Influence of CBCT enhancement filters on diagnosis of vertical root fractures: a simulation study in endodontically treated teeth with and without intracanal posts

Objectives:

To evaluate the influence of CBCT enhancement filters on the diagnosis of vertical root fractures (VRFs) in teeth with and without metal posts.

Methods:

The crowns of 40 uniradicular human teeth were removed and all roots were prepared. 20 teeth were randomly selected, and VRFs were induced using a universal testing machine. The i-CAT (Imaging Sciences International, Hatfield, PA) CBCT was used to scan teeth with and without intracanal metal posts using the following parameters: 0.2 voxel size, 8 × 8-cm scan size and acquisition time of 26.9 s. Images were evaluated by three observers with and without the use of the following filters: S9, smooth, smooth 3 × 3, sharpen, sharpen-mild and sharpen 3 × 3.

Results:

Intra- and interobserver agreement ranged from poor to moderate. Images with and without CBCT filters did not show significant differences regarding the area under the receiver operating characteristic curve, as well as sensitivity (p > 0.05). As for accuracy, the sharpen-mild filter was superior to the sharpen (p = 0.03), but these filters did not differ from all others. For specificity, S9, smooth and original images were superior to sharpen (p < 0.01). Results for teeth without posts differed from those for teeth with metal posts in all cases (p < 0.05).

Conclusions:

The use of enhancement filters in CBCT images has no influence on the diagnosis of VRFs in teeth with metal posts, and their use is not justified.     

Influence of scan setting selections on root canal visibility with cone beam CT

Objectives

The aim of this study was to assess the influence of scan setting selection, including field of view (FOV) ranging from small to large, number of projections and scan modes on the visibility of the root canal with cone beam CT (CBCT).

Methods

One human mandible cadaver was scanned with CBCT (Accuitomo 170; J Morita MPG Corp., Kyoto, Japan) using six different FOVs (4×4 cm, 6×6 cm, 8×8 cm, 10×10 cm, 14×10 cm and 17×12 cm) with either 360 or 180 projections in standard and high resolution. The right canine was selected for evaluation. Ten observers independently assessed the visibility of the canal space and overall image quality on a five-point scale.

Results

The results indicate that both selections of FOV and number of projections have significant influence on root canal visibility (p = 0.0001), whereas scan mode, whether standard or high resolution, was less relevant (p = 0.34).

Conclusions

The smallest FOV available should always be used for endodontic applications, and it is not recommended to reduce the number of projections to 180. Using the standard scan mode instead of high resolution does not negatively influence the visibility of the root canal space and is therefore recommended.     

Assessment of vertical root fractures using three imaging modalities: cone beam CT, intraoral digital radiography and film

Objectives

The aim of this study was to assess the accuracy of cone beam CT (CBCT) in detecting vertical root fractures and to compare the accuracy with images from an intraoral sensor and from conventional intraoral film.

Methods

60 extracted, single-rooted human teeth were divided equally into two groups: a control group of 30 teeth and an induced fracture group of 30 teeth. All teeth were randomly placed into sockets in six dry mandibles. Each tooth was imaged by three modalities: CBCT, intraoral digital radiography and intraoral F-speed film. Three beam angulations (an orthogonal projection and additional projections with ±20° horizontal shifts of the central ray) were used when radiographs were made using film and a digital sensor. Three oral and maxillofacial radiologists evaluated the presence of root fractures twice in each image modality using a five-point confidence rating scale. Areas under receiver operating characteristic curves (A_z) were computed for each observer and modality and were tested for statistical differences using the Kruskal–Wallis test.

Results

There was no statistical difference in the performance of the three modalities (mean of A_z values: CBCT = 0.811, film = 0.797 and sensor = 0.775; p = 0.771).

Conclusions

There was no significant difference between intraoral film, a high-resolution complementary metal oxide semiconductor digital imaging system and CBCT in detecting vertical root fractures in mandibular single-rooted teeth.     

