Imaging of acute cervical spine injuries: review and outlook

Mechanism of Injury and Clinical Variables in Thoracic Spine Fracture: A Case Control Study

Objective

To determine the mechanisms of injury and clinical findings significantly associated with traumatic thoracic spine (T-spine) fractures.

Methods

This was a case-control study in a tertiary adult trauma centre. Cases were patients admitted with traumatic T-spine fractures between January 1999 and August 2007, inclusive. Each case had two controls matched for gender, age and injury severity. Data were collected from patient medical records and the trauma service database. Factors potentially associated with T-spine fracture were derived from the literature, expert consensus and univariate analysis. Multivariate logistic regression was employed to determine factors significantly associated with T-spine fracture.

Results

Two hundred and sixty one cases and 512 controls were enrolled. Univariate analysis showed the mechanisms of fall from a height ≥2 meters (m) and motorbike accident ≥60 kilometers per hour were significantly associated with T-spine fracture (p<0.001). The clinical findings of thoracic back pain, tenderness, intoxication, step deformity and abnormal neurological symptoms were also significantly associated with T-spine fracture (p<0.05). Multivariate analysis indicated that falls from a height of ≥2 m and thoracic back pain were significantly and positively associated with T-spine fracture (p<0.001). However, intoxication was negatively associated with T-spine fracture.

Conclusions

Patients with T-spine injury are significantly more likely to have fallen from a height ≥2 m or to have had thoracic back pain but less likely to be intoxicated. These findings should be validated prospectively prior to development of clinical guidelines for the identification of patients who may benefit from CT screening of the thoracic spine.

The use of adaptive statistical iterative reconstruction (ASiR) technique in evaluation of patients with cervical spine trauma: impact on radiation dose reduction and image quality

OBJECTIVE

The aim of this study was to evaluate the impact of adaptive statistical iterative reconstruction (ASiR) technique on the image quality and radiation dose reduction. The comparison was made with the traditional filtered back projection (FBP) technique.

METHODS

We retrospectively reviewed 78 patients, who underwent cervical spine CT for blunt cervical trauma between 1 June 2010 and 30 November 2010. 48 patients were imaged using traditional FBP technique and the remaining 30 patients were imaged using the ASiR technique. The patient demographics, radiation dose, objective image signal and noise were recorded; while subjective noise, sharpness, diagnostic acceptability and artefacts were graded by two radiologists blinded to the techniques.

RESULTS

We found that the ASiR technique was able to reduce the volume CT dose index, dose-length product and effective dose by 36%, 36.5% and 36.5%, respectively, compared with the FBP technique. There was no significant difference in the image noise (p = 0.39), signal (p = 0.82) and signal-to-noise ratio (p = 0.56) between the groups. The subjective image quality was minimally better in the ASiR group but not statistically significant. There was excellent interobserver agreement on the subjective image quality and diagnostic acceptability for both groups.

CONCLUSION

The use of ASiR technique allowed approximately 36% radiation dose reduction in the evaluation of cervical spine without degrading the image quality.

ADVANCES IN KNOWLEDGE

The present study highlights that the ASiR technique is extremely helpful in reducing the patient radiation exposure while maintaining the image quality. It is highly recommended to utilize this novel technique in CT imaging of different body regions.

High-resolution human cervical spinal cord imaging at 7 T

We present high-resolution anatomical imaging of the cervical spinal cord in healthy volunteers at the ultrahigh field of 7 T with a prototype four-channel radiofrequency coil array, in comparison with 3-T imaging of the same subjects. Signal-to-noise ratios at both field strengths were estimated using the rigorous Kellman method. Spinal cord cross-sectional area measurements were performed, including whole-cord measurements at both fields and gray matter segmentation at 7 T. The 7-T array coil showed reduced sagittal coverage, comparable axial coverage and the expected significantly higher signal-to-noise ratio compared with equivalent 3-T protocols. In the cervical spinal cord, the signal-to-noise ratio was found by the Kellman method to be higher by a factor of 3.5 with the 7-T coil than with standard 3-T coils. Cervical spine imaging in healthy volunteers at 7 T revealed not only detailed white/gray matter differentiation, but also structures not visualized at lower fields, such as denticulate ligaments, nerve roots and rostral-caudal blood vessels. Whole-cord cross-sectional area measurements showed good agreement at both field strengths. The measurable gray/white matter cross-sectional areas at 7 T were found to be comparable with reports from histology. These pilot data demonstrate the use of higher signal-to-noise ratios at the ultrahigh field of 7 T for significant improvement in anatomical resolution of the cervical spinal cord, allowing the visualization of structures not seen at lower field strength, particularly for axial imaging.

