Anterior-posterior Motion Research Articles

Rehabilitation for atraumatic shoulder instability in circus arts performers: delivery via telehealth.

The Watson Instability Program (WIP1) is current best evidence for conservative management of atraumatic shoulder instability, but it is unknown if this program can be effectively delivered via tele-consultation. The purpose of this longitudinal pre-post intervention study was to determine the effects of the WIP1 on patient-reported outcome measures, scapular position, shoulder strength, and handstand stability in student circus performers with atraumatic shoulder instability when delivered via tele-consultation. Student circus performers aged between 15 and 35 years from the National Institute of Circus Arts were recruited. A 12-week shoulder exercise program was delivered via tele-consultation during the Melbourne, Australia COVID-19 (coronavirus disease 2019) lockdown. The primary outcome measures were the Western Ontario Shoulder Instability Index score and the Melbourne Instability Shoulder Scale score. Secondary outcomes measures included the Orebro Musculoskeletal Pain Questionnaire, the Tampa Scale for Kinesiophobia, and physical assessment measures including strength via handheld dynamometry, scapular position using an inclinometer, and handstand stability via center-of-pressure fluctuation. Patient-reported outcomes were collected at baseline and 6-week, 12-week, 6-month, and 9-month time points, and physical outcomes were measured at baseline and 9-month time points. A repeated-measures mixed model (with effect sizes [ESs] and 95% confidence intervals [CIs]) was used to analyze patient-reported outcomes, handstand data, strength, and scapular measures. Significance was set at P < .05. Twenty-three student circus arts performers completed the study. Significant improvements were found in both Western Ontario Shoulder Instability Index scores (effect size [ES], 0.79 [95% CI, 0.31-1.33] at 6 weeks; ES, 1.08 [95% CI, 0.55-1.6] at 12 weeks; ES, 1.17 [95% CI, 0.62-1.78] at 6 months; and ES, 1.31 [95% CI, 0.74-1.95] at 9 months; P < .001) and Melbourne Instability Shoulder Scale scores (ES, 0.70 [95% CI, 0.22-1.22] at 6 weeks; ES, 0.83 [95% CI, 0.34-1.37] at 3 months; ES, 0.98 [95% CI, 0.46-1.54] at 6 months; and ES, 0.98 [95% CI, 0.43-1.50] at 9 months; P < .001), as well as Orebro Musculoskeletal Pain Questionnaire scores at all follow-up time points. The Tampa Scale for Kinesiophobia scores reached significance at 6 weeks and 12 weeks. Following rehabilitation, we found statistically significant increases in shoulder strength in all positions tested and increased scapular upward rotation measured at end-of-range abduction, as well as during loaded external rotation. The affected arm showed greater instability than the unaffected arm with a significant intervention effect on the affected arm showing a greater consistent anterior-posterior movement pattern. In a group of circus performers with atraumatic shoulder instability, treatment with the WIP1 via telehealth resulted in clinically and statistically significant improvements in shoulder symptoms and function.

Agreement Between Two Methods for Computing the Anterior-Posterior Positions of Native Femoral Condyles Using Three-Dimensional Bone Models With and Without Articular Cartilage and Smoothing.

Knowledge of anterior-posterior (AP) movement of the femoral condyles on the tibia in healthy knees serves to assess whether an artificial knee restores natural movement. Two methods for identifying AP positions and hence condylar movements include: (1) the flexion facet center (FFC) and (2) the lowest point (LP) methods. The objectives were to determine (1) agreement between the two methods and (2) whether addition of articular cartilage and/or smoothing significantly affects AP positions. Magnetic resonance (MR) images of healthy knees were obtained from eleven subjects, who subsequently performed a dynamic, weight-bearing deep knee bend under fluoroscopy. Four different types of MR models of the distal femur were created: femur, smoothed femur, femur with articular cartilage, and femur with smoothed articular cartilage. In the medial and lateral compartments for the femur with smoothed articular cartilage at 0 deg flexion, mean AP positions of the LPs were 7.7 mm and 5.4 mm more anterior than those of the FFCs, respectively (p < 0.0001, p = 0.0002) and limits of agreement were ±5.5 mm. In the flexion range 30 deg to 90 deg, differences in mean AP positions were 1.5 mm or less and limits of agreement were bounded by ±2.4 mm. Differences in mean AP positions between model types were <1.3 mm for both LPs and FFCs. Since omitting articular cartilage from three-dimensional (3D) models of the femur minimally affected AP positions, faster and less expensive imaging techniques such as computed-tomography (CT) can be used to generate 3D bone models for kinematic analysis. In addition, the LP method is preferred over the FFC method because of its inherent accuracy in indicating the AP position of the instant center of curvature of the femoral condyles which varies with the knee in extension versus flexion.

