3D Correction Research Articles

Dual polarity encoded MRI using high bandwidth radiofrequency pulses for robust imaging with large field inhomogeneity

The ability to use dual polarity encoded MRI with the missing pulse steady-state free precession (MP-SSFP) sequence is demonstrated to perform robust MRI with low radiofrequency (RF) amplitude, where the field is distorted by embedding metallic screws in an agar phantom. Image-based estimation of the 3D ΔB0 map and image distortion correction is shown to require ~1 minute to perform. Dual polarity encoded MP-SSFP was implemented at 1.5T and used to image agar phantoms with one stainless steel and one titanium screw embedded inside. A multispectral fast spin-echo acquisition was performed for comparison. Self-consistent ΔB0 estimation is performed iteratively using a 3D B-spline basis, which is compared to the ΔB0 estimate generated by the multispectral sequence. Dual polarity encoded MP-SSFP yields image quality similar to the multispectral sequence used with substantially less imaging time, provided the MP-SSFP experimental parameters are chosen well. The multispectral sequence appears to visualize modestly closer in proximity to the metallic screws used, despite the spectral bins covering the same bandwidth as the pulses used in MP-SSFP. However, MP-SSFP avoids ripple artifacts characteristic of the multispectral sequence. The ΔB0 estimate generated by MP-SSFP is qualitatively similar to that generated by the multispectral sequence but larger in magnitude. Despite longer processing time compared to multispectral imaging, MP-SSFP yields similar image quality with significantly lower acquisition times in the absence of parallel imaging. The work herein demonstrates the ability to perform 3D ΔB0 estimation and image correction within a reasonable amount of time, ~1 minute.

Motion compensated whole-heart coronary cardiovascular magnetic resonance angiography using focused navigation (fNAV)

BackgroundRadial self-navigated (RSN) whole-heart coronary cardiovascular magnetic resonance angiography (CCMRA) is a free-breathing technique that estimates and corrects for respiratory motion. However, RSN has been limited to a 1D rigid correction which is often insufficient for patients with complex respiratory patterns. The goal of this work is therefore to improve the robustness and quality of 3D radial CCMRA by incorporating both 3D motion information and nonrigid intra-acquisition correction of the data into a framework called focused navigation (fNAV).MethodsWe applied fNAV to 500 data sets from a numerical simulation, 22 healthy subjects, and 549 cardiac patients. In each of these cohorts we compared fNAV to RSN and respiratory resolved extradimensional golden-angle radial sparse parallel (XD-GRASP) reconstructions of the same data. Reconstruction times for each method were recorded. Motion estimate accuracy was measured as the correlation between fNAV and ground truth for simulations, and fNAV and image registration for in vivo data. Percent vessel sharpness was measured in all simulated data sets and healthy subjects, and a subset of patients. Finally, subjective image quality analysis was performed by a blinded expert reviewer who chose the best image for each in vivo data set and scored on a Likert scale 0–4 in a subset of patients by two reviewers in consensus.ResultsThe reconstruction time for fNAV images was significantly higher than RSN (6.1 ± 2.1 min vs 1.4 ± 0.3, min, p < 0.025) but significantly lower than XD-GRASP (25.6 ± 7.1, min, p < 0.025). Overall, there is high correlation between the fNAV and reference displacement estimates across all data sets (0.73 ± 0.29). For simulated data, healthy subjects, and patients, fNAV lead to significantly sharper coronary arteries than all other reconstruction methods (p < 0.01). Finally, in a blinded evaluation by an expert reviewer fNAV was chosen as the best image in 444 out of 571 data sets (78%; p < 0.001) and consensus grades of fNAV images (2.6 ± 0.6) were significantly higher (p < 0.05) than uncorrected (1.7 ± 0.7), RSN (1.9 ± 0.6), and XD-GRASP (1.8 ± 0.8).ConclusionfNAV is a promising technique for improving the quality of RSN free-breathing 3D whole-heart CCMRA. This novel approach to respiratory self-navigation can derive 3D nonrigid motion estimations from an acquired 1D signal yielding statistically significant improvement in image sharpness relative to 1D translational correction as well as XD-GRASP reconstructions. Further study of the diagnostic impact of this technique is therefore warranted to evaluate its full clinical utility.

