Essentials of Spine Trauma Imaging: Radiographs, CT, and MRI

Automatic 3D reconstruction of vertebrae from orthogonal bi-planar radiographs

When conducting spine-related diagnosis and surgery, the three-dimensional (3D) upright posture of the spine under natural weight bearing is of significant clinical value for physicians to analyze the force on the spine. However, existing medical imaging technologies cannot meet current requirements of medical service. On the one hand, the mainstream 3D volumetric imaging modalities (e.g. CT and MRI) require patients to lie down during the imaging process. On the other hand, the imaging modalities conducted in an upright posture (e.g. radiograph) can only realize 2D projections, which lose the valid information of spinal anatomy and curvature. Developments of deep learning-based 3D reconstruction methods bring potential to overcome the limitations of the existing medical imaging technologies. To deal with the limitations of current medical imaging technologies as is described above, in this paper, we propose a novel deep learning framework, ReVerteR, which can realize automatic 3D Reconstruction of Vertebrae from orthogonal bi-planar Radiographs. With the utilization of self-attention mechanism and specially designed loss function combining Dice, Hausdorff, Focal, and MSE, ReVerteR can alleviate the sample-imbalance problem during the reconstruction process and realize the fusion of the centroid annotation and the focused vertebra. Furthermore, aiming at automatic and customized 3D spinal reconstruction in real-world scenarios, we extend ReVerteR to a clinical deployment-oriented framework, and develop an interactive interface with all functions in the framework integrated so as to enhance human-computer interaction during clinical decision-making. Extensive experiments and visualization conducted on our constructed datasets based on two benchmark datasets of spinal CT, VerSe 2019 and VerSe 2020, demonstrate the effectiveness of our proposed ReVerteR. In this paper, we propose an automatic 3D reconstruction method of vertebrae based on orthogonal bi-planar radiographs. With the 3D upright posture of the spine under natural weight bearing effectively constructed, our proposed method is expected to better support doctors make clinical decision during spine-related diagnosis and surgery.

Computed Tomography of the Spine

The introduction of the first whole-body CT scanner in 1974 marked the beginning of cross-sectional spine imaging. In the last decades, the technological advancement, increasing availability and clinical success of CT led to a rapidly growing number of CT examinations, also of the spine. After initially being primarily used for trauma evaluation, new indications continued to emerge, such as assessment of vertebral fractures or degenerative spine disease, preoperative and postoperative evaluation, or CT-guided interventions at the spine; however, improvements in patient management and clinical outcomes come along with higher radiation exposure, which increases the risk for secondary malignancies. Therefore, technical developments in CT acquisition and reconstruction must always include efforts to reduce the radiation dose. But how exactly can the dose be reduced? What amount of dose reduction can be achieved without compromising the clinical value of spinal CT examinations and what can be expected from the rising stars in CT technology: artificial intelligence and photon counting CT? In this article, we try to answer these questions by systematically reviewing dose reduction techniques with respect to the major clinical indications of spinal CT. Furthermore, we take a concise look on the dose reduction potential of future developments in CT hardware and software.

Influence of psychosocial and sociodemographic factors in the surgical management of traumatic cervicothoracic spinal cord injury at level I and II trauma centers in the United States

Background

Socioeconomic factors can bias clinician decision-making in many areas of medicine. Psychosocial characteristics such as diagnosis of alcoholism, substance abuse, and major psychiatric disorder are emerging as potential sources of conscious and unconscious bias. We hypothesized that these psychosocial factors, in addition to socioeconomic factors, may impact the decision to operate on patients with a traumatic cervicothoracic fracture and associated spinal cord injury (SCI).

Methods

We performed a cohort analysis using clinical data from 2012-2016 in the American College of Surgeons (ACS) National Trauma Data Bank at academic level I and II trauma centers. Patients were eligible if they had a diagnosis of cervicothoracic fracture with SCI. Using ICD codes, we evaluated baseline characteristics including race; insurance status; diagnosis of alcoholism, substance abuse, or major psychiatric disorder; admission drug screen and blood alcohol level; injury characteristics and severity; and hospital characteristics including geographic region, non-profit status, university affiliation, and trauma level. Factors significantly associated with surgical intervention in univariate analysis were eligible for inclusion in multivariate logistic regression.

Results

We identified 6,655 eligible patients, of whom 62% underwent surgical treatment (n=4,137). Patients treated non-operatively were more likely to be older; be female; be Black or Hispanic; have Medicare, Medicaid, or no insurance; have been assaulted; have been injured by a firearm; have thoracic fracture; have less severe injuries; have severe TBI; be treated at non-profit hospitals; and be in the Northeast or Western U.S. (all P<0.01). After adjusting for confounders in multivariate analysis, only insurance status remained associated with operative treatment. Medicaid patients (OR=0.81; P=0.021) and uninsured patients (OR=0.63; P<0.001) had lower odds of surgery relative to patients with private insurance. Injury severity and facility characteristics also remained significantly associated with surgical management following multivariate regression.

Conclusions

Psychosocial characteristics such as diagnosis of alcoholism, substance abuse, or psychiatric illness do not appear to bias the decision to operate after traumatic cervicothoracic fracture with SCI. Baseline sociodemographic imbalances were explained largely by insurance status, injury, and facility characteristics in multivariate analysis.