Intracranial physiological calcifications evaluated with cone beam CT

Objectives

The purpose of this study was to evaluate cone beam CT (CBCT) scans for the presence of physiological and pathological intracranial calcifications.

Methods

CBCT scans from male and female patients that met our ascertainment criteria were evaluated retrospectively (n = 500) for the presence of either physiological or pathological intracranial calcifications.

Results

Out of the 500 patients evaluated, 176 had evidence of intracranial physiological calcification (35.2% prevalence), and none had evidence of pathological calcification. There was a 3:2 male-to-female ratio and no ethnic predilection; the ages of affected patients ranged from 13 years to 82 years with a mean age of 52 years. The majority of calcifications appeared in the pineal/habenular region (80%), with some also appearing in the choroid plexus region bilaterally (12%), and a smaller subset appearing in the petroclinoid ligament region bilaterally (8%).

Conclusions

Intracranial physiological calcifications can be a common finding on CBCT scans, whereas pathological intracranial calcifications are rare.     

Effective doses from cone beam CT investigation of the jaws

Objectives

The purpose of the study was to calculate the effective dose delivered to the patient undergoing cone beam (CB) CT of the jaws and maxillofacial complex using the i-CAT Next Generation CBCT scanner (Imaging Sciences International, Hatfield, PA).

Methods

A RANDO® phantom (The Phantom Laboratory, Salem, NY) containing thermoluminence dosemeters were scanned 10 times for each of the 6 imaging protocols. Effective doses for each protocol were calculated using the 1990 and approved 2007 International Commission on Radiological Protection (ICRP) recommended tissue weighting factors (E1990, E2007).

Results

The effective dose for E1990 and E2007, respectively, were: full field of view (FOV) of the head, 47 μSv and 78 μSv; 13 cm scan of the jaws, 44 μSv and 77 μSv; 6 cm standard mandible, 35 μSv and 58 μSv; 6 cm high resolution mandible, 69 μSv and 113 μSv; 6 cm standard maxilla, 18 μSv and 32 μSv; and 6 cm high resolution maxilla, 35 μSv and 60 μSv.

Conclusions

Using the new generation of CBCT scanner, the effective dose is lower than the original generation machine for a similar FOV using the ICRP 2007 tissue weighting factors.     

Evaluation of a cone beam CT artefact reduction algorithm

Objectives

An algorithm and software to reduce metal artefact has been developed recently and is available in the Picasso Master 3D® (VATECH, Hwaseong, Republic of Korea), which under visual assessment produces better quality images than were obtainable previously. The objective of this in vitro study was to investigate whether the metal artefact reduction (MAR) algorithm of the Picasso Master 3D machine reduced the incidence of metal artefacts and increased the contrast-to-noise ratio (CNR) while maintaining the same gray value when there was no metallic body present within the scanned volume.

Methods

20 scans with a range of 50–90 kVp were acquired, of which 10 had a metallic bead inserted within a phantom. The images obtained were analysed using public domain software (ImageJ; NIH Image, Bethesda, MD). Area histograms were used to evaluate the mean gray level variation of the epoxy resin-based substitute (ERBS) block and a control area. The CNR was calculated.

Results

The MAR algorithm increased the CNR when the metallic bead was present; it enhanced the ERBS gray level independently of the presence of the metallic bead. The image quality also improved as peak tube potential was increased.

Conclusion

Improved quality of images and regaining of the control gray values of a phantom were achieved when the MAR algorithm was used in the presence of a metallic bead.     

Ex vivo comparison of Galileos cone beam CT and intraoral radiographs in detecting occlusal caries

Objective

The aim of this study was to compare the accuracy of cone beam CT (CBCT) with intraoral radiographs for detection of occlusal caries.

Methods

A set of 60 extracted teeth were imaged using a Sirona Galileos CBCT system (Sirona Dental Systems, Bensheim, Germany) and an intraoral Planmeca® system (Planmeca OY, Helsinki, Finland). Six observers looked at both modalities and used a five-point confidence scale to evaluate presence or absence of occlusal caries. Histology was used as the gold standard. Receiver operating characteristic analysis and weighted kappa statistics were used for statistical analysis. Differences in the area under the curve (AUC) values between observers and modalities were analysed using analysis of variance (ANOVA). Differences in sensitivity and specificity were analysed using the Wilcoxon test. Interobserver and intraobserver reliability was assessed by weighted kappa scores.