Correction objectives have higher impact than screw pattern and density on the optimal 3D correction of thoracic AIS: a biomechanical study

Study designAssessment of screw pattern, implant density (ID), and optimization of 3D correction through computer-based biomechanical models.ObjectiveTo investigate how screw pattern and ID affect intraoperative 3D correction of thoracic curves in adolescent idiopathic scoliosis, and how different correction objectives impact the optimal screw pattern.Summary of background dataScrew pattern, ID, correction objectives and surgical strategies for posterior fusion of AIS are highly variable among experienced surgeons. The “optimal” instrumentation remains not well defined.Methods10 patient-specific multibody models of representative adolescent idiopathic scoliosis Lenke 1A cases were built and used to compare alternative virtual correction surgeries. Five screw patterns and IDs (average: 1.6 screws/instrumented level, range: 1.2–2) were simulated, considering concave rod rotation, en bloc derotation, and compression/distraction as primary correction maneuvers. 3D correction descriptors were quantified in the coronal, sagittal and transverse planes. An objective function weighting the contribution of intraoperative 3D correction and mobility allowed rating of the outcomes of the virtual surgeries. Based on surgeon-dependent correction objectives, the optimal result among the simulated constructs was identified.ResultsLow-density (ID ≤ 1.4) constructs provided equivalent 3D correction compared to higher (ID ≥ 1.8) densities (average differences ranging between 2° and 3°). The optimal screw pattern varied from case to case, falling within the low-density screw category in 14% of considered scenarios, 73% in the mid-density (1.4 < ID < 1.8) and 13% in the high-density. The optimal screw pattern was unique in five cases; multiple optima were found in other cases depending on the considered correction objectives.ConclusionsLow-density screw patterns provided equivalent intraoperative 3D correction to higher-density patterns. Simulated surgeon’s choice of correction objectives had the greatest impact on the selection of the optimal construct for 3D correction, while screw density and ID had a limited impact.Level of evidenceN/A.

3D Technique-Based Nonsurgical Correction of Deformational Congenital Auricular Deformities

Introduction: Congenital auricular deformity (CAD) is a common postpartum deformity, and nonsurgical correction of CAD has been recognized as a safe and effective approach. Three-dimensional (3D) technique has been used in surgical reconstruction of unilateral microtia; however, 3D technique used in nonsurgical correction for deformational CAD has not been reported. Methods: In this study, 12 CAD patients aged from 0.6 to 7 months with 16 deformational CAD were treated with 3D technique-based personalized nonsurgical correction (3D-NSC). Patients’ CAD was photographed pre- and post-correction, and clinical outcome was evaluated as poor, fair, good, and excellent by comparing pre- and post-correction pictures. Different kinds of tests were used to analyze the data. Results: All patients got an improved auricle shape (10 excellent, 2 good, and 4 fair). Multivariate regression analysis showed that CAD type was significantly associated with correction outcome, sex and age were significantly associated with correction outcome for the 11 constructed types of CAD, and age was significantly associated with the correction outcome when we focused on the male constructed auricles. Conclusion: 3D-NSC provided a significant nonsurgical clinical treatment for CAD patients, with younger patients getting better clinical outcomes with shorter correction time.

