High-speed Cineradiography Research Articles

Automatic detection of spinal injuries under dynamic compressive loading using high-speed cine-radiography.

Every year, new cases of individuals suffering from traumatic spinal injuries are detected. Advances in numerical models have allowed for the understanding of the damage caused by trauma and its impact on the patient's life. However, the kinematics and dynamics of vertebral fracture formation from its point of origin to the speed of propulsion of the fragments remain unknown. This is mainly due to the lack of data that essentially includes high-speed videos, load and displacement measurements during experimental tests reproducing spinal traumatic loading conditions. This lack of data can be addressed by the analysis of X-Ray images of animal specimens acquired during the traumatic spinal injury formation process. Thus, the purpose of this study was to develop an approach to automatically detect and track in vitro vertebral fractures using high-speed cine-radiography imaging. Four segments of porcine thoracolumbar vertebrae were dynamically compressed using a servo-hydraulic test bench. The compression process was filmed with a custom high-speed cine-radiography device, and the imaging parameters were optimized based on the physical properties of vertebrae. This paper demonstrates the feasibility of using high-speed cine-radiography imaging in this way, combined with an image processing pipeline to allow automatic documentation of the fracture's appearance and its evolution in the vertebra over time.Clinical Relevance- The proposed method will provide helpful information for proper handling of traumatic spinal injuries.

Intracranial Displacement Measurements Within Targeted Anatomical Regions of a Postmortem Human Surrogate Brain Subjected to Impact

The dynamic response of the human brain subjected to impulsive loading conditions is of fundamental importance to the understanding of traumatic brain injuries. Due to the complexity of such measurements, the existing experimental datasets available to researchers are sparse. However, these measurements are used extensively in the validation of complex finite element models used in the design of protective equipment and the development of injury mitigation strategies. The primary objective of this study was to develop a comprehensive methodology to measure displacement in specific anatomical regions of the brain. A state-of-the-art high-speed cineradiography system was used to capture brain motion in post-mortem human surrogate specimens at a rate of 7500fps. This paper describes the methodology used to capture these data and presents measurements from these tests. Two-dimensional displacement fields are presented and analyzed based on anatomical regions of the brain. These data demonstrated a multi-modal displacement response in several regions of the brain. The full response of the brain consisted of an elastic superposition of a series of bulk rotations of the brain about its centre of gravity. The displacement field could be linked directly to specific anatomical regions. The methods presented mark an improvement in temporal and spatial resolution of data collection, which has implications for our developing understanding of brain trauma.

In vitro assessment of the role of the nucleus pulposus in the mechanism of vertebral body fracture under dynamic compressive loading using high-speed cineradiography.

Traumatic Spinal Cord Injuries (TSCI) have a disastrous effect on the physical and mental health of both the patients and their relatives. Around 15 % of these injuries are caused by burst fractures, a sub-type of compressive fractures of the vertebral body. The transient dynamics of these fracture have been studied through in vitro experiments coupled with numerical simulations, but no direct observation have ever been made of their genesis and evolution and the behaviour of the nucleus pulposus under compressive loading has only been hypothesized. The purpose of this study was to evaluate the interactions between the vertebral body and the nucleus pulposus under dynamic compressive loading using high-speed cineradiography. A radiopaque agent was injected into the nuclei pulposi of 4 young porcine thoraco-lumbar and lumbar cadaveric segments, and a dynamic compressive load was applied to them using a servo-hydraulic bench-test. The compression process was filmed with a custom high-speed fluoroscope. The nucleus pulposus loaded the vertebral endplate up to 14,142 ± 486 N, before fracturing it and diffusing into the vertebral body. Then, internal pressure seemingly built up until an outward projection of the nucleus pulposus, at an antero-posterior velocity up to 2.9 m.s-1, or until retroprojection of bony fragments into the spinal canal. These results directly corroborate the hypotheses previously made by other studies and stress the unprecedented advantages of using high-speed cineradiography for the study of complex fractures genesis and evolution.Clinical Relevance- Methodology and results from this study would provide an unprecedented insight on the genesis and transient evolution of complex spinal fractures.