Whole-heart non-rigid motion corrected coronary MRA with autofocus virtual 3D iNAV

PurposeRespiratory motion-corrected coronary MR angiography (CMRA) has shown promise for assessing coronary disease. By incorporating coronal 2D image navigators (iNAVs), respiratory motion can be corrected for in a beat-to-beat basis using translational correction in the foot-head (FH) and right-left (RL) directions and in a bin-to-bin basis using non-rigid motion correction addressing the remaining FH, RL and anterior-posterior (AP) motion. However, with this approach beat-to-beat AP motion is not corrected for. In this work we investigate the effect of remaining beat-to-beat AP motion and propose a virtual 3D iNAV that exploits autofocus motion correction to enable beat-to-beat AP and improved RL intra-bin motion correction. MethodsFree-breathing 3D whole-heart CMRA was acquired using a 3-fold undersampled variable-density Cartesian trajectory. Beat-to-beat 3D translational respiratory motion was estimated from the 2D iNAVs in FH and RL directions, and in AP direction with autofocus assuming a linear relationship between FH and AP movement of the heart. Furthermore, motion in RL was also refined using autofocus. This virtual 3D (v3D) iNAV was incorporated in a non-rigid motion correction (NRMC) framework. The proposed approach was tested in 12 cardiac patients, and visible vessel length and vessel sharpness for the right (RCA) and left (LAD) coronary arteries were compared against 2D iNAV-based NRMC. ResultsAverage vessel sharpness and length in v3D iNAV NRMC was improved compared to 2D iNAV NRMC (vessel sharpness: RCA: 56 ± 1% vs 52 ± 11%, LAD: 49 ± 8% vs 49 ± 7%; visible vessel length: RCA: 5.98 ± 1.37 cm vs 5.81 ± 1.62 cm, LAD: 5.95 ± 1.85 cm vs 4.83 ± 1.56 cm), however these improvements were not statistically significant. ConclusionThe proposed virtual 3D iNAV NRMC reconstruction further improved NRMC CMRA image quality by reducing artefacts arising from residual AP motion, however the level of improvement was subject-dependent.

Four-Dimensional Computed Tomography-Based Correlation of Respiratory Motion of Lung Tumors With Implanted Fiducials and an External Surrogate

PurposeOur purpose was to assess the suitability of airway-implanted internal fiducial markers and an external surrogate of respiratory motion for motion management during radiation therapy of lung tumors. Methods and MaterialsWe analyzed 4-dimensional computed tomography scans acquired during radiation therapy simulation for 28 patients with lung tumors who had anchored fiducial markers bronchoscopically implanted inside small airways in or near the tumor in a prospective trial. We used a linear mixed model to build population-based correlative models of tumor and surrogate motion. The first 24 of the 28 patients were used to build correlative models, and 4 of the 28 consecutive patients were excluded and used as an internal validation cohort. Of the 24 patients from the model building cohort, all were used for the models based on the internal fiducial. The external surrogate was completely visualized in 11 patients from the model building cohort, so only those were used for the models based on the external surrogate. Furthermore, we determined the predicted residual error sum of squares for our correlative models, which may serve as benchmarks for future research. ResultsThe motion of the internal fiducials was significantly associated with the tumor motion in the anterior-posterior (P < .0001) and superior-inferior (SI) directions (P < .0001). We also observed a strong correlation of the external surrogate anterior-posterior motion to the tumor dominant SI motion (P < .0001). In the validation cohort, the internal fiducial SI motion was the only reliable predictor of lung tumor motion. ConclusionsThe internal fiducials appear to be more reliable predictors of lung tumor motion than the external surrogate. The suitability of such airway-implanted internal fiducial markers for advanced motion management techniques should be further investigated. Although the external surrogate seems to be less reliable, its wide availability and noninvasive application support its clinical utility, albeit the greater uncertainty will need to be compensated for.

