Application of stereological estimates in patients with severe head injuries using CT and MR scanning images

¹ Research Laboratory for Stereology and Neuroscience, Copenhagen University Hospital Bispebjerg; Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital Glostrup, Denmark
² Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital Glostrup, Denmark
³ Research Laboratory for Stereology and Neuroscience, Copenhagen University Hospital Bispebjerg, Denmark
⁴ Department of Neurophysiology, Copenhagen University Hospital Glostrup, Denmark
⁵ Department of Radiology, Copenhagen University Hospital Glostrup, Denmark
⁶ Radiology, Copenhagen University Hospital Glostrup, Denmark
⁷ Charité University Medicine Berlin, Germany
⁸ King's College Hospital, London, UK
⁹ Department of Neurosurgery, University of Cincinnati, OH, USA

	Abstract

Severe brain damage is often followed by serious complications. Quantitative measurements, such as regional volume and surface area under various conditions, are essential for understanding functional changes in the brain and assessing prognosis. The affected brain tissue in patients suffering from severe brain injury is variable; hence traditional methods used in imaging are not always applicable, and automatic methods may not be able to match the individual observer. Stereological techniques are alternative tools in the quantitative description of biological structures, and have been increasingly applied to the human brain. In the present study, we applied stereological techniques to representative CT and MRI brain scans from five patients to describe how stereological methods, when applied to scans of trauma patients, can provide a useful supplement to the estimation of structural brain changes in head injuries. The reliability of the estimates was tested by obtaining repeated intra- and inter-observer estimates of selected subdivisions of the brain in patients with acute head injury, as well as in an MR phantom. The estimates of different subdivisions showed a coefficient of variation (CV) below 12% in the patients and below 7% for phantom estimation. The validity of phantom estimates was tested by the average deviation from the true geometric values, and was below 10%. The stereological methods were compared to more traditional region-based methods performed on medical imaging, which showed a CV below 7% and bias below 14%. It is concluded that the stereological estimates may be useful tools in head injury quantification.