Dentin Thickness of Pulp Chamber Floor in Primary Molars: Evaluation by Cone-Beam Computed Tomography

ABSTRACT Objective: Use cone-beam computed tomography (CBCT) images to evaluate the dentin thickness of the pulp chamber floor in primary molars. Material and Methods: Cross-sectional study, conducted with CBCT images of teeth of children. Primary molars with preserved pulp chamber floor were included. The dentin thickness of the pulp chamber floor in the primary molars was measured linearly in CBCT cross-sections. Data were descriptively analyzed and the Mann-Whitney test was applied (p<0.05). Results: 27 CBCT exams and 123 primary molars of children aged 4 to 13 years were analyzed; the majority was female (52.0%). In maxillary molars, the median dentin thickness was 1.50 (0.6-2.2) mm in the first and 1.65 (0.6-2.3) mm in the second (p=0.049) molars. In mandibular molars, the median was 1.20 (0.3-1.7) mm in the first and 1.60 (1.0-2.2) mm in the second (p<0.001) molars. Children aged 4 to 8 years showed less dentin thickness (p<0.001). Conclusion: The median dentin thickness of the pulp chamber floor in primary molars was 1.50 mm, ranging from 0.3 to 2.3 mm. Less dentin thickness was associated with younger children, teeth in the mandibular arch, and first molars.

Assessment of Endoscopic Healing by Using Advanced Technologies Reflects Histological Healing in Ulcerative Colitis.

BACKGROUND: Several studies have reported that ulcerative colitis [UC] patients with endoscopic mucosal healing may still have histological inflammation. We investigated the relationship between mucosal healing defined by modified PICaSSO [Paddington International Virtual ChromoendoScopy ScOre], Mayo Endoscopic Score [MES] and probe-based confocal laser endomicroscopy [pCLE] with histological indices in UC. METHODS: A prospective study enrolling 82 UC patients [male 66%] was conducted. High-definition colonoscopy was performed to evaluate the activity of the disease with MES assessed with High-Definition MES [HD-MES] and modified PICaSSO and targeted biopsies were taken; pCLE was then performed. Receiver operating characteristic [ROC] curves were plotted to determine the best thresholds for modified PICaSSO and pCLE scores that predicted histological healing according to the Robarts Histopathology Index [RHI] and ECAP 'Extension, Chronicity, Activity, Plus' histology score. RESULTS: A modified PICaSSO of ≤ 4 predicted histological healing at RHI ≤ 3, with sensitivity, specificity, accuracy and area under the ROC curve [AUROC] of 89.8%, 95.7%, 91.5% and 95.9% respectively. The sensitivity, specificity, accuracy and AUROC of HD-MES to predict histological healing by RHI were 81.4%, 95.7%, 85.4% and 92.1%, respectively. A pCLE ≤ 10 predicted histological healing with sensitivity of 94.9%, specificity of 91.3%, accuracy of 93.9% and AUROC of 96.5%. An ECAP of ≤ 10 was predicted by modified PICaSSO ≤ 4 with accuracy of 91.5% and AUROC of 95.9%. CONCLUSION: Histological healing by RHI and ECAP is accurately predicted by HD-MES and modified virtual electronic chromoendoscopy PICaSSO, endoscopic score; and the use of pCLE did not improve the accuracy any further.

Immersive Virtual Colonoscopy.

Virtual colonoscopy (VC) is a non-invasive screening tool for colorectal polyps which employs volume visualization of a colon model reconstructed from a CT scan of the patient's abdomen. We present an immersive analytics system for VC which enhances and improves the traditional desktop VC through the use of VR technologies. Our system, using a head-mounted display (HMD), includes all of the standard VC features, such as the volume rendered endoluminal fly-through, measurement tool, bookmark modes, electronic biopsy, and slice views. The use of VR immersion, stereo, and wider field of view and field of regard has a positive effect on polyp search and analysis tasks in our immersive VC system, a volumetric-based immersive analytics application. Navigation includes enhanced automatic speed and direction controls, based on the user's head orientation, in conjunction with physical navigation for exploration of local proximity. In order to accommodate the resolution and frame rate requirements for HMDs, new rendering techniques have been developed, including mesh-assisted volume raycasting and a novel lighting paradigm. Feedback and further suggestions from expert radiologists show the promise of our system for immersive analysis for VC and encourage new avenues for exploring the use of VR in visualization systems for medical diagnosis.

