Flexion and extension views are not cost-effective in a cervical spine clearance protocol for obtunded trauma patients

Appropriate CT cervical spine utilisation in the emergency department

Introduction

Over 40 000 CT scans are performed in our emergency department (ED) annually and utilisation is over 80% capacity. Improving medical appropriateness of CT scans may reduce total number of scans, time, cost and radiation exposure.

Methods

Lean Six Sigma methodology was used to improve the process. A National Emergency X-Radiography Utilisation Study (NEXUS)-based PowerForm was implemented in the electronic health record and providers were educated on the criteria.

Results

The rate of potentially medically inappropriate CT C-spine scans decreased from 45% (19/42) to 22% (90/403) (two-proportion test, p=0.002). After the intervention, there was no longer a difference between midlevel providers and physicians in the rate of medically inappropriate orders (19% vs 22%) (two-proportion test, p=0.850) compared with that before the intervention (56% vs 31%) (two-proportion test, p<0.01). Overall rates of CT C-spine scans ordered decreased from 69.3 to 62.6/week (t-test, p=0.019).

Conclusion

A validated clinical decision-making tool implemented into the medical record can improve quality of care. This study lays a foundation for other imaging studies with validated support tools with similar potential improvements.

Posttraumatic Spinal Cord Injury without Radiographic Abnormality

“Spinal Cord Injury without Radiographic Abnormality” (SCIWORA) is a term that denotes objective clinical signs of posttraumatic spinal cord injury without evidence of fracture or malalignment on plain radiographs and computed tomography (CT) of the spine. SCIWORA is most commonly seen in children with a predilection for the cervical spinal cord due to the increased mobility of the cervical spine, the inherent ligamentous laxity, and the large head-to-body ratio during childhood. However, SCIWORA can also be seen in adults and, in rare cases, the thoracolumbar spinal cord can be affected too. Magnetic resonance imaging (MRI) has become a valuable diagnostic tool in patients with SCIWORA because of its superior ability to identify soft tissue lesions such as cord edema, hematomas and transections, and discoligamentous injuries that may not be visualized in plain radiographs and CT. The mainstay of treatment in patients with SCIWORA is nonoperative management including steroid therapy, immobilization, and avoidance of activities that may increase the risk of exacerbation or recurrent injury. Although the role of operative treatment in SCIWORA can be controversial, surgical alternatives such as decompression and fusion should be considered in selected patients with clinical and MRI evidence of persistent spinal cord compression and instability.

Magnetic resonance imaging of traumatic injury to the craniovertebral junction: a case-based review

OBJECT

The craniovertebral junction (CVJ) is unique in the spinal column regarding the degree of multiplanar mobility allowed by its bony articulations. A network of ligamentous attachments provides stability to this junction. Although ligamentous injury can be inferred on CT scans through the utilization of craniometric measurements, the disruption of these ligaments can only be visualized directly with MRI. Here, the authors review the current literature on MRI evaluation of the CVJ following trauma and present several illustrative cases to highlight the utility and limitations of craniometric measures in the context of ligamentous injury at the CVJ.

METHODS

A retrospective case review was conducted to identify patients with cervical spine trauma who underwent cervical MRI and subsequently required occipitocervical or atlantoaxial fusion. Craniometric measurements were performed on the CT images in these cases. An extensive PubMed/MEDLINE literature search was conducted to identify publications regarding the use of MRI in the evaluation of patients with CVJ trauma.

RESULTS

The authors identified 8 cases in which cervical MRI was performed prior to operative stabilization of the CVJ. Craniometric measures did not reliably rule out ligamentous injury, and there was significant heterogeneity in the reliability of different craniometric measurements. A review of the literature revealed several case series and descriptive studies addressing MRI in CVJ trauma. Three papers reported the inadequacy of the historical Traynelis system for identifying atlantooccipital dislocation and presented 3 alternative classification schemes with emphasis on MRI findings.

CONCLUSIONS

Recognition of ligamentous instability at the CVJ is critical in directing clinical decision making regarding surgical stabilization. Craniometric measures appear unreliable, and CT alone is unable to provide direct visualization of ligamentous injury. Therefore, while the decision to obtain MR images in CVJ trauma is largely based on clinical judgment with craniometric measures used as an adjunct, a high degree of suspicion is warranted in the care of these patients as a missed ligamentous injury can have devastating consequences.

