Analysis of the mandibular canal course using unsupervised machine learning algorithm

Objectives Anatomical structure classification is necessary task in medical field, but the inevitable variability of interpretation among experts makes reliable classification difficult. This study aims to introduce cluster analysis, unsupervised machine learning method, for classification of three-dimensional (3D) mandibular canal (MC) courses, and to visualize standard MC courses derived from cluster analysis in the Korean population. Materials and methods A total of 429 cone-beam computed tomography images were used. Four sites in the mandible were selected for the measurement of the MC course and four parameters, two vertical and two horizontal parameters were measured per site. Cluster analysis was carried out as follows: parameter measurement, parameter normalization, cluster tendency evaluation, optimal number of clusters determination, and k-means cluster analysis. The 3D MC courses were classified into three types with statistically significant mean differences by cluster analysis. Results Cluster 1 showed a smooth line running towards the lingual side in the axial view and a steep slope in the sagittal view. Cluster 2 ran in an almost straight line closest to the lingual and inferior border of mandible. Cluster 3 showed the pathway with a bent buccally in the axial view and an increasing slope in the sagittal view in the posterior area. Cluster 2 showed the highest distribution (42.1%), and males were more widely distributed (57.1%) than the females (42.9%). Cluster 3 comprised similar ratio of male and female cases and accounted for 31.9% of the total distribution. Cluster 1 had the least distribution (26.0%) Distributions of the right and left sides did not show a statistically significant difference. Conclusion The MC courses were automatically classified as three types through cluster analysis. Cluster analysis enables the unbiased classification of the anatomical structures by reducing observer variability and can present representative standard information for each classified group.

Concordance and consistency in the evaluation of diagnostic images of periapical tissue in endodontics

To estimate the degree of concordance and consistency in the radiographic and tomographic evaluation of the periapical area. A study of diagnostic tests was designed. Three blind evaluators analyzed radiographic images, which were selected at two different points in time. An oral radiologist and an endodontist determined the second observation moment. The degree of similarity and variability, concordance and consistency for each radiograph was set at 95% confidence. A Kappa coefficient (κ), for radiographic findings and a correlation coefficient of Lin (CCC) for tomographic measurements was established. 12 radiographies and 19 tomographs were evaluated. The intraobserver consistency determined a k= 1 (Almost Perfect) and a CCC from 0.42 to 0.95 (Poor to Substantial) for both observation times. For radiographies, the interobserver concordance did not show changes between the first and second observation. Values include a k= 0.56-0.80 (Moderate to Good) and a CCC with greater degree of agreement, after training, as follows: axial view: CCC 0.86, 95% of Confidence Interval (CI) 0.69-0.94, coronal view: CCC 0.90 95%CI 0.75-0.96, and sagittal view: CCC 0.96, 95%CI 0.90-0.98. The statistical tests estimated the consistency and concordance to observe radiographically and tomographically the periapical tissue in endodontics.

Relationship between talofibular impingement and increased talar tilt in incongruent varus ankle osteoarthritis

Purpose This study aimed to evaluate the relationship between talofibular impingement and increased talar tilt in incongruent varus ankle osteoarthritis. Methods: Incongruent varus ankle osteoarthritis was defined as a talar tilt of more than 4° on standard ankle anteroposterior radiographs. We retrospectively reviewed 30 patients with unilateral incongruent varus ankle osteoarthritis with normal alignment of the contralateral ankle. All patients underwent bilateral weightbearing computed tomography and standing plain radiographs. The talar tilt and the distance between the talar lateral process and lateral malleolar tip were measured from a standing ankle anteroposterior radiograph of both sides. Talar and fibular spurs were assessed on the coronal and axial views of weightbearing computed tomography. After simulating the correction of the talar tilt in varus ankle osteoarthritis, talofibular bony impingement was reassessed. Results: On the varus side, the distance between the talar lateral process and the lateral malleolar tip was significantly shorter than that on the contralateral side ( p < .001). Talar spur was present in the varus side of all 30 patients on the axial view of weightbearing computed tomography and in the control side of 10 patients. After the simulation of talar tilt correction, talofibular impingement (overlap) occurred in all 30 patients with a larger extent in the severe talar tilt subgroup ( p < .001). Conclusion: Talofibular impingement by lateral gutter osteophytes is closely related to increased talar tilt in patients with incongruent varus ankle osteoarthritis. Therefore, lateral gutter osteophytes should be resected to stabilize mortise and improve clinical outcomes.