From cineradiography to biorobots: an approach for designing robots to emulate and study animal locomotion.

Robots are increasingly used as scientific tools to investigate animal locomotion. However, designing a robot that properly emulates the kinematic and dynamic properties of an animal is difficult because of the complexity of musculoskeletal systems and the limitations of current robotics technology. Here, we propose a design process that combines high-speed cineradiography, optimization, dynamic scaling, three-dimensional printing, high-end servomotors and a tailored dry-suit to construct Pleurobot: a salamander-like robot that closely mimics its biological counterpart, Pleurodeles waltl Our previous robots helped us test and confirm hypotheses on the interaction between the locomotor neuronal networks of the limbs and the spine to generate basic swimming and walking gaits. With Pleurobot, we demonstrate a design process that will enable studies of richer motor skills in salamanders. In particular, we are interested in how these richer motor skills can be obtained by extending our spinal cord models with the addition of more descending pathways and more detailed limb central pattern generator networks. Pleurobot is a dynamically scaled amphibious salamander robot with a large number of actuated degrees of freedom (DOFs: 27 in total). Because of our design process, the robot can capture most of the animal's DOFs and range of motion, especially at the limbs. We demonstrate the robot's abilities by imposing raw kinematic data, extracted from X-ray videos, to the robot's joints for basic locomotor behaviours in water and on land. The robot closely matches the behaviour of the animal in terms of relative forward speeds and lateral displacements. Ground reaction forces during walking also resemble those of the animal. Based on our results, we anticipate that future studies on richer motor skills in salamanders will highly benefit from Pleurobot's design.

Cervical spinal cord deformation during simulated head-first impact injuries

The relationship between bony spinal column and spinal cord injury during an injury event is not well understood. While several studies have measured spinal canal occlusion during axial impact, there has been limited work done to quantify the spinal cord compression or deformation during simulated injury. Because the cord is a viscoelastic solid it may provide resistance to bone fragments, ligaments or other elements that move into the canal and impinge it during column injury. This would differentiate the measurement of cord compression from the measurement of occlusion of an empty canal. In the present study, a novel method of visualizing and quantifying spinal cord deformation during dynamic head-first impact of ex vivo human cervical spine specimens ( N=6) was developed. A radiodense, biofidelic surrogate spinal cord was imaged in the spinal canal using high speed cineradiography at 1000 frames per second. The dorsal–ventral diameter of the cord was measured at 1.5 mm increments along its length for each frame of the radiographic footage. The resulting cord deformations were used to determine the theoretical neurological outcome of the impact based on published in vivo ferret studies. The corresponding probability of recovery for the spinal cord deformations in these tests ranged between 8% for atlantoaxial dislocation injury and 95% for mid-cervical spine hyperextension injury (based on the ferret data). Clinically relevant spinal column fracture patterns were produced in this study.

Aquatic feeding in a terrestrial turtle: a functional-morphological study of the feeding apparatus in the Indochinese box turtle Cuora galbinifrons (Testudines, Geoemydidae)

The Indochinese box turtle Cuora galbinifrons is regarded as a purely terrestrial species, but our results demonstrate that it can feed both on land and in water. The inverse relationship between the relative development of the hyoid apparatus and the tongue found in the most investigated chelonians is not valid in the Indochinese box turtle. Our morphological analysis of the feeding apparatus reveals that the palate shape and the design of the tongue are consistent with terrestrial feeders, but the construction of the hyoid complex is more characteristic of aquatic feeders. Previous studies have demonstrated that tongue enlargement negatively impacts the capacity of the turtles to suction feed. The present study focuses on the aquatic intraoral prey transport kinematic patterns. Our analysis is based on high-speed films with 250 fr/s and high-speed cineradiography with 50 fr/s. The aquatic intraoral food transport mechanisms differ depending on prey size: small items are transported predominantly by “inertial suction”, whereas larger items are moved by the tongue—normally a clear terrestrial strategy. As the genus Cuora is ancestrally aquatic, the use of lingual food transport in the aquatic environment is presumably an aberrant modus typical only for the most terrestrial among the Asian box turtles.

