A 3-Dimensional Morphometric Analysis of 4 Midsagittal Planes for CT Scan Reference Determination in Children with Syndromic Craniosynostosis.

OBJECTIVE: To identify the suitable and practical midsagittal plane (MSP) reference for computed tomography (CT) scan skull analysis in patients with syndromic craniosynostosis. DESIGN: Retrospective study. SETTING: Tertiary referral hospital. PATIENTS AND PARTICIPANTS: A total of 19 full skull CT scans of syndromic craniosynostosis patients. METHODS: Seven craniofacial landmarks located on the midline and 4 MSPs that was previously published and clinically recognized (Planes: SPBaS, SPNSANS, SPLOrPo and SPZFTP) were constructed from the CT images. The absolute distance of every plane from 7 landmarks were then calculated. These distances were subsequently subjected to statistical analysis. MAIN OUTCOME MEASURE(S): The absolute distance of different MSPs from 7 landmarks. RESULTS: The distances of landmarks measured to SPBaS were the highest, with the most prominent fluctuation. The fluctuation of the SPNSANS, SPLOrPo and SPZFTP had similar direction changes, with the latter being the closest. Pairwise comparisons demonstrated statistical differences (P < .008 using the Bonferroni correction) between the measured distances of A point (M = 0.25, SD = 0.16) and B point (M = 2.21, SD = 1.6) to SPNSANS. There were statistical significances between distances of B point (M = 1.68, SD = 1.07) and CG point (M = 0.55, SD = 0.37) to SPZFTP plane. There was no statistical significance on each landmark to SPLOrPo. CONCLUSIONS: The study demonstrates that SPBaS is not recommended for MSP reference. While SPNSANS should be carefully selected, the application of SPLOrPo and SPZFTP are interchangeable, with the SPZFTP plane slightly exaggerating the mandible deviation relative to the superior and posterior of the midface.

Clinical Adaptation According to Anatomical Types of Nasal Septum / Adaptación Clínica Según Tipos Anatómicos de Tabique Nasal

SUMMARY: The purpose of this study was to inform the anatomical types of the nasal septum of which including variations by dissection and to provide guidelines for clinical adaptation. For this purpose dissections were performed on 70 nasal septums of formalin fixed Korean adult cadavers (20 males, 11 females, and 39 of unknown sex) with an age at death of 13-105 years. The septal deviation was checked before midsagittal section the nasal cavity with the aid of a laryngoscope. The mucosa on the nasal septum was then removed to observe the morphology of the nasal septum. The shape of each component of the nasal septum was identified, and photographs were taken from a midsagittal plane. This study has discovered various anatomical types of the nasal septum and its variations. The correlations between septal types according to their proportions were also analyzed. The results reported herein provide detailed anatomical knowledge that can be used as a valuable reference for rhinoplasty procedures.

El propósito de este estudio fue informar los tipos anatómicos del tabique nasal incluyendo las variaciones por disección y brindar pautas para la adaptación clínica. Para este propósito, se realizaron disecciones en 70 tabiques nasales de cadáveres adultos coreanos fijados con formalina (20 hombres, 11 mujeres y 39 de sexo desconocido) con una edad de muerte de 13 a 105 años. La desviación septal se comprobó antes de la sección medio sagital de la cavidad nasal con la ayuda de un laringoscopio. A continuación, se retiró la mucosa del tabique nasal para observar la morfología del tabique nasal. Se identificó la forma de cada componente del tabique nasal y se tomaron fotografías desde un plano mediano sagital. En el estudio se descubrieron varios tipos anatómicos del tabique nasal y sus variaciones. También se analizaron las correlaciones entre los tipos septales según sus proporciones. Los resultados informados en este documento proporcionan un conocimiento anatómico detallado que se puede utilizar como una referencia valiosa para los procedimientos de rinoplastía.

Standardized measurement of mid-surface shift of brain based on deep Hough transform.

The measurement of mid-surface shift (MSS), the geometric displacement between the actual mid-surface and the ideal midsagittal plane (iMSP), is of great significance for accurate diagnosis, treatment and prognosis of patients with intracranial hemorrhage (ICH). Most previous studies are subject to inherent inaccuracy on account of calculating midline shift (MLS) based on 2D slices and ignoring pathological conditions. In this study, we propose a novel standardized measurement model to quantify the distance and the overall volume of mid-surface shift (MSS-D, MSS-V). Our work has four highlights. First, we develop an end-to-end network architecture with multiple sub-tasks including the actual mid-surface segmentation, hematoma segmentation and iMSP detection, which significantly improves the efficiency and accuracy of MSS measurement by taking advantage of the common properties among tasks. Second, an efficient iMSP detection scheme is proposed based on the differentiable deep Hough transform (DHT), which converts and simplifies the plane detection problem in the image space into a keypoint detection problem in the Hough space. Third, we devise a sparse DHT strategy and a weighted least square (WLS) method to increase the sparsity of features, improving inference speed and greatly reducing computation cost. Fourth, we design a joint loss function to comprehensively consider the correlation of features between multi-tasks and multi-domains. Extensive validation on our large in-house dataset (519 patients) and the public CQ500 dataset (491 patients), demonstrates the superiority of our method over the state-of-the-art methods.