Quantitative Romberg using a force plate: an objective measure for cervical myelopathy

Surgical decision making for cervical spondylotic myelopathy (CSM) relies on evaluation of symptoms and physical examination. The Romberg test is a clinical exam used to identify balance issues with CSM. However, the Romberg test has a subjective interpretation and has a binary (positive or negative) result. This study aims to compare force plate pressure readings during a standard Romberg test in patients with CSM to age-matched normal healthy volunteers. Prospective cross sectional observational comparative cohort from a single multi-surgeon spine center. Patients who were clinically diagnosed with CSM were compared to age-matched healthy volunteers without a clinical history of spine pathology. Quantitative Romberg Force Plate Measurements METHODS: Patients with CSM requiring surgery and healthy normal volunteers were asked to perform the Romberg test while on a force plate measuring the center of pressure (COP): standing up straight with arms extended for 30 seconds with eyes open, followed by 30 seconds with eyes closed. The change for total sway area, sway frequency and sway speed with eyes closed and eyes open were calculated and compared between patients with CSM and healthy volunteers. Thirty-four CSM patients were age-matched to 34 healthy volunteers. There was a larger change in quantitative Romberg measurements with eyes open versus eyes closed in CSM patients compared to normal volunteers for maximum lateral movement (10.79 cm vs. 0.94 cm, p=.003), maximum anterior-posterior movement (15.06 cm vs. 10.00 cm p=.201), total lateral CoP movement (89.82cm vs. 18.71cm, p=.007), total AP CoP movement (154.68 cm vs. 87.47 cm, p=.601), total CoP trace movement (199.79 cm vs. 88.44 cm, p=.014), sway area (284.74 cm2 vs. 57.76 cm2, p=.006), and average speed (7.00 cm/s vs. 2.91 cm/s, p=.006). Poor standing balance can be quantified in patients with CSM. Quantifying standing balance in patients with CSM shows significantly worse objective measures than age-matched healthy volunteers. The Romberg test on a force plate may help diagnose and evaluate patients with CSM, guide patient management and potentially grade the severity of spinal pathology. Further studies are needed to determine its utility in monitoring disease progression and measure treatment effectiveness.

Coronary Flow Assessment Using Accelerated 4D Flow MRI With Respiratory Motion Correction.

Magnetic resonance imaging (MRI) can potentially be used for non-invasive screening of patients with stable angina pectoris to identify probable obstructive coronary artery disease. MRI-based coronary blood flow quantification has to date only been performed in a 2D fashion, limiting its clinical applicability. In this study, we propose a framework for coronary blood flow quantification using accelerated 4D flow MRI with respiratory motion correction and compressed sensing image reconstruction. We investigate its feasibility and repeatability in healthy subjects at rest. Fourteen healthy subjects received 8 times-accelerated 4D flow MRI covering the left coronary artery (LCA) with an isotropic spatial resolution of 1.0 mm3. Respiratory motion correction was performed based on 1) lung-liver navigator signal, 2) real-time monitoring of foot-head motion of the liver and LCA by a separate acquisition, and 3) rigid image registration to correct for anterior-posterior motion. Time-averaged diastolic LCA flow was determined, as well as time-averaged diastolic maximal velocity (VMAX) and diastolic peak velocity (VPEAK). 2D flow MRI scans of the LCA were acquired for reference. Scan-rescan repeatability and agreement between 4D flow MRI and 2D flow MRI were assessed in terms of concordance correlation coefficient (CCC) and coefficient of variation (CV). The protocol resulted in good visibility of the LCA in 11 out of 14 subjects (six female, five male, aged 28 ± 4 years). The other 3 subjects were excluded from analysis. Time-averaged diastolic LCA flow measured by 4D flow MRI was 1.30 ± 0.39 ml/s and demonstrated good scan-rescan repeatability (CCC/CV = 0.79/20.4%). Time-averaged diastolic VMAX (17.2 ± 3.0 cm/s) and diastolic VPEAK (24.4 ± 6.5 cm/s) demonstrated moderate repeatability (CCC/CV = 0.52/19.0% and 0.68/23.0%, respectively). 4D flow- and 2D flow-based diastolic LCA flow agreed well (CCC/CV = 0.75/20.1%). Agreement between 4D flow MRI and 2D flow MRI was moderate for both diastolic VMAX and VPEAK (CCC/CV = 0.68/20.3% and 0.53/27.0%, respectively). In conclusion, the proposed framework of accelerated 4D flow MRI equipped with respiratory motion correction and compressed sensing image reconstruction enables repeatable diastolic LCA flow quantification that agrees well with 2D flow MRI.

Trial Tibial Inserts May Result in Different Knee Kinematics from Final Poly Inserts in Total Knee Arthroplasty.

