Serious cervical spinal injuries in organized youth football are rare. Cervical fracture with neurologic injury is rarely reported in organized youth football players with no pre-existing risk fractures for transient tetraplegia.
Case report and literature review.
After being improperly tackled by an opponent of significantly larger body size, a player sustained a C7 posterior cervical fracture with transient tetraplegia. He was immobilized in a cervical collar and sent to a level 1 trauma center for evaluation. Initial examination showed bilateral paresthesia of the limbs with normal motor function (ASIA D). Initial radiographs of the cervical spine showed a displaced extension-compression fracture of the C7 spinous process. Magnetic resonance imaging of the cervical spine showed edema in the spinal cord in the region of the injury along with significant posterior injury. Imaging studies showed normal volumetric measurements of the spinal canal and no pre-existing risk factors for spinal stenosis or spinal cord injury. Radiographs showed that cervical fracture was healed at 9-month follow-up examination. At 1-year follow-up, the patient was asymptomatic. Radiographs showed healed fracture with no residual instability and full range of cervical spine motion on flexion–extension views.
This case underscores the potential for serious cervical spinal injuries in organized youth sports when players are physically overmatched, and improper tackling technique is used.
Youth football; Sports injuries; Spinal injury; Cervical; Tetraplegia, transient; Neurapraxia; Fracture, cervical, hyperextension; Spinal stenosis, congenital
We wished to evaluate the incidence of non-contiguous spinal injury in the cervicothoracic junction (CTJ) or the upper thoracic spines on cervical spinal MR images in the patients with cervical spinal injuries.
Materials and Methods
Seventy-five cervical spine MR imagings for acute cervical spinal injury were retrospectively reviewed (58 men and 17 women, mean age: 35.3, range: 18-81 years). They were divided into three groups based on the mechanism of injury; axial compression, hyperflexion or hyperextension injury, according to the findings on the MR and CT images. On cervical spine MR images, we evaluated the presence of non-contiguous spinal injury in the CTJ or upper thoracic spine with regard to the presence of marrow contusion or fracture, ligament injury, traumatic disc herniation and spinal cord injury.
Twenty-one cases (28%) showed CTJ or upper thoracic spinal injuries (C7-T5) on cervical spinal MR images that were separated from the cervical spinal injuries. Seven of 21 cases revealed overt fractures in the CTJs or upper thoracic spines. Ligament injury in these regions was found in three cases. Traumatic disc herniation and spinal cord injury in these regions were shown in one and two cases, respectively. The incidence of the non-contiguous spinal injuries in CTJ or upper thoracic spines was higher in the axial compression injury group (35.3%) than in the hyperflexion injury group (26.9%) or the hyperextension (25%) injury group. However, there was no statistical significance (p > 0.05).
Cervical spinal MR revealed non-contiguous CTJ or upper thoracic spinal injuries in 28% of the patients with cervical spinal injury. The mechanism of cervical spinal injury did not significantly affect the incidence of the non-contiguous CTJ or upper thoracic spinal injury.
Spine, MR; Spine, injuries; Trauma
A patient is presented with a cervical spinal cord transection which occurred after a motor vehicle accident in which the air bag deployed and the seat belt was not in use. The patient had complete quadriplegia below the C5 level and his imaging study showed cervical cord transection at the level of the C5/6 disc space with C5, C6 vertebral bodies and laminar fractures. He underwent a C5 laminectomy and a C4-7 posterior fusion with lateral mass screw fixation. Previous reports have described central cord syndromes occurring in hyperextension injuries, but in adults, acute spinal cord transections have only developed after fracture-dislocations of the spine. A case involving a post-traumatic spinal cord transection without any evidence of radiologic facet dislocations is reported. Also, we propose a combined hyperflexion-hyperextension mechanism to explain this type of injury.