Results

The mean value and standard deviation of AUC was 0.719 ± 0.038 for CBCT and 0.649 ± 0.062 for the intraoral radiographs. The ANOVA results demonstrated that there was no significant difference between the modalities and the observers. The interobserver kappa for pairs of observers ranged from fair to substantial for bitewings (0.244–0.543) and CBCT (0.152–0.401). Four out of six observers reported higher sensitivity but lower specificity with CBCT. The Wilcoxon exact p-value showed no difference in sensitivity (0.175) or specificity (0.573) between the two modalities.

Conclusion

Based on the results we conclude that the Sirona CBCT unit cannot be used for the sole purpose of looking at occlusal caries.     

Influence of the artefact reduction algorithm of Picasso Trio CBCT system on the diagnosis of vertical root fractures in teeth with metal posts

Objectives:

To assess the influence of the artefact reduction algorithm (AR) available on the Picasso Trio 3D^® imaging system (Vatech, Hwaseong, Republic of Korea) on image quality [greyscale values, contrast-to-noise ratio (CNR) and artefact formation] and diagnosis of vertical root fractures (VRFs) in the teeth with intracanal metal posts.

Methods:

30 uniradicular teeth had their crowns removed and their roots endodontically treated to receive intracanal metal posts. In 20 teeth, both complete (n = 10) and incomplete (n = 10) VRFs were created. Each tooth was scanned twice, with and without AR activation. The mean and variation of greyscale values, as well as CNR, were calculated for all images. Subsequently, an evaluator compared the amount of artefact (cupping, white streaks and dark bands) in all images. Five evaluators rated for VRF presence using a five-point scale.

Results:

Mean greyscale values and CNR were significantly decreased in images acquired with the AR. The usage of the algorithm promoted an overall reduction of image artefacts. Regarding the diagnosis of complete and incomplete VRFs, the use of the AR had an overall negative impact on specificity and accuracy.

Conclusions:

While indeed reducing artefact formation, the use of the AR, instead of improving the impact on the diagnosis of VRFs in teeth with intracanal metal posts, had a negative impact on the diagnosis.     

Evaluation of juxta-apical radiolucency in cone beam CT images

Objectives:

The aim of this study was to analyse the position and relationship of juxta-apical radiolucency (JAR) to the mandibular canal and buccal and/or lingual cortical plates using cone beam CT (CBCT).

Methods:

A retrospective study was carried out to analyse the JAR on CBCT for 27 patients. These findings were compared with 27 age- and sex-matched patients without the presence of JAR, which acted as the control group. The CBCT images were analysed according to a checklist, to evaluate the position of the JAR and its relationship to the mandibular canal. Then, any thinning or perforation of either the buccal or lingual cortical plate due to JAR was noted, and a classification to quantify the thinning of cortical plates was proposed. The findings in the two groups were analysed using a paired comparison by McNemar test.

Results:

A statistical increased thinning of cortical plates was seen in the JAR group compared with the control group, and most of the cases were in the J3 group. None of the patients in either the JAR or the control group showed perforation of the buccal and/or lingual cortical plate on CBCT images.

Conclusions:

A classification to quantify the thinning of cortical plates was proposed, which may be used for objective evaluation of the thinning of the cortical plates in future studies. The present study gives an insight into the relationship of the juxta-apical area with the mandibular canal and cortical plates in the mandible using CBCT.     

Dental cone beam CT image quality possibly reduced by patient movement

Patient artefacts in dental cone beam CT scans can happen for various reasons. These range from artefacts from metal restorations to movement. An audit was carried out in the Glasgow Dental Hospital analysing how many scans showed signs of “motion artefact”, and then to assess if there was any correlation between patient age and movement artefacts. Specific age demographics were then analysed to see if these cohorts were at a higher risk of “movement artefacts”.     