The pearls and pitfalls of magnetic resonance imaging for the spine

Musculoskeletal imaging of the spine can be an invaluable tool to inform clinical decision making in patients with spinal pain. An understanding of the technology involved in producing and interpreting high-resolution images produced from magnetic resonance imaging (MRI) of the human spine is necessary to better appreciate which sequences can be used for, or tailored to, individual patients and their conditions. However, there is substantial variability in the clinical meaningfulness of some MRI findings of spinal tissues. For example, normal variants can often mimic significant musculoskeletal pathology, which could increase the risk of misinformed clinical decisions and, even worse, poor or adverse outcomes. This clinical commentary will highlight some of the pearls and pitfalls of MRI for the cervical, thoracic, and lumbar regions, and include cases to illustrate some of the common imaging artifacts and normal variants for MRI of the spine.

Application of imaging guidelines in patients with suspected cervical spine trauma: retrospective analysis and literature review

Safe and efficient clearance of cervical spine injury in blunt trauma patients has been a controversial topic among health professionals. The increased availability of CT scanners in major trauma centers seems to be a factor that has led to increased number of unnecessary cervical spine imaging using this imaging modality. The objective of this study was to investigate the applicability and efficacy of a pre-test clinical criterion in order to stratify post-blunt trauma victims based on their risk of sustaining cervical spine injury and in turn recommend an appropriate imaging modality accordingly. Goergen's criteria (Australas Radiol 48(3):287, 2004), a pre-investigation diagnostic algorithm was retrospectively applied to 106 blunt trauma victims who presented to a level 1 trauma center in Sydney, Australia, and had a CT scan of cervical spine as part of their initial management. Overall, nine (8.5%) of patients sustained a significant cervical spine injury. All nine patients would be classified as high-risk victims according to the algorithm investigated in this study, warranting CT scanning. No patients with low-risk injuries were demonstrated to have a significant cervical spine injury. There was a statistically significant greater proportion of acute cervical spine injuries detected in the high-risk group (p value = 0.0024). Hence, using Goergen's diagnostic algorithm could reduce the number of unnecessary cervical spine CT scans ordered, while not compromising the quality of care in post-blunt trauma victims.

Are "normal" multidetector computed tomographic scans sufficient to allow collar removal in the trauma patient?

BACKGROUND

Controversy continues as to the most safe and reliable method for clearing the cervical spine (C-spine) in a trauma patient who is rendered unable to participate in a clinical examination. Although magnetic resonance imaging (MRI) is the most sensitive test to detect soft-tissue injuries, it is impractical for routine use in every patient largely because of its cost and time of acquiescence. Recent studies have advocated the sole use of multidetector computed tomographic (MDCT) scans of the C-spine to decide if cervical collar immobilization can be discontinued. The current investigation retrospectively reviewed a series of MDCT scans obtained after an acute traumatic event that were used to direct treatment in the emergency department (ED) or intensive care unit.

METHODS

Seven-hundred and eight trauma patients consecutively admitted to the ED between June 2001 and July 2006 underwent a computed tomographic scan of their C-spine as part of an institutional protocol. We identified 91 patients with MDCT scans that were officially recorded as adequate and negative by an attending ED radiologist who had also undergone an MRI during the same trauma admission period. Retrospectively, two fellowship-trained spine surgeons independently reviewed these MDCT studies to address the following questions: (1) Is the study adequate? (2) Is it suggestive of an acute injury? (3) Is there sufficient information to safely recommend collar removal? Institutional Review Board approval was obtained before the images were reviewed. Neither clinical examination findings nor MRI readings were made available to the surgeon evaluators.

RESULTS

Both spine surgeons agreed that 76 of the 91 studies (84%) were adequate to evaluate for possible C-spine injuries. Seven of 91 MDCT scans (8%) were deemed inadequate by both surgeons (95% confidence interval, 2.3-13.1). Reasons for inadequacy included motion artifact, insufficient visualization of the cervical-thoracic or occipital-cervical junctions, incomplete reconstructive views, or poor quality. Three of the adequate MDCT scans had fractures that were identified by both of the spine surgeons; 4 additional fractures and 15 findings suspicious for instability were identified by at least one of the surgeons. Ultimately, 22 of 91 MDCT scans read as adequate and normal by attending radiologists were deemed suspicious for abnormality by the spine surgeons. Of these 22 cases, the official MRI reading was positive for a trauma-related abnormality in 17 cases.