Cervical Trauma; Spinal Cord Injuries
Nearly all children with MPS IVA develop skeletal deformities affecting the spine. At the atlanto-axial spine, odontoid hypoplasia occurs. GAG deposition around the dens, leads to peri-odontoid infiltration. Transverse/alar ligament incompetence causes instability. Atlanto-axial instability is associated with cord compression and myelopathy, leading to major morbidity and mortality. Intervention is often required. Does the presence of widened bullet shaped vertebra in platyspondily encroach on the spinal canal and cause spinal stenosis in MPS IVA? So far, there have been no standardised morphometric measurements of the paediatric MPS IVA cervical spine to evaluate whether there is pre-existing spinal stenosis predisposing to compressive myelopathy or whether this is purely an acquired process secondary to instability and compression. This study provides the first radiological quantitative analysis of the cervical spine and spinal cord in a series of affected children. MRI morphometry indicates that the MPS IVA spine is narrower at C1–2 level giving an inverted funnel shape. There is no evidence of a reduction in the Torg ratio (canal-body ratio) in the cervical spine. The spinal canal does not exceed 11 mm at any level, significantly smaller than normal historical cohorts (14 mm). The sagittal diameter and axial surface area of both spinal canal and cord are reduced. C1–2 level cord compression was evident in the canal-cord ratio but the Torg ratio was not predictive of cord compression. In MPS IVA the reduction in the space available for the cord (SAC) is multifactorial rather than due to congenital spinal stenosis.
The projectional nature of radiogram limits its amount of information about the instrumented spine. MRI and CT imaging can be more helpful, using cross-sectional view. However, the presence of metal-related artifacts at both conventional CT and MRI imaging can obscure relevant anatomy and disease. We reviewed the literature about overcoming artifacts from metallic orthopaedic implants at high-field strength MRI imaging and multi-detector CT. The evolution of multichannel CT has made available new techniques that can help minimizing the severe beam-hardening artifacts. The presence of artifacts at CT from metal hardware is related to image reconstruction algorithm (filter), tube current (in mA), X-ray kilovolt peak, pitch, hardware composition, geometry (shape), and location. MRI imaging has been used safely in patients with orthopaedic metallic implants because most of these implants do not have ferromagnetic properties and have been fixed into position. However, on MRI imaging metallic implants may produce geometric distortion, the so-called susceptibility artifact. In conclusion, although 140 kV and high milliamperage second exposures are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. MRI artifacts can be minimized by positioning optimally and correctly the examined anatomy part with metallic implants in the magnet and by choosing fast spin-echo sequences, and in some cases also STIR sequences, with an anterior to posterior frequency-encoding direction and the smallest voxel size.
CT; MRI; Artifacts
A congenitally narrow cervical spinal canal has been established as an important risk factor for the development of cervical spondylotic myelopathy. However, few reports have described the mechanism underlying this risk. In this study, we investigate the relationship between cervical spinal canal narrowing and pathological changes in the cervical spine using positional magnetic resonance imaging (MRI). Two hundred and ninety-five symptomatic patients underwent cervical MRI in the weight-bearing position with dynamic motion (flexion, neutral, and extension) of the cervical spine. The sagittal cervical spinal canal diameter and cervical segmental angular motion were measured and calculated. Each segment was assessed for the extent of intervertebral disc degeneration and cervical cord compression. Based on the sagittal canal diameter, the subjects were classified into three groups: A, subjects with a congenitally narrow canal, diameter of less than 13 mm; B, subjects with a normal canal, diameter of 13–15 mm; C, subjects with a wide canal, diameter of more than 15 mm. When compared with Groups A and B, the disc degeneration grades at the C3-4, C5-6, and C6-7 segments and the cervical cord compression scores at the C3-4 and C5-6 segments showed significant differences. Additionally, when compare with Groups A and C, the disc degeneration grades at all segments, except C2-3, and the cervical cord compression scores at all segments, except C2-3, showed significant differences. With respect to the cervical kinematics, few differences in the kinematics were observed between Groups B and C, however, the kinematics in Group A was different with other two groups. In Group A, the segmental mobility at the C4-5 and C6-7 segments were significantly higher than those observed in Group B, and the segmental mobility at the C3-4 segment was significantly lower than that observed in Groups B or C. We demonstrated the unique pathological and kinematic traits of cervical spine that exist in a congenitally narrow canal. We hypothesize that kinematic trait associated with a congenitally narrow canal may greatly contribute to pathological changes in the cervical spine. Our results suggest that cervical spinal canal diameter of less than 13 mm may be associated with an increased risk for development of pathological changes in cervical intervertebral discs. Subsequently, the presence of a congenitally narrow canal can expose individuals to a greater risk of developing cervical spinal stenosis.
