3D Digital Modeling of Dental Casts from Their 3D CT Images with Scatter and Beam-Hardening Correction.

Dental 3D modeling plays a pivotal role in digital dentistry, offering precise tools for treatment planning, implant placement, and prosthesis customization. Traditional methods rely on physical plaster casts, which pose challenges in storage, accessibility, and accuracy, fueling interest in digitization using 3D computed tomography (CT) imaging. We introduce a method that can reduce both artifacts simultaneously. To validate the proposed method, we carried out CT scan experiments using plaster dental casts created from dental impressions. After the artifact correction, the CT image quality was greatly improved in terms of image uniformity, contrast-to-noise ratio (CNR), and edge sharpness. We examined the correction effects on the accuracy of the 3D models generated from the CT images. As referenced to the 3D models derived from the optical scan data, the root mean square (RMS) errors were reduced by 8.8~71.7% for three dental casts of different sizes and shapes. Our method offers a solution to challenges posed by artifacts in CT scanning of plaster dental casts, leading to enhanced 3D model accuracy. This advancement holds promise for dental professionals seeking precise digital modeling for diverse applications in dentistry.

Metal Artifact Reduction in Dental CBCT Images Using Direct Sinogram Correction Combined with Metal Path-Length Weighting.

Metal artifacts in dental computed tomography (CT) images, caused by highly X-ray absorbing objects, such as dental implants or crowns, often more severely compromise image readability than in medical CT images. Since lower tube voltages are used for dental CTs in spite of the more frequent presence of metallic objects in the patient, metal artifacts appear more severely in dental CT images, and the artifacts often persist even after metal artifact correction. The direct sinogram correction (DSC) method, which directly corrects the sinogram using the mapping function derived by minimizing the sinogram inconsistency, works well in the case of mild metal artifacts, but it often fails to correct severe metal artifacts. We propose a modified DSC method to reduce severe metal artifacts, and we have tested it on human dental images. We first segment the metallic objects in the CT image, and then we forward-project the segmented metal mask to identify the metal traces in the projection data with computing the metal path length for the rays penetrating the metal mask. In the sinogram correction with the DSC mapping function, we apply the weighting proportional to the metal path length. We have applied the proposed method to the phantom and patient images taken at the X-ray tube voltage of 90 kVp. We observed that the proposed method outperforms the original DSC method when metal artifacts were severe. However, we need further extensive studies to verify the proposed method for various CT scan conditions with many more patient images.

Cone-Beam Angle Dependency of 3D Models Computed from Cone-Beam CT Images.

Cone-beam dental CT can provide high-precision 3D images of the teeth and surrounding bones. From the 3D CT images, 3D models, also called digital impressions, can be computed for CAD/CAM-based fabrication of dental restorations or orthodontic devices. However, the cone-beam angle-dependent artifacts, mostly caused by the incompleteness of the projection data acquired in the circular cone-beam scan geometry, can induce significant errors in the 3D models. Using a micro-CT, we acquired CT projection data of plaster cast models at several different cone-beam angles, and we investigated the dependency of the model errors on the cone-beam angle in comparison with the reference models obtained from the optical scanning of the plaster models. For the 3D CT image reconstruction, we used the conventional Feldkamp algorithm and the combined half-scan image reconstruction algorithm to investigate the dependency of the model errors on the image reconstruction algorithm. We analyzed the mean of positive deviations and the mean of negative deviations of the surface points on the CT-image-derived 3D models from the reference model, and we compared them between the two image reconstruction algorithms. It has been found that the model error increases as the cone-beam angle increases in both algorithms. However, the model errors are smaller in the combined half-scan image reconstruction when the cone-beam angle is as large as 10 degrees.

Half-scan artifact correction using generative adversarial network for dental CT.