Virtual Computed Tomography Colonography: Evaluation of 2D and Virtual 3D Image Quality of Sub-mSv Examinations Enabled by Third-generation Dual Source Scanner Featuring Tin Filtering.

RATIONALE AND OBJECTIVES: To evaluate two- and three-dimensional (2D and 3D) image quality of sub-milliSievert (mSv) computed tomography (CT) colonography utilizing a third-generation dual source CT scanner featuring a tin filter. METHODS: We retrospectively evaluated 26 consecutive patients who underwent third-generation dual source CT colonography, nine with the standard-dose clinical-scan protocol (SDP) and 17 with a low-dose protocol (LDP) featuring a tin filter. Radiation dose was evaluated by volume computed tomography dose index (CTDIvol), dose length product (DLP), effective dose (E), and size-specific dose estimate. Objective image quality was evaluated utilizing signal-to-noise ratio (SNR) derived from standardized placed regions of interest on the transverse 2D images and the ratio of SNR/CTDIvol (normalized SNR). Two radiologists in consensus assessed subjective image quality of the virtual 3D images. RESULTS: There were no significant differences in subjective image quality (P = .661). All examinations were rated "excellent" or "good" for diagnostic confidence. The mean total for DLP/E was 143.4 ± 29.8 mGy/3.00 ± 0.40 mSv in the SDP and therefore significantly higher than in the LDP with 36.9 ± 8.7 mGy/0.75 ± 0.16 mSv (P < .001). The SNR was 8.9 ± 2.1 in the SDP and 4.9 ± 0.8 in the LDP. CONCLUSIONS: Third-generation dual source CT featuring a tin filter enables consistent sub-mSv colonography without substantially impairing image quality.

Reducing the Radiation Dose for CT Colonography: Effect of Low Tube Voltage and Iterative Reconstruction.

RATIONALE AND OBJECTIVES: The purpose of this study was to assess the effect of a low-tube-voltage technique and iterative reconstruction (IR) on the radiation dose and image quality of computed tomography colonography (CTC). MATERIALS AND METHODS: We studied 30 patients (14 women and 16 men; mean age, 64.5 ± 13.1 years; range, 39-90 years) with colorectal cancer referred for surgical treatment. All underwent CTC with fecal tagging under a standard 120-kVp protocol in the supine position and a 100-kVp protocol in the prone position. The 120-kVp images were reconstructed with filtered back projection (FBP). The 100-kVp images were postprocessed using FBP and a hybrid type of IR (adaptive iterative dose reduction 3D). The effective radiation dose (ED), image noise, and contrast-to-noise ratio (CNR) were compared among the three protocols. The visual image quality was scored on a four-point scale. RESULTS: The mean ED was significantly lower under the 100-kVp protocol than the 120-kVp protocol, resulting in a 27% radiation dose decrease (3.5 ± 2.0 vs 2.5 ± 1.5 mSv; P < .01). Image noise decreased by 48%, and the mean attenuation of tagged fluid increased from 452 to 558 HU on images acquired at 100 kVp with IR compared to that in the 120-kVp protocol; these differences were significant. The mean CNR was significantly higher under the 100 kVp with IR than the other two protocols. We found no significant differences in the visual scores for diagnostic utility between the 100 kVp with IR and the 120 kVp with FBP protocol (P = .10). CONCLUSIONS: Low-tube-voltage CTC reduced the radiation dose by approximately 27% while maintaining the image quality.

History, evolution, and current status of radiologic imaging tests for colorectal cancer screening.

Colorectal cancer screening is thought to be an effective tool with which to reduce the mortality from colorectal cancer through early detection and removal of colonic adenomas and early colon cancers. In this article, we review the history, evolution, and current status of imaging tests of the colon-including single-contrast barium enema, double-contrast barium enema, computed tomographic (CT) colonography, and magnetic resonance (MR) colonography-for colorectal cancer screening. Despite its documented value in the detection of colonic polyps, the double-contrast barium enema has largely disappeared as a screening test because it is widely perceived as a labor-intensive, time-consuming, and technically demanding procedure. In the past decade, the barium enema has been supplanted by CT colonography as the major imaging test in colorectal cancer screening in the United States, with MR colonography emerging as another viable option in Europe. Although MR colonography does not require ionizing radiation, the radiation dose for CT colonography has decreased substantially, and regular screening with this technique has a high benefit-to-risk ratio. In recent years, CT colonography has been validated as an effective tool for use in colorectal cancer screening that is increasingly being disseminated.