Three-dimensional segmentation of the upper airway using cone beam CT: a systematic review

The objectives of this study were to systematically review the literature for studies that used cone beam CT (CBCT) to automatically or semi-automatically model the upper airway (including the pharyngeal, nasal and paranasal airways), and to assess their validity and reliability. Several electronic databases (MEDLINE®, MEDLINE In-Process & Other Non-Indexed Citations, all evidence-based medicine reviews including the Cochrane database, and Scopus) were searched. Abstracts that appeared to meet the initial selection criteria were selected by consensus. The original articles were then retrieved and their references were searched manually for potentially suitable articles that were missed during the electronic search. Final articles that met all the selection criteria were evaluated using a customized evaluation checklist. 16 articles were finally selected. From these, five scored more than 50% based on their methodology. Although eight articles reported the reliability of the airway model generated, only three used intraclass correlation (ICC). Two articles tested the accuracy/validity of airway models against the gold standard, manual segmentation, using volumetric measurements; however, neither used ICC. Only three articles properly tested the reliability of the three-dimensional (3D) upper airway model generated from CBCT and only one article had sufficiently sound methodology to test the airway model''s accuracy/validity. The literature lacks proper scientific justification of a solid and optimized CBCT protocol for airway imaging. Owing to the limited number of adequate studies, it is difficult to generate a strong conclusion regarding the current validity and reliability of CBCT-generated 3D models.     

Metal artefact reduction with cone beam CT: an in vitro study

Background

Metal in a patient''s mouth has been shown to cause artefacts that can interfere with the diagnostic quality of cone beam CT. Recently, a manufacturer has made an algorithm and software available which reduces metal streak artefact (Picasso Master 3D® machine; Vatech, Hwaseong, Republic of Korea).

Objectives

The purpose of this investigation was to determine whether or not the metal artefact reduction algorithm was effective and enhanced the contrast-to-noise ratio.

Methods

A phantom was constructed incorporating three metallic beads and three epoxy resin-based bone substitutes to simulate bone next to metal. The phantom was placed in the centre of the field of view and at the periphery. 10 data sets were acquired at 50–90 kVp. The images obtained were analysed using a public domain software ImageJ (NIH Image, Bethesda, MD). Profile lines were used to evaluate grey level changes and area histograms were used to evaluate contrast. The contrast-to-noise ratio was calculated.

Results

The metal artefact reduction option reduced grey value variation and increased the contrast-to-noise ratio. The grey value varied least when the phantom was in the middle of the volume and the metal artefact reduction was activated. The image quality improved as the peak kilovoltage increased.

Conclusion

Better images of a phantom were obtained when the metal artefact reduction algorithm was used.     

Radiological examination of the articular eminence morphology using cone beam CT

Objective

The purpose of the present study was to investigate the articular eminence inclination and height according to age and gender in patients with temporomandibular joint (TMJ) dysfunction and healthy controls using cone beam CT (CBCT).

Methods

The measurements were performed on CBCT records of 52 TMJ dysfunction patients (11 males and 41 females) and 41 control patients (17 males and 24 females). The eminence inclination and height were measured on the CBCT images.

Results

The eminence inclination and height values were higher in males than in females in both TMJ dysfunction patient and control groups; however, these differences were not statistically significant (p>0.05). While no statistically significant differences were found in the eminence inclination and height values between the age groups (p>0.05) in the TMJ dysfunction patient group, there were statistically significant differences in the control group. The eminence inclination was highest between the ages of 21 and 30 years and showed a decrease after the age of 30 years. Additionally, the eminence inclinations of the control patients were statistically higher than those of the TMJ dysfunction patients.

Conclusion

There were no statistically significant differences in eminence inclination and height according to gender. The eminence inclination reaches its highest value between the ages of 21 and 30 years and shows a decrease after the age of 31 years in healthy patients. The eminence inclination was steeper in healthy control patients than in patients with TMJ dysfunction.     