Half-scan image reconstruction with Parker weighting can correct motion artifacts in dental CT images taken with a slow scan-based dental CT. Since the residual half-scan artifacts in the dental CT images appear much stronger than those in medical CT images, the artifacts often persist to the extent that they compromise the surface-rendered bone and tooth images computed from the dental CT images. We used a variation of generative adversarial network (GAN), so-called U-WGAN, to correct half-scan artifacts in dental CT images. For the generative network of GAN, we used a U-net structure of five stages to take advantage of its high computational efficiency. We trained the network using the Wasserstein loss function on the dental CT images of 40 patients. We tested the network with comparing its output images to the half-scan images corrected with other methods; Parker weighting and the other two popular GANs, that is, SRGAN and m-WGAN. For the quantitative comparison, we used the image quality metrics measuring the similarity of the corrected images to the full-scan images (reference images) and the noise level on the corrected images. We also compared the visual quality of the surface-rendered bone and tooth images. We observed that the proposed network outperformed Parker weighting and other GANs in all the image quality metrics. The computation time for the proposed network to process 336×336×336 3D images on a GPU-equipped personal computer was about 3 s, which was much shorter than those of SRGAN and m-WGAN, 50 s and 54 s, respectively.

Comparative Study on Bone Marrow-Versus Adipose-Derived Stem Cells on Regeneration and Re-Innervation of Skeletal Muscle Injury in Wistar Rats.

BACKGROUND: Skeletal muscle injuries are frequent clinical challenges due to associated fibrosis and disability. Regenerative medicine is an emerging promising strategy for such cases. The aim of this study was to compare between the effects of bone marrow-mesenchymal stem cells (BM-MSCs) versus adipose tissue stromal cells (ADSCs) on regeneration and re-innervation of skeletal muscle laceration injury in Wistar rats at different time intervals. METHODS: Six young male rats were used as a source of allogenic MSCs. Eighty-four adult female rats were divided into: Group I (control), Group II (Untreated Laceration): right gluteal muscle was lacerated and left for spontaneous healing, Group III (BM-MSCs): right gluteal muscle was lacerated with concomitant local intramuscular injection of 1 × 106 BM-MSCs in the lacerated muscle, Group IV (ADSCs): right gluteal muscle was lacerated with concomitant local intramuscular injection of 1 × 106 ADSCs in lacerated muscle. Rats were sacrificed after one, two and eight weeks. Muscles were processed to prepare sections stained with H&E, Mallory's trichrome and immune-histochemical staining (neurofilament light chain). RESULTS: A significant increase in collagen fibers and failure of re-innervation were noticed in untreated laceration group. BM-MSCs-treated groups showed regeneration of muscle fibers but with increased collagen fibers. Meanwhile, ADSCs showed better regenerative effects evidenced by significant increase in the number of myotubes and significant decrease in collagen deposition. Re-innervation was noticed in MSCs-injected muscles after 8 weeks of laceration. CONCLUSION: Both BM-MSCs and ADSCs improved regeneration of skeletal muscle laceration injury at short- and long-term durations. However, fibrosis was less in ADSCs-treated rats. Effective re-innervation of injured muscles occurred only at the long-term duration.

Transanal Versus Laparoscopic Total Mesorectal Excision: A Comparative Prospective Clinical Trial from Two Centers.

Purpose: Laparoscopic total mesorectal excision (LapTME) faced many obstacles in obese male with narrow pelvis and bulky mesorectum with increased risk of incomplete mesorectal excision and positive circumferential resection margin (CRM) and distal resection margin (DRM). Transanal total mesorectal excision (TaTME) is reported to result in a better quality total mesorectal excision (TME) specimen, lower incidence of CRM and DRM involvement, and higher rates of sphincter preservation. To date, there is still a debate about the feasibility and efficacy of transanal versus the laparoscopic approach for TME in middle and low rectal cancer. Materials and Methods: This is a prospective controlled clinical trial where 38 patients of middle or low rectal cancer from two tertiary centers were nonrandomly assigned to either TaTME or LapTME. Results: Eighteen patients were operated by TaTME versus 20 patients by LapTME. Mean body mass index was significantly higher in the TaTME group (30.74 ± 7.79) than in the LapTME group (25.99 ± 4.68) (P = .03). TaTME was associated with more transanal specimen extraction (55.5% versus 20%, P = .06). No significant differences were detected in CRM, DRM, peri- or postoperative complications, or conversion rates with more reported Clavien-Dindo grade III complications in the TaTME group (P = .29). Conclusions: TaTME facilitated rectal cancer surgery in obese patients and increased the chance of transanal specimen extraction with equivalent oncological outcomes to conventional LapTME. Further studies are recommended to build better evidence.

