Prospective evaluation of selected clinical criteria for cranial computed tomography in non‐trauma adult patients

Objective: To evaluate the usefulness of previously published criteria by Rothrock et al. and Harris et al. for urgent, cranial CT in non‐trauma presentations. Methods: A prospective, observational study of consecutive adult patients with non‐trauma presentations to Westmead Emergency Department, undergoing urgent cranial CT over a period of 2 years and 10 months. Clinical data were assessed to determine the presence of the proposed Rothrock and Harris criteria. Clinically significant findings defined by CT were intracerebral haemorrhage, acute infarction, intracranial infection, acute hydrocephalus, cerebral oedema and malignancy. Results: A total of 1911 patients were studied. Among them, 21.7% (414/1911) of patients had clinically significant findings on CT. Application of the Harris criteria demonstrated a sensitivity of 93.5% (387/414, 95% CI 90.7–95.7) and a false negative rate of 6.5% (27/414, 95% CI 4.3–9.3) with a potential reduction in number of scans by 27.8%. With application of the Rothrock criteria, the possible scan reduction rate was 15% with a sensitivity of 98.8% (409/414, 95% CI 97.2–99.6) and a false negative rate of 1.2% (5/414, 95% CI 0.4–2.8). Conclusion: The Harris criteria were not validated by our study. The Rothrock criteria are also not confidently validated, but can be a useful guide for emergency physicians to help prioritize high‐risk patients who might have clinically significant cranial CT findings. We have not replicated their very high sensitivity and very low false negative rates.     

Detection of Electrolyte Abnormalities in Children Presenting to the Emergency Department: A Multicenter, Prospective Analysis

Objective : To prospectively derive high-yield criteria for the detection of clinically significant electrolyte abnormalities (CSEAs) in children presenting to the ED.
Methods : A prospective, multicenter, observational study was performed at the EDs of 2 urban teaching hospitals, a university medical center, and a children's hospital with a combined census of >275,000 patient visits/year (100,000 visits for children <13 years old). All children <13 years old who had electrolyte panels obtained were eligible for analysis. A data form containing potential predictor variables for a CSEA was completed by the clinician prior to receipt of electrolyte results. A CSEA was any abnormal electrolyte value that 1) stimulated constructive assessment of the patient's condition (monitoring, reevaluation of nonspurious laboratory values, or admission), 2) led to further diagnostic studies, 3) led to a new diagnosis, or 4) affected therapy, χ² recursive partitioning was used to derive a decision rule for ordering electrolytes.
Results : Of 715 eligible patient visits, 488 (68%) electrolyte panels contained a laboratory abnormality, with 182 (25%) CSEAs. A decision rule requiring 1 of 6 clinical criteria was 100% sensitive (95% CI 98–100%) and 24% specific (95% CI 21–28%) in detecting CSEAs with positive and negative predictive values of 31% (95% CI 28–34%) and 100% (95% CI 97–100%), respectively. If these criteria had been used to screen patients for whom electrolyte panels were ordered, 128 patients (18%) would not have had electrolyte panels obtained and no CSEAs would have been missed.
Conclusion : A set of clinical criteria was derived that may be useful for limiting electrolyte panels ordering in children. This criterion set requires prospective validation in a separate patient population.     

Identification of Ethanol-intoxicated Patients with Minor Head TVauma Requiring Computed Tomography Scans