Differences in positions of cone-beam computed tomography landmarks in patients with skeletal Class III facial asymmetry according to midsagittal planes.

Objective: This study aimed to clarify differences in the positions of cone-beam computed tomography (CBCT) landmarks according to different midsagittal planes (MSPs) in patients with skeletal Class III facial asymmetry. Methods: Pre-treatment CBCT data from 60 patients with skeletal Class III were used. The patients were classified into symmetric (menton deviations of < 2 mm) or asymmetric (menton deviations of > 4 mm) groups. Six MSPs were established based on previous studies, and three-dimensional analyses were performed for the planes in both the groups. The measurement outcomes were compared statistically. Results: A statistically significant interaction (p < 0.01) was observed between MSPs and facial asymmetry. No significant differences were observed among MSPs in the symmetric group. However, significant differences in linear measurements were identified among MSPs in the asymmetric group. Specifically, the upper facial MSP revealed both maxillary and mandibular transverse asymmetries. On the other hand, anterior nasal spine (ANS)-associated MSP could not identify maxillary asymmetry. Furthermore, the menton deviation was approximately 3 mm lower when estimated using the ANS-associated MSP than that using upper facial MSP. Conclusions: The choice of MSP can significantly affect treatment outcomes while diagnosing patients with asymmetry. Therefore, care should be taken when selecting MSP in clinical practice.

[Deep learning-assisted construction of three-demensional facial midsagittal plane].

OBJECTIVE: To establish a deep learning algorithm that can accurately determine three-dimensional facial anatomical landmarks, multi-view stacked hourglass convolutional neural networks (MSH-CNN) and to construct three-dimensional facial midsagittal plane automatically based on MSH-CNN and weighted Procrustes analysis algorithm. METHODS: One hundred subjects with no obvious facial deformity were collected in our oral clinic. Three-dimensional facial data were scanned by three-dimensional facial scanner. Experts annotated twenty-one facial landmarks and midsagittal plane of each data. Eighty three-dimensional facial data were used as training set, to train the MSH-CNN in this study. The overview of MSH-CNN network architecture contained multi-view rendering and training the MSH-CNN network. The three-dimensional facial data were rendered from ninety-six views that were fed to MSH-CNN and the output was one heatmap per landmark. The result of the twenty-one landmarks was accurately placed on the three-dimensional facial data after a three-dimensional view ray voting process. The remaining twenty three-dimensional facial data were used as test set. The trained MSH-CNN automatically determined twenty-one three-dimensional facial anatomical landmarks of each case of data, and calculated the distance between each MSH-CNN landmark and the expert landmark, which was defined as position error. The midsagittal plane of the twenty subjects' could be automatically constructed, using the MSH-CNN and Procrustes analysis algorithm. To evaluate the effect of midsagittal plane by automatic method, the angle between the midsagittal plane constructed by the automatic method and the expert annotated plane was calculated, which was defined as angle error. RESULTS: For twenty subjects with no obvious facial deformity, the average angle error of the midsagittal plane constructed by MSH-CNN and weighted Procrustes analysis algorithm was 0.73°±0.50°, in which the average position error of the twenty-one facial landmarks automatically determined by MSH-CNN was (1.13±0.24) mm, the maximum position error of the orbital area was (1.31±0.54) mm, and the minimum position error of the nasal area was (0.79±0.36) mm. CONCLUSION: This research combines deep learning algorithms and Procrustes analysis algorithms to realize the fully automated construction of the three-dimensional midsagittal plane, which initially achieves the construction effect of clinical experts. The obtained results constituted the basis for the independent intellectual property software development.

Assessment of the Nasal Bone by 2-Dimensional Ultrasound in 2 Different Planes: Do They Give the Same Results?