Metal artifact reduction using common dental materials

Objectives To determine the effect of different dental lab materials on cone beam computed tomography (CBCT) metal artifact at different resolutions. Methods A total of seven common dental lab materials were molded to a dental sextant of four extracted, restored teeth. In addition to base alone (control), each material was scanned using the Carestream 9600 CBCT unit at three resolutions – 0.3 mm, 0.15 mm, and 0.075 mm – at manufacturer established exposure parameters. A single, representative axial view of each trial was evaluated for metal artifact both quantitatively by histogram analysis and qualitatively by profile plot analysis in ImageJ. Results No statistically significant differences between the control and the dental materials were found; however, post-hoc tests showed significance between Blu-mousse® and polyvinyl siloxane with dental materials and control, predominantly in lower resolutions. Conclusions The current study provides initial evidence on the influence of dental materials have on CBCT metal artifact as described by beam hardening, photon starvation, scatter, and noise, especially at lower resolutions. Blu-Mousse® and polyvinyl siloxane reduced the perceived beam hardening and photon starvation artifact the greatest, relative to other materials, at all three resolutions and lower resolutions, respectively.

Abdominal CT Scan Based Estimation of Splenic Index and Splenic Volume in North Indian Adults

BACKGROUND Exposure of various tropical infections and infestations like tuberculosis, filariasis, malaria, anemia, kala-azar and poor sanitation are major health concerns in Bihar and it’s neighboring state. Spleen size increases in several other diseases e.g., metabolism or storage disorder, malignancies and hematological disorders. Determining the normal parameters of spleen is essential for assessment of splenomegaly in routine ultrasonography (USG) or in the computed tomography (CT) scan. In this study, we wanted to estimate the CT based measurement of splenic dimensions in various planes, splenic index (linear dimension) and splenic volume and also to estimate the relationship of splenic index and splenic volume with age, gender and other splenic dimensions. METHODS It was a retrospective study and data was collected from January 2019 to December 2019. A total of 154 cases (including both genders) of age range 18 - 60 years were collected from the vitrea system (Vitrea software used for the 3-D assessment of splenic volume) and clinical data was collected from the medical record section. CT scan data of only those patients were included who had the clinical history of pain in abdomen, abdominal trauma or other diseases not affecting the spleen. Various measurements including splenic length and thickness at hilum and maximum thickness in axial view and height (maximum interpolar and true vertical height) in coronal views were recorded. RESULTS 154 cases including both gender and age range of 18 - 60 years were included in our study. There were 60 males and 94 females. The average age of the male and female patients was 45.93 +/- 15.19 years and 45.87 +/- 15.12 years respectively. The mean splenic dimensions were 9.03 +/- 1.49 cm in length (axial view), 3.69 +/- 0.05 cm thickness at hilum (axial view) and 9.05 +/- 2.23 cm maximum craniocaudal length and 7.9 +/- 2.96 cm true vertical length (coronal view). Mean splenic index and mean splenic volume were 340.30 +/- 107.39 cm3 and 227.02 +/- 62.22 cm3 respectively. There was statistically significant correlation between splenic volume and maximum craniocaudal length (r2 = 0.4848, P = 0.001), maximum axial length (r2 = 0.4765, P < 0.001) and true vertical length (r2 = 0.3142, P = 0.001) with 95 % confidence interval. For all splenic measurements, there was stronger correlation with maximum craniocaudal length followed by maximum axial length. However, there was no statistically significant correlation either of splenic volume with age in either gender (r2 = 0.019, P = 0.043) or splenic index with age in either gender present (r2 = 0.016, P = 0.059). CONCLUSIONS Maximum splenic length both in coronal (craniocaudal) and axial sections are positively and strongly correlated with splenic volume and splenic index but age of the individuals doesn’t show any correlation either with the splenic volume or with splenic index. Hence, a regional reference of splenic parameters was established with a slightly different range of values reported previously. KEY WORDS Splenic Volume, Splenic Index, Computed Tomography

EFFECT OF 1% Nа ON THE INTENSITY DISTRIBUTION OF THE SAMPLE ATOMS IN NITROGEN MICROWAVE PLASMA WITH AXIAL AND RADIAL OBSERVATION

The effect of 1% Na with axial and radial observation of microwave plasma on the analytical characteristics of the optical spectrometer “Grand-Microwave” is investigated. The presence of 1% Na in the analyzed sample leads to a decrease in the intensities of spectral lines with energies of 6 - 14 eV with the axial observation method by 8 - 50 times, and with the radial method by 2,5 - 8 times, depending on the observation area. The intensity of lines with energies of 1.6 - 6 eV increases by up to 20 times in the axial view, and by 4 to 6 times in the radial view. In the presence of Na, the ratio of the intensities of Mg (II) 280 nm and Mg (I) 285 nm decreases by 2 orders of magnitude for both observation methods, the temperature at the periphery of the axial view of the plasma decreases by 1300 K, and the temperature at the lower boundary of the radial view decreases by 2300 K. The method and scope of the review for the analysis of 25 chemical elements with minimal matrix influences Na and the efficiency of using the recommended areas was evaluated.