Objective: To determine whether clinical parameters and neurologic scores can be used to guide the decision to obtain computed tomography (CT) head scans for ethanol-intoxicated patients with presumed-minor head injuries.
Methods: In a prospective cohort analysis, 107 consecutive adult patients who presented to a county emergency department (ED) with serum ethanol levels >80 mg/dL and minor head trauma were studied. Commonly used clinical variables were determined for each patient. Each patient also underwent an abbreviated neurologic scoring examination and a Glasgow coma scale (GCS) score evaluation at the time of presentation and one hour later, after which a cranial CT scan was done. For purposes of analysis, patients with and patients without intracerebral injuries visible on CT scans of the head were compared.
Results: Nine of 107 patients (8.4%; 95% confidence interval [CI] = 3.9–15.4%) had CT scans that were positive for intracerebral injury. Two patients (1.9%; 95% CI = 0.2–6.6%) needed craniotomy. Five patients had hemotympanum and two patients had bilateral periorbital ecchy-mosis, but CT scans were negative for intracerebral injury in these patients. There was no statistically significant difference between the patients with and without CT scan abnormalities, based on the clinical variables, the GCS scores, or the abbreviated neurologic scoring examinations at presentation or at one hour.
Conclusion: The prevalence of intracerebral injury in CT scans of ethanol-intoxicated patients with minor head injuries was 8.4%. Commonly used clinical parameters and neurologic scores at presentation and one hour later were unable to predict which patients would have intracerebral injuries as evidenced by CT scans. Our low (1.9%) neurosurgical intervention rate supports the need to develop a selective approach to CT scanning in this population.     

The application of North American CT scan criteria to an Australian population with minor head injury

Objective: To determine potential changes in the number of CT head scans performed if the New Orleans Criteria (NOC) or Canadian CT Head Rule (CCTR) was applied to an Australian emergency department population of minor head injured (MHI) patients. Methods: A retrospective chart review was conducted in an adult metropolitan teaching hospital in Brisbane. All patients presenting over a 3‐month period with a GCS Score of 15 following an MHI and had a CT head scan performed were selected for analysis. Using clinically significant CT abnormalities and neurological intervention as the outcome measures, the NOC and CCTR were applied to determine if CT scanning was considered necessary. Results: Of the 240 patients reviewed, 230 had a normal CT scan and 10 had clinically significant CT abnormalities. One patient with CT abnormality required neurosurgical intervention. Application of the NOC would have resulted in a 3.8% (95% CI 1.7–7.0%) reduction in CT scans performed without missing any patients with CT abnormalities or requiring neurological intervention. Application of the CCTR using both high and low risk factors would have resulted in a 46.7% (95% CI 40.2–53.2%) reduction in CT scans performed without missing the patient requiring neurological intervention, but would not have detected two patients with clinically significant CT abnormalities. Conclusion: Neither the NOC nor the CCRT appear suitable for significantly reducing the number of normal CT head scans performed without missing clinically significant CT abnormalities when applied to our current clinical practice.     

Implementation of a guideline for computed tomography head imaging in head injury: A prospective study

Objective: To improve appropriate ordering of head computed tomography (CT) in patients presenting with a head injury by applying an evidence‐based head injury guideline. Methods: This was a comparison observational study of CT head ordering in the setting of head trauma between two groups of patients. There was a pre‐guideline implementation group and a post‐guideline implementation group. Our Southernhealth Head Injury Guideline was largely based on the Canadian CT Head Rule by Steill et al. 2001.We also applied the Canadian CT Head Rule to our post‐guideline implementation group. Results: CT ordering rate in the pre‐guideline group was 31.6% compared with 59% in the post‐guideline group with a relative risk of 1.88 (95% confidence interval [CI]: 1.56–2.27). Abnormal head CT were reported in 6.8% in the pre‐guideline group and 5% in the post‐guideline group (relative risk 0.88, 95% CI 0.44–1.51). When we applied the Canadian CT Head Rule to the prospective group, four patients with clinically significant abnormal head CT would not have been scanned. The sensitivity of the guideline was 100% (95% CI 79–100%), with a specificity of 43.22% (95% CI 37–48%) in diagnosing a significant head injury on CT. Conclusion: The Southernhealth Head Injury Guideline is safe and easy to apply to minor and major head injuries.     

