Anas Almukhtar
University of Glasgow
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Featured researches published by Anas Almukhtar.
PLOS ONE | 2014
Anas Almukhtar; Xiangyang Ju; Balvinder Khambay; Jim McDonald; Ashraf Ayoub
Purpose Superimposition of two dimensional preoperative and postoperative facial images, including radiographs and photographs, are used to evaluate the surgical changes after orthognathic surgery. Recently, three dimensional (3D) imaging has been introduced allowing more accurate analysis of surgical changes. Surface based registration and voxel based registration are commonly used methods for 3D superimposition. The aim of this study was to evaluate and compare the accuracy of the two methods. Materials and methods Pre-operative and 6 months post-operative cone beam CT scan (CBCT) images of 31 patients were randomly selected from the orthognathic patient database at the Dental Hospital and School, University of Glasgow, UK. Voxel based registration was performed on the DICOM images (Digital Imaging Communication in Medicine) using Maxilim software (Medicim-Medical Image Computing, Belgium). Surface based registration was performed on the soft and hard tissue 3D models using VRMesh (VirtualGrid, Bellevue City, WA). The accuracy of the superimposition was evaluated by measuring the mean value of the absolute distance between the two 3D image surfaces. The results were statistically analysed using a paired Student t-test, ANOVA with post-hoc Duncan test, a one sample t-test and Pearson correlation coefficient test. Results The results showed no significant statistical difference between the two superimposition methods (p<0.05). However surface based registration showed a high variability in the mean distances between the corresponding surfaces compared to voxel based registration, especially for soft tissue. Within each method there was a significant difference between superimposition of the soft and hard tissue models. Conclusions There were no significant statistical differences between the two registration methods and it was unlikely to have any clinical significance. Voxel based registration was associated with less variability. Registering on the soft tissue in isolation from the hard tissue may not be a true reflection of the surgical change.
British Journal of Oral & Maxillofacial Surgery | 2016
Anas Almukhtar; Ashraf Ayoub; Balvinder Khambay; Jim McDonald; Xianyang Ju
We describe the comprehensive 3-dimensional analysis of facial changes after Le Fort I osteotomy and introduce a new tool for anthropometric analysis of the face. We studied the cone-beam computed tomograms of 33 patients taken one month before and 6-12 months after Le Fort I maxillary advancement with or without posterior vertical impaction. Use of a generic facial mesh for dense correspondence analysis of changes in the soft tissue showed a mean (SD) anteroposterior advancement of the maxilla of 5.9 (1.7) mm, and mean (SD) minimal anterior and posterior vertical maxillary impaction of 0.1 (1.7) mm and 0.6 (1.45) mm, respectively. It also showed distinctive forward and marked lateral expansion around the upper lip and nose, and pronounced upward movement of the alar curvature and columella. The nose was widened and the nostrils advanced. There was minimal forward change at the base of the nose (subnasale and alar base) but a noticeable upward movement at the nasal tip. Changes at the cheeks were minimal. Analysis showed widening of the midface and upper lip which, to our knowledge, has not been reported before. The nostrils were compressed and widened, and the lower lip shortened. Changes at the chin and lower lip were secondary to the limited maxillary impaction.