IntroductionTrialling is a key step in total knee arthroplasty (TKA) and helps the surgeon assess for adequate balancing, range of motion, and stability. Despite this, there are no studies investigating knee kinematics when using trial versus final polyethylene tibial inserts.Materials and MethodsFourteen fresh frozen cadaveric specimens were cycled in a VIVO joint motion simulator. Using both simple compression and simulated muscle loads, joints were tested after TKA with a trial insert or a final tibial poly insert. Anterior/posterior (AP), internal/external (IE), and varus/valgus (VV) kinematics and laxities were analyzed.ResultsKnees with trial poly inserts had significantly greater AP hysteresis (difference between flexion and extension motion) than those with final poly inserts (p=0.001). There was no significant difference in IE (p=0.563) or VV (p=0.580) hysteresis. There was no difference in AP, IE, or VV motion or laxities when considering the flexion path alone. Prosthetic joints followed different paths in flexion versus extension.ConclusionWhile trial tibial inserts impart valuable information, they may not accurately reproduce the same joint kinematics as final inserts. Balancing of the knee at specific degrees of flexion may depend on the path taken to get there.

Quantification of the geometric uncertainty when using implanted markers as a surrogate for lung tumor motion

Fiducial markers are used as surrogates for tumor location during radiation therapy treatment. Developments in lung fiducial marker and implantation technology have provided a means to insert markers endobronchially for tracking of lung tumors. This study quantifies the surrogacy uncertainty (SU) when using endobronchially implanted markers as a surrogate for lung tumor position. We evaluated SU for 17 patients treated in a prospective electromagnetic-guided MLC tracking trial. Tumor and markers were segmented on all phases of treatment planning 4DCTs and all frames of pretreatment kilovoltage fluoroscopy acquired from lateral and frontal views. The difference in tumor and marker position relative to end-exhale position was calculated as the SU for both imaging methods and the distributions of uncertainties analyzed. The mean (range) tumor motion amplitude in the 4DCT scan was 5.9mm (1.7-11.7mm) in the superior-inferior (SI) direction, 2.2mm (0.9-5.5mm) in the left-right (LR) direction, and 3.9mm (1.2-12.9mm) in the anterior-posterior (AP) direction. Population-based analysis indicated symmetric SU centered close to 0mm, with maximum 5th/95th percentile values over all axes of -2.0mm/2.1mm with 4DCT, and -2.3/1.3mm for fluoroscopy. There was poor correlation between the SU measured with 4DCT and that measured with fluoroscopy on a per-patient basis. We observed increasing SU with increasing surrogate motion. Based on fluoroscopy analysis, the mean (95% CI) SU was 5% (2%-8%) of the motion magnitude in the SI direction, 16% (6%-26%) of the motion magnitude in the LR direction, and 33% (23%-42%) of the motion magnitude in the AP direction. There was no dependence of SU on marker distance from the tumor. We have quantified SU due to use of implanted markers as surrogates for lung tumor motion. Population 95th percentile range are up to 2.3mm, indicating the approximate contribution of SU to total geometric uncertainty. SU was relatively small compared with the SI motion, but substantial compared with LR and AP motion. Due to uncertainty in estimations of patient-specific SU, it is recommended that population-based margins are used to account for this component of the total geometric uncertainty.

Robust Treatment Planning in Intrafraction Motion Using TomoDirect™ Intensity-modulated Radiotherapy for Breast Cancer.

To evaluate the robustness of radiotherapy treatment planning optimization for respiratory-moving breast cancer using fixed-angle beams planning TomoDirect™ intensity-modulated radiotherapy (IMRT). A minimax optimisation algorithm was applied to 10 breast cancer patients. Two sets of treatment plans with or without robust techniques were prepared considering anterior-posterior and head-tail movements due to respiration. Parameters were compared between treatment plans: 95% planned target volume (PTV) dose, conformal index and homogeneity index (HI), and organs at risk (OAR) parameters including the lung volume receiving 20 Gy or more (V20) and 5 Gy (V5). Robust planning significantly improved parameters of 95% PTV dose and HI, without deteriorating V20 or V5 in the anterior-posterior movement, while it slightly improved 95% PTV and slightly deteriorated V20 in the head-tail movement. Robust treatment planning improves coverage of targets moving because of respiration in the treatment of breast cancer using TomoDirect; however, normal lung doses should be cautiously evaluated on a case-by-case basis.

Radiologic Analysis of Malar Arch Movement in Reduction Malarplasty Without Bony Resection.