Short-Term Surgical Outcomes of Standard and Lateral Video Endoscopic Inguinal Lymphadenectomy: A Multinational Retrospective Study.

Background: Video endoscopic inguinal lymphadenectomy (VEIL) is a minimally invasive technique that gives superior surgical outcomes than open inguinal lymphadenectomy (IL) for treating lymph node metastasis in penile, vulvar, and skin cancers. This study compared surgical outcomes obtained with two different approaches of VEIL, standard VEIL and lateral VEIL (L-VEIL), in cancer patients. Methods: Sixty-two patients who underwent standard VEIL (n = 15) or L-VEIL (n = 47) for treatment of lymph node metastasis were evaluated retrospectively from three centers in Brazil, Egypt, and India. Primary endpoint analyzed was conversion rate to open IL in the two groups, and the secondary endpoints included operative time, estimated blood loss, nodal yield, nodal positivity, postoperative drain duration, and postoperative complications. Results: The conversion rate to open IL was higher in L-VEIL compared with VEIL group (2% vs. 0%). Significantly lesser blood loss was reported with L-VEIL compared with VEIL (mean difference: 3.63 mL; P = .01). Postoperative drain duration was significantly lower with L-VEIL (-4.34 days; P < .05) than VEIL. The L-VEIL group had a higher number of lymph nodes without infiltration (mean difference: -0.48; P = .02). Operative time, nodal yield, nodal positivity, and hospitalization duration were similar in both groups. Postoperative complications were higher in the L-VEIL versus VEIL group (35 vs. 11 cases). Lymphedema events were significantly higher with L-VEIL in comparison with VEIL (38.8% vs. 16.7%; P = .03). Among patients with penile cancer, no significant difference was observed in outcomes obtained with VEIL and L-VEIL. Conclusion: As L-VEIL and VEIL approaches lead to comparable surgical outcomes, surgeons may choose either of these as per their convenience.

Image denoising by transfer learning of generative adversarial network for dental CT.

The successful development of the image denoising techniques for low-dose computed tomography (LDCT) was largely owing to the public-domain availability of spatially-aligned high- and low-dose CT image pairs. Even though low-dose CT scans are also highly desired in dental imaging, public-domain databases of dental CT image pairs have not been established yet. In this paper, we propose a dental CT image denoising method based on the transfer learning of a generative adversarial network (GAN) from the public-domain CT images. We trained a generative adversarial network with the Wasserstein loss function (WGAN) using 5,100 high- and low-dose medical CT image pairs of human chest and abdomen. For the generative network of GAN, we used the U-net structure of five stages to exploit its high computational efficiency. After training the proposed network, named U-WGAN, we fine-tuned the network with 3,006 dental CT image pairs of two different human skull phantoms. For the high- and low-dose scans of the phantoms, we set the tube current of the dental CT to 10 mA and 4 mA, respectively, with the tube voltage set to 90 kVp in both scans. We applied the trained network to denoising of low-dose dental CT images of dental phantoms and adult humans. The U-net processed images showed over-smoothing effects even though U-net had a good performance in the quantitative metrics. U-WGAN showed similar denoising performance to WGAN, but it reduced the computation time of WGAN by a factor of 10. The fine-tuning procedure in the transfer learning scheme enhanced the network performance in terms of the quantitative metrics, and it also improved visual appearance of the processed images. Even though the number of fine-tuning images was very limited in this study, we think the transfer learning scheme can be a good option for developing deep learning networks for dental CT image denoising.

Gigantic submandibular pleomorphic adenoma: A rare case report.

INTRODUCTION: Pleomorphic adenoma (PA) is the most common benign salivary gland tumor. When neglected on some occasions, its size and weight can enormously augment. CASE PRESENTATION: We report a case of a giant submandibular pleomorphic adenoma in a 75 years old female patient which measured 34 × 26 × 20 cm and weighed 8.1 kg. CONCLUSION: Neglecting such tumors without treatment, can cause severe facial disfigurement and can even hinder the airway.