PLOS ONE | 2016
Man Yan Cheung; Anas Almukhtar; Andrew Keeling; Tai-Chiu Hsung; Xiangyang Ju; Jim McDonald; Ashraf Ayoub; Balvinder Khambay
Purpose Three dimensional analysis of the face is required for the assessment of complex changes following surgery, pathological conditions and to monitor facial growth. The most suitable method may be “dense surface correspondence”. Materials and Methods This method utilizes a generic facial mesh and “conformation process” to establish anatomical correspondences between two facial images. The aim of this study was to validate the use of conformed meshes to measure simulated maxillary and mandibular surgical movements. The “simulation” was performed by deforming the actual soft tissues of the participant during image acquisition. The study was conducted on 20 volunteers and used 77 facial landmarks pre-marked over six anatomical regions; left cheek, right cheek, left upper lip, philtrum, right upper lip and chin region. Each volunteer was imaged at rest and after performing 5 different simulated surgical procedures using 3D stereophotogrammetry. The simulated surgical movement was determined by measuring the Euclidean distances and the mean absolute x, y and z distances of the landmarks making up the six regions following digitization. A generic mesh was then conformed to each of the aligned six facial 3D images. The same six regions were selected on the aligned conformed simulated meshes and the surgical movement determined by determining the Euclidean distances and the mean absolute x, y and z distances of the mesh points making up the six regions were determined. Results In all cases the mean Euclidian distance between the simulated movement and conformed region was less than 0.7mm. For the x, y and z directions the majority of differences in the mean absolute distances were less than 1.0mm except in the x-direction for the left and right cheek regions, which was above 2.0mm. Conclusions This concludes that the conformation process has an acceptable level of accuracy and is a valid method of measuring facial change between two images i.e. pre- and post-surgery. The conformation accuracy is higher toward the center of the face than the peripheral regions.
Journal of Oral and Maxillofacial Surgery | 2016
Mohammed Almuzian; Anas Almukhtar; Xiangyang Ju; Ali Al-Hiyali; Philip Benington; Ashraf Ayoub
PURPOSE The literature discussing the impact of a single Le Fort I osteotomy on nasopharyngeal airways is limited. This study assessed the volumetric changes in the nasopharyngeal airway after a single Le Fort I osteotomy and explored the correlation between these changes and 3-dimensional surgical movements of the upper jaw. MATERIALS AND METHODS This retrospective study was conducted in 40 patients who had undergone a single Le Fort I (maxillary advancement with or without impaction) to correct Class III malocclusion with maxillary hypoplasia. Preoperative (T1) and 6-month postoperative (T2) cone-beam computed tomographic (CBCT) scans of these patients were used for analysis. Maxillary surgical movements and volumetric changes in the nasopharyngeal airway were measured. The reproducibility of the measurements was evaluated using paired t tests and intraclass correlation coefficients. The Wilcoxon test and Pearson correlation coefficient were applied to evaluate the volumetric changes in the nasopharyngeal airway space and assess the correlations of these changes to the maxillary surgical movements. RESULTS Six patients were excluded from the study owing to major differences (>5°) in their head and neck posture between the T1 and T2 CBCT scans. The errors of the repeated measurements were insignificant (P > .05), with a high level of agreement (r = 0.99; P < .05) between the repeated digitization of the landmarks. There was a statistically significant impact of a Le Fort I osteotomy on the right maxillary sinus (decreased by 17.8%) and the lower retropalatal space (expanded by 17.3%; P < .05). The correlation between the change in airway volume and the magnitude of surgical maxillary movements was moderate (r = .4). Similarly, there was a moderate correlation between changes in the upper nasopharynx and those in the hypopharynx. CONCLUSION The single Le Fort I osteotomy was found to increase the retroglossal airway volume. This could be important for the treatment of obstructive sleep apnea in patients with maxillary deficiency. A long-term follow-up assessment of a larger sample with a functional assessment of airway would be beneficial to confirm these findings.
International Journal of Oral and Maxillofacial Surgery | 2017
Anas Almukhtar; Balvinder Khambay; Xiangyang Ju; Ashraf Ayoub
This study was performed to compare soft tissue changes in response to mandibular and bimaxillary advancement osteotomy. Preoperative and postoperative cone beam computed tomography scans of 24 cases were analysed: 12 underwent bimaxillary advancement and 12 underwent mandibular advancement. The skeletal surgical movements were measured and soft tissue changes were displayed on a three-dimensional colour map. The intensity and shade of the colour indicated the magnitude and direction of the changes. In the bimaxillary advancement group, maxillary advancement was 5.5±2.7mm with anterior vertical impaction of 2.7±2.5mm; mandibular advancement was 4.6±3.2mm. Most of the mediolateral soft tissue changes were limited to the anatomical boundaries of the paranasal region - the columella together with the alar bases of the nose; these showed clear forward movement, which extended to involve most of the cheeks. In the mandibular surgery group, the mean advancement was 3.5±2.6mm. The chin region, lower lip, and inferior parts of the cheek showed forward shift with minimal changes at the vermilion border, which was only displaced in an upward direction. In conclusion, dense anatomical correspondence is a clinically meaningful method of producing a visual comprehensive analysis of the changes in response to orthognathic surgery.