Subcretionary tectonics: Linking variability in the expression of subduction along the Cascadia forearc

A number of seismic and other geophysical phenomena exhibit significant lateral heterogeneity along the strike of the Cascadia forearc. Both the overriding and downgoing plate have been invoked to play the dominant role in controlling along-strike correlations between seismogenic behavior, potential field measurements, morphological/tectonic characteristics, and seismic structure; however, significant feedbacks likely exist between the two. In this study, we apply a 3D velocity correction to receiver function data and interpret the resulting discontinuity model alongside a recently published shear-wave velocity model to understand the possible causative relationships between correlative along-strike variations. Our discontinuity model indicates that the forearc crust thickens as it approaches the mantle wedge corner before progressively thinning toward the magmatic arc, likely due to the basal accretion of material from the downgoing plate to the overriding plate. In the northern and southern portions of the forearc, this “subcreted” material is characterized by thick (∼10 km) anomalously low shear-wave velocity zones. The thickness, high internal reflectivity, and low Bouguer gravity signatures associated with the low velocity zones likely indicate that this subcreted material is composed of dominantly (meta)sedimentary material that has been emplaced through successive subcretion events over geologic timescales. Furthermore, the anomalously low velocities and spatial correlation with high non-volcanic tremor (NVT) density and short slow slip recurrence intervals indicate that these regions are fluid-rich. While first-order variations in the fluids that control NVT and slow slip likely result from differences in the permeability of the downgoing slab as inferred from its stress state and the distribution of intraslab seismicity, these subcreted packages likely represent thick, vertically-impermeable regions in the lower crust that further accentuate this correlation. Variability in the amount of subcretion explains patterns of exhumation and uplift along the Cascadia margin and the resulting forearc topography over geologic timescales, and is likely controlled by some combination plate interface geometry/rheology and overriding plate architecture.

Numerical simulation of the Mexico wind turbine using the actuator disk model along with the 3D correction of aerodynamic coefficients in OpenFOAM

A foremost element in aerodynamic behavior analysis of wind turbines is numerical simulation. Actuator disk model is a method which enables us to simulate and analyze the flow fields and wakes behind the rotor by reducing the fluid computation around the rotor and solving the Navier-Stokes equations without considering the blade boundary layer. In addition of the need for constructing a realistic geometrical model, one also must run a simulation with very small grid spacing and time steps to resolve the blade boundary layer dynamics leading to the aerodynamic forces, which is also extremely expensive. In this paper actuator disk model along with a 3D corrected aerodynamic coefficients was implemented in the OpenFOAM software to simulate the MEXICO wind turbine rotor. The simulations were performed under three conditions: turbulent, design and stall conditions. The results of simulation including an estimation of the blade forces and the wakes velocity field were compared with the experimental results. It was found that the 3D corrected aerodynamic coefficients of airfoils led to an improved agreement between the simulation and experimental results, compared to a model implementing original aerodynamic coefficients.

In silico patient-specific optimization of correction strategies for thoracic adolescent idiopathic scoliosis

BackgroundWith modelling and simulation (or in silico) techniques, patient-specific optimization algorithms represent promising tools to support the surgical decision-making process, particularly in 3D correction of adolescent idiopathic scoliosis, where the best intraoperative instrumentation strategy and the correction goals are debated. Methods1080 biomechanical intraoperative simulations of a representative pediatric thoracic curve were run according to a full-factorial design approach. Widely accepted instrumentation configurations (5 screw patterns, 4 upper and 3 lower instrumented vertebrae, 6 rod curvatures and 3 rod stiffnesses) were analyzed, assuming concave rod rotation and en bloc derotation as main correction maneuvers. Results in terms of 3D correction and mobility were rated using an objective function for thoracic scoliosis also including surgeon-dependent correction objectives. An extensive sensitivity analysis on correction objectives was performed. FindingsMultiple optimal strategies were identified, depending on the selected correction objective. They provided significantly better coronal (67% vs. 55%) correction, using comparable instrumented levels (9.9 ± 1.6 vs. 10.7 ± 2.1), screw patterns and significantly higher implant density (1.6 ± 0.3 vs. 1.4 ± 0.2 screws/vertebra) compared to worst ones. Optimal strategies typically included the neutral and the last touching vertebrae in the construct and high stiffness (CoCr, 6 mm) differentially/highly contoured rods. InterpretationThe computerized algorithm determined the best instrumentation parameters to achieve optimal correction for the considered thoracic case. Multiple clinically equivalent strategies may be used, as supported by the variety of considered correction objectives. The current approach could be translated to any scoliotic curves, including surgeon preferences in terms of instrumentation parameters, intraoperative correction maneuvers and correction objectives.