U-net based metal segmentation on projection domain for metal artifact reduction in dental CT.

Unlike medical computed tomography (CT), dental CT often suffers from severe metal artifacts stemming from high-density materials employed for dental prostheses. Despite the many metal artifact reduction (MAR) methods available for medical CT, those methods do not sufficiently reduce metal artifacts in dental CT images because MAR performance is often compromised by the enamel layer of teeth, whose X-ray attenuation coefficient is not so different from that of prosthetic materials. We propose a deep learning-based metal segmentation method on the projection domain to improve MAR performance in dental CT. We adopted a simplified U-net for metal segmentation on the projection domain without using any information from the metal-artifacts-corrupted CT images. After training the network with the projection data of five patients, we segmented the metal objects on the projection data of other patients using the trained network parameters. With the segmentation results, we corrected the projection data by applying region filling inside the segmented region. We fused two CT images, one from the corrected projection data and the other from the original raw projection data, and then we forward-projected the fused CT image to get the fused projection data. To get the final corrected projection data, we replaced the metal regions in the original projection data with the ones in the fused projection data. To evaluate the efficacy of the proposed segmentation method on MAR, we compared the MAR performance of the proposed segmentation method with a conventional MAR method based on metal segmentation on the CT image domain. For the MAR performance evaluation, we considered the three primary MAR performance metrics: the relative error (REL), the sum of square difference (SSD), and the normalized absolute difference (NAD). The proposed segmentation method improved MAR performances by around 5.7% for REL, 6.8% for SSD, and 8.2% for NAD. The proposed metal segmentation method on the projection domain showed better MAR performance than the conventional segmentation on the CT image domain. We expect that the proposed segmentation method can improve the performance of the existing MAR methods that are based on metal segmentation on the CT image domain.

Morbidity Profile of Cases Attended Oncology Center of Mansoura University (OCMU), Egypt: A Cross-Sectional Study.

OBJECTIVES: In Egypt, the National Cancer Registry Program integrates hospital-based data from multiple Egyptian governorates to obtain representative rates. Unfortunately, Dakahlia (one of the largest Egyptian governorates) was not integrated in the National Cancer Registry Program. This research aimed to acquire malignancy rates from the Oncology Center of Mansoura University, which is one of the two oncology centers present in Dakalia Governorate in Egypt. METHODS: Electronic records of patients who attended the Oncology Center of Mansoura University during 2016 were accessed with permission. Analysis was performed to extract diagnostic categories (age, gender, and geographic distribution of cases). RESULTS: Most commonly diagnosed malignancies were breast cancer which represented about 10% of cases in the Oncology Center of Mansoura University during 2016. This was followed by leukemia (3.80%), lymphoma (3.59%), and liver cancer (3.44%). Diagnoses encountered included benign and malignant tumors as well as non-tumor diagnoses. The Mansoura district had the highest proportionate rate of breast cancer cases. Females in the age group ≥ 35 < 60 years had the highest incidence of malignancy cases across all diagnoses. CONCLUSION: The burden of breast cancer in Mansoura district is high. Risk factors need further evaluation with a recommendation to perform an environmental risk assessment.

