Analysis of intensity variability in multislice and cone beam computed tomography.
ABSTRACT The aim of this study was to evaluate the variability of intensity values in cone beam computed tomography (CBCT) imaging compared with multislice computed tomography Hounsfield units (MSCT HU) in order to assess the reliability of density assessments using CBCT images.
A quality control phantom was scanned with an MSCT scanner and five CBCT scanners. In one CBCT scanner, the phantom was scanned repeatedly in the same and in different positions. Images were analyzed using registration to a mathematical model. MSCT images were used as a reference.
Density profiles of MSCT showed stable HU values, whereas in CBCT imaging the intensity values were variable over the profile. Repositioning of the phantom resulted in large fluctuations in intensity values.
The use of intensity values in CBCT images is not reliable, because the values are influenced by device, imaging parameters and positioning.
- SourceAvailable from: Azin Parsa[Show abstract] [Hide abstract]
ABSTRACT: The first purpose of this study was to analyze the correlation between bone volume fraction (BV/TV) and calibrated radiographic bone density Hounsfield units (HU) in human jaws, derived from micro-CT and multislice computed tomography (MSCT), respectively. The second aim was to assess the accuracy of cone beam computed tomography (CBCT) in evaluating trabecular bone density and microstructure using MSCT and micro-CT, respectively, as reference gold standards. Twenty partially edentulous human mandibular cadavers were scanned by three types of CT modalities: MSCT (Philips, Best, the Netherlands), CBCT (3D Accuitomo 170, J Morita, Kyoto, Japan), and micro-CT (SkyScan 1173, Kontich, Belgium). Image analysis was performed using Amira (v4.1, Visage Imaging Inc., Carlsbad, CA, USA), 3Diagnosis (v5.3.1, 3diemme, Cantu, Italy), Geomagic (studio(®) 2012, Morrisville, NC, USA), and CTAn (v1.11, SkyScan). MSCT, CBCT, and micro-CT scans of each mandible were matched to select the exact region of interest (ROI). MSCT HU, micro-CT BV/TV, and CBCT gray value and bone volume fraction of each ROI were derived. Statistical analysis was performed to assess the correlations between corresponding measurement parameters. Strong correlations were observed between CBCT and MSCT density (r = 0.89) and between CBCT and micro-CT BV/TV measurements (r = 0.82). Excellent correlation was observed between MSCT HU and micro-CT BV/TV (r = 0.91). However, significant differences were found between all comparisons pairs (P < 0.001) except for mean measurement between CBCT BV/TV and micro-CT BV/TV (P = 0.147). An excellent correlation exists between bone volume fraction and bone density as assessed on micro-CT and MSCT, respectively. This suggests that bone density measurements could be used to estimate bone microstructural parameters. A strong correlation also was found between CBCT gray values and BV/TV and their gold standards, suggesting the potential of this modality in bone quality assessment at implant site.Clinical Oral Implants Research 12/2013; DOI:10.1111/clr.12315 · 3.12 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: OBJECTIVES: The objective of this study was to investigate the stability of voxel values from cone-beam CT (CBCT) using a flat panel detector in changing surrounding circumstances mimicking clinical situations. MATERIALS AND METHODS: Seven hydroxyapatite (HA) rods (0, 40, 80, 120, 160, 199, and 239 mg Ca/cm(3) ) were set in a 16 cm diameter water phantom and scanned with CBCT (FineCube) and also with multislice CT (MSCT) used as reference. The voxel values from CBCT were measured by the obtained images with OsiriX software (http://www.osirix-viewer.com), and compared with the CT numbers from MSCT. We examined the correlation between the voxel values and the HA contents, the variance of voxel values, and the influence of changing surrounding circumstances on the voxel values. RESULTS: The voxel values from CBCT were different from the CT numbers from MSCT, but there was a linear Pearson correlation between the voxel values and the HA contents. The voxel values were greatly influenced when the samples were scanned surrounded in air. However, the voxel values were not affected significantly in the existence of materials simulating oral hard tissues and/or a metal core post. CONCLUSIONS: There was a linear correlation between the voxel values of CBCT and the contents of HA rod samples. Our study indicated that it might be possible to evaluate bone mineral content(BMC) from the voxel values of CBCT for dental implant treatment.Clinical Oral Implants Research 02/2012; DOI:10.1111/j.1600-0501.2012.02420.x · 3.12 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The purpose of this study was to evaluate preoperative CT-derived bone densities in Hounsfield units (HU) at implant sites that acquired primary stability, and to compare these values to the optimal bone densities proposed in the literature. Fifty-one patients, 18 males (37 implant sites) and 33 females (67 implant sites) between 2003 and 2010 were assessed. CT data for different jaw sections, regions, and operating procedures were compared using the Kruskal-Wallis test and Scheffe's test for multiple comparisons (P < 0.05). The mean bone density in the maxilla was significantly lower than that in the mandible (P < 0.05); the mean bone densities in the 4 jaw regions decreased in the following order: anterior mandible > anterior maxilla > posterior mandible > posterior maxilla. The bone densities assessed by HU fell into the range of optimal bone densities associated with acquired primary implant stability proposed in the literature.11/2011; 2011:678729. DOI:10.5402/2011/678729