Impact of 3-Dimensional Versus 2-Dimensional Image Distortion Correction on Stereotactic Neurosurgical Navigation Image Fusion Reliability for Images Acquired With Intraoperative Magnetic Resonance Imaging.

Fusion of preoperative and intraoperative magnetic resonance imaging (iMRI) studies during stereotactic navigation may be very useful for procedures such as tumor resections but can be subject to error because of image distortion. To assess the impact of 3-dimensional (3D) vs 2-dimensional (2D) image distortion correction on the accuracy of auto-merge image fusion for stereotactic neurosurgical images acquired with iMRI using a head phantom in different surgical positions. T1-weighted intraoperative images of the head phantom were obtained using 1.5T iMRI. Images were postprocessed with 2D and 3D image distortion correction. These studies were fused to T1-weighted preoperative MRI studies performed on a 1.5T diagnostic MRI. The reliability of the auto-merge fusion of these images for 2D and 3D correction techniques was assessed both manually using the stereotactic navigation system and via image analysis software. Eight surgical positions of the head phantom were imaged with iMRI. Greater image distortion occurred with increased distance from isocenter in all 3 axes, reducing accuracy of image fusion to preoperative images. Visually reliable image fusions were accomplished in 2/8 surgical positions using 2D distortion correction and 5/8 using 3D correction. Three-dimensional correction yielded superior image registration quality as defined by higher maximum mutual information values, with improvements ranging between 2.3% and 14.3% over 2D correction. Using 3D distortion correction enhanced the reliability of surgical navigation auto-merge fusion of phantom images acquired with iMRI across a wider range of head positions and may improve the accuracy of stereotactic navigation using iMRI images.

A modular phantom and software to characterize 3D geometric distortion in MRI

Magnetic resonance imaging (MRI) offers outstanding soft tissue contrast that may reduce uncertainties in target and organ-at-risk delineation and enable online adaptive image-guided treatment. Spatial distortions resulting from non-linearities in the gradient fields and non-uniformity in the main magnetic field must be accounted for across the imaging field-of-view to prevent systematic errors during treatment delivery. This work presents a modular phantom and software application to characterize geometric distortion (GD) within the large field-of-view MRI images required for radiation therapy simulation. The modular phantom is assembled from a series of rectangular foam blocks containing high-contrast fiducial markers in a known configuration. The modular phantom design facilitates transportation of the phantom between different MR scanners and MR-guided linear accelerators and allows the phantom to be adapted to fit different sized bores or coils. The phantom was evaluated using a 1.5 T MR-guided linear accelerator (MR-Linac) and 1.5 T and 3.0 T diagnostic scanners. Performance was assessed by varying acquisition parameters to induce image distortions in a known manner. Imaging was performed using T1 and T2 weighted pulse sequences with 2D and 3D distortion correction algorithms and the receiver bandwidth (BW) varied as 250–815 Hz pixel−1. Phantom set-up reproducibility was evaluated across independent set-ups. The software was validated by comparison with a non-modular phantom. Average geometric distortion was 0.94 ± 0.58 mm for the MR-Linac, 0.90 ± 0.53 mm for the 1.5 T scanner, and 1.15 ± 0.62 mm for the 3.0 T scanner, for a 400 mm diameter volume-of-interest. GD increased, as expected, with decreasing BW, and with the 2D versus 3D correction algorithm. Differences in GD attributed to phantom set-up were 0.13 mm or less. Differences in GD for the two software applications were less than 0.07 mm. A novel modular phantom was developed to evaluate distortions in MR images for radiation therapy applications.

