ORIGINAL COMMUNICATION Dependence of Computed Tomography Volume Measurements Upon Section Thickness: An Application to Human Dry Skulls BUNYAMIN SAHIN, 1 * MICHAEL MAZONAKIS, 2 HUSEYIN AKAN, 3 SULEYMAN KAPLAN, 4 AND YUKSEL BEK 5 1 Department of Anatomy, Medical School, Ondokuz Mayis University, Samsun, Turkey 2 Division of Radiology, Department of Medical Physics, University Hospital of Iraklion, Iraklion, Crete, Greece 3 Department of Radiology, Medical School, Ondokuz Mayis University, Samsun, Turkey 4 Department of Histology and Embryology, Medical School, Ondokuz Mayis University, Samsun, Turkey 5 Department of Biostatistics, Medical School, Ondokuz Mayis University, Samsun, Turkey Estimation of intracranial volume (ICV) using computed tomography (CT) scans has previously been described. However, we were not able to identify a gold standard study that analyzed the effect of section thickness on the esti- mation of ICV. Therefore, we conducted the present study, scanning five dry skulls in the coronal and axial planes using a multislice CT machine (Toshiba TSX-101A, Aquilion 16 Slice, Tochigi, Japan). Consecutive sections of variable thicknesses of 2, 3, 5, 7, and 10 mm, respectively, were used to estimate ICV by means of the planimetry method of the Cavalieri principle. All estimations were done by the same observer. However, the estimated volumes did not concur with the actual volumes of the skulls as determined by the fluid dis- placement technique (P < 0.05). In fact, results revealed that the section thicknesses created over- or under-projection effects for the estimated vol- umes. The results were analyzed to reveal the deviation principles of the esti- mates based on section thickness. Prediction formulas were calculated to esti- mate the deviation percentage of the ICV depending on section thickness and section plane. Ultimately, the results showed that the effect of section thick- ness on ICV estimates could not be overlooked, but that the values obtained could be corrected using the proposed prediction formulas presented in this study. Clin. Anat. 21:479–485, 2008. V V C 2008 Wiley-Liss, Inc. Key words: Cavalieri principle; skull; computed tomography; section thick- ness; intracranial volume INTRODUCTION Noninvasive imaging modalities such as conven- tional radiography, sonography, scintigraphy, spec- tral photon emission computed tomography, com- puted tomography (CT), and magnetic resonance imaging (MRI) have been used extensively for esti- mating the volume of human organs. However, each method has its associated drawbacks. Measurements with simple radiographs are always based on the assumption that the object of interest has a regular geometrical shape. Sonographic assessments often rely on geometric assumptions and are strongly affected by both the acoustic window used and the operator’s experience. Meanwhile, nuclear medicine *Correspondence to: B. Sahin, Department of Anatomy, Medical School, Ondokuz Mayis University, 55139, Samsun, Turkey. E-mail: bsahin@omu.edu.tr Received 27 September 2007; Revised 12 May 2008; Accepted 13 May 2008 Published online 14 July 2008 in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/ca.20664 V V C 2008 Wiley-Liss, Inc. Clinical Anatomy 21:479–485 (2008)