Volatile Anesthetics versus Total Intravenous Anesthesia for Cardiac Surgery

BACKGROUND: Volatile (inhaled) anesthetic agents have cardioprotective effects, which might improve clinical outcomes in patients undergoing coronary-artery bypass grafting (CABG). METHODS: We conducted a pragmatic, multicenter, single-blind, controlled trial at 36 centers in 13 countries. Patients scheduled to undergo elective CABG were randomly assigned to an intraoperative anesthetic regimen that included a volatile anesthetic (desflurane, isoflurane, or sevoflurane) or to total intravenous anesthesia. The primary outcome was death from any cause at 1 year. RESULTS: A total of 5400 patients were randomly assigned: 2709 to the volatile anesthetics group and 2691 to the total intravenous anesthesia group. On-pump CABG was performed in 64% of patients, with a mean duration of cardiopulmonary bypass of 79 minutes. The two groups were similar with respect to demographic and clinical characteristics at baseline, the duration of cardiopulmonary bypass, and the number of grafts. At the time of the second interim analysis, the data and safety monitoring board advised that the trial should be stopped for futility. No significant difference between the groups with respect to deaths from any cause was seen at 1 year (2.8% in the volatile anesthetics group and 3.0% in the total intravenous anesthesia group; relative risk, 0.94; 95% confidence interval [CI], 0.69 to 1.29; P = 0.71), with data available for 5353 patients (99.1%), or at 30 days (1.4% and 1.3%, respectively; relative risk, 1.11; 95% CI, 0.70 to 1.76), with data available for 5398 patients (99.9%). There were no significant differences between the groups in any of the secondary outcomes or in the incidence of prespecified adverse events, including myocardial infarction. CONCLUSIONS: Among patients undergoing elective CABG, anesthesia with a volatile agent did not result in significantly fewer deaths at 1 year than total intravenous anesthesia. (Funded by the Italian Ministry of Health; MYRIAD ClinicalTrials.gov number, NCT02105610.). (AU)

A motion artifact reduction method for dental CT based on subpixel-resolution image registration of projection data.

High-resolution imaging is essential in three-dimensional (3D) CT image-based digital dentistry. A small amount of head motion during a CT scan can degrade the spatial resolution of the images to the extent where the efficacy of 3D image-based digital dentistry is greatly compromised. We introduce a retrospective motion artifact reduction (MAR) method for dental CTs that eliminates the necessity for any external motion tracking devices. Assuming that rigid-body motions are dominant in a dental scan of a human head, we extracted motion information from the projection data. By taking the cross-correlation between two successive projection data for every projection view, we determined the displacement of the projection data at each view. We experimentally found that any motion of the imaging object during the scan resulted in displacement of the projection data proportional to the motion amplitude. We decomposed the displacement into two components, one caused by translational motion and the other caused by rotational motion. The displacement components were used to correct the projection data before CT image reconstruction. We experimentally verified the MAR method using the projection data of a few phantoms acquired through a clinical dental CT machine. When the MAR performance was evaluated by the structural similarity index (SSIM) and the normalized absolute error (NAE) in reference to the motion-less images, the SSIM improved to 99% while the NAE was reduced by 80-90%.

Transanal Total Mesorectal Excision for Rectal Cancer: Short Term Outcomes from Two Centers.

BACKGROUND: Rectal cancer is now an increasing problem in both developed and developing countries. In the last 7 years, minimally invasive surgery for this disease has entered a new era of transanal resection with/without laparoscopic assistance. MATERIALS AND METHODS: We present here a prospective study done in Egypt (probably the earliest experience) and Spain on the feasibility of hybrid NOTES in rectal cancer. RESULTS: From September 2015 till November 2017, 18 cases underwent transanal total mesorectal excision with no detected mortality and with morbidities in 44% of cases, from which 5 were class III on Clavien-Dindo scale requiring intervention. Good quality total mesorectal excision was obtained in more than three quarters of our patients. CONCLUSIONS: In our experience, the technique was technically demanding with a long learning curve; however, the short term results were very good in alliance with other few similar reports.

A head motion estimation algorithm for motion artifact correction in dental CT imaging.

A small head motion of the patient can compromise the image quality in a dental CT, in which a slow cone-beam scan is adopted. We introduce a retrospective head motion estimation method by which we can estimate the motion waveform from the projection images without employing any external motion monitoring devices. We compute the cross-correlation between every two successive projection images, which results in a sinusoid-like displacement curve over the projection view when there is no patient motion. However, the displacement curve deviates from the sinusoid-like form when patient motion occurs. We develop a method to estimate the motion waveform with a single parameter derived from the displacement curve with aid of image entropy minimization. To verify the motion estimation method, we use a lab-built micro-CT that can emulate major head motions during dental CT scans, such as tilting and nodding, in a controlled way. We find that the estimated motion waveform conforms well to the actual motion waveform. To further verify the motion estimation method, we correct the motion artifacts with the estimated motion waveform. After motion artifact correction, the corrected images look almost identical to the reference images, with structural similarity index values greater than 0.81 in the phantom and rat imaging studies.