Investigations of HAWT Airfoil Shape Characteristics and 3D Rotational Augmentation Sensitivity Toward the Aerodynamic Performance Improvement

This study investigates the impacts of dierent airfoil shapes on the 3D augmentationand power production of horizontal axis wind turbines (HAWTs). The aerodynamic eect fromchanging the leading and trailing edge of the airfoil is the emphasis of the research. Varied powerproduced from modifying sensitivity on 3D augmentations, caused by revamping airfoil shapes, areshown. The 3D correction law, considering the chord to radius ratio and the blades’ pitch angle inthe rotation, is applied to the airfoil lift coecients. The blade element method (BEM) embeddedin the software Qblade with modified lift coecients simulates the power productions of threewind turbines from these airfoils. The comparisons of the boundary layer characteristics, sectionalforces, and inflow angle of the blade sections are calculated. The k-omega SST turbulence model inOpenFoam visualizes the stall and separation of the blades’ 2D section. The airfoils with a roundedleading edge show a reduced stall and separated flow region. The power production is 2.3 timeshigher for the airfoil constructed with a more rounded leading edge S809r and two times higher forthe airfoil S809gx of the symmetric structure.

Three-dimensional analysis of spinal deformity correction in adolescent idiopathic scoliosis: comparison of two distinct techniques

To compare 3D postoperative deformity correction using two distinct commonly utilized techniques for the treatment of adolescent idiopathic scoliosis (AIS). AIS patients with major thoracic (Lenke 1-2) curves at two sites who underwent deformity correction via posterior spinal instrumented fusion using one of two distinct techniques were retrospectively reviewed. Patients were matched 1:1 between sites for Lenke type (95% Lenke 1) and follow-up time. The "band site" performed posteromedial translation using thoracic sublaminar bands and 5.5-mm rods. The "screw site" performed spine derotation using differential rod contouring with pedicle screws and 5.5-mm rods. 3D measures of deformity from spinal reconstructions were compared between sites. Preoperatively, the groups had similar thoracic curve magnitudes (band, 55 ± 12° vs. screw, 52 ± 10°; p > 0.05); the "screw site" had less T5-T12 kyphosis (2 ± 14° vs. 7 ± 12°, p = 0.05) and greater thoracic apical rotation (- 19 ± 7° vs. - 14 ± 8°, p = 0.007). Postoperatively, the "screw site" had greater percent correction (61% vs. 76%, p < 0.001) and kyphosis restoration (p = 0.002). The groups achieved a similar amount of apical derotation (p = 0.9). The "band site" used cobalt chromium rods exclusively; the "screw site" used cobalt chromium (3%) and stainless steel (97%; p < 0.001). The "band site" performed significantly longer fusions. Significant variations were found between two commonly utilized techniques in AIS surgery, including rod material, correction mechanisms, and fusion levels. Significantly, a greater 3D deformity correction of the coronal and sagittal planes was observed at the "screw site" compared to the "band site", but with no difference in axial plane correction.

New growth rod concept provides three dimensional correction, spinal growth, and preserved pulmonary function in early-onset scoliosis.

This study aims to describe a novel minimal invasive early-onset scoliosis (EOS) growth rod concept, the Cody Bünger (CB) Concept, which combines concave interval distraction and contralateral-guided growth with apical control and to investigate the 3D deformity correction, the spinal growth, and the pulmonary development. A series of 38 children with progressive EOS and growth potential, receiving a highly specialized surgical treatment, including primary and conversion cases. Mean age was 10.2years (4.4-15.8) with a mean follow-up of 5.6years, and they underwent 168/184 open/magnetic lengthening procedures. Outcomes were as follows: scoliosis, kyphosis, and lordosis angles; apical rotation; spinal length; apical translation; coronal and sagittal vertical alignment; complications; and pulmonary function in a subgroup. Scoliosis improved from mean 76° (46-129) to 35° (8-74) post-op and was 42° (13-83) at end of treatment. Apical rotation was reduced by 30% but was partially lost during treatment. Thoracic kyphosis initially decreased by mean 15° and was partially lost during treatment. Lordosis was largely unaltered during treatment. Mean T1-S1 height increased from 30.7cm (22.7-39.2) to 34.6cm (27.8-45.1) postop and further increased to 38.5cm (30.1-48.1) during treatment. This corresponded to a T1-S1 growth rate of 12mm/year, and positive growth rates were found in all height parameters evaluated. Frontal balance and apical translation improved, whereas sagittal balance was unaltered. Complications occurred in 22/38 patients, and 11/38 had an unintended reoperation. Pulmonary function (FVC and FEV) increased but the relative lung function was unchanged. The new growth rod concept provided 3D correction and spinal growth at complication rates comparable with other growth-friendly techniques for EOS, while pulmonary function was preserved. Single magnetic rod distraction was incorporated successfully, replacing surgical elongations.

