Computer Assisted Determination of Mandibular Cystic Lesion Volume from Computed Tomographic Data Tamer M. Nassef Computer and Programming Engineering Dept. Misr University for Science and Technology, MUST 6 th of October City, Egypt tamer.nassef@k-space.org Reham M. Fliefel, Mona K. Marei Tissue Engineering Lab. Alexandria University Alexandria, Egypt Nahed H. Solouma National Institute of Laser Science Cairo University Giza, Egypt Yasser M. Kadah Biomedical Engineering Dept. Cairo University Giza, Egypt Abstract— In this paper, a new approach for computing different anatomical regions in dental Computed Tomography (CT) is presented. The approach consists of two steps. First, a HU threshold window sets to separate between different regions upon their gray-level values; second, a set of objects are generated and texture descriptors are calculated for selected windows from the image data sample. Finally, identification of different anatomical regions set for mandible bones to determine the cystic lesion volume based on numerical methods. Preliminary results obtained for dental CT of female patient aged 14 years old complaining of bilateral swelling in her mandible are presented. Keywords-cyctic lesion; tissue engineering; 3D reconstruction; mandible bone simulation; computed tomography I. INTRODUCTION The term ‘cyst’ is derived from the Greek word ‘kystis’ meaning sac or bladder [1]. A cyst may be found in the bone or soft tissue, with an outer wall of connective tissue and an inner wall composed of epithelium most commonly stratified squamous epithelium [2]. Odontogenic cysts are the most common form of cystic lesions that affect the maxillofacial region [3], by definition, these are cysts (i.e. pathological cavities with fluid or semi-fluid contents but excluding pus) with an epithelial lining that derives from the tooth forming organ epithelia, the so-called glands of Serres (rests of the dental lamina), the rests of Malassez (rests of the root sheath of Hertwig) and the reduced enamel epithelium (remnants of the enamel organ after dental crown formation) – although for odontogenic keratocysts it has also been proposed that the lining may derive from mucosal basal cells. In terms of their incidence, radicular cysts are the commonest (mostly associated to teeth with pulp necrosis due to advanced dental caries), followed by dentigerous and odontogenic keratocysts (OKs) [4]. Separate to epithelial-lined cysts, some cystic lesions do not have epithelial linings including mucous extravasation cyst of the salivary glands, the aneurysmal bone cyst and the solitary bone cyst. Despite these examples, most pathologists prefer to describe those pathological cavities not lined by epithelium as ‘pseudocysts’ [5]. Reichart and Philipsen describe these as ‘cavities’ rather than cysts; hence, for example, ‘aneurysmal bone cavity’ [6]. Classifications of cysts are constructed by selecting certain features which are common to a number of conditions and grouping them together on the basis of their shared properties. Either clinical features, histological appearances, concepts of embryological development or the tissue of origin may form the basis of classification or indeed combinations of these considerations [7]. The main factors responsible for cyst development include (in varying degree) [8], proliferation of the epithelial lining and connective tissue capsule, accumulation of fluid within the cyst, and resorption of the surrounding bone and incomplete compensatory repair. The importance of the correct diagnosis of odontogenic cysts is that some variants, i.e., dentigerous cysts, odontogenic keratocysts, and botroid cysts are aggressive lesions, and it is necessary to distinguish them clinically, radiographically and microscopically from other tumors (such as ameloblastoma and myxoma) so that correct surgical treatment is applied and adequate follow-up instituted [9], It is well known the importance of X-ray diagnostic for the surgical treatment of mandibular cysts. The clinical practice shows that the conventional X-ray methods (extra-oral and intra-oral) ensure enough information concerning removal of the cyst when they are single and small in size. Oblique projections of the left and right mandible, orthopan-tomography and occlusal radiographs for the cortical plates would give precise information for the cyst and its relationship with the surrounding bone and structures. 978-1-4244-7000-6/11/$26.00 ©2011 IEEE