A congenitally narrow canal; Cervical spine; Intervertebral disc; Cervical spinal stenosis; Positional MRI
Unstable cervical fractures commonly require fusion surgery. We present a case of an unstable cervical fracture (AO classification A2.2) affecting the fifth cervical vertebra which was managed by kyphoplasty to achieve a pain-free, functional and stable outcome. The decision to undertake a kyphoplasty procedure was made in the hope of preserving motion and limiting the degree of future adjacent segment disease. We believe this to be the first case of the use of kyphoplasty to be published in the literature in relation to a traumatic cervical fracture. Additionally, at one-year follow-up the patient reports no pain, a near full range of motion in the cervical spine and no neurological deficit.
Kyphoplasty; Fracture; Cervical spine; Minimally invasive; Stability
Prospective, observational case series evaluating the value of cervical spine computed tomography (CT) scans in the initial evaluation of a helmeted football player with suspected cervical spine injury.
Five asymptomatic male football players, fully equipped and immobilized on a backboard.
Multiple 3.0-mm, helically acquired, axially displayed CT images of the cervical spine were obtained from the skull base inferiorly through T1, with images filmed at soft tissue and bone windows. Sagittal and coronal reformatted images were performed. Software was used to minimize metallic artifact.
All series were reviewed by a Board-certified neuroradiologist for image clarity and diagnostic capability.
Lateral scout films demonstrated mild segmental degradation, depending on the location of the metallic snaps overlying the spine. Anteroposterior scout films and bone window images were of diagnostic quality. The soft tissue windows showed minimal localized artifact occurring at the same levels as in the lateral scout views. This minimal beam-hardening streak artifact did not affect the diagnostic quality of the soft tissue windows. Reconstructed images were uniformly of clinical diagnostic quality.
When CT scans were reviewed as a unit, sufficient information was available to allow reliable clinical decisions about the helmeted football player. In light of recent publications demonstrating the difficulty of obtaining adequate radiographs to evaluate cervical spine injury in equipped football players, helmeted athletes may undergo CT scanning without any significant diagnostic limitations.
helmet removal; cervical spine; trauma; injury
The 'classical' or 'Hangman' neck fracture involves the odontoid peg (process) of the second cervical vertebra (C2), and is described as an axial, dens or odontoid peg fracture in both the veterinary and human literature. Possible surgical treatment in both foals and adult horses requires a technique that allows decompression, anatomical alignment and stabilisation of the odontoid fracture. A limited number of surgical cases in foals have been reported in literature, but never in an adult horse. A mature Irish Thoroughbred racehorse was diagnosed with a type 2a odontoid peg fracture. Clinical signs included reluctance to move the head and neck, a left hind limb lameness and a neurological status of grade 2. The horse was treated conservatively and raced successfully five months after the diagnosed injury.
cervical; equine; fracture; odontoid; vertebra
C1 fracture accounts for 2% of all spinal column injuries and 10% of cervical spine fractures, and is most frequently caused by motor vehicle accidents and falls. We present a rare case of C1 anterior arch fracture following standard foramen magnum decompression for Chiari malformation type 1.
A 63-year-old man underwent standard foramen magnum decompression (suboccipital craniectomy and C1 laminectomy) under a diagnosis of Chiari malformation type 1 with syringomyelia in June 2009. The postoperative course was uneventful until the patient noticed progressive posterior cervical pain 5 months after the operation. Computed tomography of the upper cervical spine obtained 7 months after the operation revealed left C1 anterior arch fracture. The patient was referred to our hospital at the end of January 2010 and C1–C2 posterior fusion with C1 lateral mass screws and C2 laminar screws was carried out in March 2010. Complete pain relief was achieved immediately after the second operation, and the patient resumed his daily activities.
Anterior atlas fracture following foramen magnum decompression for Chiari malformation type 1 is very rare, but C1 laminectomy carries the risk of anterior arch fracture. Neurosurgeons should recognize that fracture of the atlas, which commonly results from an axial loading force, can occur in the postoperative period in patients with Chiari malformation.
Anterior atlas fracture; C1 laminectomy; C1–C2 posterior fusion; Chiari malformation type 1; foramen magnum decompression
Motorcycle riding and diving into shallow water continue to present a high risk of cervical spine injury, often complicated by spinal cord damage. In patients with high cervical cord trauma, differentiation of arterial hypotension due to losing vasomotor control from the effects of internal hemorrhage can cause difficulty. In a series of 123 consecutive cases of cervical spine injury, no evidence was found that either early surgical treatment or steroid administration exert a favorable influence on recovery from traumatic myelopathy. When compared with other series, differences were found in the nature, frequency and severity of both spinal and associated injuries, resulting from the relative frequency among the population studied of trauma due to a particular mechanism—traffic accident, diving, industrial injury—and the special functions and location of the hospital from which information is gathered.
