Volumetric difference evaluation of registered three-dimensional pre-operative and post-operative CT dental data

Abstract

Objective: The purpose of this study is to propose a complete methodology for automatically registering three-dimensional (3D) pre-operative and post-operative CT scan dental volumes as well as to provide a toolset for quantifying and evaluating their volumetric differences. Methods: The proposed methodology was applied to cone beam CT (CBCT) data from 20 patients in order to assess the volume of augmented bone in the alveolar region. In each case, the pre-operative and post-operative data were registered using a 3D affine-based scheme. The performance of the 3D registration algorithm was evaluated by measuring the average distance between the edges of the registered sets. The differences between the registered sets were assessed through 3D subtraction radiography. The volume of the differences was finally evaluated by defining regions of interest in each slice of the subtracted 3D data and by combining all respective slices to model the desired volume of interest. The effectiveness of the algorithm was verified by applying it to several reference standard-shaped objects with known volumes. Results: Satisfactory alignment was achieved as a low average offset of 1.483 ¡ 1.558 mm was recorded between the edges of the registered sets. Moreover, the estimated volumes closely matched the volumes of the reference objects used for verification, as the recorded volume differences were less than 0.4 mm 3 in all cases. Conclusion: The proposed method allows for automatic registration of 3D CBCT data sets and the volumetric assessment of their differences in particular areas of interest. The proposed approach provides accurate volumetric measurements in three dimensions, requiring minimal user interaction.

Three-dimensional evaluation of the different donor sites of the mandible for autologous bone grafts

“…At the beginning of analysis of the mandible as a donor site for bone grafts, a calliper was used to estimate the bone volume. Meanwhile, the CT technique was used to evaluate bone, because it allows highly accurate volumetric measurements in three dimensions [26,27]. Yavuz et al [13] were the first to evaluate the volume and density of mandibular symphysis bone grafts using threedimensional CT.…”

An automatic panoramic image reconstruction scheme from dental computed tomography images

“…The alignment of medical imaging data allows the use of digital subtraction radiography techniques which can be utilized to automatically highlight possible differences between the compared images. 14 The usefulness of registration is illustrated in Figure 10, where any differences are annotated using red and cyan tones (red corresponds to information present only in the post-operative and cyan to information present exclusively in the pre-operative panoramic image). In particular, Figure 10a shows the fused pre-operative and post-operative panoramic images produced from misaligned CBCT volumes.…”

“…14 The first stage involved an augmentation surgical procedure, using a partial thickness flap design and the insertion of implants where possible. After 9-12 months, re-entry was performed.…”

“…The employed 3D registration scheme included an affine transformation, together with the Downhill Simplex optimization method and the Mattes mutual information metric for aligning the postoperative data according to the spatial characteristics of the pre-operative data. 14 The usefulness of the particular step is further examined in the Discussion section.…”

Detection of Bone Mineral Density Changes by Subtraction of Cone-Beam Computed Tomography Images: A Pilot Study

“…25 and is a suitable option for analysing bone mass, being as feasible as periapical radiographs for the DSR technique. 17,18 Economomopoulos et al 26 presented a method for automatically aligning 3D CBCT dental data sets. This proposed method was able to evaluate volumetric differences between data sets.…”