Small field of view cone beam CT temporomandibular joint imaging dosimetry

Objectives:

Cone beam CT (CBCT) is generally accepted as the imaging modality of choice for visualisation of the osseous structures of the temporomandibular joint (TMJ). The purpose of this study was to compare the radiation dose of a protocol for CBCT TMJ imaging using a large field of view Hitachi CB MercuRay™ unit (Hitachi Medical Systems, Tokyo, Japan) with an alternative approach that utilizes two CBCT acquisitions of the right and left TMJs using the Kodak 9000^® 3D system (Carestream, Rochester, NY).

Methods:

25 optically stimulated luminescence dosemeters were placed in various locations of an anthropomorphic RANDO^® Man phantom (Alderson Research Laboratories, Stanford, CT). Dosimetric measurements were performed for each technique, and effective doses were calculated using the 2007 International Commission on Radiological Protection tissue weighting factor recommendations for all protocols.

Results:

The radiation effective dose for the CB MercuRay technique was 223.6 ± 1.1 μSv compared with 9.7 ± 0.1 μSv (child), 13.5 ± 0.9 μSv (adolescent/small adult) and 20.5 ± 1.3 μSv (adult) for the bilateral Kodak acquisitions.

Conclusions:

Acquisitions of individual right and left TMJ volumes using the Kodak 9000 3D CBCT imaging system resulted in a more than ten-fold reduction in the effective dose compared with the larger single field acquisition with the Hitachi CB MercuRay. This decrease is made even more significant when lower tube potential and tube current settings are used.     

Accuracy assessment of the axial images obtained from cone beam computed tomography

Objective

The aim of this study was to evaluate accuracy of linear measurements assessed from axial tomograms and the influence of the use of different protocols in two cone beam CT (CBCT) units.

Methods

A cylinder object consisting of Nylon® (Day Brazil, Sao Paulo, Brazil) with radiopaque markers was radiographically examined applying different protocols from NewTom 3G^TM (Quantitative Radiology s.r.l, Verona, Veneto, Italy) and i-CAT^TM (Imaging Sciences International, Hatfield, PA) units. Horizontal (A–B) and vertical (C–D) distances were assessed from axial tomograms and measured using a digital calliper that provided the gold standard for actual values.

Results

There were differences when considering acquisition protocols to each CBCT unit. Concerning all analysed protocols from i-CAT^TM and Newtom 3G^TM, both A–B and C–D distances presented underestimated values. Measurements of the axial images obtained from NewTom 3G^TM (6 inch 0.16 mm and 9 inch 0.25 mm) were similar to the ones obtained from i-CAT^TM (13 cm 20 s 0.3 mm, 13 cm 20 s 0.4 mm and 13 cm 40 s 0.25 mm).

Conclusion

The use of different protocols from CBCT machines influences linear measurements assessed from axial images. Linear distances were underestimated in both equipments. Our findings suggest that the best protocol for the i-CAT^TM is 13 cm 20 s 0.3 mm and for the NewTom 3G^TM, the use of 6 inch or 9 inch is recommended.     

The effect of cone beam CT (CBCT) on therapeutic decision-making in endodontics

Objectives:

The aim was to assess to what extent cone beam CT (CBCT) used in accordance with current European Commission guidelines in a normal clinical setting has an impact on therapeutic decisions in a population referred for endodontic problems.

Methods:

The study includes data of consecutively examined patients collected from October 2011 to December 2012. From 2 different endodontic specialist clinics, 57 patients were referred for a CBCT examination using criteria in accordance with current European guidelines. The CBCT examinations were performed using similar equipment and standardized among clinics. After a thorough clinical examination, but before CBCT, the examiner made a preliminary therapy plan which was recorded. After the CBCT examination, the same examiner made a new therapy plan. Therapy plans both before and after the CBCT examination were plotted for 53 patients and 81 teeth. As four patients had incomplete protocols, they were not included in the final analysis.

