Center Of Gravity Distance Research Articles

Image fusion technique for target volume delineation in 125I seed implant brachytherapy for parotid gland cancers.

Variability in volume delineation is a possible error source in brachytherapy. This study assessed the interobserver variations in clinical target volume (CTV) delineation in postoperative adjuvant 125I seed implant brachytherapy after parotid gland cancer surgical resection and evaluated the image fusion technique for target volume delineation. Five radiation oncologists delineated gross tumor volume (GTV) and CTV in 20 patients using conventional delineation and image fusion methods. The consistency in target volume delineation was determined on the basis of differences between the oncologists. Variability was determined using Kendall's W-test, the mean conformity index (CI), the mean distance to conformity (MDC), and the center of gravity distance (CGD). There were significant variations in the delineated target volumes among radiation oncologists, but the CTV consistency was significantly enhanced using the image fusion technique, based on Kendall's W, mean CI, average MDC, and average CGD, which were 0.752, 0.41, 2.75, and 4.997, respectively, using the conventional method, and 0.987, 0.86, 0.55, and 1.27, respectively, using the image fusion method. The interobserver variation in the delineation of the postoperative parotid target volume is large, but it can be considerably decreased using image fusion technology, which resulted in a noticeable improvement in the delineation precision of the target volume for parotid gland cancer. Thus, this technology can enhance the efficacy of 125I seed implant brachytherapy and decrease any adverse effects induced by errors in target delineation.

The Application of Biological Feedback in the Rehabilitation of Patients after Ischemic Stroke.

Balance disorders are the main concern for patients after an ischemic stroke. They are caused by an abnormal force on the affected side or paresis, which causes uneven loading and visuospatial disorders. Minimizing the effects of stroke is possible through properly conducted rehabilitation. One of the known ways to achieve this objective is biological feedback. The lack of proper muscle tone on one side of the body is manifested by the uneven pressure of the lower extremities on the ground. The study and control groups were composed of two equal groups of 92 people each, in which the same set of kinesiotherapeutic exercises were applied. Patients in the study group, in addition to standard medical procedures, exercised five days a week on a Balance Trainer for four weeks. The examination and training with the device were recorded on the first day of rehabilitation, as well as after two and four weeks of training. The assessment was performed using the following functional tests and scales: Brunnström, Rankin, Barthel, Ashworth, and VAS. Patients in the control group started exercising on the Balance Trainer two weeks after the first day of rehabilitation using traditional methods. The study results reveal statistically significant reductions in the time the body’s center of gravity (COG) spent in the tacks, outside the tracks and in the COG distance, lower COG excursions in all directions. Post-stroke patients that received biofeedback training presented significantly better results than patients that did not receive such training.

Improvement in Gait Pattern and its Relationship With Preoperative Pelvic Compensation After Surgery in Patients With Sagittal Plane Deformity.

Prospective observational study. The aim of this study was to investigate the improvement in gait parameters after surgery and whether corrective surgery for sagittal imbalance would be influenced by preoperative pelvic compensation. There have been no other studies investigating the influence of preoperative pelvic compensation on surgical outcomes. A total of 32 patients who were scheduled to undergo corrective surgery for sagittal plane deformity were included and were followed-up for 1 year after surgery. Radiological parameters were measured on biplanar full-body imaging. Before surgery and 6 months after surgery, three-dimensional motion analyses were performed to estimate center of gravity (CoG) deviation from the center of mass (CoM), mean trunk kyphosis (TK) angle, gait deviation index (GDI), and kinematic parameters. Before surgery, the patients were classified into CoG+ and CoG- groups. "+" and "-" representing increases and decreases in the distance of CoG from CoM of the pelvic segment from first to third trials, respectively. Oswestry Disability Index (ODI) and EuroQol-5D (EQ-5D) were measured for 1 year after surgery. All radiological parameters improved significantly after surgery. For gait parameters, CoG from CoM, mean TK angle, and minimum angle of the hip and knee joints in the stance phase during walking were significantly decreased after surgery and GDI scores significantly improved after surgery. The mean changes of the CoG distance from the CoG and the mean TK from first to third trials of gait analysis significantly decreased postoperatively. There were no significant differences in ODI and EQ-5D scores over 1-year follow-up assessment between CoG+ and CoG- groups. Preoperative abnormal stooping gait, and progressive worsening of sagittal imbalance in patients with sagittal plane deformity improved after corrective surgery. Patients with preoperative dynamic sagittal imbalance could have similar surgical results to those without it after corrective surgery. 3.

Does corrective spine surgery improve the standing balance in patients with adult spinal deformity?