Reducing image noise in computed tomography (CT) colonography: effect of an integrated circuit CT detector.

OBJECTIVE: To investigate whether the integrated circuit (IC) detector results in reduced noise in computed tomography (CT) colonography (CTC). METHODS: Three hundred sixty-six consecutive patients underwent clinically indicated CTC using the same CT scanner system, except for a difference in CT detectors (IC or conventional). Image noise, patient size, and scanner radiation output (volume CT dose index) were quantitatively compared between patient cohorts using each detector system, with separate comparisons for the abdomen and pelvis. RESULTS: For the abdomen and pelvis, despite significantly larger patient sizes in the IC detector cohort (both P < 0.001), image noise was significantly lower (both P < 0.001), whereas volume CT dose index was unchanged (both P > 0.18). Based on the observed image noise reduction, radiation dose could alternatively be reduced by approximately 20% to result in similar levels of image noise. CONCLUSION: Computed tomography colonography images acquired using the IC detector had significantly lower noise than images acquired using the conventional detector. This noise reduction can permit further radiation dose reduction in CTC.

3D Reconstruction of virtual colon structures from colonoscopy images.

This paper presents the first fully automated reconstruction technique of 3D virtual colon segments from individual colonoscopy images. It is the basis of new software applications that may offer great benefits for improving quality of care for colonoscopy patients. For example, a 3D map of the areas inspected and uninspected during colonoscopy can be shown on request of the endoscopist during the procedure. The endoscopist may revisit the suggested uninspected areas to reduce the chance of missing polyps that reside in these areas. The percentage of the colon surface seen by the endoscopist can be used as a coarse objective indicator of the quality of the procedure. The derived virtual colon models can be stored for post-procedure training of new endoscopists to teach navigation techniques that result in a higher level of procedure quality. Our technique does not require a prior CT scan of the colon or any global positioning device. Our experiments on endoscopy images of an Olympus synthetic colon model reveal encouraging results with small average reconstruction errors (4.1 mm for the fold depths and 12.1 mm for the fold circumferences).

Plataforma colaborativa multimídia para apoio ao diagnóstico de lesões bucais em ambientes de teleodontologia / Collaborative multimedia platform to support oral diagnosis in teledentistry environments

Este artigo tem por objetivo apresentar uma solução tecnológica desenvolvida para permitir atividades colaborativas de diagnóstico de lesões bucais em ambientes de Teleodontologia. Trata-se de uma plataforma totalmente baseada na web e que permite o gerenciamento e compartilhamento de imagens clínicas, radiográficas e histopatológicas, dispensando a instalação de qualquer programa adicional no computador do usuário. Como suporte à colaboração através do navegador, as ações efetuadas por um usuário são replicadas e visíveis ao outro usuário conectado, sendo possível a discussão e troca de informações sobre o caso através de chat e/ou áudiovideoconferência. Ferramentas de Telessaúde podem ofereçe diferentes oportunidades para assistência e educação em Odontologia. Ao permitir a visualização de diferentes aspectos da doença do paciente, a solução aqui apresentada tem potencial para viabilizar: (1) a troca de informações entre profissionais de saúde atuantes em distintos níveis de assistência e (2) a tutoria, à distância, nos diferentes níveis de formação (graduação, pós-graduação e educação continuada) (AU).

This paper presents a technological solution developed to enabling collaborative activities in Teledentistry environments. This is a platform composed by a set of tools for the management and sharing of clinical, radio graphic and histopathologic images. The proposed solution is fully web-based, requiring only a web browser installed; it's not necessary to install any other software on the user's computer. As collaboration support, the actions performed by a user with mouse and keyboard are replicated and visible to the other connected user. This toolkit allows the discussion of disease via chat and/or videoconferen ing. Telehealth's tools offer opportunities for assistance and education in Dentistry. By allowing realtime viewing and discussion of different aspects of a disease this technological solution has potential to facilitate: (1) exchange of information between health professionals at different levels of assistance and (2) distance tutoring at different levels of training (undergraduate, postgraduate and continuing education) (AU).

Predicting polyp location on optical colonoscopy from CT colonography by minimal-energy curve modeling of the colonoscope path.