No trade-off between biting and suction feeding performance in clariid catfishes

It is generally assumed that biting performance trades off with suction performance in fish because both feeding types may place conflicting demands on the cranial musculo-skeletal system. However, the functional consequences of morphological adaptations enhancing biting on the mechanics and performance of suction feeding in fish remain obscure. In this study, suction feeding performance was compared between three clariid catfish species differing considerably in their biting capacity, by measuring the velocity of a standardized prey being sucked into the buccal cavity using high-speed cineradiography. In addition, buccal volume changes during prey capture were quantified by ellipse modelling. As all species were able to accelerate the prey to similar peak velocities, our results demonstrate the possibility for catfishes to increase bite performance considerably without compromising suction performance. The amount of buccal expansion in the ventral direction is approximately equal for all species. Consequently, the system generating expansion through ventral rotation of the lower jaw, hyoid and pectoral girdle is apparently not constrained (mechanically or architectonically) by the hypertrophy of the jaw adductors. As the effect of a reduced magnitude of lateral expansion (suspensorium abduction) on suction performance in Clariidae appears to be negligible (for example in Gymnallabes typus), these data demonstrate the dominant role of ventral expansion for producing suction in these fish.

Sagittal spine movements of small therian mammals during asymmetrical gaits

Mammalian locomotion is characterized by the use of asymmetrical gaits associated with extensive flexions and extensions of the body axis. Although the impact of sagittal spine movements on locomotion is well known, little information is available on the kinematics of spinal motion. Intervertebral joint movements were studied in two metatherian and three eutherian species during the gallop and halfbound using high-speed cineradiography. Fast-Fourier transformation was used to filter out high frequency digitizing errors and keep the lower frequency sinusoid oscillations that characterize the intervertebral angular movements. Independent of their regional classification as thoracic or lumbar vertebrae, 7+/-1 presacral intervertebral joints were involved in sagittal bending movements. In only one species, no more than five intervertebral joints contributed to the resulting 'pelvic movement'. In general, the trunk region involved in sagittal bending during locomotion did not correspond to the traditional subdivisions of the vertebral column (e.g. as thoracic and lumbar or pre- and postdiaphragmatic region). Therefore, these classifications do not predict the regions involved in spinal oscillations during locomotion. Independent of the gait, maximum flexion of the spine was observed in the interval between the last third of the swing phase and touch-down. This results in a retraction of the pelvis and hindlimbs before touch-down and, we hypothesize, enhances the stability of the system. Maximum extension occurred during the first third of the swing phase (i.e. after lift-off) in all species. In general, the observed timing of dorsoventral oscillations of the spine are in accordance with that observed in other mammals and with activity data of respiratory and epaxial back muscles. Although no strict craniocaudal pattern was observable, the more cranial intervertebral joints tend to flex and extend earlier than the more caudal ones. This is in accordance with the organization and the activation of the paravertebral musculature in mammals. The amplitude of intervertebral joint movements increased caudally, reaching its highest values in the presacral joint. The more intense sagittal bending movements in the caudal intervertebral joints are reflected by the muscle fiber type composition of the back muscles involved. Despite the highly similar amplitude of 'pelvic motion', touch-down and lift-off positions of the pelvis were clearly different between the species with a long, external tail and those with no external tail.

A test of mouth-opening and hyoid-depression mechanisms during prey capture in a catfish using high-speed cineradiography