High yield criteria for emergency cranial computed tomography in adult patients with no history of head injury

OBJECTIVES: A recent American study identified clinical factors which effectively predicted those patients who would have significant findings on cranial computed tomography. It was proposed to apply these criteria in a UK setting and to determine whether modifications could be made to improve their efficiency. METHODS: A prospective observational study was conducted over a four month period including all non-trauma adult patients referred from the accident and emergency (A&E) department for urgent cranial computed tomography. Presenting symptoms and signs were analysed for ability to predict clinically significant computed tomography findings, namely: acute infarct, malignancy, acute hydrocephalus, intracranial haemorrhage, or intracranial infection. RESULTS: Sixty two patients were included; 22 (35%) had significant findings on computed tomography. Applying the original criteria (any of: age 60 years or older, focal neurology, headache with nausea or vomiting, altered mental status) to the study population showed that no clinically significant tomograms would have been omitted but only 11% fewer performed. Modifying the criteria by removing "age 60 years or older" and replacing "altered mental status" with a Glasgow coma score <14, still ensured 100% sensitivity and would have resulted in 19% fewer scans being performed. CONCLUSION: Simple clinical criteria can be usefully applied to patients presenting to an A&E department in this country to target patients most likely to have clinically significant findings on urgent cranial computed tomography.     

Biochemical Markers of Cerebral Injury in Patients with Minor Head Trauma and Ethanol Intoxication

Objective: To determine whether biochemical markers can selectively identify those intoxicated patients with presumed minor head injuries who are likely to have CT evidence of intracranial injury. Methods: Patients presenting to the ED with simultaneous presumed minor head trauma and ethanol intoxication were prospectively entered into this cross-sectional study. Following phlebotomy, all patients received cranial CT. Associations between the presence of an abnormal CT scan for injury and serum levels of the following biochemical markers were sought: serum catecholamines, creatine kinase-brain band (CK-BB), and serum amylase. Serum levels are reported as mean ± SEM. Results: Nine of the 107 patients (8.4%; 95% CI 3.9–15.4%) had evidence of intracranial injury on CT. Mean serum CK-BB (16.1 ± 3.7 vs 13.2 ± 9.6 ng/mL), serum norepinephrine (913 ± 117 vs 1,089 ± 76 pg/mL), and serum amylase (64.9 ± 14.8 vs 84 ± 4.7 U/L) levels were not significantly different in patients with and without CT evidence of intracranial injury, respectively. Mean serum epinephrine (298 ± 54 vs 167 ± 18 pg/mL; p = 0.03) and serum dopamine (218 ± 50 vs 130 ± 9 pg/mL; p = 0.014) levels were significantly elevated in the group with intracranial injury on CT. A threshold level of serum dopamine ±140 pg/mL yields a sensitivity of 89% (95% CI 52–100%) and a specificity of 80% (95% CI 70–87%) for CT-evident injury. A threshold level of serum epinephrine ±218 pg/mL yields a sensitivity of 89% (95% CI 52–100%) and a specificity of 80% (95% CI 70–87%) for CT-evident injury. Conclusion: Elevated serum epinephrine and dopamine levels are associated with intracranial CT-evident injury for ethanol-intoxicated patients with presumed minor head injuries. The potential use of these biochemical markers to guide a more selective approach to cranial CT scanning warrants further evaluation.     

Can Patients with Brain Herniation on Cranial Computed Tomography Have a Normal Neurologic Exam?

Objectives:  Herniation of the brain outside of its normal intracranial spaces is assumed to be accompanied by clinically apparent neurologic dysfunction. The authors sought to determine if some patients with brain herniation or significant brain shift diagnosed by cranial computed tomography (CT) might have a normal neurologic examination.
Methods:  This is a secondary analysis of the National Emergency X-Radiography Utilization Study (NEXUS) II cranial CT database compiled from a multicenter, prospective, observational study of all patients for whom cranial CT scanning was ordered in the emergency department (ED). Clinical information including neurologic examination was prospectively collected on all patients prior to CT scanning. Using the final cranial CT radiology reports from participating centers, all CT scans were classified into three categories: frank herniation, significant shift without frank herniation, and minimal or no shift, based on predetermined explicit criteria. These reports were concatenated with clinical information to form the final study database.
Results:  A total of 161 patients had CT-diagnosed frank herniation; 3 (1.9%) had no neurologic deficit. Of 91 patients with significant brain shift but no herniation, 4 (4.4%) had no neurologic deficit.
Conclusions:  A small number of patients may have normal neurologic status while harboring significant brain shift or brain herniation on cranial CT.     