Cervical spine clearance protocols in Level I, II, and III trauma centers in California

BACKGROUND CONTEXT

Cervical spine clearance protocols were developed to standardize the clearance of the cervical spine after blunt trauma and prevent secondary neurologic injuries. The degree of incorporation of evidence-based guidelines into protocols at trauma centers in California is unknown.

PURPOSE

To evaluate the cervical spine clearance protocols in all trauma centers of California.

STUDY DESIGN

An observational cross-sectional study.

PATIENT SAMPLE

Included from Level I, II, III trauma centers in California.

OUTCOME MEASURES

The self-reported outcomes of each trauma center's cervical spine clearance protocols were assessed.

METHODS

Level I (n=15), II (n=30), and III (n=11) trauma centers in California were contacted. Each available protocol was reviewed for four scenarios: clearing the asymptomatic patient, the initial imaging modality used in patients not amenable to clinical clearance, and the management strategies for patients with persistent neck pain with a negative computed tomography (CT) scan and those who are obtunded. Results were compared with the 2009 Eastern Association for the Surgery of Trauma (EAST) cervical spine clearance guidelines.

RESULTS

The response rate was 96%. Sixty-three percent of California's trauma centers (Level I, 93%; Level II, 60%; Level III, 27%) had written cervical spine clearance protocols. For asymptomatic patients, 83% of Level I and 61% of Level II centers used National Emergency X-Radiography Utilization Study criteria with/without painless range of motion. For those requiring imaging, 67% of Level I and 56% of Level II centers stated a CT scan should be the first line of imaging. For obtunded patients and patients with persistent neck pain and a negative CT scan, more than 90% of Level I and more than 70% of Level II trauma centers incorporated the 2009 EAST recommendations. No institution recommended passive flexion-extension radiographs for the obtunded patient.

CONCLUSIONS

Written cervical spine clearance protocols exist in 63% of California's trauma centers and only 51% of the centers have protocols that follow current evidence-based guidelines. Standardization and utilization of these protocols should be encouraged to prevent missed injuries and secondary neurologic injuries.

Cervical spine clearance protocols in level 1 trauma centers in the United States

STUDY DESIGN

Observational, cross-sectional.

OBJECTIVE

To evaluate cervical spine clearance protocols in level 1 trauma centers in the United States.

SUMMARY OF BACKGROUND DATA

Cervical spine clearance protocols were developed to prevent missed injuries that could result in neurological deficits. The degree of incorporation of evidence-based guidelines into protocols at trauma centers in the United States is unknown.

METHODS

Level 1 trauma (n = 191) centers in the United States were contacted. Each available protocol was reviewed for 4 scenarios: clearing the asymptomatic patient, the imaging used in patients not amenable to clinical clearance, the management strategies for patients with persistent neck pain with a negative computed tomographic (CT) scan, and those who are obtunded.

RESULTS

The response rate was 87%. Cervical spine clearance protocols existed in 57% of the institutions. National Emergency X-Radiography Utilization Study criteria to clear asymptomatic patients were recommended in 89% of protocols. Sixty percent of protocols used CT scans as the first line of imaging. In patients with persistent neck pain with negative CT scan flexion-extension plain radiographs were the most common (30%) next step for clearance. In patients who are obtunded, a CT scan followed by a magnetic resonance imaging was the most common method (31%) of clearance. Eight percent of the protocols recommended dynamic flexion-extension views in patients who are obtunded, which are contraindicated.

CONCLUSION

Written cervical spine clearance protocols exist in 57% of level 1 trauma centers in the United States. These protocols are highly variable and standardization and utilization of these protocols should be encouraged in all trauma centers to prevent missed injuries and neurological catastrophes.

LEVEL OF EVIDENCE

4.