Reduction malarplasty has been popular among Asians with a wide facial width. In general, malar setback after bony resection is regarded as the standard objective of reduction malarplasty. However, unnecessary bony resection may lead to various postoperative complications. Therefore, we suggest the use of reduction malarplasty without bony resection to achieve a similar narrowing effect of the facial width, based on radiographic analysis of malar arch movement. This retrospective study analyzed 48 patients with a wide midface who underwent reduction malarplasty between September 2018 and December 2019. We included 40 cases of advancement repositioning malarplasty (AR) without bony resection and 8 cases of setback reduction malarplasty (SR) with bony resection. The three-dimensional position of the malar arch expressed by coordinates (x, y, and z) on three-dimensional computed tomography scans was used to compare the positional change between the surgical methods. The paired t-test, Wilcoxon text, and independent t-test were used in data analysis, and statistical analysis was performed using SPSS 23.0 software. Medial and superior movement of the freed malar arch segment was significantly different between AR and SR (P < 0.05). Although medialization and superiorization were not significantly different between AR and SR, there was a significant difference in anterior-posterior movement between AR and SR (P < 0.05). The radiologic analysis based on malar arch movement between AR and SR showed similar narrowing effects on medialization and superiorization of the malar arch regardless of bony resection. Therefore, the AR can be effectively applied in case of arch dominant type or malar asymmetry. In addition, further comprehensive study including analysis on movement of facial soft tissue following malar bony movement is expected based on this study in near future.

Audio Feedback for Device-Supported Balance Training: Parameter Mapping and Influencing Factors

Recent studies suggest that real-time auditory feedback is an effective method to facilitate motor learning. The evaluation of the parameter mapping (sound-to-movement mapping) is a crucial, yet frequently neglected step in the development of audio feedback. We therefore conducted two experiments to evaluate audio parameters with target finding exercises designed for balance training. In the first experiment with ten participants, five different audio parameters were evaluated on the X-axis (mediolateral movement). Following that, in a larger experiment with twenty participants in a two-dimensional plane (mediolateral and anterior-posterior movement), a basic and synthetic audio model was compared to a more complex audio model with musical characteristics. Participants were able to orient themselves and find the targets with the audio models. In the one-dimensional condition of experiment one, percussion sounds and synthetic sound wavering were the overall most effective audio parameters. In experiment two, the synthetic model was more effective and better evaluated by the participants. In general, basic sounds were more helpful than complex (musical) sound models. Musical abilities and age were correlated with certain exercise scores. Audio feedback is a promising approach for balance training and should be evaluated with patients. Preliminary evaluation of the respective parameter mapping is highly advisable.

Commissioning a four-dimensional Computed Tomography Simulator for minimum target size due to motion in the Anterior-Posterior direction: a procedure and treatment planning recommendations.

The purpose of this work is to develop a procedure for commissioning four‐dimensional computed tomography (4DCT) algorithms for minimum target reconstruction size, to quantify the effect of anterior–posterior (AP) motion artifacts on known object reconstruction for periodic and irregular breathing patterns, and to provide treatment planning recommendations for target sizes below a minimum threshold. A mechanical platform enabled AP motion of a rod and lung phantom during 4DCT acquisition. Static, artifact‐free scans of the phantoms were first acquired. AP sinusoidal and patient breathing motion was applied to obtain 4DCT images. 4DCT reconstruction artifacts were assessed by measuring the apparent width and angle of the rod. Comparison of known tumor diameters and volumes between the static image parameters with the 4DCT image sets was used to quantify the extent of AP reconstruction artifact and contour deformation. Examination of the rod width, under sinusoidal motion, found it was best represented during the inhale and exhale phases for all periods and ranges of motion. From the gradient phases, the apparent width of the rod decreased with increasing amplitude and decreasing period. The rod angle appeared larger on the reconstructed images due to the presence of motion artifact. The apparent diameters of the spherical tumors on the gradient phases were larger/equivalent than the true values in the AP/LR direction, respectively, while the exhale phase consistently displayed the spheres at the approximately correct diameter. The Eclipse calculated diameter matched closely with the true diameter on the exhale phase and was found to be larger on the inhale, MIP, and Avg scans. The procedure detailed here may be used during the acceptance and commissioning period of a computed tomography simulator or retroactively when implementing a SBRT program to determine the minimum target size that can be reliably reconstructed.