OBJECTIVES: Measurement of the nasal bone is an important part of the genetic sonogram. This study aimed to compare nasal bone length measurements taken in 2 different planes and to determine whether there is consistency between the measurements. METHODS: The nasal bone was measured in 103 fetuses whose mothers were admitted to our clinic for second-trimester ultrasound examinations and who did not have any accompanying diseases. In this prospective study, the gestational ages of fetuses ranged from 19 to 23 weeks. Nasal bones were measured in both coronal and midsagittal planes, and the similarity between the measurements was evaluated. Pearson correlation, Wilcoxon signed rank, and Kruskal-Wallis tests were used to evaluate the results. RESULTS: The median nasal bone length increased with increasing gestational age in both planes, as expected. There were no statistically significant differences between the fetal nasal bone lengths taken in the midsagittal and coronal planes at 19 to 23 weeks' gestation (P > .05). CONCLUSIONS: The coronal plane may be used as an alternative to evaluate the nasal bone in the second trimester of pregnancy.

Landmark-based midsagittal plane analysis in patients with facial symmetry and asymmetry based on CBCT analysis tomography.

PURPOSE: Reconstruction of the facial midplane is relevant in anthropometry, orthodontics, maxillofacial surgery, and the accurate measurement of symmetry deviation is relevant in many fields of medicine especially when planning surgical treatment. In the literature, three different means of midplane generation have been published; however, there is currently no consensus regarding the approach to use. Morphometric methods are used to determine the true midsagittal plane (MSP), but its use in clinical practice is difficult. A regression plane based on N­ANS-PNS landmarks reportedly approximates the morphometric MSP. As these points are vulnerable, we investigated which combination of landmarks can be substituted in symmetric and asymmetric faces. PATIENTS AND METHODS: Thirty symmetric and 30 asymmetric faces were analyzed on cone-beam computed tomography scans. A total of 50 regression planes were generated based on three unpaired landmarks and 35 regression planes were generated based the midpoints of paired landmarks. The Na-ANS-PNS plane was used as reference plane, and the mean angle between it and each generated MSP was calculated. The differences from the reference plane were compared by t­test between the groups. RESULTS: In the symmetric group, 86% of angles deviated by <5° using unpaired points, whereby 74% of angles deviated by <5° for paired points. Between the two groups 50% of planes from midline points, and 77% of planes from paired points were significantly different. All planes deviated more in the asymmetric group. CONCLUSIONS: The N­ANS-PNS reference plane can be substituted with the following combinations: ANS-G-Ba, ANS-G-S, ANS-S-De, PNS-G-Ba, PNS-S-Ba, PNS-ANS-G, and PNS-N-Ba.

Accuracy of two midsagittal planes in three-dimensional analysis and their measurement in patients with skeletal mandibular deviation: a comparative study.

Our aim was to evaluate the accuracy of two midsagittal planes (MSP) to provide a better reference plane for studying the 3-dimensional structural symmetry in patients with skeletal mandibular deviation. Thirty adult patients with facial asymmetry were admitted to the Department of Orthodontics, Hospital of Stomatology, between January 2015 and 2017. The DICOM data were collected and reconstructed using ProPlan CMF® 2.0 (Materialise). Two sets of reference planes were set up. In the orbital margin plane group, the plane crossing the nasion (N) point and perpendicular to the frontozygomatic (FZ) suture line was used as the MSP. In the skull base plane group, the MSP was established using the sella turcica (S), N, and basion (Ba). The distances from the craniofacial skeletal and soft tissue midline landmarks to the two MSP were separately measured, and the significance of differences between measurements corresponding to two reference planes were assessed using the paired t test. Except for the posterior nasal spine (PNS)-MSP, the distances from other soft and hard tissue landmarks to the MSP in the orbital margin plane group were significantly shorter than those in the skull base plane group. In the 3-dimensional measurement analysis, the skeletal and soft tissue anatomical midline landmarks were closer to the MSP in the orbital margin plane group. The MSP crossing point N, perpendicular to the FZ suture line, was more accurate and suitable.

New approach to establish an object reference frame for dental arch in computer-aided surgical simulation.

The purpose of this study was to develop a principal component analysis-based adaptive minimum Euclidean distances (PAMED) approach to establish an optimal object reference frame for symmetrical alignment of the dental arch during computer-aided surgical simulation (CASS). It was compared with our triangular methods and the standard principal component analysis (PCA) method. Thirty sets of maxillary digital models were used. Midsagittal and occlusal planes were ranked by three experienced evaluators based on their clinical judgment. The results showed that for the midsagittal plane, all three evaluators ranked "ideal" for all 30 models with the PAMED method, 28 with the triangular method, and at least 11 with the PCA method. For the occlusal plane, one evaluator ranked all 30 models "ideal" with both the PAMED and the PCA methods while the other two evaluators ranked all 30 models "ideal" with the triangular method. However, the differences among the three methods were minimal. In conclusion, our PAMED method is the most reliable and consistent approach for establishing the object reference frame for the dental arch in orthognathic surgical planning. The triangular method should be used with caution because it can be affected by dental arch asymmetry. The standard PCA method is not recommended.