Predictores en el cuadro SCIWORA del adulto

OBJETIVOS: Analizar cinemática, reconocer cuadro clínico de presentación, describir imágenes, considerar posibilidades terapéuticas y evaluar evolución. MÉTODO: Se analizan 13 pacientes del sexo masculino que presentaron SCIWORA (en inglés Spinal cord injury without radiographic abnormality) entre el 2005 al 2012. Se evalúan cuadro clínico, tratamiento, complicaciones y evolución. RESULTADOS: 10 pacientes mayores de 45 años presentaban signos de espondiloartrosis con mínimos síntomas. De los tres menores de esta edad solo uno presentaba estenosis de canal constitucional asintomática. Todos sufrieron trauma de baja energía. En la resonancia magnética prevaleció el hematoma intramedular y clínicamente todos los pacientes presentaban un síndrome medular central, con cuadro severo (ASIA A-B) en los mayores de 45 años. Siete pacientes fueron tratados inicialmente en forma conservadora; un paciente empeoró y tuvo que ser sometido a intervención quirúrgica 18 meses después y otro falleció en las primeras horas, el resto de los pacientes tuvieron buena evolución. Seis pacientes requirieron cirugía (laminoplastía) en los primeros 10 días; tres fallecieron y el resto mejoro por lo menos un nivel ASIA. CONCLUSIONES: La menor edad, los cuadros leves y el edema intramedular son factores de buen pronóstico y se ven favorecidos con el tratamiento conservador. La mayor edad, la espondiloartrosis y los cuadros severos o progresivos, son factores de mal pronóstico y puede ser necesario su tratamiento quirúrgico.

Cervical spine clearance in the traumatically injured patient: is multidetector CT scanning sufficient alone? Clinical article

OBJECT

Clearance of the cervical spine in patients who have sustained trauma remains a contentious issue. Clinical examination alone is sufficient in neurologically intact patients without neck pain. Patients with neck pain or those with altered mental status or a depressed level of consciousness require further radiographic evaluation. However, no consensus exists as to the appropriate imaging modality. Some advocate multidetector CT (MDCT) scanning alone, but this has been criticized because MDCT is not sensitive in detecting ligamentous injuries that can often only be identified on MRI.

METHODS

Patients were identified retrospectively from a prospectively maintained database at a Level I trauma center. All patients admitted between January 2004 and June 2011 who had a cervical MDCT scan interpreted by a board-certified radiologist as being without evidence of acute traumatic injury and who also had a cervical MRI study obtained during the same hospital admission were included. Data collected included patient demographics, mechanism of injury, Glasgow Coma Scale score at the time of MRI, the indication for and findings on MRI, and the number, type, and indication for cervical spine procedures.

RESULTS

A total of 1004 patients were reviewed, of whom 614 were male, with an overall mean age of 47 years. The indication for MRI was neck pain in 662 patients, altered mental status in 467, and neurological signs or symptoms in 157. The MRI studies were interpreted as normal in 645 patients, evidencing ligamentous injury alone in 125, and showing nonspecific degenerative changes in the remaining patients. Of the 125 patients with ligamentous injuries, 66 (52.8%) had documentation of clearance (29 clinical, 37 with flexion-extension radiographs). Another 32 patients were presumed to be self-cleared, bringing the follow-up rate to 82% (98 of 119). Five patients died prior to clearance, and 1 patient was transferred to another facility prior to clearance. Based on these data, the 95% confidence interval for the assertion that clinically irrelevant ligamentous injury in the face of normal MDCT is 97%-100%. No patient with ligamentous injury on MRI was documented to require a surgical procedure or halo orthosis for instability. Thirty-nine patients ultimately underwent cervical surgical procedures (29 anterior and 10 posterior; 5 delayed) for central cord syndrome (21), quadriparesis (9), or discogenic radicular pain (9). None had an unstable spine.

CONCLUSIONS

In this study population, MRI did not add any additional information beyond MDCT in identifying unstable cervical spine injuries. Magnetic resonance imaging frequently detected ligamentous injuries, none of which were found to be unstable at the time of detection, during the course of admission, or on follow-up. Magnetic resonance imaging provided beneficial clinical information and guided surgical procedures in patients with neurological deficits or radicular pain. An MDCT study with sagittal and coronal reconstructions negative for acute injury in patients without an abnormal motor examination may be sufficient alone for clearance.

