Analysis of intensity variability in multislice and cone beam computed tomography. Clin Oral Implants Res

Oral Imaging Center, Faculty of Medicine, K.U. Leuven, Belgium.
Clinical Oral Implants Research (Impact Factor: 3.12). 08/2011; 22(8):873-9. DOI: 10.1111/j.1600-0501.2010.02076.x
Source: PubMed

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.

    • "When it comes to the assessment of bone density, crucial differences exist between MCT and CBCT. The measurements of bone density in CBCT are not easily comparable, because the grey values in CBCT are influenced by different factors, such as the CBCT device, the exposure parameters, and the position of the region of interest within the field of view (Nackaerts et al. 2011). Although attempts have been made to correct for grey value variability, no reliable system has been developed so far. "
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    ABSTRACT: To examine the literature on novel digital imaging techniques for the assessment of outcomes in oral rehabilitation with dental implants. An electronic search of Medline and Embase databases including studies published prior to 28th December 2014 was performed and supplemented by a manual search. A synthesis of the publications was presented describing the use of computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography, optical scanning, spectrophotometry or optical coherence tomography (OCT) related to the outcome measures in implant therapy. Most of the digital imaging techniques have not yet sufficiently been validated to be used for outcome measures in implant dentistry. In clinical research, cone beam CT (CBCT) is increasingly being used for 3D assessment of bone and soft tissue following augmentation procedures and implant placement. Currently, there are no effective methods for the reduction of artifacts around implants in CBCT. Optical scanning is being used for the 3D assessment of changes in the soft tissue contour. The combination of optical scan with pre-operative CBCT allows the determination of the implant position and its spatial relation to anatomical structures. Spectrophotometry is the method most commonly used to objectively assess the color match of reconstructions and peri-implant mucosa to natural dentition and gingiva. New optical imaging techniques may be considered possible approaches for monitoring peri-implant soft tissue health. MRI and ultrasonography appear promising non-ionizing radiation imaging modalities for the assessment of soft tissue and bone defect morphologies. Optical scanners and OCT may represent efficient clinical methods for accurate assessment of the misfit between the reconstructions and the implants. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
    Clinical Oral Implants Research 05/2015; DOI:10.1111/clr.12616 · 3.12 Impact Factor
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    • "Thus, although the measurements is reliable (ICC > 0.97) and validated between two compared systems (r = 0.82), the density measurement using CBCT is less accurate when compared to its gold standard system (MSCT). It should be considered that CBCT density measurement can be effected by scanning parameters and the location of the ROI within the scanner (Nackaerts et al. 2011; Parsa et al. 2013). Using micro-CT as gold standard, the reliability of CBCT in trabecular microstructure assessment has been validated in human mandibles, but BV/TV was not among the assessed microstructural parameters (Ibrahim et al. 2013b). "
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    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; 26. DOI:10.1111/clr.12315 · 3.12 Impact Factor
    • "Dental CBCT has recently been widely used to evaluate alveolar bone density prior to dental implant placement (Arisan et al., 2012; Benavides et al., 2012; Fuster-Torres et al., 2011). Although Nackaerts et al. (2011) contended that the intensity values obtained using dental CBCT were unreliable because they are influenced by the device, the imaging parameters and the positioning of the subject being evaluated, most CBCT models use a flat-panel detector instead of an image intensifier (Nomura et al., 2013) because they have less noise and a wider dynamic range, and hence can improve the image quality (Baba et al., 2004). Nomura et al. (2013) stated that it may be possible to evaluate the BMC from the voxel values of dental CBCT. "
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    ABSTRACT: This study compared the capabilities of micro-computed tomography (micro-CT) and dental cone-beam computed tomography (CBCT) in assessing trabecular bone parameters and cortical bone strength. Micro-CT and CBCT scans were applied to 28 femurs from 14 rats to obtain independent measurements of the volumetric cancellous bone mineral density (vCanBMD) in the femoral head, volumetric cortical bone mineral density (vCtBMD) in the femoral diaphysis, cross-sectional moment of inertia (CSMI), and bone strength index (BSI) (=CSMI×vCtBMD). Five structural parameters of the trabecular bone of the femoral head were calculated from micro-CT images. A three-point bending test was then conducted to measure the fracture load of each femur. Bivariate linear Pearson analysis was conducted to calculate the correlation coefficients (r values) of the micro-CT, dental CBCT, and three-point bending measurements. The statistical analyses showed a strong correlation between vCanBMD values obtained using micro-CT and dental CBCT (r=0.830). There were strong or moderate correlation between vCanBMD measured using dental CBCT and five parameters of trabecular structure measured using micro-CT. Additionally, the results were satisfactory regardless of whether micro-CT or dental CBCT was used to measure the femoral diaphysis vCtBMD (r=0.733 and 0.680, respectively), CSMI (r=0.756 and 0.726, respectively), or BSI (r=0.846 and 0.847, respectively) to predict fracture loads. This study has yielded a new method for using dental CBCT to evaluate bone parameters and bone strength; however, further studies are necessary to validate the use of dental CBCT on humans.
    Journal of Biomechanics 08/2013; 46(15). DOI:10.1016/j.jbiomech.2013.08.004 · 2.50 Impact Factor
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