Herniated Lumbar Disc Generation and Classification Using Cycle Generative Adversarial Networks on Axial View MRI

A frequent cause of lower back pain presenting with leg pain is a herniated lumbar intervertebral disc. A herniation or a herniated lumbar disc is a change of position of disc material (nucleus pulpous or annulus fibrosis). Usually, the lower back pain goes away within days or weeks. Regular treatment techniques for lower back pain include medication, exercises, relaxation methods and surgery. Back pain and back problems regularly occur in the lumbar region. The spinal canal is made up of vertebrae; each one protects the spinal nerves. Intervertebral discs and facet joints connect the vertebrae above and below. Groups of muscles and ligaments hold the vertebrae and the discs together. Muscles support the spine and the body weight, and they allow us to move. Pressure can result in excessive wear and tear of the other structures. For example, a common problem in the lower back is disc herniation. In this case, pressure on an intervertebral disc makes its center, the nucleus pulposus, protrude backwards and push against the spinal nerves, leading to lower back pain. Detection and classification are the two most important tasks in computer aided diagnosing systems. Detection of a herniated lumbar disc from magnetic resonance imaging (MRI) is a very difficult task for radiologist. The extraction of herniated discs has been achieved by different approaches such as active contours, region growing, watershed techniques, thresholding and deep learning. In this study, to detect intervertebral disc from axial MRIs we develop a method using generative adversarial networks (GANs), especially the CycleGAN model, to automatically generate and detect intervertebral disc and to classify the type of the herniated lumbar disc such as foraminal or median. We propose to explore the importance of axial view MRI to determine the herniation type. Accurately, GANs and other generative networks have created several ways to tackle different problems well known and challenging of medical image analysis, such as segmentation, reconstruction, data simulation, medical image de-noising, and classification. Moreover, their efficiency to synthesize images and data at unprecedented levels of realism also gives hope that the chronic scarcity of labeled data in the medical field can be resolved with the help of these generative models. In our case, having a database that contains several images is a very difficult task. In this paper, we put forward a new approach based on GANs, in order to solve the problem of lumbar intervertebral disc images reduction. This method is based especially on CycleGAN. Consequently, the essential objective of our work is to generate and automatically classify the herniation type as foraminal or median using GANs. Our computer aided diagnosis (CAD) system achieved a 97.2% accuracy on our dataset. This result represents a very high-performance results by providing the state of the art and our work utilizing the GANs technique. Our CAD is very effective and efficient for classifying herniations of lumbar intervertebral discs. Therefore, the contribution of this study appears in: firstly, the use of the CycleGAN model based on convolutional layers to detect and classify the herniation type (median or foraminal) in lumbar intervertebral discs, secondly, the use of axial view MRI in order to classify the type of the herniated intervertebral disc. The main objective of this paper is to help radiologists automatically recognize and classify herniated lumbar discs.

Aging Process of Lateral Facial Fat Compartments: A Retrospective Study

Background Since 2007, when the anatomy of facial fat compartment was described, an increasing number of studies on the aging process of the compartment of cadavers has emerged. Objectives The authors evaluated the aging changes of lateral facial fat compartments on the same person. Methods Sixty-three patients were included in this retrospective study. All patients had magnetic resonance imaging scans with at least 4 years apart. The authors targeted the fat compartments of the superficial temporal, subcutaneous temporal, and buccal fat pad, comparing the data on different time points. Results The thickness of the subcutaneous temporal fat did not change significantly. The 3 diameters of the superficial temporal fat compartment all became thinner on the axial view (P &lt; 0.05). On the sagittal view, the superficial temporal fat elongated from 38.89 mm to 43.74 mm (P &lt; 0.05). The buccal fat compartment also lengthened from 68.73 mm to 74.39 mm (P &lt; 0.05) and had a positive correlation with follow-up duration only. Conclusions The study revealed the fat compartment change on the same person with time. The temporal hollow mainly originates from the thinner part of the superficial temporal fat. The descending of the buccal fat pad aggravates the labiomandibular fold. By understanding the aging process more fully, we can rejuvenate our patients more naturally.