Traumatic injuries to the craniovertebral junction: a review of rare events

The craniovertebral junction is a specific region of the spine with unique anatomical and biomechanical properties that yields a wide variety of injury patterns. Junctional traumatic fractures and/or dislocations are widely reported in clinical practice, but we could identify only a subgroup of upper cervical spine traumatic injuries with very few cases reported in the literature, and for this reason may be considered rare. In some of these cases, the absence of spinal biomechanical instability, in association with moderate clinical symptoms (neck stiffness and pain) and the difficulty in fracture identification through standard cervical radiographs, leads to a high percentage of missed injuries. In other cases, traumatic events have been commonly described only in autopsy series due to the high degree of spinal biomechanical instability. Herein, we have summarized all the relevant literature concerning this issue and also included our cases, with the aim of emphasizing prompt diagnosis and correct management. We provide a guide for correctly identifying "rare" craniovertebral junction traumatic injuries.

The daunting task of "clearing" the cervical spine

The evaluation of the cervical spine in the emergency department is a common and often challenging task. We report the case of a 70-year-old female who presented intoxicated with evidence of a recent fall. A 64-slice computed tomographic (CT) scan with sagittal and coronal reconstructions revealed no acute injury. The patient was re-examined when alert and had persistent neck pain. Flexion-extension static views revealed severe subluxation of C5 on C6 with jumped facets, and subsequent magnetic resonance imaging confirmed significant ligamentous injury. The evidence available suggests that although CT with reconstruction is highly sensitive for clinically significant cervical injury, the possibility of severe injury remains.

Advances in the management of spinal cord and spinal column injuries

Spinal cord injury (SCI) is a significant public problem, with recent data suggesting that over 1 million people in the U.S.A. alone are affected by paralysis resulting from SCI. Recent advances in prehospital care have improved survival as well as reduced incidence and severity of SCI following spine trauma. Furthermore, increased understanding of the secondary mechanisms of injury following SCI has provided improvements in critical care and acute management in patients suffering from SCI, thus limiting morbidity following injury. In addition, improved technology and biomechanical understanding of the mechanisms of spine trauma have allowed further advances in available techniques for spinal decompression and stabilization. In this chapter we review the most recent data and salient literature regarding SCI and address current controversies, including the use of pharmacological adjuncts in the setting of acute SCI. We will also attempt to provide a reader with basic understanding of the classifications of SCI and spinal column injury. Finally, we review advances in spinal column stabilization including improvements in instrumented fusion and minimally invasive surgery.

Evaluation of acute cervical spine imaging based on ACR Appropriateness Criteria®

The objectives of this study were to determine the rate of acute blunt cervical spine injury at an academic urban level 1 trauma center and to evaluate the utilization of cervical spine imaging based on the established American College of Radiology (ACR) Appropriateness Criteria®. We retrospectively reviewed all radiography and CT imaging of the cervical spine performed over a year period in adult patients presenting with acute blunt cervical spine trauma. Exclusion criteria were children ≤17 years, non-acute trauma of ≥72 h, and penetrating trauma. Any fracture, dislocation, or ligamentous instability demonstrated by diagnostic imaging and requiring stabilization or specialized follow-up was defined as clinically significant cervical spine injury. A total of 1,325 cervical spine studies were reviewed in 1,245 patients; 32.7% (433/1,325) were cervical spine radiographs and 67.3% (892/1,325) were CT examinations. Approximately 1.5% (19/1,245) of the patients demonstrated clinically significant acute cervical spine injury. There were 6.4% (80/1,245) patients who received both cervical spine radiographs and CT as imaging evaluation. Based on the ACR Appropriateness Criteria®, all of the cervical spine radiographs performed (433) were determined to be "inappropriate" imaging in the setting of acute cervical spine injury.

Clearance of the cervical spine in clinically unevaluable trauma patients

STUDY DESIGN

Meta-analytic costeffectiveness analysis.

OBJECTIVE

Our goal was to compare the results of different management strategies for trauma patients in whom the cervical spine was not clinically evaluable due to impaired consciousness, endotracheal intubation, or painful distracting injuries.

SUMMARY OF BACKGROUND DATA

We performed a structured literature review related to cervical spine trauma, radiographic clearance techniques (plain radiography, flexion/extension, CT, and MRI), and complications associated with semirigid collar use.

METHODS

Meta-analytic techniques were used to pool data from multiple sources to calculate pooled mean estimates of sensitivities and specificities of imaging techniques for cervical spinal clearance, rates of complications from various clearance strategies and from empirical use of semirigid collars. A decision analysis model was used to compare outcomes and costs among these strategies.