Dual-energy-based metal segmentation for metal artifact reduction in dental computed tomography.

PURPOSE: In a dental CT scan, the presence of dental fillings or dental implants generates severe metal artifacts that often compromise readability of the CT images. Many metal artifact reduction (MAR) techniques have been introduced, but dental CT scans still suffer from severe metal artifacts particularly when multiple dental fillings or implants exist around the region of interest. The high attenuation coefficient of teeth often causes erroneous metal segmentation, compromising the MAR performance. We propose a metal segmentation method for a dental CT that is based on dual-energy imaging with a narrow energy gap. METHODS: Unlike a conventional dual-energy CT, we acquire two projection data sets at two close tube voltages (80 and 90 kVp ), and then, we compute the difference image between the two projection images with an optimized weighting factor so as to maximize the contrast of the metal regions. We reconstruct CT images from the weighted difference image to identify the metal region with global thresholding. We forward project the identified metal region to designate metal trace on the projection image. We substitute the pixel values on the metal trace with the ones computed by the region filling method. The region filling in the metal trace removes high-intensity data made by the metallic objects from the projection image. We reconstruct final CT images from the region-filled projection image with the fusion-based approach. We have done imaging experiments on a dental phantom and a human skull phantom using a lab-built micro-CT and a commercial dental CT system. RESULTS: We have corrected the projection images of a dental phantom and a human skull phantom using the single-energy and dual-energy-based metal segmentation methods. The single-energy-based method often failed in correcting the metal artifacts on the slices on which tooth enamel exists. The dual-energy-based method showed better MAR performances in all cases regardless of the presence of tooth enamel on the slice of interest. We have compared the MAR performances between both methods in terms of the relative error (REL), the sum of squared difference (SSD) and the normalized absolute difference (NAD). For the dental phantom images corrected by the single-energy-based method, the metric values were 95.3%, 94.5%, and 90.6%, respectively, while they were 90.1%, 90.05%, and 86.4%, respectively, for the images corrected by the dual-energy-based method. For the human skull phantom images, the metric values were improved from 95.6%, 91.5%, and 89.6%, respectively, to 88.2%, 82.5%, and 81.3%, respectively. CONCLUSIONS: The proposed dual-energy-based method has shown better performance in metal segmentation leading to better MAR performance in dental imaging. We expect the proposed metal segmentation method can be used to improve the MAR performance of existing MAR techniques that have metal segmentation steps in their correction procedures.

A bench-top micro-CT capable of simulating head motions.

Computational three-dimensional (3D) models of a dental structure generated from 3D dental computed tomography (CT) images are now widely used in digital dentistry. To generate precise 3D models, high-resolution imaging of the dental structure with a dental CT is required. However, a small head motion of the patient during the dental CT scan could degrade the spatial resolution of CT images to the extent that digital dentistry is no longer possible. A bench-top micro-CT has been built to evaluate the head motion effects on the dental CT images. A micro-CT has been built on an optic table with a micro-focus x-ray source and a flat-panel detector. A rotation stage, placed in between the x-ray source and the detector, is mounted on two-directional goniometers that can rotate the rotation stage in two orthogonal directions while the rotation stage is performing the CT scan. The goniometers can make object motions of an arbitrary waveform to simulate head tilting or head nodding. CT images of a phantom have been taken with and without introducing the motions, and the motion effects on the CT images have been evaluated. Object motions parallel to the detector plane have greater effects on the CT images than those against the detector plane. With the bench-top micro-CT, the motion effects have been visually seen at a tiny rotational motion as small as 0.3°. The bench-top micro-CT can be used to evaluate head motion effects on the dental CT images. The projection data, taken with the motion effects, would be used to develop motion artifact correction methods for a high-resolution dental-CT.

A metal artifact reduction method for a dental CT based on adaptive local thresholding and prior image generation.