Background ContextThe effect of corrective spine surgery on standing stability in adult spinal deformity (ASD) has not been fully documented. PurposeTo compare pre- and postoperative standing balance and posture in patients with ASD. Study Design/SettingThis study is a prospective case series. Patient SampleStanding balance before and after corrective spine surgery was compared in 35 consecutive female patients with ASD (65.6±6.9 years, body mass index 22.3±2.7 kg/m2, Cobb angle 50.2±19.2°, C7 plumb line 9.3±5.6 cm, and pelvic incidence-lumbar lordosis mismatch 40.8±23.3°). Outcome MeasuresThe Scoliosis Research Society Patient Questionnaire, the Oswestry Disability Index, and force-plate analysis were used to evaluate the patient outcomes. Materials and MethodsWe reviewed patient charts and X-rays and compared standing balance before and after corrective spine surgery. All subjects were assessed by force-plate analysis using optical markers while standing naturally on a custom-built force platform. The spinal tilt, pelvic obliquity, pelvic tilt, and joint angle were calculated. The lower leg lean volume was obtained by whole-body dual X-ray absorptiometry to assess muscle strength. ResultsASD patients showed significant differences between the left and right sides in ground reaction force (dGRFs), hip (dHip), and knee angle (dKnee) while standing (dGRF 15.1±8.7%, dHip 7.1±6.6°, dKnee 5.9±5.5°). The recorded center-of-gravity (CoG) area was not improved after surgery, whereas the dGRF, dHip, and dKnee all decreased. The spinal tilt, pelvic obliquity, and pelvic tilt were all significantly improved after surgery. We found significant correlations between the radiographic trunk shift and the postoperative coronal CoG distance and recorded CoG area, and between the sagittal CoG distance and the age and the lean volume of the lower extremities (trunk shift R=0.33, 0.45; age R=0.32; lean volume R=0.31). ConclusionsCorrective spinal surgery improved the spinal alignment and joint angles in patients with ASD but did not improve the standing stability. A correlation found between the sagittal CoG distance and the lean volume of the lower extremities indicated the importance of the leg muscles for stability when standing, whereas a correlation found between the coronal CoG distance and trunk shift reflected the attenuated postural response in the ASD patients.

Standing Balance and Compensatory Mechanisms in Patients With Adult Spinal Deformity.

A prospective case series. The aim of this study was to compare the standing balance and posture between patients with adult spinal deformity (ASD) and healthy volunteers (HVs). The effect of ASD on standing posture and balance has not been fully documented. Forty consecutive female patients with ASD (65.4 ± 6.7 yrs, Cobb angle 48.6 ± 20.2°, C7PL 9.1 ± 6.4 cm, and PI-LL 41.1 ± 25.2°) and 33 matched HV (72.4 ± 4.6 yrs) were included. We reviewed charts and x-rays from ASDs and categorized the patients as having a PI-LL mismatch that was severe (>20°) or moderate (10°<PI-LL<20°). We compared the standing balance with that of 33 matched HVs. All subjects underwent motion analysis while standing naturally on a custom-built force platform using optical markers on the ear canal and on all joints and spinal processes. The distances from the center of gravity (CoG) to the head, heel, and sacrum were also measured, and the spinal tilt, pelvic obliquity, and pelvic tilt were calculated. There were significant differences between the ASDs and HVs in the recorded CoG area (RecCoG), and the left-to-right differences in ground reaction force (dGRF), hip angle (dHip), and the knee angle (dKnee) while standing. The sagittal CoG distance, head-CoG distance, and sacrum-CoG distance were significantly worse in ASDs. Multiple regression analysis showed a significant correlation between two-dimensional head deviation and hip angle, thoracolumbar kyphosis, spinal tilt, and head-sacrum distance in the severe PI-LL mismatch group and in knee angle, pelvic obliquity, and pelvic retroversion in the moderate PI-LL mismatch group. ASDs had significantly worse standing balance, and were found to compensate for spinal malalignment mostly through the knee and pelvis in both the coronal and sagittal planes to maintain the CoG. As a surrogate of this compensation, we observed significant head deviation, pelvic shift, and truncal sway in ASDs. 4.

F-18 FDG PET-CT Influences Target Delineation When Combined With Standard CT-Based Radiotherapy Planning in the Palliative Setting in Malignant Pleural Mesothelioma; an Exploratory Study

Background: Positron emission tomography computerized tomography (PET-CT) is useful in radiotherapy planning for lung cancer. However, its role in malignant pleural mesothelioma (MPM) is unknown. Objectives: This exploratory study investigated the possible role for PET-CT in radiotherapy planning for MPM. Patients and Methods: Patients receiving radiotherapy for the treatment of pain in MPM, had fluorodeoxyglucose (FDG) PET-CT scanning in addition to their standard CT scan. PET-CT images were then fused with CT planning images, termed Planning-PET-CT. Target volume delineation was undertaken first using CT and subsequently incorporated Planning-PET-CT. Planning treatment volume (PTV), conformity index (CI), mean distance to conformity (MDC), center of gravity distance (CGD) and standard uptake values (SUV) were examined. Results: Sixteen patients were recruited into the study. PET-CT upstaged nine patients. No association between SUV max and either survival or pain response was seen. Volumes contoured using Planning-PET-CT differed markedly from those outlined using CT alone as shown by the following parameters: CI = 0.3 (0.24 - 0.38). MDC = 21.47 (16.73 - 33.70) and CGD = 16.40 (11.80 - 33.87). The median percentage of over contouring was 44.00% (34.33 - 72.50) with 46.67% under contoured (34.00 - 55.00). Conclusions: PET-CT alters the position of the PTV in MPM and upstaged a proportion of patients. Further work to elucidate the role of Planning-PET-CT in target volume definition is justified.