X-ray scatter is a significant problem in cone-beam computed tomography when thicker objects and larger cone angles are used, as scattered radiation can lead to reduced contrast and CT number inaccuracy. Advances have been made in x-ray computed tomography (CT) by incorporating a high quality prior image into the image reconstruction process. In this paper, we extend this idea to correct scatter-induced shading artifacts in cone-beam CT image-guided radiation therapy. Specifically, this paper presents a new scatter correction algorithm which uses a prior image with low scatter artifacts to reduce shading artifacts in cone-beam CT images acquired under conditions of high scatter. The proposed correction algorithm begins with an empirical hypothesis that the target image can be written as a weighted summation of a series of basis images that are generated by raising the raw cone-beam projection data to different powers, and then, reconstructing using the standard filtered backprojection algorithm. The weight for each basis image is calculated by minimizing the difference between the target image and the prior image. The performance of the scatter correction algorithm is qualitatively and quantitatively evaluated through phantom studies using a Varian 2100 EX System with an on-board imager. Results show that the proposed scatter correction algorithm using a prior image with low scatter artifacts can substantially mitigate scatter-induced shading artifacts in both full-fan and half-fan modes.
Study design: Two cases of intraoperative, iatrogenic cervical spine fractures in patients with ankylosing spondylitis are reported. Objective: To describe the uncommon complication of iatrogenic cervical spine fractures occurring during spine surgery in patients with ankylosing spondylitis. Summary of background data: To our knowledge, this is the first report on this rare complication. Methods: A 39-year-old patient (1) with ankylosing spondylitis was operated on for cervical stenosis due to C1/2 anterolisthesis. Fifteen hours postoperatively, he developed acute quadriplegia. MRI revealed a fracture/dislocation of C6 on C7 and compression of the spinal cord at this level. Revision was performed with decompression and instrumentation from the occiput to T3. A 55-year-old patient (2) with ankylosing spondylitis and thoracic hyperkyphosis underwent a correction procedure consisting of costotransversectomy, anterior cage implantation at T8/9, and posterior instrumentation from T4 to L1. Halo traction was temporarily applied for correction. At the end of the operation, with the patient still under anesthesia, increased mobility of the cervical spine was noticed. Emergent MRI revealed a fracture of the anterior structures of C6/7. Posterior instrumentation from C5 to T1 was then performed. Results: Quadriplegia persisted in patient 1 until his death secondary to further complications. Patient 2 was mobilized without any neurologic deficits. The fracture healed in good alignment. Conclusions: Iatrogenic fractures of the cervical spine during surgery in ankylosing spondylitis patients are a rare but potentially severe complication. Early diagnosis and therapy are necessary before dislocation, cord compression, and subsequent neurologic impairment occur.
Ankylosing spondylitis; Iatrogenic fracture; Cervical spine fracture
This report presents a case of non-traumatic posterior atlanto-occipital dislocation. A 36-year-old female was referred with a history of numbness of the extremities, vertigo and neck pain for 1 year. The patient had no history of trauma. The axial rotation of range of motion of the cervical spine was severely restricted. A lateral cervical radiograph in the neutral position demonstrated a posterior atlanto-occipital dislocation. A coronal view on a computed tomography (CT) reconstruction image showed a loss of angle of the bilateral atlanto-occipital joint, and a sagittal reconstruction view of CT images also demonstrated flatness of atlanto-occipital joint. Instrumented occipito-cervical fusion was performed after reduction. A lateral cervical radiograph in the neutral position 1 year after surgery showed the reduction of atlanto-occipital joint, moreover, it was maintained even in an extended position. The patient had neurologic improvement after surgery. Flatness of the bilateral atlanto-occipital joint may have induced this instability. Occipital–cervical fusion was chosen in the present case since the patient showed restricted axial rotation of the neck before surgery. The surgery improved the preoperative symptoms including the function of cervical spine evaluated by JOACMEQ.