A 3D Parameter Can Guide Concave Rod Contour for the Correction of Hypokyphosis in Adolescent Idiopathic Scoliosis.

Retrospective. To evaluate the effect of preoperative rod shape on 3D spinal deformity correction. Differential rod contouring is a surgeon-dependent process based on an estimate of 3D deformity correction sought and the flexibility of the spine. An objective measure to this otherwise subjective scoliosis correction technique is lacking. A series of adolescent idiopathic scoliosis (AIS) patients with right, thoracic major curves, preoperative rod contour tracings, and EOS imaging was evaluated. All patients underwent posterior spinal fusion with 5.5 mm steel rods contoured prior to insertion. 3D reconstructions were generated pre- and postoperatively using sterEOS software (EOS Imaging) and imported into MATLAB (Mathworks) for analysis. A new measurement of the maximum perpendicular distance from the preinsertion concave rod contour to the preoperative 3D sagittal spinal reconstruction was defined as rod to 3D spine distance (RSD). Linear regressions were used to identify relationships between pre and postoperative parameters, including RSD and 3D thoracic kyphosis. Ninety-nine patients were included. Average preoperative concave rod angle decreased from (48 ± 10°) preoperatively to 26 ± 6° postoperatively (P < 0.001) for an average flattening of ∼20°. Average convex rod angle increased from 30 ± 6° to 34 ± 5° (P < 0.001). Average preoperative thoracic curve magnitude and apical vertebral rotation were 57 ± 8° and 16 ± 5° and decreased to 11 ± 6° and 5 ± 6° (P < 0.001). Average 2D and 3D thoracic kyphosis increased from 19 ± 14° and 2 ± 12° to 27 ± 6° and 22 ± 5° (P < 0.001). Preoperative RSD strongly correlated with 3D thoracic kyphosis change (P < 0.001, r = 0.796, R = 0.633). On average, the concave rod flattened ∼20° after connection to the spine. Similarly, kyphosis increased ∼20° following rod insertion. A strong correlation was identified between RSD and 3D thoracic kyphosis restoration. This novel 3D parameter can guide the degree of concave rod bend necessary to achieve a desired increase in thoracic kyphosis in AIS. 2.

Anterior Vertebral Body Growth Modulation: Assessment of the 2-year Predictive Capability of a Patient-specific Finite-element Planning Tool and of the Growth Modulation Biomechanics.

Numerical planning and simulation of immediate and after 2 years growth modulation effects of anterior vertebral body growth modulation (AVBGM). The objective was to evaluate the planning tool predictive capability for immediate, 1-year, and 2-year postoperative correction and biomechanical effect on growth modulation over time. AVBGM is used to treat pediatric scoliotic patients with remaining growth potential. A planning tool based on a finite element model (FEM) of pediatric scoliosis integrating growth was previously developed to simulate AVBGM installation and growth modulation effect. Forty-five patients to be instrumented with AVBGM were recruited. A patient-specific FEM was preoperatively generated using a 3D reconstruction obtained from biplanar radiographs. The FEM was used to assess different instrumentation configurations. The strategy offering the optimal 2-year postoperative correction was selected for surgery. Simulated 3D correction indices, as well as stresses applied on vertebral epiphyseal growth plates, intervertebral discs, and instrumentation, were computed. On average, six configurations per case were tested. Immediate, 1-year, and 2-year postoperative 3D correction indices were predicted within 4° of that of actual results in coronal plane, whereas it was <0.8 cm (±2%) for spinal height. Immediate postoperative correction was of 40%, whereas an additional correction of respectively 13% and 3% occurred at 1- and 2 year postoperative. The convex/concave side computed forces difference at the apical level following AVBGM installation was decreased by 39% on growth plates and 46% on intervertebral discs. This study demonstrates the FEM clinical usefulness to rationalize surgical planning by providing clinically relevant correction predictions. The AVBGM biomechanical effect on growth modulation over time seemed to be maximized during the first year following the installation. 3.