Quantifying the Interfractional motion of Esophagus Using Daily Cone Beam Computed Tomography with Oral Contrast During Radiation Therapy for Locally Advanced Non-Small Cell Lung Cancer

PurposeTo quantify the interfractional motion of the esophagus during fractionated radiation therapy for locally advanced non-small cell lung cancer. Methods and MaterialsWe registered simulation 4-dimensional computed tomography (CT) and daily cone beam CT (CBCT) and documented the motion of the esophagus centroid at 5-mm interval slices in right–left (RL) and anterior–posterior (AP) directions. Oral barium sulfate was administrated during CBCT to help localize the esophagus. Thirty-five patients were enrolled. Thirty-five 4-dimensional CT scans, 595 CBCT scans, and 25,970 slices were analyzed. The slice-derived motion values for all patients were presented as 2.5 to 97.5 percentiles and ranges stratified by segments. The magnitude of motion for each individual patient was defined as the standard deviation (SD) of daily motion values stratified by segments. Correlations between the magnitude of motion and clinical variables were explored. ResultsThe 2.5 to 97.5 percentiles of RL and AP motion were –4.2 to 7.1 and –4.4 to 5.1; –10.3 to 6.0 and –4.3 to 3.8; –8.7 to 5.5 and –6.4 to 2.8; and –9.1 to 4.7 and –5.8 to 3.3 mm for cervical, proximal, middle, and distal thoracic esophagus, respectively. The interfractional motion was direction- and location-dependent. The magnitude of RL motion was greater than that of AP motion for the 4 segments (P < .05). In the RL direction, the magnitude of motion was greater for the middle thoracic esophagus than for the cervical (median SD 2.7 vs 2.0 mm, P = .001) and proximal thoracic esophagus (median SD 2.7 vs 2.1 mm, P = .002). Patients with right lung tumor and bulky lymph nodes tended to display greater RL esophageal motion. ConclusionsThe interfractional motion of the esophagus can be considerable during radiation therapy in locally advanced non-small cell lung cancer, especially for middle thoracic esophagus in RL direction. Strategies to minimize the effect of interfractional esophageal motion on dosimetry should be considered.

Automatic registration of 2D MR cine images for swallowing motion estimation.

PurposeTo automate the estimation of swallowing motion from 2D MR cine images using deformable registration for future applications of personalized margin reduction in head and neck radiotherapy and outcome assessment of radiation-associated dysphagia.MethodsTwenty-one patients with serial 2D FSPGR-MR cine scans of the head and neck conducted through the course of definitive radiotherapy for oropharyngeal cancer. Included patients had at least one cine scan before, during, or after radiotherapy, with a total of 52 cine scans. Contours of 7 swallowing related regions-of-interest (ROIs), including pharyngeal constrictor, epiglottis, base of tongue, geniohyoid, hyoid, soft palate, and larynx, were manually delineated from consecutive frames of the cine scan covering at least one swallowing cycle. We applied a modified thin-plate-spline robust-point-matching algorithm to register the point sets of each ROI automatically over frames. The deformation vector fields from the registration were then used to estimate the motion during swallowing for each ROI. Registration errors were estimated by comparing the deformed contours with the manual contours.ResultsOn average 22 frames of each cine scan were contoured. The registration for one cine scan (7 ROIs over 22 frames) on average took roughly 22 minutes. A number of 8018 registrations were successfully batch processed without human interaction after the contours were drawn. The average registration error for all ROIs and all patients was 0.36 mm (range: 0.06 mm– 2.06 mm). Larynx had the average largest motion in superior direction of all structures under consideration (range: 0.0 mm– 58.7 mm). Geniohyoid had the smallest overall motion of all ROIs under consideration and the superior-inferior motion was larger than the anterior-posterior motion for all ROIs.ConclusionWe developed and validated a deformable registration framework to automate the estimation of swallowing motion from 2D MR cine scans.

A Random Forest Approach for Quantifying Gait Ataxia With Truncal and Peripheral Measurements Using Multiple Wearable Sensors

Gait disturbance is one of the most pronounced and disabling symptoms of cerebellar disease (CD). Generally, gait studies quantify human gait characteristics under natural walking speeds while mainly considering upper body movements. Therefore, the primary goal of this study was to investigate the influence of different walking speeds on different gait parameters of both the upper and lower body, as a result of disabilities caused by Cerebellar Ataxia (CA). We employed wearable sensor technology to identify the kinematic characteristics which best identify the gait abnormalities seen in CA. Measurements were made at self-selected slow, preferred and fast walking speeds. Velocity irregularity and resonant frequency characteristics were identified as key features of truncal and lower limb movements respectively. Subsequently, the differentiating features for both trunk and lower limb movements were combined to produce an even greater separation between the patients and the normal subjects, as well as better correlation with the expert clinical assessment (ECA) (0.86) and the Scale for the Assessment and Rating of Ataxia (SARA) (0.62). The different speed of walking conditions resulted in varying degrees of the separation and the correlation. Moreover, the contribution of the extracted features was examined using the random forest algorithm. Clinically observable truncal medio-lateral movements express the disability at relatively slow gait speeds while the anterior-posterior movements captured by the sensory mechanisms characterises the disability across all walking speeds. The importance of selected dominant features from the trunk and lower limb suggest that overall clinical assessments are predominantly influenced by the lower body peripheral movements, particularly at higher cadences.