The ability to accurately locate a polyp found on computed tomographic colonography (CTC) at subsequent optical colonoscopy (OC) is an important task in colorectal cancer screening. We present a method to more accurately match polyp locations at CTC and OC. A colonoscope was modeled as a flexible tube with negligible stretch and minimal strain. The path of the colonoscope was estimated using a minimal-energy curve method. The energy function was defined and optimized by a subdivision scheme. The prediction of polyp locations at OC from CTC was converted to an optimization problem. The prediction performance was evaluated on 134 polyps by comparing the predicted with the true polyp locations at OC. The method can accurately predict polyp locations at OC to within ±0.5 colonoscope mark (5 cm) for more than 58% of polyps and to within ±1 colonoscope mark (10 cm) for more than 96% of polyps, significantly improving upon previously published methods. This method can be easily incorporated into routine OC practice and allow the colonoscopist to begin the examination by targeting locations of potential polyps found at CTC.

Flexible sigmoidoscopy does not significantly increase polyp and cancer detection yield when used to supplement CT colonography.

BACKGROUND AND AIMS: Flexible sigmoidoscopy (FS) increases polyp and carcinoma detection in addition to double contrast barium enema (DCBE). However, CT colonography (CTC) is now the preferred technique. Our aim was to explore whether FS increases polyp and carcinoma detection rates when used in addition to CTC. METHODS: Patients who underwent FS and CTC between 2007 and 2009 were included and data were collected from patient records. Yields of polyp, adenoma and carcinoma detection were calculated for FS and CTC. RESULTS: In a cohort of 294 patients, CTC detected 36 patients with carcinomas while FS detected 28. One rectal cancer not seen on CTC was diagnosed by FS. Polyps were seen by CTC in 66 and FS in 45 patients. In 5 patients FS found polyps that were not detected by CTC; 3 of which were small adenomas. FS detected extra adenomas or carcinomas in 1.36% (4/294). Adding FS to CTC neither increased the cancer nor the polyp detection yield significantly. CONCLUSIONS: This first study investigating the use of FS in addition to CTC detected little additional pathology. The routine use of FS as a supplement to CTC for adenoma and carcinoma detection is of questionable utility.

[A virtual visualization system for colon polyp inspection].

The virtual colonoscopy, virtual flattening and virtual splitting method are enhanced by the GPGPU model. The novel virtual eversion method is integrated for fast polyp detection. The experimental result showed that the system and various visualization methods can represent the colon inner-surface clearly and exactly, supporting real-time man-machine interaction. The proposed system is promising in human gastrointestinal cancer and polyp inspection.

Clinical aspects of MR colonography as a diagnostic tool.

Since first described in 1997, MR colonography (MRC) has since been labelled as a promising new, non-invasive technique for examining the colon. At present time, the examination is ready to be implemented as a supplement to incomplete colonoscopy or preoperative colonic evaluation. Furthermore, MRC seems to have a great potential in the screening for colorectal cancer, since detection of polyps and polypectomy might reduce on the incidence of colorectal cancer. This is speculated in the adenoma-carcinoma sequence theory, which states that most cancers evolve from polyps over a long period and that polypectomy might be curative. Colonoscopy remains the gold standard for full colon evaluation. However, the result of our studies can justify clinical use of MRC on selected indications, e.g. in the cases where colonoscopy is incomplete or technically difficult. Since up to 54% of all preoperative colon evaluations in patients with colorectal cancer and up to 17-23% of regular colonoscopies are incomplete, the clinical potential of MRC is evident. Furthermore, in our studies we have shown the insufficiency of preoperative colonic evaluation by CC. In addition, considering the invasiveness, the serious complications (perforation, bleeding, death) and the lack of patient acceptance in colonoscopy, the need for a safe, patient friendly alternative examination with high sensitivity, is clear. In conclusion, in the three studies that made up this PhD thesis, we have shown: that there are some flaws to the present gold standard of colonic evaluation; that there is an increased morbidity and mortality in the group of patients with missed SC; that patients have a preference for MRC and for fecal tagging compared to CC and bowel purgation and that there is a potential gain in doing preoperative colonic evaluation with MRC on all patients with rectal- or sigmoid colon cancer.

CT colonography and non-polypoid colorectal neoplasms.