CONCLUSIONS

C-spine clearance of patients without the ability participate in a clinical examination remains difficult. A multidisciplinary, algorithmic approach generally yields the most consistent results. However, our data highlight that reliance on a single imaging modality may lead to missed diagnosis of C-spine injuries. These data suggest that early involvement of the spine service for radiographic clearance may help identify occult injuries or suspicious findings necessitating further evaluation.

Comparison of low-dose with standard-dose multidetector CT in cervical spine trauma

BACKGROUND AND PURPOSE

The purpose of this work was to evaluate the possible use of low-dose multidetector CT (MDCT) in cervical clearance of patients with blunt trauma.

MATERIALS AND METHODS

A total of 191 patients underwent cervical spine MDCT with 6- and 16-MDCT: standard-dose (n = 51) and low-dose MDCT with tube current modulation at high (n = 70) and low (n = 70) tube voltage (kilovolts). Effective dose, image noise, and subjective image quality were calculated in all of the patients.

RESULTS

MDCT found 18 patients (9.4%) with a cervical spine fracture, 3 in the standard-dose and 15 in the low-dose group, 14 of them with unstable lesions. Tube current modulation reduced the dose by 50%-61% in all of the low-dose examinations. The mean effective dose was 3.75, 1.57, and 1.08 mSv, and mean image noise was 14.82, 17.46, and 19.72 Hounsfield units for standard dose and low dose with high and low kilovolt examinations, respectively. These differences in mean effective dose and image noise were significant between the 3 examination groups (Kruskal-Wallis test: P < .0001 and P = .0001). Evaluation of subjective image quality by 2 radiologists and 2 residents showed no significant difference in image quality score among the 3 examination groups (Kruskal-Wallis tests, P = .61, .32, .18, and .31). All of the reviewers correctly detected 18 fractures, except 1 resident, who missed 3 fractures.

CONCLUSION

Low-dose cervical spine MDCT in patients with blunt trauma gives a substantial dose reduction of 61%-71%, compared with standard-dose MDCT, with a small increase in image noise and without difference in subjective image quality evaluation.

Evolving standards of practice for cervical spine imaging in trauma: A retrospective review

Recently published works on radiology and emergency medicine suggest an increasing role for primary CT imaging of the cervical spine (C-spine) in trauma, rather than plain X-rays. This observational retrospective study of 406 patients was undertaken to examine current practice in a metropolitan teaching hospital setting and to define factors affecting the use of primary imaging for suspected C-spine fracture. This study supports the increasing recognition of the limited accuracy and adequacy of plain films, especially among the more severely injured patients. It is suggested that intubated patients, patients with severe trauma or patients with Glasgow Coma Scale <13 have CT as a primary screening examination for suspected C-spine fracture rather than X-ray. Patients having head CT for suspected intracranial injury may also benefit from included C-spine CT. The increasing usage of primary CT will increase overall imaging costs and resource utilization.

Controversies in "clearing" trauma to the cervical spine

Clearance of the traumatic cervical spine is a subject affecting most healthcare professionals dealing with trauma patients. There is a host of often contradictory literature making it hard for an interested reader to come to their own informed opinion based on the current evidence. This review aims to outline the relevant literature for the clearance of the traumatic cervical spine with the particular aim of highlighting the contradictions, controversies and unanswered questions still besetting this important subject. A brief, subjective opinion for a combined clinical and imaging protocol for clearance of the traumatic cervical spine is given.

Prospective Evaluation of Multislice Computed Tomography Versus Plain Radiographic Cervical Spine Clearance in Trauma Patients

BACKGROUND

The objective of this study was to compare the utility of plain radiographs to multislice computed tomography (MCT) for cervical spine (c-spine) evaluation. We hypothesized that plain radiographs add no clinically relevant diagnostic information to MCT in the screening evaluation of the c-spine of trauma patients.

METHODS

This was a prospective, unblinded, consecutive series of injured patients requiring c-spine evaluation that were imaged with three-view plain films and MCT (occiput to T1 with 3-dimensional reconstruction). The final discharge diagnosis based on all prospectively collected clinical data, MCT, and plain films was utilized as the gold standard for the sensitivity calculation.

RESULTS

From October 2004 to February 2005, 667 trauma patients requiring c-spine evaluation were enrolled. Average age was 35.4 years and 70% were male. The mechanism of injury was blunt in 99% and 48.7% occurred as a result of motor vehicle collision. Sixty of 667 (9%) sustained acute c-spine injuries. MCT had a sensitivity of 100% and specificity of 99.5%. Plain films had a sensitivity of 45% and specificity of 97.4%. Plain radiography missed 15 of 27 (55.5%) clinically significant c-spine injuries.

