(PR67) Use of Maximum Intensity and Average Intensity Projection of a User-Defined Region of Interest Around a Root Crack for Enhanced Crack Visualization: a Pilot Study

To explore the use of minimum and averaged intensity projections of a region of interest (ROI) around a suspected root crack or fracture as an adjunct to routine survey of CBCT images.

Methods: Eight extracted anterior teeth with root cracks (n total cracks =11) were imaged by CBCT in empty sockets of a human mandible at 75 micron voxel- resolution (PlanMeca Promax 3D) and by microcomputed tomography as the gold standard (10 micron voxel resolution). Two evaluators manually defined ROIs around suspected cracks in the dentinal wall using the exported Dicom images on a microCT analysis program (CTAn, Bruker-Skyscan). After extension of this region by five slices both a minimum and averaged projections of the ROI on the axial plane were generated. Projections were evaluated for presence of a number of low intensity adjacent voxels using color-rendered pixel intensities at a maximum contrast. Cracks and negative controls were scored as crack present/probably present/absent based on a routine image survey and the minimum and averaged intensity projections.

Results: Designation of three out of seven suspected cracks changed to crack present from probably present when the minimum and averaged intensity projection were added to the routine survey. A falsely identified as probably present crack in a negative control area was also changed to absent.

Conclusions: Sensitivity or specificity in CBCT-based root crack identification of cracks on CBCT images may be improved using minimum and/or averaged intensity projections of a user-defined ROI around a suspected crack.