The primal sagittal plane of the head: a new concept.

To assess facial form, one has to determine the size, position, orientation, shape, and symmetry of the different facial units. Many of these assessments require a frame of reference. The customary coordinate system used for these assessments is the 'standard anatomical frame of reference', a three-dimensional Cartesian system made by three planes: the sagittal, the axial, and the coronal. Constructing the sagittal plane seems simple, but because of universal facial asymmetry, it is complicated. Depending on the method one selects, one can build hundreds of different planes, never knowing which one is correct. This conundrum can be solved by estimating the sagittal plane a patient would have had if his or her face had developed symmetrically. We call this the 'primal sagittal plane'. To estimate this plane we have developed a mathematical algorithm called LAGER (Landmark Geometric Routine). In this paper, we explain the concept of the primal sagittal plane and present the structure of the LAGER algorithm.

Retrograde lag screw placement in anterior acetabular column with regard to the anterior pelvic plane and midsagittal plane -- virtual mapping of 260 three-dimensional hemipelvises for quantitative anatomic analysis.

Percutaneous screw placement can be used for minimally invasive treatment of none or minimally displaced fractures of the anterior column. The complex pelvic geometry can pose a major challenge even for experienced surgeons. The present study examined the preformed bone stock of the anterior column in 260 hemipelvises (130 male and 130 female). Screws were virtually implanted using iPlan(®) CMF (BrainLAB AG, Feldkirchen, Germany); the maximal implant length and the maximal implant diameter were assessed. The study showed, that 6.5mm can generally be used in men; in women however individual planning is essential in regard to the maximal implant diameter since we found that in 15.4% of women, screws with a diameter less than 6.5mm were necessary. The virtual analysis of the preformed bone stock corridor of the anterior column showed two constrictions of crucial clinical importance. These can be found after 18% and 55% (men) respectively 16% and 55% (women) measured from the entry point along the axis of the implant. The entry point of the retrograde anterior column screw in our collective was located lateral of tuberculum pubicum at the level of the superior-medial margin of foramen obturatum. In female patients, the entry point was located significantly more lateral of symphysis and closer to the cranial margin of ramus superior ossis pubis. The mean angle between the screw trajectory and the anterior pelvic plane in sagittal section was 31.6 ± 5.5°, the mean angle between the screw trajectory and the midsagittal plane in axial section was 55.9 ± 4.6° and the mean angle between the screw trajectory and the midsagittal plane in coronal section was 42.1 ± 3.9° with no significant deviation between both sexes. The individual angles formed by the screw trajectory and the anterior pelvic and midsagittal plane are independent from anthropometric parameters sex, age, body length and weight. Therefore, they can be used for orientation in lag screw placement keeping in mind that the entry point differs in both sexes.

Automated interhemispheric surface extraction in T1-weighted MRI using intensity and symmetry information.

BACKGROUND: Localizing the human interhemispheric region is of interest in image analysis mainly because it can be used for hemisphere separation and as a preprocessing step for interhemispheric structure localization. Many existing methods focus on only one of these applications. NEW METHOD: Here a new Intensity and Symmetry based Interhemispheric Surface extraction method (ISIS) that enables both applications is presented. A combination of voxel intensity and local symmetry is used to optimize a surface from T1-weighted MRI. RESULTS: ISIS was evaluated in regard to cerebral hemisphere separation using manual segmentations. It was also evaluated in regard to being a preprocessing step for interhemispheric structure localization using manually placed landmarks. COMPARISON WITH EXISTING METHODS: Results were compared to cerebral hemisphere separations by BrainVisa and Freesurfer as well as to a midsagittal plane (MSP) extraction method. ISIS had less misclassified voxels than BrainVisa (ISIS: 0.119±0.114%, BrainVisa: 0.138±0.084%, p=0.020). Freesurfer had less misclassified voxels than ISIS for one dataset (ISIS: 0.063±0.056%, Freesurfer: 0.049±0.044%, p=0.019), but failed to produce usable results for another. Total voxel distance from all manual landmarks did not differ significantly between ISIS and the MSP method (ISIS: 4.00±1.88, MSP: 4.47±4.97). CONCLUSIONS: ISIS was found successful in both cerebral hemisphere separation and as a preprocessing step for interhemispheric structure localization. It needs no time consuming preprocessing and extracts the interhemispheric surface in less than 30 s.