Atlanto-occipital joint; Subluxation
Hypopharyngeal perforation is mainly reported in association with high velocity road traffic accidents, or with low velocity direct blows to the neck. We report a case of hypopharyngeal perforation following a low velocity motorcycle accident where neither of these mechanisms of injury was apparent. A 52 year old man was referred from the emergency department (ED) with a sore throat and dysphagia, following a low speed side impact accident. A gastrograffin swallow demonstrated a posterior pharyngeal wall tear. After 11 days of conservative hospital treatment, he recovered and was discharged. The presumed mechanism of injury in this case was cervical spine hyperextension without cervical compression.
hypopharyngeal; perforation; trauma
Tibial eminence fractures occur as a result of high amounts of tension placed upon the anterior cruciate ligament (ACL). The incidence of these fractures is higher among adolescent girls due to their inherent skeletal immaturity. In such an injury, direct trauma causes an avulsion fracture occurring at the tibial eminence while the ACL is spared. Imaging is used to confirm the diagnosis of a tibial eminence fracture and regardless of the extent of injury, rehabilitation is crucial for a full recovery. The following is a case study of a 17-year-old girl who was involved in a motor vehicle accident. In the accident, she sustained a left lateral tibial eminence fracture, along with soft tissue injuries at the cervical and lumbar spine. Her treatment included passive and active range of motion (ROM), strength training, physical modalities, and proprioceptive training of the injured areas. An improvement was noted post-treatment and after a 5-month follow-up according to subjective reports and objective assessments (ROM and girth measurements).
tibial eminence; fracture; rehabilitation; éminence du tibia; fracture; réadaptation
This report presents a case of missed upper cervical spine fracture following a motor vehicle accident and illustrates various clinical and radiographic considerations necessary in the evaluation of post traumatic cervical spine injuries. Specific clinical signs and symptoms, as well as radiographic clues should prompt the astute clinician to suspect a fracture even when plain film radiographs have been reported as normal.
A 44-year-old male was referred for an orthopaedic consultation for assessment of headaches following a high speed head-on motor vehicle accident eleven weeks prior to his presentation. Cervical spine radiographs taken at an emergency ward the day of the collision were reported as essentially normal.
Subsequent radiographs taken eleven weeks later revealed a fracture through the body of axis with anterior displacement of atlas. A review of the initial radiographs clearly demonstrated signs suggesting an upper cervical fracture.
Intervention and outcome:
Initially the patient was prescribed a soft collar which he wore daily until an orthopaedic consultation eleven weeks later. Fifteen weeks following trauma, the patient was considered for surgical intervention, due to persistent headaches associated with the development of neurological signs suggestive of early onset of cervical myelopathy.
Cervical spine fractures can have disastrous consequences if not detected early. A thorough clinical and radiological evaluation is essential in any patient presenting with a history of neck or head trauma. Repeated plain film radiographs are imperative in the event of inadequate visualization of the cervical vertebrae. When in doubt, further imaging studies such as computed tomography or magnetic resonance imaging are required to rule out a fracture.
upper cervical fracture; odontoid fracture; cervical spine trauma; chiropractic
Background and aims
At present, cone beam computed tomography (CBCT) has become a substitute for computed tomography (CT) in dental procedures. The metallic materials used in dentistry can produce artifacts due to the beam hard-ening phenomenon. These artifacts decrease the quality of images. In the present study, the number of artifacts as a result of beam hardening in the images of dental implants was compared between two NewTom VG and Planmeca Promax 3D Max CBCT machines.
Materials and methods
An implant drilling model was used in the present study. The implants (Dentis) were placed in the canine, premolar and molar areas. Scanning procedures were carried out by two CBCT machines. The corresponding sections (coronal and axial) of the implants were evaluated by two radiologists. The number of artifacts in each image was determined using the scale provided. Mann-Whitney U test was used for two-by-two comparisons at a significance level of P<0.05.
There were statistically significant differences in beam hardening artifacts in axial and coronal sections between the two x-ray machines (P<0.001), with a higher quality in the images produced by the NewTom VG.
Given the higher quality of the images produced by the NewTom VG x-ray machine, it is recommended for imaging of patients with extensive restorations, multiple prostheses or previous implant treatments.
Artifacts; beam hardening; cone beam computed tomography
Usually, cervical pedicle screw fixation has been considered too risky for neurovascular structures. The purpose of this study was to investigate the method and efficacy of the cervical pedicle screw system for fracture-dislocation of the cervical spine because of its rigid fixation.
