JPEG 2000 Extensions for Scalable Coding of Discontinuous Media.

In this paper we propose novel extensions to JPEG 2000 for the coding of discontinuous media which includes piecewise smooth imagery such as depth maps and optical flows. These extensions use breakpoints to model discontinuity boundary geometry and apply a breakpoint dependent Discrete Wavelet Transform (BP-DWT) to the input imagery. The highly scalable and accessible coding features provided by the JPEG 2000 compression framework are preserved by our proposed extensions, with the breakpoint and transform components encoded as independent bit streams that can be progressively decoded. Comparative rate-distortion results are provided along with corresponding visual examples which highlight the advantages of using breakpoint representations with accompanying BD-DWT and embedded bit-plane coding. Recently our proposed extensions have been adopted and are in the process of being published as a new Part 17 to the JPEG 2000 family of coding standards.

Evaluation of Orthodontic Mini-Implant Placement in the Maxillary Anterior Alveolar Region in 15 Patients by Cone Beam Computed Tomography at a Single Center in South India.

BACKGROUND In this study, we aimed to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region by cone beam computed tomography (CBCT) in 15 patients at a single center in South India. MATERIAL AND METHODS A total of 15 CBCT scans of orthodontic patients after completion of leveling and aligning stage were included. The thickness of labial alveolar bone, labio-palatal bone, and inter-radicular distance between the maxillary central incisors (U1-U1), maxillary central and lateral incisor (U1-U2), and maxillary lateral incisor and canine (U2-U3) at vertical levels 4 mm, 6 mm, and 8 mm above the interdental cementoenamel junction were measured. Descriptive statistics, ANOVA, and Tukey post hoc tests were done to assess the differences among the groups. An independent t test was done to analyze differences by sex. RESULTS The thickness of cortical bone in the labial region was higher in the U2-U3 site than in the U1-U1 site, at a height of 4 mm. Also, there was a significant difference between 4 mm and 8 mm heights in the U2-U3 region. No significant difference was noted in bone dimensions among men and women and in the labio-palatal bone thickness among the different sites. The inter-radicular distance was the highest between the U2-U3 site, while it was the lowest in the U1-U2 site. CONCLUSIONS The findings from this center showed that when CBCT was used to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region, the U2-U3 and U1-U1 locations at heights between 6 mm to 8 mm apical to the interdental cementoenamel junction were optimal for placement of the mini-implants.

Neural networks for classification of cervical vertebrae maturation: a systematic review.

OBJECTIVE: To assess the accuracy of identification and/or classification of the stage of cervical vertebrae maturity on lateral cephalograms by neural networks as compared with the ground truth determined by human observers. MATERIALS AND METHODS: Search results from four electronic databases (PubMed [MEDLINE], Embase, Scopus, and Web of Science) were screened by two independent reviewers, and potentially relevant articles were chosen for full-text evaluation. Articles that fulfilled the inclusion criteria were selected for data extraction and methodologic assessment by the QUADAS-2 tool. RESULTS: The search identified 425 articles across the databases, from which 8 were selected for inclusion. Most publications concerned the development of the models with different input features. Performance of the systems was evaluated against the classifications performed by human observers. The accuracy of the models on the test data ranged from 50% to more than 90%. There were concerns in all studies regarding the risk of bias in the index test and the reference standards. Studies that compared models with other algorithms in machine learning showed better results using neural networks. CONCLUSIONS: Neural networks can detect and classify cervical vertebrae maturation stages on lateral cephalograms. However, further studies need to develop robust models using appropriate reference standards that can be generalized to external data.

The Expression of Allele Changes in NLRP3 (rs35829419) and IL-1ß (+3954) Gene Polymorphisms in Periodontitis and Coronary Artery Disease.