International Journal of Oral and Maxillofacial Surgery | 2017
T. Mundluru; Anas Almukhtar; Xiangyang Ju; Ashraf Ayoub
The accuracy of three-dimensional (3D) predictions of soft tissue changes in the surgical correction of facial asymmetry was evaluated in this study. Preoperative (T1) and 6-12-month postoperative (T2) cone beam computed tomography scans of 13 patients were studied. All patients underwent surgical correction of facial asymmetry as part of a multidisciplinary treatment protocol. The magnitude of the surgical movement was measured; virtual surgery was performed on the preoperative scans using Maxilim software. The predicted soft tissue changes were compared to the actual postoperative appearance (T2). Mean (signed) distances and mean (absolute) distances between the predicted and actual 3D surface meshes for each region were calculated. The one-sample t-test was applied to test the alternative hypothesis that the mean absolute distances had a value of <2.0mm. A novel directional analysis was applied to analyse the accuracy of the prediction of soft tissue changes. The results showed that the distances between the predicted and actual postoperative soft tissue changes were less than 2.0mm in all regions. The predicted facial morphology was narrower than the actual surgical changes in the cheek regions. 3D soft tissue prediction using Maxilim software in patients undergoing the correction of facial asymmetry is clinically acceptable.
Between | 2016
Anas Almukhtar; Balvinder Khambay; Ashraf Ayoub; Xiangyang Ju; Ali Al-Hiyali; James MacDonald; Norhayati Jabar; Tazuko K. Goto
The limitations of the current methods of quantifying the surgical movements of facial bones inspired this study. The aim of this study was the assessment of the accuracy and reproducibility of directly landmarking of 3D DICOM images (Digital Imaging and Communications in Medicine) to quantify the changes in the jaw bones following surgery. The study was carried out on plastic skull to simulate the surgical movements of the jaw bones. Cone beam CT scans were taken at 3mm, 6mm, and 9mm maxillary advancement; together with a 2mm, 4mm, 6mm and 8mm “down graft” which in total generated 12 different positions of the maxilla for the analysis. The movements of the maxilla were calculated using two methods, the standard approach where distances between surface landmarks on the jaw bones were measured and the novel approach where measurements were taken directly from the internal structures of the corresponding 3D DICOME slices. A one sample t-test showed that there was no statistically significant difference between the two methods of measurements for the y and z directions, however, the x direction showed a significant difference. The mean difference between the two absolute measurements were 0.34±0.20mm, 0.22±0.16mm, 0.18±0.13mm in the y, z and x directions respectively. In conclusion, the direct landmarking of 3D DICOM image slices is a reliable, reproducible and informative method for assessment of the 3D skeletal changes. The method has a clear clinical application which includes the analysis of the jaw movements “orthognathic surgery” for the correction of facial deformities.
Surgeon-journal of The Royal Colleges of Surgeons of Edinburgh and Ireland | 2016
Mohammed Almuzian; Xiangyang Ju; Anas Almukhtar; Ashraf Ayoub; Lubna Al-Muzian; Jim McDonald
JPRAS Open | 2017
Anas Almukhtar; Balvinder Khambay; Xiangyang Ju; Jim McDonald; Ashraf Ayoub
Archive | 2015
Mohammed Almuzian; Anas Almukhtar; Xiangyang Ju; Ali Al-Hiyali; Philip Benington; Ashraf Ayoub