Elder Patients with Closed Head Trauma: A Comparison with Nonelder Patients

Abstract. Objective: Little is known about the circumstances surrounding closed head trauma (CHT) in elders, and how they differ from nonelders. The study objective was to compare the 2 populations for outcome (positive cranial CT scan depicting traumatic injury, or the need for neurosurgery), mechanism of injury, and the value of the neurologic examination to predict a CT scan positive for traumatic injury or the need for neurosurgical intervention. Methods: A retrospective study was conducted by collecting a case series of patients with blunt head trauma who underwent CT scanning, and comparing elder (aged s60 years) with nonelder patients. The setting was the ED of a university-affiliated Level-1 trauma center. Results: Twenty percent of the elders and 13% of the nonelders had CT scans positive for traumatic injury, which conferred a risk ratio of 1.58 (95% CI 1.21–2.05). Older women were more at risk for the need for neurosurgery than were younger ones (3.1 vs 0.3%, RR 10.66, 95% CI 1.26–90.46). Among the elders, falls were the dominant mechanism of closed head trauma, followed by motor vehicle collisions (MVCs), then being struck as a pedestrian. In the nonelders, MVCs, falls, and assaults were the most important mechanisms of injury. A focally abnormal neurologic examination imparted an increased risk for both a CT scan positive for traumatic injury (elder 4.39, 95% CI 2.91–6.62; nonelder 7.75, 95% CI 5.53–10.72) and the need for neurosurgery (elder 35.68, 95% CI 4.58–275.89; nonelder 142.58, 95% CI 19.11–1064.22) in both age groups. Conclusions : Significant differences exist between elder and nonelder victims of CHT with respect to mechanisms of trauma and outcomes (CT scan positive for traumatic injury, or the need for neurosurgery).     

Low Yield of Paired Head and Cervical Spine Computed Tomography in Blunt Trauma Evaluation

Background

With increased computed tomography (CT) utilization, clinicians may simultaneously order head and neck CT scans, even when injury is suspected only in one region.

Use of a complete neurological examination to screen for significant intracranial abnormalities in minor head injury

Indications for head computed tomography (CT) scans are unclear in patients with nonpenetrating head injury and Glasgow Coma Scale (GCS) scores of 15. We performed a prospective study to determine if significant intracranial injury could be excluded in patients with GCS-15 and a normal complete neurological examination. A prospective trial of clinically sober adult patients with GCS = 15 on emergency department (ED) presentation after closed head injury with loss of consciousness or amnesia was conducted from May 1996 through April 1997. All subjects underwent a standardized neurological examination including mental status evaluation, and assessment of motor, sensory, cerebellar and reflex function before CT scan. During the study period, 58 patients met inclusion criteria. Fifty-five patients (95%) had normal CT scans and 23 (42%) had focal neurological abnormalities. Three patients (5%) had CT scan findings of acute intracranial injury, two of whom had normal neurological examinations. One patient had an acute subdural hematoma requiring emergent surgical decompression; the other had both an epidural hematoma and pneumocephalus that did not require surgery. Significant brain injury and need for CT scanning cannot be excluded in patients with minor head injury despite a GCS = 15 and normal complete neurological examination on presentation.     

Utility of an Initial D-dimer Assay in Screening for Traumatic or Spontaneous Intracranial Hemorrhage