BACKGROUND: Inflammasomes have been shown to play a pivotal role in periodontal disease pathogenesis. However, their role in periodontitis subjects with coronary heart disease remains unclear. This study aimed to obtain the expression of NLRP3 (rs35829419) and IL-1ß (+3954) gene polymorphisms in the subgingival plaque and blood samples of generalized periodontitis (GP) subjects with and without coronary heart disease (CHD). METHODS: A total of 70 subjects were grouped into two; GP and GP with CHD. Demographic variables and periodontal and cardiac parameters were recorded from both the groups. Subgingival plaque and blood samples were obtained from both the groups and were further subjected to the identification of NLRP3 (rs35829419) and IL-1ß (+3954) expression and allele change using a conventional polymerase chain reaction (PCR) and gene sequencing (Sanger's method). RESULTS: Amongst the demographic variables, age and monthly income were statistically significant between the two groups. Plaque index (PI), clinical attachment level (CAL), high-density lipoprotein (HDL), and low density-lipoprotein (LDL) exhibited statistically significant levels between the two groups. The NLRP3 (rs35829419) and IL-1ß (+3954) genes showed a statistically significant association with allele change (frequency) among the groups. The general comparison of all the parameters with the allele change of NLRP3 (rs35829419) and IL-1ß (+3954) in the subgingival plaque and blood samples showed statistically significant associations among the two groups. CONCLUSION: The present study highlighted an allele change in IL-1ß (+3954) gene polymorphisms which may play an important role in the pathogenesis of periodontitis and coronary heart disease.

Illumination Estimation and Compensation of Low Frame Rate Video Sequences for Wavelet-Based Video Compression.

In this paper, we are interested in the compression of image sets or video with considerable changes in illumination. We develop a framework to decompose frames into illumination fields and texture in order to achieve sparser representations of frames which is beneficial for compression. Illumination variations or contrast ratio factors among frames are described by a full resolution multiplicative field. First, we propose a Lifting-based Illumination Adaptive Transform (LIAT) framework which incorporates illumination compensation to temporal wavelet transforms. We estimate a full resolution illumination field, taking heed of its spatial sparsity by a rate-distortion (R-D) driven framework. An affine mesh model is also developed as a point of comparison. We find the operational coding cost of the subband frames by modeling a typical t + 2D wavelet video coding system. While our general findings on R-D optimization are applicable to a range of coding frameworks, in this paper, we report results based on employing JPEG 2000 coding tools. The experimental results highlight the benefits of the proposed R-D driven illumination estimation and compensation in comparison with alternative scalable coding methods and non-scalable coding schemes of AVC and HEVC employing weighted prediction.

Base-Anchored Model for Highly Scalable and Accessible Compression of Multiview Imagery.

We present a compression scheme for multiview imagery that facilitates high scalability and accessibility of the compressed content. Our scheme relies upon constructing at a single base view, a disparity model for a group of views, and then utilizing this base-anchored model to infer disparity at all views belonging to the group. We employ a hierarchical disparity-compensated inter-view transform where the corresponding analysis and synthesis filters are applied along the geometric flows defined by the base-anchored disparity model. The output of this inter-view transform along with the disparity information is subjected to spatial wavelet transforms and embedded block-based coding. Rate-distortion results reveal superior performance to the x.265 anchor chosen by the JPEG Pleno standards activity for the coding of multiview imagery captured by high-density camera arrays.

A Novel Motion Field Anchoring Paradigm for Highly Scalable Wavelet-Based Video Coding.

Existing video coders anchor motion fields at frames that are to be predicted. In this paper, we demonstrate how changing the anchoring of motion fields to reference frames has some important advantages over conventional anchoring. We work with piecewise-smooth motion fields, and use breakpoints to signal discontinuities at moving object boundaries. We show how discontinuity information can be used to resolve double mappings arising when motion is warped from reference to target frames. We present an analytical model that allows to determine weights for texture, motion, and breakpoints to guide the rate-allocation for scalable encoding. Compared with the conventional way of anchoring motion fields, the proposed scheme requires fewer bits for the coding of motion; furthermore, the reconstructed video frames contain fewer ghosting artefacts. The experimental results show the superior performance compared with the traditional anchoring, and demonstrate the high scalability attributes of the proposed method.

