The efficacy of a video-based marker-less tracking system for gait analysis

Most clinical gait analyses are conducted using motion capture systems which track retro-reflective markers that are placed on key landmarks of the participants. An alternative to a three-dimensional (3D) motion capture, marker-based, optical camera system may be a marker-less video-based tracking system. The aim of our study was to investigate the efficacy of the use of a marker-less tracking system in the calculation of 3D joint angles for possible use in clinical gait analysis. Ten participants walked and jogged on a treadmill and their kinematic data were captured with a marker and marker-less tracking system simultaneously. The hip, knee and ankle angles in the frontal, sagittal and transverse planes were computed. Root Mean Square differences (RMS_diff) between corresponding angles for each participant’s support phase were calculated and averaged to derive the mean within-subject RMS_diff. These within-subject means were averaged to obtain the mean between-subject RMS_diff for the relevant joint angles in the two gait conditions (walking and jogging). The RMS_diff between the two tracking systems was less than 1° for all rotations of the three joint angles of the hip and knee. However, there were slightly larger differences in the ankle joint angles. The results of this study suggest a potential application in gait analysis in clinical settings where observations of anatomical motions may provide meaningful feedback.     

A computerized database-management system for curriculum analysis.

This report describes a computerized database-management system designed to allow users to retrieve and report information on the curriculum of an undergraduate pathophysiology course. With the system the user can locate where and in what context a topic is covered in the course and can answer queries and prepare reports concerning, for example, format and duration of sessions, teaching aids used and instructors. The system is a unique tool that can be used to optimize course structure and content. It can easily be expanded to include other undergraduate medical courses, and the techniques can be applied to other disciplines.     

Quantitative ultrastructural immunocytochemistry using a computerized image analysis system

Secretory granules in human pituitary adenoma cells have been examined indirectly for hormone epitopes by immunogold labelling of resin-embedded ultrathin sections. The specific binding of different immunoglobulin-gold complexes to the antigrowth hormone antibodies over the secretory granules was measured using a computerized image analysis system. This facilitated the assessment of the preferential binding to the target granules of gold particles with three different average particle diameters (Au7, Au11, Au17). The time of pretreatment of sections with H2O2 or a buffer was found to influence the staining considerably. The scanning electron microscopic findings of protruded secretory granules with a mountain-like surface might be relevant to the uneven distribution of immunolabels seen over the secretory granules in the adenohypophysis.     

Proposal for a dynamic study of the temporo-mandibular joint, using a computerized image analyzer

With the aim to go deep into the knowledge of the morpho-functional anatomical characteristics of the temporo-mandibular joint in humans, a dynamic method of study by means of a computerized analyzer of images is suggested. The acquired advantages are the following: a) the accuracy of evaluation of the chosen morphometric parameters; b) the working speed, from which results: c) the possibility to increase adequately the number of cases and d) the possibility to easily investigate many parameters with a very high accuracy of the quantitative results. Both right and left temporo-mandibular joints of adult individuals aged from 18 to 53 have been studied utilizing lateral tomographies focused at 3.3 mm to the lateral surface of the condylar head. The evaluations were done both in the position of completely closed mouth and in extreme opening. From the barycentre of the condyle several straight lines were drawn according to the figure 2. The length of the segment a-b (distance of profiles of the condyle and mandibular fossa) were evaluated in all the lines counter-clockwise and the results submitted to a statistical analysis. The results furnish very good information on the normal or pathological anatomical characteristics, of the joint.     

A microcomputer-based video vector system for clinical gait analysis

A microcomputer-based video vector system has been developed to display the resultant ground reaction force vector on a television image of the subject in real-time. For each television field the force platform signals are acquired and processed and the resultant force vector superimposed on the video image of the walking subject. The force platform results are stored on disc and the composite video signals recorded on video tape for further analysis. The system is easy to set up and use and the results can be readily interpreted. The external moments produced at the joint centres by the ground reaction forces can be observed visually and, if required, quantification of the external moments can be achieved following data collection. The spatial resolution of the system is 0.342% vertically and 0.156% horizontally. The force vector visualization technique has routine applications in orthotics and prosthetics. It is also a useful technique for the teaching of biomechanics.     

