Volumetric determination of normal and scoliotic vertebral bodies

Abstract

IntroductionVertebral growth is a determining factor for the configuration of the spine in health and disease. There are several reports on vertebral growth per se [4,18] and in relation to clinical aspects of idiopathic scoliosis (IS) [19,22], in Scheuermann's disease [6,20] and in relation to the pathomechanism in experimental scoliosis [15]. There are also reports on vertebral growth asymmetry during developement of scoliosis [3,18] and still others vertebral growth after posterior spinal fusion [11,14,17] or after spinal inAbstract A new method is presented for stereological evaluation of the volume of the vertebral body in vivo. The height of the vertebral body is measured at three standardised points on an anteroposterior radiograph and at two other points on a lateral one. The area of the body is also measured using a special grid superimposed on a CT scan from the middle part of the vertebra. The volume of the vertebral body is then calculated using Cavalieri's principle for irregular objects: V = ∆a × H, where V is the volume of the vertebral body, ∆a is the mean cross-section surface area on the CT scan and H is the mean of the heights at the five points on the radiographs, computed as mean weighted circumferential height. The volume of one normal and one scoliotic vertebra was evaluated in vitro using this formula. The obtained values were compared with the values derived from serial CT scans of the two vertebrae. The results showed that the volume of the normal vertebra measured with our new method was 15.9 cm 3 and measured with serial CT scans using the same grid it was 15.07 cm 3 .For the scoliotic vertebra the values were 17.6 and 17.3 cm 3 , respectively. The degree of accuracy of the measurements with the presented method as compared with the serial CT method was 95% for the normal and 98.5% for the scoliotic vertebra. To prove the clinical applicability of the method, the heights of the apical and of the upper and the lower end vertebrae of the curve and the volume of the apical vertebrae were evaluted in eight scoliotic girls (nine curves) before and 3 years after spinal instrumentation and posterior fusion. The results showed that the mean circumferential height of the three vertebrae had increased significantly at the last follow-up. The volume of the apical vertebra had also increased, but the difference was not significant. It is concluded that the described method is easy to apply and has satisfactory accuracy for in vivo longitudinal studies of the volume of the vertebral body on radiographs and CT scans.

Comparison of disc and body volumes in degenerated and nondegenerated lumbar discs: a stereological study

“…The validity of this principle has been proven and applied in previous studies using different scanning techniques (2,(6)(7)(8)(9)(10). This principle allows us to adopt a simple and inexpensive stereological approach that is suited to rapid and accurate volumetric estimation of normal and degenerative vertebral bodies (11).…”

Effect of aging and degeneration on disc volume and shape: A quantitative study in asymptomatic volunteers

“…[19][20][21][22][23][24] A recent study has demonstrated that an edge-tracing method and the Cavalieri method reveal very comparable results but that the latter has the advantage of greater speed and, therefore, efficiency. 19 The point-counting method consists of overlaying, uniformly at random on the section (sagittal image), a transparent film containing a systematic array of test points, and counting the number of occasions on which a grid point lies within the feature.…”

A stereological study of MRI and the Cavalieri principle combined for diagnosis and monitoring of brain tumor volume

“…6,25 The unbiased volume estimate of any structure, which is sliced using radiological techniques, can be obtained easily and efficiently with a simple point-counting approach. 11,[38][39][40][41] Moreover, point counting techniques represent a more reliable and efficient approach than a planimetric technique. 19,20,[42][43][44][45] Results obtained through point counting will be a direct and assumption-free estimate of the total volume of the structure of interest, and hence very valuable in monitoring brain tumors.…”