Utility of the computed tomography indices on cone beam computed tomography images in the diagnosis of osteoporosis in women

Abstract

Purpose: This study evaluated the potential use of the computed tomography indices (CTI) on cone beam CT (CBCT) images for an assessment of the bone mineral density (BMD) in postmenopausal osteoporotic women.

Materials and methods: Twenty-one postmenopausal osteoporotic women and 21 postmenopausal healthy women were enrolled as the subjects. The BMD of the lumbar vertebrae and femur were calculated by dual energy X-ray absorptiometry (DXA) using a DXA scanner. The CBCT images were obtained from the unilateral mental foramen region using a PSR-9000N™ Dental CT system. The axial, sagittal, and coronal images were reconstructed from the block images using OnDemend3D™. The new term "CTI" on CBCT images was proposed. The relationship between the CT measurements and BMDs were assessed and the intra-observer agreement was determined.

Results: There were significant differences between the normal and osteoporotic groups in the computed tomography mandibular index superior (CTI(S)), computed tomography mandibular index inferior (CTI(I)), and computed tomography cortical index (CTCI). On the other hand, there was no difference between the groups in the computed tomography mental index (CTMI: inferior cortical width).

Conclusion: CTI(S), CTI(I), and CTCI on the CBCT images can be used to assess the osteoporotic women.

Keywords: Bone Density; Cone-Beam Computed Tomography; Osteoporosis.

Fig. 1

A. On the axial image, an antero-posterior tangent line "x" is drawn, and line "y" and "z" are drawn perpendicular to line "x" through the center of the mental foramen, then these lines become perpendicular mutually. B. On the coronal image, line "x" is moved to line "x°", the bisecting position of the bucco-lingual dimension of the mandibular body. C. On the sagittal image, line "z" is moved to line "z°", parallel position with the mandibular inferior border of the mandible, then line "y" corresponds with line "y°", perpendicular line "z°" at the same time.

Fig. 2

A. Distance "S" from the superior margin of the mental foramen to the inferior border of the mandible is measured on coronal image. B. Distance "I" is measured from the inferior margin of the mental foramen to the inferior border of the mandible. C. Inferior cortical width (W) of the mandible is measured.

Fig. 3

The types of the inferior mandibular cortex are subjectively classified as follows. A. Type 1: the cortical endosteal margin appears even and regular. B. Type 2: the endosteal margin appears semilunar defects or 1 to 2 layers of cortical endosteal residues. C. Type 3: the cortical layer has numerous (>3) endosteal residues and is clearly porous.