Footprint analysis of gait using a pressure sensor system.

The purpose of this study was to investigate if the detailed pressure data of the footprints of normal gait add essential information to the spatio-temporal variables of gait. The gait of 62 healthy adult subjects was investigated using GAITRite pressure sensor system. Each footprint was divided into 12 equal trapezoids and after that the hindfoot, midfoot and forefoot analysis was developed. A typical activation pattern of the sensors with two peaks of active area and peak pressure distribution during normal walking was obtained. The first peak reflected the heel strike, and the second peak reflected push-off at the end of the stance phase. The lowest pressure values were in the midfoot, where the lateral part of the foot activated sensors more than the medial part. The footprint patterns of right and left legs were symmetrical and corresponded with the symmetry found in the spatio-temporal variables of gait. The variability for the active area and the peak pressure were more pronounced for the lateral part of the midfoot and a smaller variation was seen in areas with concentrated observations (e.g. 1st, 2nd and 5th lateral trapezoids). Increasing active area in the forefoot was associated with decreasing pressure sensor activity in the midfoot. The footprint patterns identified the symmetry between the legs and at the same time revealed the velocity performance.     

Starch determination in plant tissues using a computerized image analysis system

Starch is the main reserve compound in woody plant species. Changes in starch content are clear indicators of a variety of plant developmental processes. Thus, carbohydrate extraction and other analytical methods have been widely used to measure changes in starch content. However, the use of these methods can be limited by the fact that starch is often compartmentalized in very small portions of tissue. While changes in these small structures can be histochemically characterized and localized under the microscope, they cannot be quantified. As an alternative, an image analysis system attached to a microscope has been developed to detect quantitative variations in starch in particular tissues or cells. The system has been successfully used to study the differences in starch content of sections from pistillar structures in apricot ( Prunus armeniaca L.). The procedure is based on the measurement of the optical density of black and white images obtained from the microscope. Two staining methods, I₂KI (potassium iodide-iodine) and PAS (periodic acid Schiff's reagent), and two embedding techniques, paraffin and JB4 plastic resin, were compared. The best results were obtained using I₂KI-stained sections of paraffin-embedded material. Since the procedures used are non-destructive for the tissues studied, additional information can be obtained, on the same section, by the subsequent use of additional stains. The method described here can be used to detect quantitative variations in starch content under the microscope in different plant tissues and thus to follow changes in starch reserves in small structures.     

A mobile gait monitoring system for abnormal gait diagnosis and rehabilitation: a pilot study for Parkinson disease patients

Conventional gait rehabilitation treatment does not provide quantitative information on abnormal gait kinematics, and the match of the intervention strategy to the underlying clinical presentation may be limited by clinical expertise and experience. Also the effect of rehabilitation treatment may be reduced as the rehabilitation treatment is achieved only in a clinical setting. In this paper, a mobile gait monitoring system (MGMS) is proposed for the diagnosis of abnormal gait and rehabilitation. The proposed MGMS consists of Smart Shoes and a microsignal processor with a touch screen display. It monitors patients' gait by observing the ground reaction force (GRF) and the center of GRF, and analyzes the gait abnormality. Since visual feedback about patients' GRFs and normal GRF patterns are provided by the MGMS, patients can practice the rehabilitation treatment by trying to follow the normal GRF patterns without restriction of time and place. The gait abnormality proposed in this paper is defined by the deviation between the patient's GRFs and normal GRF patterns, which are constructed as GRF bands. The effectiveness of the proposed gait analysis methods with the MGMS has been verified by preliminary trials with patients suffering from gait disorders.     

A low-cost system for computerized rodent weight logging with statistical analysis

A system comprising a suite of 4 computer programs has been developed for on-line rodent weight data collection and statistical analysis using an IBM personal computer. Data can be collected from up to 3 separate trials simultaneously, and can be stored for later statistical analysis. Mettler balances were used for the animal weighing. A Mettler current loop adapter and a multiplexer were used to interface the balances with the computer.     