3-Year follow-up of a single magnetically controlled growing rod with contralateral gliding system and apical control for early onset scoliosis

Study designTwo-center retrospective cohort study.ObjectiveThe aim of this study is to investigate the clinical effectiveness and safety of the MCGR hybrid in terms of spinal growth, 3D correction, balance, and complications.Summary of background dataThe magnetic-controlled growing-rod (MCGR) growth instrumentation method has gained popularity for early onset scoliosis (EOS) treatment in the past years due to the non-invasiveness of the subsequent interval elongation procedures. To improve 3D correction and reduce the costs, we combined a single concave MCGR with a sliding rod on the convex side to control the apex.MethodsA retrospective cohort study of 18 EOS children with an average 3-year follow-up (range 2.0–3.7) from two European spine centers treated with the single MCGR hybrid concept; 14 primary and 4 conversion cases. The primary and conversion cases were both evaluated preoperatively, postoperatively, 1 year, 2 years, and last follow-up.ResultsMean age was 9.9 (SD ± 2.9 years). The average frontal Cobb angle was reduced from mean 65° to 30° postoperatively, and had increased to 37° at latest follow-up. Rotation of the apical vertebra improved from mean 27° to 20° postoperatively which was partially lost to 23°. Kyphosis and lordosis both increased by an average of 5° during the time of follow-up. Spinal balance was improved. The post-implantation T1–S1 spine growth rate averaged 10 mm/year at last follow-up. There were 13 implant-related complications in 6 out of 18 patients. No screw pull-outs and nor surgical site infections were registered.ConclusionsThis is the first medium-term results of a single MCGR hybrid construct. Maintenance of correction and growth are reasonable, and the complication rate is relatively low as compared to bilateral MCGR application.Level of evidenceIII.

Clinical application of individualized 3D-printed navigation template to children with cubitus varus deformity

BackgroundCubitus varus deformity is a common sequela of elbow fractures in children. Cubitus varus deformity treatment is tending toward 3D correction, which is challenging for orthopedic surgeons. This study aims to explore whether individualized 3D-printed navigation templates can assist with accurate and effective corrective treatment of children with cubitus varus deformity.MethodsThirty-five patients were treated for cubitus varus deformity from June 2015 to April 2017, including 21 boys and 14 girls, aged 4.6–13.2 years (average, 7.5 years). Of these cases, 17 deformities were on the left side and 18 were on the right side. All were treated with wedge osteotomy of the lateral distal humerus. 3D-printed navigation templates were used in 16 cases, while traditional surgery was used in 19 cases. All patients underwent computed tomography scans before surgery. Computer software was used to analyze the measurements and design and print individualized navigation templates. The navigation templates were matched, and surgery was initially simulated. Intraoperative individualized navigation templates were used to assist with accurate osteotomy and Kirschner wire fixation. Operation times were recorded in all cases, the carrying angles before and after surgery were assessed by computer, and postoperative elbow joint function was evaluated using Bellemore criteria. All measurement data were presented as means ± SD, and Student’s t test was used to examine differences between groups. All count data between both groups were compared using the chi-square test or Fisher’s exact test analysis.ResultsAll individualized navigation templates matched well with the corresponding anatomical markers and were consistent with preoperative planning, simulated surgery, and intraoperative procedures. Average operation times from clear exposure to fixed Kirschner wire were 11.69 min (9.6–13.5 min) for the individualized navigation template group and 22.89 min (17.7–26.8 min) for the traditional operation group (p < 0.001). Average differences in postoperation carrying angles between affected and healthy sides were 1.13° (0–2.0°) and 4.21° (0–7.5°), respectively (p < 0.001). Follow-up 6–12 months postoperation showed that elbow function did not differ significantly between groups using the Bellemore criteria (p > 0.05).ConclusionsIndividualized navigation templates simplify procedures, reduce operation time, and improve accuracy when used in orthopedic surgery to treat children with cubitus varus deformity.