Computed tomographic colonography (CTC) has been reported to be as effective as optical colonoscopy in the detection of significant adenomas. However, there are widely conflicting performance data in relation to detection of flat neoplasia. This article describes the potential and limitations of CTC and computer-aided diagnosis in the detection of flat neoplasms.

Current techniques in the performance, interpretation, and reporting of CT colonography.

The technical objective of computed tomographic colonography (CTC) is to acquire high-quality computed tomography images of the cleansed, well-distended colon for polyp detection. In this article the authors provide an overview of the technical components of CTC, from preparation of the patient to acquisition of the imaging data and basic methods of interpretation. In each section, the best evidence for current practices and recommendations is reviewed. Each of the technical components must be optimized to achieve high sensitivity in polyp detection.

Colonoscopy versus computed tomography colonography for colorectal cancer screening.

Colorectal cancer is second only to lung cancer as the leading cause of death among North Americans of both sexes. Although screening rates for colorectal cancer in the United States have increased over the past decade, these rates (in the range of 45%-60%) are still lower than the screening rates for breast cancer (approximately 80%). Optical colonoscopy has been recognized as the preferred method for colorectal cancer screening in the United States, but computed tomography colonography has recently been gaining favor. This article compares the 2 methods with respect to both advantages and disadvantages.

Dose optimisation of double-contrast barium enema examinations.

The purpose of the present work was to optimise the filtration and dose setting for double-contrast barium enema examinations using a Philips MultiDiagnost Eleva FD system. A phantom study was performed prior to a patient study. A CDRAD phantom was used in a study where copper and aluminium filtration, different detector doses and tube potentials were examined. The image quality was evaluated using the software CDRAD Analyser and the phantom dose was determined using the Monte Carlo-based software PCXMC. The original setting [100 % detector dose (660 nGy air kerma) and a total filtration of 3.5 mm Al, at 81 kVp] and two other settings identified by the phantom study (100 % detector dose and additional filtration of 1 mm Al and 0.2 mm Cu as well as 80 % detector dose and added filtration of 1 mm Al and 0.2 mm Cu) were included in the patient study. The patient study included 60 patients and up to 8 images from each patient. Six radiologists performed a visual grading characteristics study to evaluate the image quality. A four-step scale was used to judge the fulfillment of three image quality criteria. No overall statistical significant difference in image quality was found between the three settings (P > 0.05). The decrease in the effective dose for the settings in the patient study was 15 % when filtration was added and 34 % when both filtrations was added and detector dose was reduced. The study indicates that additional filtration of 1 mm Al and 0.2 mm Cu and a decrease in detector dose by 20 % from the original setting can be used in colon examinations with Philips MultiDiagnost Eleva FD to reduce the patient dose by 30 % without significantly affecting the image quality. For 20 exposures, this corresponds to a decrease in the effective dose from 1.6 to 1.1 mSv.

Computed tomographic colonography: hope or hype?

Computed tomographic colonography (CTC) is a promising emerging technology for imaging of the colon. This concise review discusses the currently available data on CTC technique, test characteristics, acceptance, safety, cost-effectiveness, follow-up strategy, and extracolonic findings. In summary, CTC technique is still evolving, and further research is needed to clarify the role of automated colonic insufflation, smooth-muscle relaxants, intravenous and oral contrast, software rendering, and patient positioning. Currently, full bowel preparation is still required to achieve optimal results. The sensitivity for detecting large polyps (> 1 cm) can be as high as 85%, with specificity of up to 97%. These test characteristics are almost comparable to those of conventional colonoscopy. Patient acceptance of CTC is generally higher than that for colonoscopy, especially in patients who have never undergone either procedure. CTC is generally safe, although uncommon instances of colonic perforation have been documented. In terms of cost-effectiveness, most decision analyses have concluded that CTC would only be cost-effective if it were considerably cheaper than conventional colonoscopy. The proper follow-up strategy for small polyps or incidental extracolonic findings discovered during CTC is still under debate. At present, the exact clinical role of virtual colonoscopy still awaits determination. Even though widespread CTC screening is not available today, in the future there may eventually be a role for this technology. Technological advances in this area will undoubtedly continue, with multi-detector row CT scanners allowing thinner collimation and higher resolution images. Stool-tagging techniques are likely to evolve and may eventually allow for low-preparation CTC. Perceptual and fatigue-related reading errors can potentially be minimized with the help of computer-aided detection software. Further research will define the exact role of this promising technology in our diagnostic armamentarium.