Scalable coding of depth maps with R-D optimized embedding.

Recent work on depth map compression has revealed the importance of incorporating a description of discontinuity boundary geometry into the compression scheme. We propose a novel compression strategy for depth maps that incorporates geometry information while achieving the goals of scalability and embedded representation. Our scheme involves two separate image pyramid structures, one for breakpoints and the other for sub-band samples produced by a breakpoint-adaptive transform. Breakpoints capture geometric attributes, and are amenable to scalable coding. We develop a rate-distortion optimization framework for determining the presence and precision of breakpoints in the pyramid representation. We employ a variation of the EBCOT scheme to produce embedded bit-streams for both the breakpoint and sub-band data. Compared to JPEG 2000, our proposed scheme enables the same the scalability features while achieving substantially improved rate-distortion performance at the higher bit-rate range and comparable performance at the lower rates.

Enormous aneurysmal bone cyst of the mandible: case report and radiologic-pathologic correlation.

A 33-year-old patient with a huge aneurysmal bone cyst (ABC) was imaged using cone-beam CT, MRI, and angiography. ABC is an uncommon non-neoplastic, expansile lesion of bone. Although common in the appendicular skeleton and spine, only 2% of the lesions occur in the craniofacial skeleton. The plain radiographic features of gnathic ABC may show an omni-expansile unilocular or multilocular radiolucency. Fluid-fluid levels have been reported in cystic compartments of ABCs; however, this feature is not diagnostically specific for ABC. In this article, we present a case of a rapidly growing, extraordinarily large ABC of the posterior mandible, with emphasis on comparative imaging features of this lesion in cone-beam CT, MRI, and carotid angiography.

Unusual cone-beam computerized tomography presentation of traumatic (simple) bone cyst: case report and radiographic analysis.

Traumatic (simple) bone cyst (TBC) is an empty nonepithelial-lined cavity of the jaws. The majority of TBCs are located in the body or symphysis of the mandible. Clinically, the lesion is asymptomatic and often discovered incidentally on routine radiographic examination as a noncorticated sharply defined radiolucent area with undulating borders. Because tissues for histologic examination may be scant or nonexistent, the definite diagnosis is invariably achieved during surgery when the lesion is empty. In this report, we present a case of unusual bilateral synchronous TBCs of the mandible with possible traumatic etiology, featuring significant buccolingual expansion of the mandibular ramus and body, presence of septa, and probable displacement of the inferior alveolar canal.

The neglected anatomical and clinical aspects of pterygoid canal: CT scan study.

PURPOSE: To present the variable positions of pterygoid canal (PC) relative to sphenoid sinus floor and cavity, which may be helpful for understanding pathologic and surgical conditions related to sphenoid sinus region. MATERIALS AND METHODS: Coronal sinonasal CT images of 300 adult patients, in the Department of Radiology at Al-Jala Traumatology Hospital, Benghazi, Libya, were investigated for the positional variation and dehiscence of PC. Of the patients, there was equal gender distribution, ages ranged between 16 and 82 years (mean age 34.6 years). The position of PC was categorized as below the sinus floor, within the floor, and within the sinus cavity (protrusion). RESULTS: Canals located under the floor were identified in 38.3% (230/600), within-the-floor canals were encountered in 39.6% (238/600); and canals protruding into the sinus cavity (i.e., within sinus cavity) were observed in 22% (132/600). Dehiscence of the bony wall of PC was recognized in 26% (157/600). Coexistence of PR and protruding PC was found in 16.5% (99/600), 7.3% (44/600) on the right side and 9.2% (55) on the left side. Statistically, there was significant association between PR and PC protrusion (p = 0.000). CONCLUSION: The anatomical and positional variations of PC are highly encountered. Surgeons addressing vidian neurectomy must be familiar with the positional variations of PC in the preoperative CT images for easier and safer nerve identification and transection.