OBJECTIVE: To evaluate the sensitivity of a D-dimer assay as a screening tool for possible traumatic or spontaneous intracranial hemorrhage. If adequately sensitive, the D-dimer assay may potentially permit omission of a more expensive computed tomography (CT) scan of the head when such hemorrhage is clinically suspected. METHODS: Prospective, consecutive, blinded study of patients (age > 16 years) requiring a CT scan of the head for suspected intracranial hemorrhage over a five-month period at a university, Level I trauma center. All study patients had a serum D-dimer assay obtained prior to their CT scans. Sensitivity and specificity, with 95% confidence intervals (95% CIs), of the enzyme-linked immunosorbent assay (ELISA) D-dimer assay for the detection of intracranial hemorrhage were calculated. RESULTS: Of the 319 patients entered in the study, 25 (7.8%) had a CT scan positive for intracranial hemorrhage. Patients with intracranial hemorrhage were more likely to have a positive D-dimer assay (chi-square = 13.075, p < 0.001). The D-dimer assay had 21 true-positive and four false-negative tests, resulting in a sensitivity of 84.0% (95% CI = 63.7% to 95.5%) and a specificity of 55.8% (95% CI = 55.5% to 55.9%). The four false-negative cases included one small intraparenchymal hemorrhage, one small subarachnoid hemorrhage, one moderate-sized intraparenchymal hemorrhage with mid-line shift, and one large subdural hematoma requiring emergent surgery. CONCLUSIONS: Due to the catastrophic nature of missing an intracranial hemorrhage in the emergency department, the D-dimer assay is not adequately sensitive or predictive to use as a screening tool to allow routine omission of head CT scanning.     

High yield criteria for obtaining non-trauma chest radiography in the adult emergency department population

To develop a clinical decision rule for predicting significant chest radiography abnormalities in adult Emergency Department (ED) patients, a prospective, observational study was conducted of consecutive adults (>or=18 years old) who underwent chest radiography for nontraumatic complaints at an urban ED with an annual census of 85,000. The official radiologist interpretation of the film was used as the gold standard for defining radiographic abnormalities. Using predefined criteria and author consensus, patients were divided into two groups: those with clinically significant abnormalities (CSA) and those with either normal or nonclinically significant abnormalities. Chi square recursive partitioning was used to derive a decision rule. Odds ratios and kappa statistics were calculated for derived criteria. The results showed 284 (17%) of 1650 patients had clinically significant abnormal radiographs. The presence of any of 10 criteria (age >or= 60 years, temperature >or= 38 degrees C, oxygen saturation < 90%, respiratory rate > 24 breaths/min, hemoptysis, rales, diminished breath sounds, a history of alcohol abuse, tuberculosis, or thromboembolic disease) was 95% sensitive (95% CI: 92-98%) and 40% specific (95% CI: 37-43%) in detecting CSA radiographs. Positive and negative predictive values were 25% (95% CI: 23-27%) and 98% (95% CI: 96-99%), respectively. A highly sensitive decision rule for detecting clinically significant abnormalities on chest radiographs in nontraumatized adults has been developed. If prospectively validated, these criteria may permit clinicians to confidently reduce the number of radiographs in this population.     

The impact of body mass index on concordance in the interpretation of matched noncontrast and contrast abdominal pelvic computed tomographic scans in ED patients with nontraumatic abdominal pain

OBJECTIVE: To determine if body mass index (BMI) is associated with interpretation agreement between matched abdominal pelvic computed tomographic (CT) scan performed with and without oral contrast in emergency department (ED) patients. METHODS: A prospective observational trial of a convenience sample of 100 adult patients undergoing an abdominal pelvic CT was done at a tertiary care academic ED from September 4, 2001, to August 30, 2002. Patients with trauma, renal colic, pregnancy, need of intravenous contrast, or who were clinically unstable were excluded. Height, weight, and waist circumference were recorded and BMI was calculated. Patients had a helical abdominal pelvic CT without oral contrast followed by two drinks of oral contrast 90 minutes apart and then a repeat CT. Attending staff radiologists interpreted the CT scans using explicit data sheets and were blinded to the results of the matching CT. Clinically important discordance between the matching scans was determined by a panel of attending staff from radiology and emergency medicine departments. RESULTS: Of the 100 patients who completed the protocol, 21% (95% confidence interval, 13%-30%) had clinically significant disagreement between noncontrast and oral contrast CT interpretations. Logistic regression analyses yielded an odds ratio of 1.0 (95% confidence interval, 0.9-1.1) for BMI. CONCLUSIONS: This study did not find an association between BMI, sex, or waist circumference and concordance of radiologists' interpretation of noncontrast and oral contrast abdominal pelvic CT scans in ED patients.     

High yield criteria for emergency cranial computed tomography in adult patients with no history of head injury

Objectives—A recent American study identified clinical factors which effectively predicted those patients who would have significant findings on cranial computed tomography. It was proposed to apply these criteria in a UK setting and to determine whether modifications could be made to improve their efficiency.