CONCLUSION

MCT outperformed plain radiography as a screening modality for the identification of acute c-spine injury in trauma patients. All clinically significant injuries were detected by MCT. Plain films failed to identify 55.5% of clinically significant fractures identified by MCT and added no clinically relevant information.

Spinal Trauma

Approximately 30,000 spinal injuries occur in the United States every year. Injuries to the spine and its contents affect predominately young, healthy individuals and are a major cause of disability, with significant socioeconomic consequences. The main cause for spinal injuries is blunt trauma, most commonly caused by motor vehicle accidents, followed by falls and sport injuries. Already, in the initial evaluation of patients who have blunt trauma, multislice CT with two-dimensional (and threedimensional) reformatting is the method of choice. The liberal use of MR imaging is recommended to assess for injuries to soft tissue, the spine and its contents, intervertebral discs, and ligaments.

RADIOGRAPHIC SENSITIVITY AND NEGATIVE PREDICTIVE VALUE FOR ACUTE CANINE SPINAL TRAUMA

The objectives of this study were to establish the sensitivity and negative predictive value of radiography for acute spinal osseous lesions in the canine trauma patient, and to evaluate the interobserver variability in radiographic assessment of the spine in traumatized dogs. This was a retrospective multiple observer blinded study. The study population included 30 canine patients that presented following acute trauma, with clinical signs attributable to the spinal column. Radiography and computed tomography (CT) were performed in all cases. Radiographic interpretation was performed independently by four observers with different experience levels who were blinded to clinical information (other than trauma) and the CT results. CT studies were interpreted by a further three radiologists who formed a consensus opinion on the presence of specific osseous lesions. Using the CT results as a gold standard, the sensitivities and negative predictive values of radiography for specific osseous lesions were calculated. Interobserver agreement was also evaluated. Radiography was found to have only a moderate sensitivity for fractures (72%) and subluxations (77.5%). Low negative predictive values were found for the presence of vertebral canal narrowing (58%) and fracture fragments within the vertebral canal (51%). Interobserver agreement was only moderate to fair for most lesion types. In conclusion, radiography cannot be used to reliably rule out potentially unstable acute vertebral lesions in the canine trauma patient, and further imaging is therefore often indicated in the patient with a high risk of such injuries.

Changing face of spine trauma care in North America

STUDY DESIGN

An evidence-based review and summary of literature from multiple disciplines involved in spine trauma.

OBJECTIVES

To outline epidemiologic, clinical, and research issues influencing spine trauma in a longitudinal perspective. In addition, to provide guidance to clinicians and researchers to ensure that philosophies pertaining to the betterment of spine trauma care are understood and supported.

SUMMARY OF BACKGROUND DATA

Epidemiologic data have provided insight into future demands the elderly patient with spine injury will place on the health care system. Regional trauma programs have emerged with further specialization resulting in regionalized spine trauma care. Evidence-based guidelines have streamlined imaging, and biomaterial advancements have facilitated the stabilization of the spinal column and decompression of the spinal cord. Promising experimental therapies promoting axonal regeneration and neuroprotective agents are beginning clinical trials, generating cautious optimism that effective therapies for spinal cord injuries will emerge. The unsustainable economics of increasing technology and patient expectations will make economic evaluation critical.

METHODS

Evidence-based review of current literature and expert opinion.

CONCLUSIONS

Multicenter spine trauma registries with patient-reported outcomes will allow many questions around spine trauma to be answered using the highest levels of evidence. This process in synergy with technical and biologic developments should ensure progress toward optimal care of the spine trauma patient. Future challenges will be to treat the breadth and magnitude of the discoveries within the fiscal restraints of the health care system and ensure its affordability for society.

Interpretation of cervical spine radiographs

Patients who present to emergency departments following neck trauma are frequently investigated with plain radiographs. The great majority of radiographs will be normal, but interpreting these films can be a daunting task for a junior doctor as the findings may be subtle and the consequences of missing an injury may be catastrophic. The process can be made simpler by understanding which patients require X-rays, developing a systematic approach to reading the films and being able to decide whether further investigation is required. A basic comprehension of the types of cervical spine trauma is useful as well as understanding the principles of stable and unstable injuries.

Imaging of spinal trauma

Approximately 2% to 3% of blunt trauma victims suffer injury to the spinal column each year, often with devastating consequences. This article discusses clinical criteria for screening for spinal injury and the increasing roles of multidetector CT and MR imaging in the evaluation of spinal trauma. Both CT and MR imaging safety issues also are addressed. Lastly, the role of imaging in the evaluation of whiplash injury, instability, vascular injury, and delayed traumatic sequelae is discussed.