Volumetric Measurement of Alveolar Bone Defect in CLP using CBCT

Objectives: Volumetric measurement of alveolar cleft obtained using cone beam CT (CBCT)

Methods: The volume of the alveolar cleft was determined by Micro CT. The skull was then scanned using an i-CAT CBCT scanner (Imaging Sciences International, Hatfield, Pennsylvania, USA) at 0.3mm 3 voxel size. The CBCT volume was then calculated by 3D computational analysis using an algorithm which recognised the boundary of the void or cleft on each slice. From these boundary points discrete tetrahedrons were constructed to constitute the volume. The summation of the volumes of these discrete tetrahedral shapes was used to calculate the volume. These values were compared with the results from the Micro CT. A threshold of 10% for clinical significance was set.

Results: The difference between the volume of the computed volumes from the CBCT images and Micro CT was 9.8%. Conclusions: 3D computational analysis of alveolar clefts using CBCT underestimates the volume by 9.8%.