Virtual reconstruction of the posterior cruciate ligament for mechanical testing of total knee arthroplasty implants

BackgroundTotal knee arthroplasty (TKA) design continues to be refined. As part of the pre-clinical design process, kinematic evaluation under ideal circumstances must be simulated. Previously, this was accomplished mechanically through the use of elastomeric bumpers and human cadaver models, which can be costly and time-intensive. With improved technology, a six-axis joint simulator now allows for virtual ligament reconstruction. The aim of this study was to create and evaluate a virtual posterior cruciate ligament (PCL) model to simulate native knee kinematics for component testing in TKA. MethodsThree human cadaveric knee specimens were utilized, each mounted in a six-axis joint simulator and the femoral and tibial ligament insertion points digitized. Ligament stiffness and kinematics were first tested with the intact knee, followed by retesting after PCL transection. Knee kinematic testing was then repeated, and the virtual PCL was reconstructed until it approximated that of the intact knee by achieving less than 10% random mean square (RMS) error. ResultsA virtual three-bundle PCL was created. The RMS error in anterior–posterior motion between the virtually reconstructed PCL and the intact knee ranged from six to eight percent for simulated stair climbing in the three knee specimens tested, all within our target goal of less than 10%. ConclusionThis study indicated that a virtually reconstructed three-bundle PCL with a joint simulator can replicate knee kinematics. Such an approach is valuable to obtain clinically relevant kinematics when testing cruciate-retaining total knee arthroplasty under force control.

Coordination of tongue muscle shortening and volume shifting in speech

Tongue motion to execute speech motions uses complex 3-D muscle architecture. For example, the motion into /s/ requires the tongue to extend its tip anteriorly, groove its superior surface, and brace itself laterally. To facilitate this, orthogonal, interdigitated tongue muscles allow complex deformations and motions, which create subtle and local shape changes along the tongue surface. This talk will examine anterior-posterior tongue motion from two perspectives: muscle shortening and volume shifting. We measure tagged and cine MR images for two speech tasks, “a geese” versus “a souk,” which move the tongue primarily forward versus backward. The talk will focus on the genioglossus, verticalis, transverse, superior, and inferior longitudinal muscles. These five muscles comprise over 50% of the tongue mass and deform it in three major directions: anterior-posterior, superior-inferior, and medial-lateral. The muscle shortening patterns will be compared to the percent of the tongue anterior to specific tooth landmarks for the consonant /s/ in both words. The /s/’s differ in word position and vowel context. Similarities between the two will help specify the coordination between muscles and deformation for /s/; differences will inform us as to the effect of vowel context/word placement.

Stability of joint orthognathic and orthodontic treatment for dental-facial deformity in patients with cleft lip and palate

Objective To evaluate the skeletal stability of joint orthognathic and orthodontic treatment for cleft patients compared with non-cleft patients. Methods Fifteen cleft patient diagnosed with dental facial deformities underwent joint orthognathic and orthodontic treatment. Cephalometric analysis was carried out at T0 (before treatment), T1 (2 weeks after surgery), T2 (6 months after surgery) and T3 (24 months after surgery). The comparison of maxillary anterior-posterior and superior-inferior movement was performed with non-cleft orthognathic group (n=15) at the same follow-up time point. Results The maxilla was move forward for (3.8±1.5) mm and downward for (2.4±0.8) mm of cleft group. The relapse distance was (1.2±0.7) mm (T1-T2: 31.6%) in AP direction and (0.9±0.6) mm (T1-T2: 37.5%) in vertical direction. At the time of 24 months after operation, the relapse distance was (1.0±0.5) mm (T1-T3: 26.0%) in AP direction and (0.8±0.8) mm (T1-T3: 33.3%) vertically. In non-cleft group, the maxilla was move (4.3±1.2) mm anteriorly and (2.2±1.9) mm vertically. The relapse distance was (0.9±1.2) mm (T1-T2: 20.9%) anteriorly and (0.8±0.9) mm (T1-T2: 36.6%) vertically at 6 months post-operatively. At 24 months after surgery the relapse distance was (1.1±0.6) mm (T1-T3: 25.6%) anteriorly and (0.9±0.5) mm (T1-T3: 40.9%) vertically. There were no statistical significant in both 6 months and 24 months follow-up between cleft and non-cleft group (P>0.05). Conclusions There is no statistic difference of post-surgical relapse rate between cleft and non-cleft orthognathic and orthodontic treatments, although the relapse distances are greater than that in cleft group. Key words: Cleft lip; Cleft palate; Orthognathic surgical procedures; Orthodontic anchorage procedures; Recurrence