RESULTS

Slightly more than 7.5% of patients who are clinically unevaluable have cervical spine injuries, and 42% of these injuries are associated with spinal instability. Sensitivity of plain radiography or fluoroscopy for spinal clearance was 57% (95% CI: 57%-60%). Sensitivities for CT and MRI alone were 83% (82%-84%) and 87% (84%-89%), respectively. Complications associated with collar use ranged from 1.3% (2 days) to 7.1% (10 days) but were usually minor and short-lived. Quadriplegia resulting from spinal instability missed by a clearance test had enormous impacts on longevity, quality of life, and costs. These impacts overshadowed the effects of prolonged collar application, even when the incidence of quadriplegia was extremely low.

CONCLUSION

As currently used, neuroimaging studies for cervical spinal clearance in clinically unevaluable patients are not cost-effective compared with empirical immobilization in a semirigid collar.

Clearing the cervical spine in the blunt trauma patient

The goal of cervical spine clearance is to establish that injuries are not present. Patients are classified into four groups: asymptomatic, temporarily nonassessable secondary to distracting injuries or intoxication, symptomatic, and obtunded. Level I evidence supports that the asymptomatic patient can be cleared on clinical grounds and does not require imaging. The temporarily nonassessable patient may have short-term mental status changes (eg, intoxication, painful distracting injuries) and can be evaluated by two methods. When there is urgency, the evaluation is similar to that for the obtunded patient. Alternatively, the patient can be reevaluated within 24 to 48 hours, after return of mentation or following treatment of painful injuries. The patient then can be assessed as the asymptomatic patient is. The symptomatic patient requires advanced imaging. The obtunded patient should undergo, at minimum, a multidetector CT scan. Two methods are advocated. One uses only multidetector CT; a normal result is sufficient to clear the obtunded patient. The alternative method is obtaining a magnetic resonance image subsequent to a negative multidetector CT scan. Because at present information is insufficient to determine whether MRI is indicated, this is an area of controversy.

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.

[Evidence based diagnostic procedures for the determination of suspected blunt cervical spine injuries. Development of an algorithm]

BACKGROUND

The aim of this study was to present existing publications, describing various diagnostic procedures as well as considering the evidence supporting them, to develop a recommendation for diagnosis.

MATERIAL AND METHODS

We reviewed relevant publications between 1966 and 2004 by a systemic literature search in MEDLINE, EMBASE, National Guideline Clearinghouse, Cochrane Library as well as a manual reference search. Keywords were cervical spine, cervical vertebrae, spinal, spinal cord, injury, trauma, fracture, dislocation, imaging, radiography, flexion, extension, fluoroscopy, computed tomography, computed scanning, and magnetic resonance imaging. The selected search results were then classified into levels of evidence.

RESULTS

From among a total of 10,000 publications, 137 relevant publications were stringently reviewed. The level of evidence is on the whole limited due to deficit data; therefore, only class II-III recommendations are possible. We developed an algorithm for the diagnostic approach to suspected trauma of the cervical spine. This clinical algorithm displays the complex diagnosis of cervical spine injury in a clear and logically structured process.

CONCLUSIONS

The diagnostic algorithm for cervical spine injury meets the presently required standards and maximizes care for the newly injured. The development, which can be followed using evidence-based medicine, is transparent and therefore aids the decision process when choosing an adequate diagnostic procedure.

Exclusion of Unstable Cervical Spine Injury in Obtunded Patients with Blunt Trauma: Is MR Imaging Needed when Multi–Detector Row CT Findings Are Normal?

PURPOSE

To retrospectively determine what information, if any, magnetic resonance (MR) imaging of the cervical spine in obtunded and/or "unreliable" patients with blunt trauma adds to multi-detector row computed tomography (CT) of the entire cervical spine (including routine multiplanar sagittal and coronal reformations) when the CT findings are normal.

MATERIALS AND METHODS

The study was HIPAA compliant and institutional review board approved. Informed consent was not required. From April 2001 to November 2003, 1400 trauma patients underwent MR imaging of the cervical spine to evaluate potential cervical spine injuries. Multi-detector row CT of the cervical spine was performed with a four- or 16-detector row scanner. MR imaging of the cervical spine was performed with transverse gradient-echo, sagittal intermediate-weighted, sagittal short inversion time inversion-recovery, and sagittal T1- and T2-weighted fast spin-echo sequences. Many MR examinations were performed to exclude soft-tissue injuries in the cervical spine of obtunded patients with blunt trauma in whom cervical spine injury could not be excluded with physical examination. Complete cervical spine MR studies were obtained to evaluate soft-tissue injuries in 366 obtunded patients with blunt trauma (281 male and 85 female patients; age range, 13-92 years; mean age, 42.1 years). The patients had previously undergone total cervical spine multi-detector row CT with normal findings. The results obtained with these two modalities were compared.