Results:

4% of the patients referred to endodontic clinics during the study period were examined with CBCT. The most frequent reason for referral to CBCT examination was to differentiate pathology from normal anatomy, this was the case in 24 patients (45% of the cases). The primary outcome was therapy plan changes that could be attributed to CBCT examination. There were changes in 28 patients (53%).

Conclusions:

CBCT has a significant impact on therapeutic decision efficacy in endodontics when used in concordance with the current European Commission guidelines.     

The importance of cone beam CT in the radiological detection of osteomalacia

Although osteomalacia is one of the most common osteometabolic diseases among the elderly, there is no case in the literature that presents the effects of osteomalacia in detail using cone beam CT (CBCT). While thin and porous bones are the most common radiographic sign of the disease, the radiological hallmarks are pseudofractures (Looser's zone). We coincidentally detected osteomalacia in a 23-year-old female and we showed the pseudofracture on CBCT images. In the present case, we aim to present the images of osteomalacia that were detected by CBCT in detail. CBCT has an important value in screening for osteomalacia.     

Comparative diagnostic yield of cone beam CT reconstruction using various software programs on the detection of vertical root fractures

Objectives:

To evaluate the effect on diagnostic yield in the detection of experimentally induced vertical root fractures on cone beam CT images using four dental software program.

Methods:

190 single-rooted extracted human teeth were divided into three groups according to the pulp canal status: unrestored (UR), filled with gutta-percha (GP) and restored with a metallic custom post (Post). One-half of the sample of each group was artificially fractured and the segments repositioned. All teeth were scanned on a cone beam CT device at 0.2 mm nominal voxel resolution (i-CAT Platinum; Imaging Sciences International, Hatfield, PA). The data were exported as digital imaging and communications in medicine files and imported into Dolphin Imaging & Management Solutions, v. 11.5 (Patterson Dental Supply Inc., St Paul, MN), InVivoDental, v. 5.0 (Anatomage Inc., San Jose, CA) and Kodak Dental Imaging Software 3D module, v. 2.1.11 (Carestream Health Inc., Rochester, NY) software. Cross-sectional images in the acquisition (using Xoran CAT™, v. 3.0.34 software; Xoran Technologies, Ann Arbor, MI) and additional software were presented to three calibrated oral radiologists who rated the presence or absence of root fracture on a five-point scale. Receiver operating characteristic analysis was performed, and treatment comparisons compared by analysis of variance and pairwise comparisons were performed using Tukey''s test at an a priori value of α < 0.05%.

Results:

All dental software performed equally at detecting fractures. Fractures were significantly more difficult to detect when posts were present.

Conclusions:

The diagnosis of root fracture is software-independent. The presence of an intracanal metallic post significantly decreases the detection of artificially created root fractures.     

Optimization of exposure parameters for cone beam computed tomography sialography

Objectives

The assessment of image quality is a crucial step in the development of a new imaging protocol. Having proposed and reported on a preliminary protocol for sialography using cone beam CT (CBCT), the purpose of this study was to further optimize this protocol by maximizing the image signal difference-to-noise ratio (SDNR) and to relate these new data to previously published dosimetric data for CBCT sialography.

Methods

An imaging phantom was constructed using samples with different concentrations of iodine and a water-immersed mandible. The CB MercuRay (Hitachi Medical Systems, Tokyo, Japan) was used to image the phantom using different peak kilovoltage (kVp) and milliamperage (mA) settings. SDNR was then calculated using the raw images based on mean pixel values (MPV) measured in selected regions of interest (ROI). Finally, a figure of merit (FOM) was calculated to examine the trade-off between image SDNR and effective radiation dose.

Results

The SDNR demonstrated an expected increase as the kVp increased from 60 to 120. Also, images made with the higher mA setting (15) had greater SDNR. The iodine concentration also influenced the image quality such that SDNR increased with increased amounts of iodine. The calculated FOM was greatest for the technique using 80 kVp, with equivalent results for 10 mA and 15 mA.

Conclusion

An optimized protocol for CBCT sialography using CB MercuRay entails a 6 inch field of view with 80 kVp and 10 mA.