Detailed morphological analyses have identified a number of different mechanical pathways by which the morphologically complex cranial system of fishes can achieve mouth opening and hyoid depression. However, many of these proposed mechanisms remain untested. Furthermore, very little is known about the precise timing of activity of each of these mechanisms, and about the magnitude of each mechanism's total contribution to its proposed function. In the present study, all mouth opening and hyoid depression mechanisms described for Clarias gariepinus, an air-breathing catfish, are analysed. High-speed X-ray videos were recorded during prey capture of three catfish implanted with small, radio-opaque markers in the cranial elements potentially involved. A kinematic analysis was performed from which data were used as input in planar four-bar models. This analysis shows that the opercular mouth-opening mechanism initiates mouth opening, but is not able to cause the complete mouth openings as observed on the X-ray videos. The latter is accomplished through the protractor hyoidei muscles, which couple hyoid depression to lower jaw depression in a four-bar system and also reinforce lower jaw depression by shortening during the final stage of mouth opening. Although the angulo-ceratohyal ligament was previously hypothesised to play a part in mouth opening, our results show that it probably does not, but rather functions as a hyoid-elevator during mouth closure. Finally, hyoid depression is exclusively achieved by the four-bar mechanism involving neurocranial elevation and pectoral girdle retraction, generally without any reinforcement by shortening of the sternohyoideus muscle. In contrast to the results from a recent analysis on sunfish, the catfish's sternohyoideus gradually elongates during hyoid depression.

Discharge-based sources of XUV-X radiations: development and applications

There is an increasing use of high energy photons in many fields of research and in industry. Where large installations such as synchrotrons or dedicated laser based source facilities can provide solutions for specific needs, they are presently unable to bring convenient solutions for on-site experiments or industrial processes. Compact discharge based devices appear to be a very interesting response to the demand in many cases. They can provide high photon fluxes in a wide spectral range, from VUV to hard x-rays, covering most of the actual needs. Certainly, they still need a lot of improvement and optimization to meet the most stringent requirements. In this paper, we will present some of the recent results we obtained in that field along with new applications. Among them, we will present our report on the performance of a novel and truly compact xenon-filled fast capillary discharge system which generates radiation mostly in the EUV region (10–16 nm) developed in the framework of an EUV lithography program. We will also present results obtained in the field of hard x-ray generation with a new source capable of producing high dose pulses in quasi-continuous or burst mode at a very high frequency developed for high speed cineradiography.

Surface EMG-recordings using a miniaturised matrix electrode: a new technique for small animals

A new method for multichannel surface-EMG measurements in small animals is presented. The underlying scientific aim is the characterisation of the spreading and the co-ordination of skeletal muscle activation between different muscles or muscle parts, depending on various motor tasks. The myoelectrical signals were recorded monopolarly by a 16-channel matrix electrode on the muscle surface directly under the skin on the fascia of the investigated muscle, without damaging the muscle. Surface-EMG's were recorded for at least 5 days after surgery without electrical interferences. During defined motor tasks, the projection of the myoelectrical activation of the different parts of the M. triceps brachii of rats ( Rattus norvegicus), pikas ( Ochotona rufescens) and cuis ( Galea musteloides) or the M. anconeus of toads ( Bufo marinus) on the muscle surface was mapped. The locomotion of the investigated animals was monitored by a three-dimensional kinematic analysis (video and/or high-speed cineradiography). There was no perceptible influence from application of EMG matrix electrode. The miniaturised matrix electrode seemed practicable in gaining insight into changes in myoelectrical activation patterns (EMG mapping). This allows a characterisation of the intramuscular co-ordination processes corresponding to the actual morphofunctional state of the investigated animals.

Cinematographic functional diagnosis of swallowing after plastic reconstruction of large tumor defects of the mouth cavity and pharynx

