Utility of CT head in the acute setting: value of contrast and non-contrast studies

Is Contrast-Enhanced Computed Tomography Redundant for Suspected Intracranial Infection in the Emergency Setting?

OBJECTIVE

There are currently no guidelines for when to use intravenous contrast with head computed tomography (CT) when there is suspected acute intracranial infection. The purpose of our study was to determine the proportion of cases with enhancing findings on CT that also have conspicuous correlating associated findings on noncontrast CT, which would have on their own merited further evaluation with magnetic resonance imaging, the criterion standard for evaluating central nervous system pathology.

METHODS

A retrospective keyword search of the history and clinical information fields in radiology reports for CT examinations of the head without and with contrast from the period January 1, 2004, to October 31, 2021 was performed. Patients with prior head surgery or a history of cancer were excluded. For remaining patients, the noncontrast CT was reviewed for vasogenic edema or mass effect as markers of a possible acute infection, and the presence of background hypodense white matter changes was noted and graded as either absent, mild/scattered, or confluent. Subsequently, the companion contrast-enhanced CT was reviewed for an enhancing abnormality. Chart review was performed to confirm that an infectious process was the ultimate clinical diagnosis in patients with enhancing abnormalities.

RESULTS

Of 343 patients meeting study inclusion/exclusion criteria, 39 had acute infections with an enhancing abnormality on CT (prevalence 11.3%). Thirty-two of these 39 patients also had correlative findings on the noncontrast CT. Noncontrast CT had a positive predictive value of 100%, negative predictive value of 97.7%, sensitivity of 82.1%, specificity of 100%, and accuracy of 98.0% for detecting markers (vasogenic edema and/or mass effect) associated with an enhancing abnormality. Vasogenic edema was the most common noncontrast CT finding in patients who had an infectious enhancing lesion (32 of 39), followed by mass effect (22 of 39). The 7 cases where the acute infection was occult on noncontrast CT were due to leptomeningitis (n = 3), confluent background white matter changes masking the vasogenic edema surrounding intra-axial lesions (n = 3), and a small 0.5 cm extra-axial abscess.

CONCLUSIONS

Most acute intracranial infections with an enhancing CT finding also have a correlative conspicuous noncontrast finding that on its own would merit further evaluation with magnetic resonance imaging, the criterion standard for investigating central nervous system disease, and therefore, in the setting of suspected intracranial infection, contrast-enhanced CT is redundant in most cases. Contrast-enhanced CT primarily provides diagnostic benefit in patients with confluent background white matter changes that may mask vasogenic edema on noncontrast CT.

Use of Computed Tomography of the Head in Patients With Acute Atraumatic Altered Mental Status: A Systematic Review and Meta-analysis

Importance

The usefulness of computed tomography of the head (CTH) in patients with acute-onset atraumatic altered mental status (AMS) is poorly understood, but use in these patients remains high.

Objective

To evaluate the use of CTH (event rate) in patients with AMS and the positive outcome event rate of the performed CTH studies.

Data Sources

The PubMed/MEDLINE, PubMed Central, Embase, and CINAHL databases were searched using predefined Boolean parameters. All studies that met inclusion criteria until January 31, 2022, were included.

Study Selection

Randomized clinical trials and observational, cohort, and case-control studies were included. Conference abstracts, reviews, letters, case reports, case series, systematic literature, and meta-analyses were excluded.

Data Extraction and Synthesis

The systematic literature review was performed per Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Data were independently extracted by 2 authors. Data were pooled using a random-effects method.

Main Outcomes and Measures

Event rate of CTH use in patients with acute atraumatic AMS. The CTH event rates and positive CTH event rates were calculated with 95% CIs.

Results

Of 9338 studies identified, 26 qualified for the systematic review and 25 for the meta-analysis. The 25 studies in the meta-analysis included a total of 79 201 patients. The CTH event rate was 94% (proportion, 0.94; 95% CI, 0.76-1.00), and the positive CTH event rate was 11% (proportion, 0.11; 95% CI, 0.07-0.15). There was significant heterogeneity among the studies included (I2 > 50%, P < .001), for which a random-effects model was used. There was significant publication bias, as evident by an asymmetric funnel plot. There was no fluctuation of the results during the sensitivity analysis, which reassured the reliability of the data.

