelatin;
Tomography, X-Ray Computed;
Water;
Weight-Bearing
- From:Journal of the Korean Radiological Society
1984;20(1):152-157
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
With the availability of accurate localizer and markedly improved resolution of CT, precise anatomicalpositioning of the structure of interest, proper gantry angulation, thin slicing and magnification technique of CTimage can be easily achieved. Recently there have appeared many articles on normal and abnormal CT findings of thelumber discs. These articles, however, were concerned with more or less indirect evaluation of the discs byobserving the contour of the posterior margin of the disc, compression or displacement of the adjacent structuresby protruded disc materials and the obliteration of the epidural fat. The present study has been carried out toinvestigated basically the normal internal architectures of the lumbar discs to set up a baseline by which onewell be able to judge abnormality of that structure. The materials consisted of 127 lumbar discs of 30 healthyadult subjects studied by the measure set technique (MST). The subjects were sampled randomly from the individualsundergoing a CT study for the reasons other than spnal diseases. To obviate sample bias the age, sex and disclevels were adjusted so that the uniformity in sample number of each category was maintained. CT scans wereperformed with a Siemens Somatom 2 Scanner immediately after calibration. Technical factors involved were tubevoltage 125 kVp, exposure time 10 seconds, 460 mAs, 256 x 256 matrices, and pixel size 0.4mm. Contiguous2-mm-thick slices of each disc were obtained parallel to the disc plane at 3-mm interval from the lower margin ofthe vertebral body for 5 lumbar discs. Out of multiple scan slices of each disc one image was chosen which hadneither partial volume effect with the adjacent vertebral body nor an out the nucleus pulposus (NP) and annulusfibrosus (AF) clearly. The internal architectures of each disc as revealed by MST were classified arbitrarily into3 types as follows; (1) When AF was discerned distinctly as a “white ring-like” structure from the “black” NP, thedisc was classified as well defined type: (2) When AF appeared as a fairly uniform “white ring-llike” structureand NP appeared as uniformly mottled densities with indistinct demarcation between the two, the disc was classifedas intermediate type ; and (3) When both AF and NP were diffusely mottled without any demarcation, the disc wasclassifed as diffuse type . With age, the internal architectures of the lumbar disc changed from the well-definedthrough intermediate to diffuse type. The relative increase in the density of NP was considered to representdegenerative change characterized by gradual replacement of the gelatinous tissue of NP by a fibrocartilaginoustissue and decrease in the water therein contained. The diffuse type were most frequently seen in the discs ofL4-5 and L5-S1 suggesting the maximum intensity of stress and strain due to weight bearing at these two disclevels.