BACKGROUND: Metal artifacts appearing as streaks and shadows often compromise readability of computed tomography (CT) images. Particularly in a dental CT in which high resolution imaging is crucial for precise preparation of dental implants or orthodontic devices, reduction of metal artifacts is very important. However, metal artifact reduction algorithms developed for a general medical CT may not work well in a dental CT since teeth themselves also have high attenuation coefficients. METHODS: To reduce metal artifacts in dental CT images, we made prior images by weighted summation of two images: one, a streak-reduced image reconstructed from the metal-region-modified projection data, and the other a metal-free image reconstructed from the original projection data followed by metal region deletion. To make the streak-reduced image, we precisely segmented the metal region based on adaptive local thresholding, and then, we modified the metal region on the projection data using linear interpolation. We made forward projection of the prior image to make the prior projection data. We replaced the pixel values at the metal region in the original projection data with the ones taken from the prior projection data, and then, we finally reconstructed images from the replaced projection data. To validate the proposed method, we made computational simulations and also we made experiments on teeth phantoms using a micro-CT. We compared the results with the ones obtained by the fusion prior-based metal artifact reduction (FP-MAR) method. RESULTS: In the simulation studies using a bilateral prostheses phantom and a dental phantom, the proposed method showed a performance similar to the FP-MAR method in terms of the edge profile and the structural similarity index when an optimal global threshold was chosen for the FP-MAR method. In the imaging studies of teeth phantoms, the proposed method showed a better performance than the FP-MAR method in reducing the streak artifacts without introducing any contrast anomaly. CONCLUSIONS: The simulation and experimental imaging studies suggest that the proposed method can be used for reducing metal artifacts in dental CT images.

Metastatic rhabdomyosarcoma of the thyroid gland, a case report.

The thyroid gland is a known but an unusual site for metastatic tumors from various primary sites. Despite the fact that it is one of the largest vascular organs in the body, clinical and surgical cases have given an incidence of 3% of secondary malignances of the organ. Nevertheless, thyroid metastases are not an exceptional finding at autopsy, they are encountered in 2% to 24% of the patients with malignant neoplasm.Soft tissue sarcomas metastatic to the thyroid are extremely rare as the majority of thyroid metastasis are caused by tumors of the kidneys, lungs, mammary glands, ovaries , and colon or by melanomas.We report a case of 22-years-old woman with right leg rhabdomyosarcoma metastatic to the thyroid gland.

Minimally invasive video-assisted thyroidectomy for small follicular thyroid nodules.

Minimal access surgery in the thyroid compartment has evolved considerably over the past 10 years and now takes many forms. This study examined the feasibility and reliability of minimally invasive thyroid surgery for the management of small benign thyroid lesions. A total of 68 patients with small thyroid nodules admitted to the Oncology Center of Mansoura University, Egypt, were enrolled in this prospective randomized trial. Patients were allotted to one of two procedures: minimally invasive video-assisted thyroidectomy (MIVAT) or minimally invasive open thyroidectomy using the Sofferman technique of strap muscle transection. Exclusion criteria were nodules > 4 cm, presence of thyroiditis, and thyroid gland volume > 20 ml. Preoperative diagnosis, operating time, blood loss, postoperative pain, complications, and cosmetic outcome were all evaluated. The MIVAT group included 35 patients, and the Sofferman group included 33 patients. The main preoperative pathology was a benign follicular lesion (70.5%), and the main postoperative final pathology was follicular adenoma (54.4%). The two groups were comparable regarding age, sex, and extent of thyroid surgery. Operating time was significantly longer in the MIVAT group (115.4 +/- 33.5 minutes) compared to the Sofferman group (65.6 +/- 23.7 minutes). The postoperative course was significantly less painful in the MIVAT group (p < 0.05). Although patients in the MIVAT group had smaller incisions (p < 0.05), the cosmetic outcome in the two groups was comparable. No long-term complication was encountered in either group. Two distinct approaches of minimally invasive thyroidectomy are now available and can be performed safely in selected patients. Despite some MIVAT advantages of less postoperative pain and slightly better cosmesis, minimally invasive open thyroidectomy offers an advantage of less operating time with comparable cosmetic results.