Synchronized, concurrent optical coherence tomography and videostroboscopy for monitoring vocal fold morphology and kinematics

Voice disorders affect a large number of adults in the United States, and their clinical evaluation heavily relies on laryngeal videostroboscopy, which captures the medial-lateral and anterior-posterior motion of the vocal folds using stroboscopic sampling. However, videostroboscopy does not provide direct visualization of the superior-inferior movement of the vocal folds, which yields important clinical insight. In this paper, we present a novel technology that complements videostroboscopic findings by adding the ability to image the coronal plane and visualize the superior-inferior movement of the vocal folds. The technology is based on optical coherence tomography, which is combined with videostroboscopy within the same endoscopic probe to provide spatially and temporally co-registered images of the mucosal wave motion, as well as vocal folds subsurface morphology. We demonstrate the capability of the rigid endoscopic probe, in a benchtop setting, to characterize the complex movement and subsurface structure of the aerodynamically driven excised larynx models within the 50 to 200 Hz phonation range. Our preliminary results encourage future development of this technology with the goal of its use for in vivo laryngeal imaging.

Every Breath You Take – Evaluating Respiratory Motion of the Bony Thorax in the Context of Bone SBRT

Stereotactic Body Radiation Therapy (SBRT) delivers highly conformal treatment in a single or few fractions of high-dose radiation yielding excellent local control rates with minimal toxicity. There is growing interest in using SBRT to treat oligometastases, which potentially includes any anatomical site where metastases can occur. Bone is one of the most common sites of metastatic disease and although methodology to treat SBRT spine is well established, very little is known about the technical considerations of bone SBRT, particularly regarding respiratory motion in the bony thorax. The purpose of this study was to evaluate respiratory motion in thoracic bone metastases and to determine if the motion differs based on anatomic location. The first 70 patients treated with thoracic bone SBRT planned with four-dimensional computed tomography (4DCT) were identified from a prospective institutional database. To quantify motion, a region of interest representative of the treatment target was contoured by a single user in Pinnacle on the 0% (inhale) and 50% (exhale) datasets using fixed autocontour threshold values to eliminate subjectivity. A point of interest was automatically placed in the centroid of each volume and the relative positional difference of these points was calculated to measure the lateral (LR), anterior/posterior (AP) and superior/inferior (SI) motion. A total linear distance (LD) vector was calculated from these values. Rib lesions were further categorized as anterior, lateral or posterior based on axial position as well as superior (1-4), middle (5-7) and inferior (8-12) depending on rib location. Rib motion was analyzed using analysis of variance (ANOVA), if it was significant (p<0.05) a post hoc analysis was done to evaluate pairwise comparisons amongst the rib location groups. There were 15/16 sternal lesions assessed as 1 patient had significant bone destruction and could not be reliably contoured. Mean (range) LR, AP and SI sternum motion was 0.2 mm (0-0.7), 1.2 mm (0-2.6) and 0.1 mm (0-0.3) respectively and the LD was 1.2 mm (0-2.6). Forty-seven rib lesions were assessed for motion; 7 were excluded due to bone destruction preventing use of auto contour tool. The mean (range) LR, AP and SI motion for all rib lesions was 1.1 mm (0-4.0), 2.4 mm (0-8.4) and 0.1 mm (0-0.8) respectively and LD was 2.8 mm (0.1-8.5). When categorized by rib location, there were 9 superiorly, 22 middle and 16 inferior located rib lesions. The mean LD was 3.2 mm, 3.5 mm and 1.6 mm for superior, middle and inferior lesions respectively. There was a significant difference between the groups, with the inferiorly located moving less in terms of AP motion (p=0.02) and LD (p=0.04). In terms of axial position, there were 6 anterior lesions, 27 lateral lesions and 14 posterior lesions. The mean LD was 3.6 mm, 3.3 mm and 1.3 mm for anterior, lateral and posterior lesions respectively. There was a significantly less motion for posteriorly located lesions in terms of AP motion (p=0.005) and LD (p=0.02). This data suggests that the respiratory motion of the bony thorax is variable but not trivial in the context of high precision radiation therapy techniques with small margins. It appears that lesions located in the sternum and posterior and/or inferior aspect of the ribs move less; however, contouring guidelines, margins and image guidance technique need to be strongly considered before eliminating motion assessment when planning thoracic bone SBRT.