Intra- and Intersubject Reliability of Abductor Pollicis Brevis Muscle Motor Map Characteristics With Transcranial Magnetic Stimulation

Corneal SF, Butler AJ, Wolf SL. Intra- and intersubject reliability of abductor pollicis brevis muscle motor map characteristics with transcranial magnetic stimulation. Objective To determine consistency in motor maps of the abductor pollicis brevis (APB) muscle using transcranial magnetic stimulation (TMS) with conventional and close-spaced surface electrode recording placements. Design Nonrandom convenience sample. Setting TMS laboratory. Participants Eleven participants without any known neurologic disorders. Interventions The left hemisphere of right-hand-dominant subjects was mapped using TMS at each of 2 sessions, separated by 1 to 8 weeks. Main Outcome Measures Measurements at each session included the resting motor threshold, active site locations and average motor response amplitude for active sites, normalized map volume, and center of gravity (COG) for both electrode array configurations. Results The normalized map volume was larger for the conventional electrode placement than for the close electrode placement (4.23cm 2 vs 3.44cm 2, P=.010). Resting motor threshold was higher for the close-spaced than for the conventional-spaced electrodes (48.36% vs 46.59%, P=.028). No statistical difference was found between sessions and within electrode placements for the normalized map volume, for resting motor threshold, or for the mean motor amplitude of the most active site for each map. No statistical difference was observed for the COG distance between electrode placements. Conclusions This study revealed differences between close-spaced and conventional-spaced surface electrode placement for TMS motor map volumes and for resting motor thresholds. The motor maps for the APB muscle were reliably reproducible between sessions for each electrode array.

Finger extensor variability in TMS parameters among chronic stroke patients

BackgroundThis study determined the reliability of topographic motor cortical maps and MEP characteristics in the extensor digitorum communis (EDC) evoked by single-pulse TMS among patients with chronic stroke.MethodsEach of ten patients was studied on three occasions. Measures included location of the EDC hotspot and center of gravity (COG), threshold of activation and average amplitude of the hotspot, number of active sites, map volume, and recruitment curve (RC) slope.ResultsConsistent intrahemispheric measurements were obtained for the three TMS mapping sessions for all measured variables. No statistically significant difference was observed between hemispheres for the number of active sites, COG distance or the RC slope. The magnitude and range of COG movement between sessions were similar to those reported previously with this muscle in able-bodied individuals. The average COG movement over three sessions in both hemispheres was 0.90 cm. The average COG movement in the affected hemisphere was 1.13 (± 0.08) cm, and 0.68 (± 0.04) cm) for the less affected hemisphere. However, significant interhemispheric variability was seen for the average MEP amplitude, normalized map volume, and resting motor threshold.ConclusionThe physiologic variability in some TMS measurements of EDC suggest that interpretation of TMS mapping data derived from hemiparetic patients in the chronic stage following stroke should be undertaken cautiously. Irrespective of the muscle, potential causes of variability should be resolved to accurately assess the impact of pharmacological or physical interventions on cortical organization as measured by TMS among patients with stroke.

Intra-subject reliability of parameters contributing to maps generated by transcranial magnetic stimulation in able-bodied adults

Objective: This study evaluated the reliability of several parameters contributing to topographic motor cortical maps of the extensor digitorum communis (EDC) within able-bodied participants, across 3 sessions and from both hemispheres with greater precision than previously reported. Methods: Nine healthy right-handed males aged 44–75 years were studied at 3 separate sessions, spaced 7–14 days apart. Transcranial magnetic stimulation (TMS) was used to elicit motor evoked potentials (MEP) in the contralateral EDC. Closely spaced surface electrodes were used to record the MEPs. Results: TMS-related parameters did not demonstrate a significant difference within participants across sessions and between hemispheres, with the exception of the hotspot distance, center of gravity distance, and normalized map volume. Hotspot and COG distances were determined from the Euclidean equation to calculate the distance in x,y coordinates traveled over sessions: one to two (distance A) and two to three (distance B). The hotspot distance, center of gravity distance and normalized map volume demonstrated a significant difference between right and left hemispheres, within participants. Adjusting for time and examining mean changes for hemispheres across sessions revealed that there was a 9-fold greater movement over sessions in the left hemisphere among these variables. Conclusions: TMS-related parameters are reliable within participants across 3 sessions. These data should be useful for planning and interpreting TMS studies using a healthy or patient population before and after an intervention.