Subaxial spine trauma: radiological approach and practical implications

The cervical spine is part of the axial skeleton and is responsible for protecting vital structures, such as the spinal cord and the vertebral arteries and veins. Traumatic injury to the cervical spine occurs in approximately 3% of blunt trauma injuries, and approximately 80% are below the level of C2. The AO Spine society divides the spine into four segments: the upper cervical spine (C0-C2), subaxial spine (C3-C7), thoracolumbar spine, and sacral spine. Various classifications have been proposed for the subaxial segment since that of Allen and Ferguson in 1982; however, none is universally accepted, and treatment remains controversial. The complex anatomy and biomechanics of the subaxial spine and the lack of a widely accepted classification system make these injuries difficult to evaluate on imaging. The Subaxial Injury Classification System (SLIC) uses fracture morphology, the integrity of discoligamentous complex, and neurological status to score the patient and determine between operative and non-operative management; however, other factors may influence management, such as time for immobilisation, osteoporosis, surgeon's experience, and hospital circumstances. SLIC classifies fracture morphology in a crescent order of severity based on Allen and Ferguson's classification. Compression fractures are the simpler ones, while both distraction injuries and translation/rotation are severe injuries, which are always associated with some degree of discoligamentous complex (DLC) injury. This article will review the indications for imaging, the basis of the SLIC classification, the different types of fracture morphology, evaluation of the DLC, and other features important in decision making in subaxial spine trauma.

Traumatic cervical spine fracture patterns on CT: a retrospective analysis at a level 1 trauma center

PURPOSE

The purpose of our study was to determine common acute traumatic cervical spine fracture patterns on CT cervical spine (CTCS).

METHODS

We retrospectively reviewed 1091 CTCS positive for traumatic fractures performed over a 10-year period at a level 1 trauma center. Fractures were classified by vertebral level, laterality, and anatomic location (anterior/posterior arch, body, odontoid, pedicle, facet, lateral mass, lamina, spinous process, transverse foramina, and transverse processes).

RESULTS

C2 was the most commonly fractured vertebra (38% of all studies), followed by C7 (32.4%). 48.7% of studies had upper cervical spine (C1 and/or C2) fractures. 39.7% of positive studies involved > 1 vertebral level. Conditioned on fractures at one cervical level, the probability of fracture was greatest at adjacent levels with a 50% chance of sustaining a C7 fracture with C6 fracture. However, 31.3% (136) of studies with multi-level fractures had non-contiguous fractures. The most common isolated vertebral process fracture was of the transverse process, seen in 89 (8.2%) studies at a single level, 27 (2.5%) studies at multiple levels. Subaxial spine vertebral process fractures outnumbered body fractures with progressive dominance of vertebral process fracture down the spine.

CONCLUSION

C2 was the most commonly fractured vertebral level. Multi-level traumatic cervical spine fractures constituted 40% of our cohort, most commonly at C6/C7 and C1/C2. Although the conditional probability of concurrent fracture in studies with multi-level fractures was greatest in contiguous levels, nearly one-third of multi-level fractures involved non-contiguous fractures.

Current updates on various treatment approaches in the early management of acute spinal cord injury

Spinal cord injury (SCI) is a debilitating condition which often leads to a severe disability and ultimately impact patient's physical, psychological, and social well-being. The management of acute SCI has evolved over the couple of decades due to improved understanding of injury mechanisms and increasing knowledge of disease. Currently, the early management of acute SCI patient includes pharmacological agents, surgical intervention and newly experimental neuroprotective strategies. However, many controversial areas are still surrounding in the current treatment strategies for acute SCI, including the optimal timing of surgical intervention, early versus delayed decompression outcome benefits, the use of methylprednisolone. Due to the lack of consensus, the optimal standard of care has been varied across treatment centres. The authors have shed a light on the current updates on early treatment approaches and neuroprotective strategies in the initial management of acute SCI in order to protect the early neurologic injury and reduce the future disability.

The Utility of Magnetic Resonance Imaging for Detecting Unstable Cervical Spine Injuries in the Neurologically Intact Traumatized Patient Following Negative Computed Tomography Imaging

BACKGROUND

Neurologically intact blunt trauma patients with persistent neck pain and negative computed tomography (CT) imaging frequently undergo magnetic resonance imaging (MRI) for evaluation of occult cervical spine injury. There is a paucity of data to support or refute this practice. This study was therefore performed to evaluate the utility of cervical spine MRI in neurologically intact blunt trauma patients with negative CT imaging.

METHODS

A retrospective review was performed of all neurologically intact blunt trauma patients presenting to a level 1 trauma center from 2005 to 2015 with persistent neck pain and negative CT imaging. The proportion of patients with positive MRI findings, subsequent treatment, and time required to obtain MRI results was evaluated.

RESULTS

Of 223 patients meeting inclusion criteria, 11 had positive MRI findings; however, no patients were found to have unstable injuries requiring surgical treatment. The process for a complete evaluation of unstable cervical spine injury from the time of obtaining a CT scan was 19 hours and 43 minutes.

CONCLUSIONS

Eleven patients had positive MRI findings, yet these findings did not alter treatment. In contrast, the time required to obtain MRI results may substantially delay patient care.

LEVEL OF EVIDENCE

IV (retrospective case series) CLINICAL RELEVANCE: Our results demonstrate that MRI has limited utility in neurologically intact blunt trauma patients with negative CT imaging.