Reestablishing good swallowing function after resection and reconstruction of head and neck tumors is very important for our patients' well-being. Today many different surgical concepts for reconstruction after tumor surgery are in common use. It is necessary to establish a good diagnostic procedure for postoperative assessment of the swallowing function. High-speed cineradiography at a minimum of 50 frames per second is well established for evaluating swallowing problems in head and neck patients. Thirty-six patients divided into three groups were examined using high speed cineradiography after surgical treatment of pharyngeal and oral cavity cancer. Group 1 (n = 12) included patients with a subtotal or total tongue resection and reconstruction with infrahyoid myofascial flap and jejunal flap; Group II (n = 8), patients with total resection of the oropharynx soft palate and velum and reconstruction with a free radial forearm flap; Group III (n = 15), patients with total laryngopharyngektomy and reconstruction with jejunal flap and siphon and with or without repair of the digastric muscle. Group I: All patients with tongue reconstruction were able to swallow normally from the oral cavity into the pharynx. All patients had normal bolus propulsion because of a good tongue volume and tongue motility. There was only one case of aspiration after total glossectomy with the larynx left in place. All patients could swallow with the head and neck in a normal position. Group II: All patients with reconstruction of the soft palate and velum were able to initiate proper bolus propulsion without nasal regurgitation or rhinolalia aperta. Only one patients suffered from chronic aspiration after hemiresection of the oropharynx and hypopharynx. Group III: All patients with pharynx reconstruction had no problems with bolus transfer through the reconstructed pharynx. Aspiration into the reconstructed pharynx was a major problem for those patients without repair of the digastric muscle (5/8 = 63%). Better results were observed in the patients who underwent repair of the digastric muscle. There was only one case (13%) of aspiration. By using high-speed cineradiography it is possible to make a detailed description of the swallowing function after extensive surgical treatment of pharyngeal and oral cavity cancer. We think that high-speed cineradiography is a very sensitive diagnostic procedure capable of detecting all functional aspects of swallowing. High-speed cineradiography should be one of the standard diagnostic studies performed surgery of the oral cavity and pharynx.

Use of high frequency cinematography in diagnosis of globus sensation

Globus pharyngis is a frequent symptom in patients who consult an otolaryngologist. In many cases, routine diagnostic work-up including history, clinical examination, and barium swallow fail to revealing the underlying pathogenesis. In a retrospective study, we present 51 selected patients suffering from globus pharyngis of unknown origin who were investigated by high-speed cineradiography in a standardized manner. Twenty-four of the patients enrolled in the study (47.1%) showed functional and/or structural swallowing disorders. In 13 cases (25.5%) dyskinesias of the superior esophagus sphincter muscle were found. Five of these patients (9.8%) also had an inconstant hypopharyngeal diverticulum. Six cases (11.8%) showed laryngeal penetration or tracheal aspiration. In four cases (7.8%) functional disorders of pharyngeal, and in three cases (5.9%) functional disorders of oral bolus transport were found. Furthermore one hypopharyngeal web (1.9%) and two benign tumors (3.9%) were detected. In many cases, varying combinations of these findings occurred. Using high-speed cineradiography for evaluation of globus pharyngis results in an increased incidence of pathologic findings, and thus is an important method for interdisciplinary diagnostic work up of patients suffering from this symptom.

Kinematographische Untersuchung des Pathomechanismus der Aspirationspneumonie

6% of all patients suffering from a cerebrovascular injury die from aspiration pneumonia within the first year. The high temporal resolution of high-speed cineradiography (HFK) (50 frames/sec.) allows the recording of the 0.7 sec. process of pharyngeal swallow. Five case-examples are presented (total number of cases: 95) illustrating the possibility of differentiation between three types of aspiration by means of cineradiography. These types are the so-called pre-, intra- and postdeglutitive aspiration, that is aspiration before or after triggering of the swallowing reflex. This differentiation is of great therapeutic importance. The analysis of disturbances of pharyngo-laryngeal motility and the temporal coordination allows setting up individual surgical and/or conservative programme for rehabilitation.

Comparison of cineradiographic and photodetection techniques for assessing velopharyngeal function during speech.

This study investigated the extent to which high-speed lateral-view cineradiography and a photodetector system described by Dalston (1982) provided comparable information concerning velopharyngeal activity. We observed the production of isolated utterances and running speech for 2 subjects in three contexts. A comparison was made between the times at which the velopharyngeal port was observed by each method to begin opening, reach maximal opening, begin closing, and initially attain closure. The photodetector system was found to be sensitive to changes in velar position observed by cineradiography. The correlation between the magnitude of photodetector output and the magnitude of velar displacement from the posterior pharyngeal wall was .89 for Subject 1 and .78 for Subject 2. The lack of a perfect relation between the output of the photodetector device and movements of the velum observed by cineradiography was not unexpected given the two-dimensional limitation of lateral cineradiography and the complexity of events associated with changing port size. The significance of these findings is discussed with respect to the potential research and clinical uses of this photodetector system.