Implantable telemetry system for long-term EMG

Our aim was to record the uterine muscular activity of the badger or the fox. For long-term physiological experiments, commercial transmitters cannot be used. The operating time of commercial transmitters with a single set of batteries does not exceed 15 days at the most. In addition, the dimensions render implantation of such equipment impossible. It is not always necessary to record permanently but sometimes a few minutes a day are sufficient to assess the evolution of a phenomenon. We have conceived and constructed a miniature implantable receiver module which allows the transmitter to be switched on and off in order to be operated only during selected periods of time.     

The methods of surface EMG analysis

The use of surface emg as a tool for quantification is described. First, the specific advantages of the surface emg are discussed. Techniques for analysis of the emg signal which estimate and detect the action potentials of the individual motor units and estimate some global properties of muscle activity are reviewed. A survey of data on relations between the properties of motor unit action potential, the properties of motor unit activity and the results of signal processing are given.     

Multielectronic computerized EMG: technical notes on the recording and parallel off-line elaboration

A Multielectrodic EMG analysis program is developing. The purpose is to get as short as possible the main EMG parameters (amplitude, duration, frequency) of most motor units, and to reach an estimation of the anatomical extent of single units. According to the muscle extent a variable number of electrodes are inserted crosswise the fibers. EMG signals are simultaneously recorded on a multichannel AMPEX FR1300 and then off-line processed by a 21MX HP minicomputer connected with a 5Mbytes disc drive. Some technical problems had to be solved:channel amplification adjustment to avoid any difference among preamplifiers calibration and filtering, severe hum filtering of main power that is specially strong in nultielectrodic recording systems, the need of sampling at the same Nyquist time the signals of different channels. The computer is instructed to identify the "sinchronous" units i.e. the motor units recorded from more than one channel. These motor units are detected, counted and deleted from all the channels, except the one where they show the maximum amplitude. The percentage of these sinchronous units depends upon the interelectrodic distance and their anatomical area, thus it can support an evaluation of motor unit anatomical spread.     

Reliability of segmental accelerations measured using a new wireless gait analysis system

The purpose of this study was to determine the inter- and intra-examiner reliability, and stride-to-stride reliability, of an accelerometer-based gait analysis system which measured 3D accelerations of the upper and lower body during self-selected slow, preferred and fast walking speeds. Eight subjects attended two testing sessions in which accelerometers were attached to the head, neck, lower trunk, and right shank. In the initial testing session, two different examiners attached the accelerometers and performed the same testing procedures. A single examiner repeated the procedure in a subsequent testing session. All data were collected using a new wireless gait analysis system, which features near real-time data transmission via a Bluetooth network. Reliability for each testing condition (4 locations, 3 directions, 3 speeds) was quantified using a waveform similarity statistic known as the coefficient of multiple determination (CMD). CMD's ranged from 0.60 to 0.98 across all test conditions and were not significantly different for inter-examiner (0.86), intra-examiner (0.87), and stride-to-stride reliability (0.86). The highest repeatability for the effect of location, direction and walking speed were for the shank segment (0.94), the vertical direction (0.91) and the fast walking speed (0.91), respectively. Overall, these results indicate that a high degree of waveform repeatability was obtained using a new gait system under test-retest conditions involving single and dual examiners. Furthermore, differences in acceleration waveform repeatability associated with the reapplication of accelerometers were small in relation to normal motor variability.     

Quantification of angiogenesis by a computerized image analysis system in renal cell carcinoma

OBJECTIVE: To ascertain whether tumor angiogenesis quantitated by a computerized image analysis system correlates with clinical outcome in renal cell carcinoma. STUDY DESIGN: Microvessels were immunohistochemically labeled with antibodies to CD34 in sections from 62 cases of renal cell carcinoma. Computerized image analysis was used to evaluate the mean microvessel count (MMC) and mean percentage microvessel area (MPMA). RESULTS: MMC ranged from 19.3 to 315.0, while MPMA was 0.6-17.9%. There was a highly significant correlation between MMC and MPMA (r = .867, P < .01). Although MMC and MPMA decreased with increasing nuclear grade and TNM stage, this difference failed to achieve statistical significance. No statistically significant differences in survival were found for MMC or MPMA. CONCLUSION: Our results indicate that computerized image analysis can evaluate accurately tumor angiogenesis, but tumor angiogenesis in renal cell carcinoma does not provide significant prognostic information in renal cell carcinoma.