PATIENTS AND METHODS
A prospective study was conducted involving 48 patients with cervical spine fracture-dislocation who underwent cervical pedicle screw fixation surgery between January 2003 and January 2007. All patients had various degrees of cord injury, and they were classified according to the American Spinal Cord Injury Association (ASIA) Impairment Scale: 18 cases were grade A, 15 grade B, 10 grade C, and 5 grade D.
Six months after the operation, all patients had achieved solid bony fusion and stable fixation of the related segments. Thirty patients with incomplete spinal cord injury improved their ASIA Impairment Scale classification by 1 to 2 grades after the operation. Eighteen patients with complete spinal cord injury had no improvement in neural function. However, nerve root symptoms such as pain and numbness were alleviated to some extent.
The cervical pedicle screw system is an effective and reliable method for the restoration of cervical stability. Sufficient pre-operative imaging studies of the pedicles and strict screw insertion technique should be emphasised.
Lower cervical spine; Fracture-dislocation; Cervical pedicle screw
During skeletal development the two ossification centers of the odontoid process are separated from the corpus of the axis by a subdental synchondrosis. This synchondrosis is thought to close and disappear spontaneously in adolescence although this has never been studied in detail. The basis of the dens is of clinical relevance as type II dens fractures are located here. To characterize the morphological architecture of the axis with particular attention to the subdental synchondrosis, the complete axis was harvested from thirty age-matched and gender-matched patients of the three different age groups at autopsy. The subdental synchondrosis and the bone structure of the dens, the basis of the dens and the body of C2 were analyzed by radiography, histology and quantitative histomorphometry. At the macroscopic level the persistency of the subdental synchondrosis in the adult cervical spine was detected in 87% (26 of 30) of the specimens. Histomorphometry revealed a residual disc blastema with an average size of 25.8% of the sagittal depth of the basis of the dens at this level. Bony integration of the synchondrosis was poor throughout all ages. Histologically a cartilaginous matrix composition of the subdental synchondrosis persisted throughout all groups. The trabecular microarchitecture demonstrated a significant reduction of bone volume and trabecular number as well as an increased trabecular separation within the basis of the dens as compared to the corpus or the dens of C2. This histomorphometric data regarding a poor integration of the synchondrosis into the trabecular network and the reduced bone mass within the basis of the dens might offer a previously underestimated explanation for the occurrence of type II dens fractures and their association with pseudoarthrosis, respectively.
Subdental synchondrosis; Axis; Type II dens fracture; Bone microstructure; Histomorphometry
Diffusion Tensor imaging (DTI) is an emerging noninvasive method for evaluating tissue microstructure, but is highly susceptible to in vivo motion artifact. Ex vivo experiments on fixed tissues are needed to improve DTI techniques, which require fixed tissue specimens. Several efforts have been made to study the effect of fixation on both human and mouse tissue, with varying results. Four human cervical cords and three segments of pig vivo cervical spinal cord specimens were imaged both before and after tissue fixation using 3D multi-shot diffusion weighted imaging (ms-DWEPI). Fixation caused a significant decrease in the longitudinal diffusivity while the relative anisotropy (RA), and radial diffusivity remained unaffected. Additionally, once adequately preserved the diffusivity parameters of fixed tissue remain constant over time. Fixation has important effects on the diffusivity of tissue specimens. These findings have important implications for the determination of tissue microstructure and function using DTI technologies.
Diffusion MRI; microstructure of cells; effect of fixation
Cone-beam computed tomography (CBCT) has been clinically used to verify patient position and to localize the target of treatment in image-guided radiation therapy (IGRT). However, when the chest and the upper abdomen are scanned, respiratory-induced motion blurring limits the utility of CBCT. In order to mitigate this blurring, respiratory-gated CBCT, i.e. 4D CBCT, was introduced. In 4D CBCT, the cone-beam projection data sets acquired during a gantry rotation are sorted into several respiratory phases. In these gated reconstructions, the number of projections for each respiratory phase is significantly reduced. Consequently, undersampling streaking artifacts are present in the reconstructed images, and the image contrast resolution is also significantly compromised. In this paper, we present a new method to simultaneously achieve both high temporal resolution (~100 ms) and streaking artifact-free image volumes in 4D CBCT. The enabling technique is a newly proposed image reconstruction method, i.e. prior image constrained compressed sensing (PICCS), which enables accurate image reconstruction using vastly undersampled cone-beam projections and a fully sampled prior image. Using PICCS, a streak-free image can be reconstructed from 10–20 cone-beam projections while the signal-to-noise ratio is determined by a denoising feature of the selected objective function and by the prior image, which is reconstructed using all of the acquired cone-beam projections. This feature of PICCS breaks the connection between the temporal resolution and streaking artifacts’ level in 4D CBCT. Numerical simulations and experimental phantom studies have been conducted to validate the method.