Motion-corrected and high-resolution anatomically assisted (MOCHA) reconstruction of arterial spin labeling MRI.

PurposeA model‐based reconstruction framework is proposed for motion‐corrected and high‐resolution anatomically assisted (MOCHA) reconstruction of arterial spin labeling (ASL) data. In this framework, all low‐resolution ASL control‐label pairs are used to reconstruct a single high‐resolution cerebral blood flow (CBF) map, corrected for rigid‐motion, point‐spread‐function blurring and partial volume effect.MethodsSix volunteers were recruited for CBF imaging using pseudo‐continuous ASL labeling, two‐shot 3D gradient and spin‐echo sequences and high‐resolution T1‐weighted MRI. For 2 volunteers, high‐resolution scans with double and triple resolution in the partition direction were additionally collected. Simulations were designed for evaluations against a high‐resolution ground‐truth CBF map, including a simulated hyperperfused lesion and hyperperfusion/hypoperfusion abnormalities. The MOCHA technique was compared with standard reconstruction and a 3D linear regression partial‐volume effect correction method and was further evaluated for acquisitions with reduced control‐label pairs and k‐space undersampling.ResultsThe MOCHA reconstructions of low‐resolution ASL data showed enhanced image quality, particularly in the partition direction. In simulations, both MOCHA and 3D linear regression provided more accurate CBF maps than the standard reconstruction; however, MOCHA resulted in the lowest errors and well delineated the abnormalities. The MOCHA reconstruction of standard‐resolution in vivo data showed good agreement with higher‐resolution scans requiring 4‐times and 9‐times longer acquisitions. The MOCHA reconstruction was found to be robust for 4‐times‐accelerated ASL acquisitions, achieved by reduced control‐label pairs or k‐space undersampling.ConclusionThe MOCHA reconstruction reduces partial‐volume effect by direct reconstruction of CBF maps in the high‐resolution space of the corresponding anatomical image, incorporating motion correction and point spread function modeling. Following further evaluation, MOCHA should promote the clinical application of ASL.

Prospects for CNC Machine Tools

The main global trends in the production of high-technology CNC systems are identified. Topics analyzed include system architecture; the use of high-speed industrial networks based on fieldbus technologies; the potential of multiple-channel and multiple-axis machining; spline interpolation in the machining of complex contours and free surfaces; and five-coordinate machining with 3D correction of the tool radius and length. In the light of global trends, decisions are made regarding the development of the AksiOMA Kontrol CNC system.

Yves Cotrel and the Revolution of Scoliosis Surgery, in Memoriam

In Brief Yves Cotrel passed away on January 29, 2019, at the age of 93. Dr Yves Cotrel created a spine fixation system with multiple hooks, allowing quickly recovering of walking and suppression of postoperative brace. He and Jean Dubousset introduced scoliosis 3D correction using bended rods and rotation of the concave rod.

3D nonrigid motion correction for quantitative assessment of hepatic lesions in DCE‐MRI

Magnetic Resonance in MedicineVolume 82, Issue 5 p. C1-C1 COVER IMAGEFree Access 3D nonrigid motion correction for quantitative assessment of hepatic lesions in DCE-MRI First published: 26 July 2019 https://doi.org/10.1002/mrm.27915AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume82, Issue5November 2019Pages C1-C1 RelatedInformation