Methods—A prospective observational study was conducted over a four month period including all non-trauma adult patients referred from the accident and emergency (A&E) department for urgent cranial computed tomography. Presenting symptoms and signs were analysed for ability to predict clinically significant computed tomography findings, namely: acute infarct, malignancy, acute hydrocephalus, intracranial haemorrhage, or intracranial infection.

Results—Sixty two patients were included; 22 (35%) had significant findings on computed tomography. Applying the original criteria (any of: age 60 years or older, focal neurology, headache with nausea or vomiting, altered mental status) to the study population showed that no clinically significant tomograms would have been omitted but only 11% fewer performed. Modifying the criteria by removing "age 60 years or older" and replacing "altered mental status" with a Glasgow coma score <14, still ensured 100% sensitivity and would have resulted in 19% fewer scans being performed.

Conclusion—Simple clinical criteria can be usefully applied to patients presenting to an A&E department in this country to target patients most likely to have clinically significant findings on urgent cranial computed tomography.

     

A New Clinical Scoring System Fails to Differentiate Hemorrhagic from Ischemic Stroke When Used in the Acute Care Setting

Recently, a new diagnostic scoring system has been proposed to help differentiate intracranial hemorrhage (ICH) from ischemic infarct. The system, derived using data from hospitalized stroke patients, is based on eight variables readily available to all clinicians. A diagnostic score <1.0 is reportedly 100% predictive of ischemic infarct. The clinical scoring system is asserted to be a useful adjunct in the initial evaluation of patients with acute stroke syndrome. The purpose of this study was to prospectively evaluate this clinical scoring system in our emergency department (ED). Sixty-one ED patients with focal neurologic deficit undergoing cranial computed tomography (CT) scan to rule out ICH were entered in the study. Thirteen [21% (95% CI, 12–34%)] were found to have an ICH. Twenty-two [36% (95% CI, 24–49%)] had a diagnostic score <1.0. The CT scans on 4 of these 22 patients showed ICH. The positive predictive value for ischemic infarct for these 22 patients using the diagnostic scoring system was 82% (95% CI, 60–95%). Our results suggest that this new clinical scoring system is of no value in helping to differentiate ICH from ischemic stroke in the acute care setting.     

Computerized tomography of the brain for elderly patients presenting to the emergency department with acute confusion

Objective: Confusion is a common reason for presentation of elderly patients to the ED. There are many potential causes of confusion, which include acute neurological events. Computerized tomography (CT) scans are often routinely ordered to investigate confusion, despite the recommendation of guidelines against routine use. The aim of the present study was to determine the usefulness of CT brain scans in a prospective cohort of confused elderly patients presenting to an ED. Methods: The progress notes of 106 consecutive patients over 70 years of age who had a CT brain scan for a presentation of acute confusion were reviewed for indications for the scan and the presence of neurological examination findings. Official radiology reports of CT brain scans were assessed for the presence of abnormalities. Results: Of the 106 patients, 12 (11%, 95% CI 5.29–17.35) had no documented neurological examination. Fifteen patients (14%, 95% CI 7.51–20.79) had acute abnormalities on CT scan, one of whom had two abnormalities. There were ten acute ischaemic strokes, four cerebral haemorrhages and two meningiomas. Thirteen of the patients with positive CT findings (93%, 95% CI 80.7–105.96) had new findings on neurological examination. The only patient with no neurological findings with a positive CT scan had had a fall. A history of a fall or the presence of neurological findings on examination was predictive of a positive CT scan (odds ratio 17.07, 95% CI 2.15–135.35). Conclusion: The results add further support to guidelines that suggest that CT scans of the brain for confused elderly patients should only be performed for those with acute neurological findings, head trauma or a fall.     

Magnetic resonance imaging identifies occult hip fractures missed by 64-slice computed tomography

Background

Citing the enhanced resolution of 64-slice computed tomography (CT), some clinicians now use CT instead of magnetic resonance imaging (MRI) to detect occult hip fracture.