Avulsion of spinous process, also called Clay-shoveler's fracture, is most prevalent among those engaged in hard physical labor. To the best of the author's knowledge, only one case of multiple spinous process fractures of the upper thoracic spine in a novice golfer has been reported. A 45-year-old female presented with intractable posterior neck pain. The patient experienced a sharp, sudden pain on the neck while swinging a golf club, immediately after the club head struck the ground. Dynamic cervical radiographic findings were C6 and C7 spinous process fractures. Magnetic resonance imaging revealed C6 and C7 spinous process fractures without spinal cord pathology. The patient was treated with pain medications and cervical bracing. The patient's pain gradually improved. The injury mechanism was speculated to be similar to Clay-shoveler's fracture. Lower cervical spinous process fractures can be associated with a golf swing. If the patient complains of long lasting neck pain and has a history of golf activity, further study should be conducted to rule out lower cervical spinous fracture.
Golf injury; Cervical spinous process fracture; Trapezius muscle
It is very important to pay more attention to spine from the biomechanical perspective. It would allow the analysis of initial conditions of the vertebral disc degeneration syndrome and adopting of normal spine kinematics to compare and match it with a degenerated disc and providing a biomechanical index as an indicator for the conduct of any surgical intervention including arthroplasty to maximize restoring spinal biomechanical motion. It is clear that the head movement is possible with the help of muscles. However, the shape and type of motion depends on the structure and shape of the cervical spine and the interaction between them. Cervical spine kinematics depends on the anatomy of the bones and joints.
Bazhdok et al (2000) investigated the cervical kinematics and mechanical behavior of the spine and its anatomical connections. They have examined the atlanto- occipital joint motion during flexion-extension and rotation as well as the mechanism of paradoxical motion of atlanto- axial joint by radiography. Bifalkou et al (2011) studied the inter-vertebral motion based on arc kinematic commentary of video fluoroscopy. They showed that the diagnosis of biomechanical instability can be done based on the kinematic examination of the spine obtained in sagittal images. They also declared that the fluoroscopy can be used as a tool for study. Using an automated algorithm, image adaption was carried out and the motion direction of vertebrae was tracked.
In the present study, some patients were selected among patients with cervical disc degeneration. Following imaging by fluoroscopy, the instantaneous center of the spinal action was calculated. It was used as a biomechanical criterion and the treatment group was compared with the healthy group. The loci of the instantaneous centers of the two groups were compared and its difference with the value of healthy group was calculated. A biomechanical criterion was introduced as a basis for comparison of normal and degenerated discs.
Cervical, Degeneration, Cases selection
Intracoronary optical coherence tomography and optical frequency domain imaging (OFDI) have been utilized for two-dimensional and three-dimensional imaging of vascular microanatomy. Image quality and the spatial accuracy of multidimensional reconstructions, however, can be degraded due to artifacts resulting from relative motion between the intracoronary catheter and the vessel wall. To track the relative motion of a catheter with regard to the vessel, a motion tracking system was incorporated with a standard OFDI system by using wavelength division multiplexing techniques. Motion of the vessel was acquired by a frequency shift of the backscattered light caused by the Doppler effect. A single monochromatic beam was utilized for tracking the relative longitudinal displacements of a catheter-based fiber probe with regard to the vessel. Although two tracking beams are, in general, required to correct for longitudinal motion artifacts, the accurate reconstruction in a longitudinal view was achieved by the Doppler frequency information of a single beam. Our results demonstrate that the single beam based motion tracking scheme is a cost-effective, practical approach to compensating for longitudinal distortions due to cardiac dynamics, thus leading to accurate quantitative analysis of 3D intracoronary OFDI.
Motion artifacts; Image compensation; OCT; OFDI