Conclusions and Relevance

In this meta-analysis, CTH use among patients with acute-onset atraumatic AMS was very high with a low yield. Large-scale studies are needed to guide clinical decision-making in such a situation.

An audit of CT brain findings in adults with new-onset seizures in a resource restricted setting in South Africa

Background

Globally, adults presenting with seizures account for 1% – 2% of visits to emergency departments (EDs), of which 25% are new-onset seizures. Neuroimaging is essential as part of the initial workup. Multiple studies have demonstrated abnormal CT brain (CTB) findings in these patients.

Objectives

To review the CTB findings in adults presenting with new-onset seizures in a resource restricted setting.

Method

A retrospective review of 531 CTBs was conducted at a tertiary hospital in Gauteng on adults presenting to the ED with new-onset seizures.

Results

The mean age of the patients was 45.6 ± 17.1 years, and the male to female ratio was 1.2:1. Generalised and focal seizure types were almost equally represented. Of the total 531 patients, 168 (31.6%) were HIV positive. The CTB findings were abnormal in 257 (48.4%) patients, albeit vascular pathology accounted for 21.9%. Infective pathology accounted for 14.1% with a statistically significant association with HIV (p = 0.003). Trauma related pathology was 2.4%, whilst neoplastic pathology was seen in 3.0%. Other causes included congenital pathology, calcifications, atrophy and gliosis. Clinical factors associated with abnormal CTB findings were age ≥ 40 years, HIV infection, hypertension, focal seizures, low Glasgow Coma Scale (GCS), raised cerebrospinal fluid (CSF) protein and presence of lymphocytes.

Conclusion

A high yield of abnormal CTB findings was noted in adult patients who presented with new-onset seizures, supporting the use of urgent CTB in patients with certain clinical risk factors. Patients without these risk factors can be scanned within 24–48 h in a resource restricted setting.

Rapid Response: To Scan or Not to Scan? The Utility of Noncontrast CT Head for Altered Mental Status

OBJECTIVES

The aims of the study were the following: (1) to determine how often computed tomography (CT) scans of the head are obtained on rapid responses called for altered mental status (AMS), (2) to determine whether CT imaging of the head is required during all rapid responses called for AMS, (3) to determine which patients would benefit from CT scans of the head in this setting, (4) to note whether an adequate neurologic exam was documented, (5) to determine the cost of CT scans that did not change management, and (6) to examine the role of medications leading to AMS.

METHODS

The study was a retrospective chart review at Abington Jefferson Hospital. Data collected included the age, sex, time of rapid response, clinical condition of the patient, whether an arterial blood gas and blood glucose were done, and whether a neurological exam was documented in the resident's rapid response team note. The patien's medications were also reviewed. Computed tomography scan findings as well as changes made in a patient's care as a result of the scan were recorded. Any findings that did not lead to a change in management were considered a "negative" scan.

RESULTS

Overall, 610 rapid responses were activated from January to August 2016. One hundred four (17.04%) of the total rapid responses were for AMS and 83 (79.8%) of these patients underwent noncontrast CT scan of the head. The mean (SD) age of the patients was 74.7 (13.6) years. A total of 56.6% were female. The most frequent clinical conditions documented at the time of rapid responses were noted as confused (33.7%, 28/83), either lethargic or unconscious (32.5%, 27/83), and concern for stroke (21.7%, 18/83). A total of 96.4% (80/83) of the CT scans done were negative for any acute changes. The three patients with positive scans (3/83) had a change in management as a result of the scans. If patients with symptoms concerning for stroke and unconscious patients are excluded, the total number of remaining patients is 56. Of these, zero patients had a positive scan. A total of 64.7% of the rapid response teams were activated either in the afternoon (31.3%) or at night (33.7%). A total of 33.7% had a complete neurological exam documented. A total of 66.2% were either incomplete (34.9%) or absent (31.3%). Sixty percent of the patients who had a CT head for AMS also had a blood sugar checked at bedside. Thirty-eight percent had an arterial blood gas. More than half the patients were taking one or more sedating medications (45/83, 57.8%). Most patients were not on anticoagulants (79.5%).