RESULTS

MR images were negative for acute injury in 354 of the 366 patients and negative for cervical spine ligamentous injury in 362. Seven of the 366 patients had cervical cord contusions, four patients had ligamentous injuries, three patients had intervertebral disk edema, and one patient had a cord contusion, a ligamentous injury, and an intervertebral disk injury. Four patients had ligamentous injuries; however, all of these patients had ligament injuries limited to only one of the three columns of cervical spine ligament support. Multi-detector row CT had negative predictive values of 98.9% (362 of 366 patients) for ligament injury and 100% (366 of 366 patients) for unstable cervical spine injury.

CONCLUSION

A normal multi-detector row CT scan of the total cervical spine in obtunded and/or "unreliable" patients with blunt trauma enabled the authors to exclude unstable injuries on the basis of findings at follow-up cervical spine MR imaging.

The importance of maintaining spinal precautions

Spinal injuries are devastating, often leaving the patient paralyzed or with a permanent deficit. Aspiring athletes may not be able to persue their dreams secondary to a spinal injury; families are often left without a major wage earner to support them; and individuals are dependent upon others for the fulfillment of their basic needs. Education is essential for the prevention of primary and secondary spinal injuries; nurses play a key role in both these areas.

Cervical spine clearance: a review

Ethical concerns have hindered any randomised control blinded studies on the imaging required to assess the cervical spine in an unconscious trauma patient. The issue has been contentious for many years and has resulted in burgeoning but inconclusive guidance. MRI and multislice CT technology have made rapid advances, but the literature is slower to catch up. Never the less there appears to be an emerging consensus for the multiply injured patient. The rapid primary clinical survey should be followed by lateral cervical spine, chest and pelvic radiographs. If a patient is unconscious then CT of the brain and at least down to C3 (and in the USA down to D1) has now become routine. The cranio-cervical scans should be a maximum of 2 mm thickness, and probably less, as undisplaced type II peg fractures, can be invisible even on 1 mm slices with reconstructions. If the lateral cervical radiograph and the CT scan are negative, then MRI is the investigation of choice to exclude instability. Patients with focal neurological signs, evidence of cord or disc injury, and patients whose surgery require pre-operative cord assessment should be imaged by MRI. It is also the investigation of choice for evaluating the complications and late sequela of trauma. If the patient is to have an MRI scan, the MR unit must be able to at least do a sagittal STIR sequence of the entire vertebral column to exclude non-contiguous injuries, which, since the advent of MRI, are now known to be relatively common. Any areas of oedema or collapse then require detailed CT evaluation. It is important that cases are handled by a suitably skilled multidisciplinary team, and avoid repeat imaging due to technical inadequacies. The aim of this review is to re-examine the role of cervical spine imaging in the context of new guidelines and technical advances in imaging techniques.

Imaging of acute cervical spine injuries: review and outlook

Advances in imaging technology have been successfully applied in the emergency trauma setting with great benefit providing early, accurate and efficient diagnoses. Gaps in the knowledge of imaging acute spinal injury remain, despite a vast wealth of useful research and publications on the role of CT and MRI. This article reviews in a balanced manner the main questions that still face the attending radiologist by embracing the current and evolving concepts to help define and provide answers to the following; Imaging techniques -- strengths and weaknesses; what are the implications of a missed cervical spine injury?; who should be imaged?; how should they be imaged?; spinal immobilisation -- help or hazard?; residual open questions; what does all this mean?; and what are the implications for the radiologist? Although there are many helpful guidelines, the residual gaps in the knowledge base result in incomplete answers to the questions posed. The identification of these gaps in knowledge however should act as the initiating stimulus for further research. All too often there is a danger that the performance and productivity of the imaging modalities is the main research focus and not enough attention is given to the two fundamental prerequisites to the assessment of any imaging technology -- the clinical selection criteria for imaging and the level of expertise of the appropriate clinician interpreting the images.