Lung volume changes during respiration in ducks

The avian lung has been considered to be rigid and to remain isovolumetric during the respiratory cycle. We tested this hypothesis by implanting radiopaque markers of tantalum on the dorsal pulmonary surfaces and ventral pulmonary aponeuroses of Pekin ducks ( Anas platyrhynchos) and measuring changes in lung thickness during the respiratory cycle using high speed cineradiography. We found small but regular changes in lung thickness that were synchronous with respiratory phase. Lung thickness was greatest at mid-inspiration (0.6% greater than mean) and least at mid-expiration (0.8% less than mean). Measurements made on ostrich ( Struthio camelus) respiratory structures suggest that the maximal force that could be generated by the muscles ( Mm. costopulmonales) at the margins of the ventral pulmonary aponeurosis is more than two orders of magnitude greater than would be required to resist pressure-induced changes in lung volume during respiration at rest. The action of these muscles could account for the very small magnitute of the volume changes measured during the respiratory cycle.

Cardiovascular distortion in experimental nonpenetrating chest impacts.

High-speed cineradiography and flash radiography were used to determine cardiac distortion and the motion of the heart within the thorax following nonpenetrating chest impact. Maximum ventricular distortion occurred approximately 3 ms after impact which was also the time of maximum chest wall displacement. Between +3 ms and +10 ms the heart moved posteriorly and regained much of its initial shape. Maximal posterior displacement of the body of the heart occurred at approximately +10 ms. Three-dimensional reconstruction showed that the heart moved caudally and to the right, with little rotation. The aortic arch moved cranially with consequent stretching of the thoracic aorta.

Epiglottic dysfunction during deglutition in patients with dysphagia.

Among 250 patients with dysphagial complaints, 83 had dysfunction of the epiglottis as revealed by high-speed cineradiography. Nineteen patients had a totally immobile epiglottis and of these 11 had concomitant pharyngeal constrictor paresis. Sixteen of the patients with immobile epiglottis had misdirected swallowing. An absence of the second movement of the epiglottis during deglutition was registered in 53 patients. Thirteen of these had pharyngeal constrictor paresis and 45 had misdirected swallowing. In 11 patients the epiglottis attained an obliquity of 30 degrees to 90 degrees as seen in the anteroposterior projection during its second movement. One of these had a pharyngeal constrictor paresis, while four had misdirected swallowing. The results of this study indicate that epiglottic dysfunction is common among patients with dysphagia and is often accompanied by other functional abnormalities.

Movement of the epiglottis during deglutition. A cineradiographic study.

The movements of epiglottis during swallowing of barium were studied by high-speed cineradiography in 150 volunteers who had no dysphagia. In 137 individuals the epiglottis tilted down in a two-step fashion during deglutition. The first movement from an upright to transverse position was accomplished by elevation of the larynx and approximation of the hyoid bone and thyroid cartilage. This first movement is evidently a passive one and induced by the muscles that lift the hyoid bone. The second movement of the epiglottis, from transverse to an inverted position, occurs later in swallowing and seems related to contraction of the thyroepiglottic muscle. The second epiglottic movement was absent in 7 individuals, and 6 others demonstrated obliquity of their epiglottis (30-90 degrees) when studied in AP projection.

Relationship between stroke volume and pneumocardiogram.

The intratracheal pressure oscillations produced by the heartbeat, called the pneumocardiogram, were recorded in 15 dogs. It was found that a linear relationship existed between the amplitude of the major negative deflection of the pneumocardiogram and the cardiac stroke volume, the latter determined either by indicator dilution (avg r = 0.94) or by use of an electromagnetic flow probe (avg r = 0.95). This relationship existed in animals with both an open and a closed chest. The vector of left ventricular wall motion directed toward the lungs, determined by high-speed cineradiography of the motion of a tantalum marker inserted in the wall of the left ventricle, looked very similar to the pneumocardiogram. This study showed that the pneumocardiogram can be used as a noninvasive technique to measure changes in stroke volume and is caused primarily by the motion of the cardiac walls.