Objective

Our objective was to determine the incidence of occult hip fractures missed by 64-slice CT but detected by MRI.

Methods

We reviewed the medical records and radiology reports of patients over age 60 years with a hip fracture (acetabular, intertrochanteric, trochanteric, femoral neck, and femoral head) during a 3-year period, January 1, 2007 through December 31, 2009. We also reviewed all hip CT and MRI scans ordered during that period. Occult fractures were those visualized on CT or MRI but with negative plain films. We compared CT and MRI findings, and calculated percentages and 95% confidence intervals (CIs).

Results

Of 235 hip fractures, 211 were visible on initial plain films (90%, 95% CI 85–93%) and 24 (10%, 95% CI 6–15%) were occult. Eighteen occult fractures (7.6%, 95% CI 4.6–11.8%) were identified by CT (MRI not done), one (0.4%, 95% CI 0–2%) by MRI (CT not done), one (0.4%, 95% CI 0–2%) by both CT and MRI, and 4 patients (1.7%, 95% CI 0.5–4.3%) had a positive MRI but negative CT scan.

Conclusion

Although 64-slice CT detected the majority of occult fractures, it missed four (2%) significant fractures detected by MRI. CT scan is helpful in the diagnosis of occult hip fracture, but one should not completely exclude the diagnosis based on a negative 64-slice CT scan in a patient with persistent, localized hip pain who cannot bear weight.     

Subarachnoid Hemorrhage Diagnosis: Lumbar Puncture Is Still Needed When the Computed Tomography Scan Is Normal

Objectives: To determine the sensitivity of third-generation CT scanners for diagnosed nontraumatic subarachnoid hemorrhage (SAH) and to assess the impact of symptom duration on sensitivity.
Methods: A retrospective chart review was performed in a university-affiliated tertiary care hospital with an annual ED volume of >100,000 patients. The target population was all patients who presented to the ED from January 1991 to September 1994 with symptoms suggestive of SAH and who had a final diagnosis of nontraumatic SAH based on either a positive CT scan or positive spinal fluid analysis. Patients referred from outside facilities were included if they had a CT done at the study site. All CT scans were done using third-generation scanners. Official CT scan reports were used to categorize scans as positive or negative.
Results: There were 140 patients identified with SAH, with a mean age of 56 years (range 10–88). The sensitivity of CT in the diagnosis of nontraumatic SAH when performed at or before 12 hours of symptom duration was 100% (80/80), and 81.7% (49/60) after 12 hours of symptom duration (95% CI 95–100% and 69.5–90.4%, respectively; p < 0.0001). Eleven of the 140 patients had a negative CT and positive spinal fluid analysis, yielding an overall sensitivity of 92.1% (129/140).
Conclusion: The sensitivity of third-generation CT scans for SAH decreases with time from the onset of symptoms. In this sample population, CT was able to detect all patients scanned ^12 hours after symptom onset. Although the study demonstrated good sensitivity of CT scan reports for SAH when the scan was performed after S12 hours of symptom onset, additional real-time experience is needed to better define the potential risk of a missed SAH should this population not receive the customary lumbar puncture examination in the setting of a negative CT scan.     

Cranial computed tomography in trauma: the accuracy of interpretation by staff in the emergency department

Objectives: Cranial computed tomography (CT) is replacing skull radiography in head trauma. Rapid radiological opinions on these images may not always be available. We assessed the ability of our permanent emergency department staff to interpret the images. Methods: A retrospective series of 100 consecutive cases was reviewed and interpreted by five permanent emergency department medical staff, and their interpretation compared with the consensus opinion of two radiologists. Results: An overall agreement of 86.6% (95% confidence interval (CI) 83.4 to 89.9) was achieved, with a false negative rate of 4.2% (95% CI 3.9 to 4.3). No findings that would have changed the overnight management of any patient were missed. Conclusions: Our results for CT scans are similar to studies of interpretation of other radiographic images in emergency departments. Our emergency staff could safely make the initial interpretation of cranial CT images in trauma out of hours, and formal reporting may wait until a suitably experienced radiologist is available.