CONCLUSIONS

The findings of this study suggest that CT scan of the head is useful in older patients, patients with symptoms concerning for stroke, or cases of sudden onset of impaired consciousness. Noncontrast CT scans of the head are not useful for other presentations of AMS.

Yield of head CT for acute findings in patients presenting to the emergency department

OBJECTIVES

The aim of our study was to evaluate the yield of head CT in the ED in different age groups and different referral indications.

PATIENTS AND METHODS

Records of one large academic tertiary care ED were retrospectively reviewed for consecutive adult patients who underwent a head CT between January 1st 2017 and February 10th 2017. CT referral forms and interpretations were obtained and evaluated for demographics, referral indications, and findings. Scans were divided into three groups: acute findings, chronic findings, and normal. The cohort was divided into three age groups. Associations between referral indications and acute findings were calculated.

RESULTS

Overall, 1536 of adult patients with ED head CT were included. Acute findings were found in 239/1536 (15.5%) of the CTs. The frequency of acute findings increased with age (p = 0.027). The most common acute findings were brain hemorrhage (32.6%), infarct (27.6%), and mass (23%). The top three referral indications were focal neurologic deficit (28%), trauma (24.7%), and headache (17.5%). The rates of positive acute findings for different referral indications were seizure 27%, confusion 20%, syncope 19%, focal neurologic deficit 16%, head injury 15%, headache 12%, and dizziness 8%.

CONCLUSION

This study shows the yield of ED head CT for acute findings for different age groups and for different referral indications. The frequency of acute findings increased with age. Suspected seizure had the highest association with an acute finding, whereas dizziness had the lowest association.

ACR Appropriateness Criteria® Acute Mental Status Change, Delirium, and New Onset Psychosis

Acute changes in mental status represent a broad collection of symptoms used to describe disorders in mentation and level of arousal, including the more narrowly defined diagnoses of delirium and psychosis. A wide range of precipitating factors may be responsible for symptom onset including infection, intoxication, and metabolic disorders. Neurologic causes that may be detected on neuroimaging include stroke, traumatic brain injury, nonconvulsive seizure, central nervous system infection, tumors, hydrocephalus, and inflammatory disorders. Not infrequently, two or more precipitating factors may be found. Neuroimaging with CT or MRI is usually appropriate if the clinical suspicion for an acute neurological cause is high, where the cause of symptoms is not found on initial assessment, and for patients whose symptoms do not respond appropriately to management. There was disagreement regarding the appropriateness of neuroimaging in cases where a suspected, nonneurologic cause is found on initial assessment. Neuroimaging with CT is usually appropriate for patients presenting with delirium, although the yield may be low in the absence of trauma or a focal neurological deficit. Neuroimaging with CT or MRI may be appropriate in the evaluation of new onset psychosis, although the yield may be low in the absence of a neurologic deficit. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Evaluating Radiology Result Communication in the Emergency Department

PURPOSE

To assess the pattern of result communication that occurs between radiologists and referring physicians in the emergency department setting.

METHODS

An institutional review board-approved prospective study was performed at a large academic medical center with 24/7 emergency radiology cover. Emergency radiologists logged information regarding all result-reporting communication events that occurred over a 168-hour period.

RESULTS

A total of 286 independent result communication events occurred during the study period, the vast majority of which occurred via telephone (232/286). Emergency radiologists spent 10% of their working time communicating results. Similar amounts of time were spent discussing negative and positive cross-sectional imaging examinations. In a small minority of communication events, additional information was gathered through communication that resulted in a change of interpretation from a normal to an abnormal study.

CONCLUSIONS

Effective and efficient result communication is critical to care delivery in the emergency department setting. Discussion regarding abnormal cases, both in person and over the phone, is encouraged. However, in the emergency setting, time spent on routine direct communication of negative examination results in advance of the final report may lead to increased disruptions, longer turnaround times, and negatively impact patient care. In very few instances, does the additional information gained from the communication event result in a change of interpretation?

[When are contrast agents really needed? : Cross-sectional imaging with computed tomography and magnetic resonance imaging]

CLINICAL ISSUE

The intravenous administration of contrast agents increases the contrast between diverse tissues and vessels against their surroundings in both computed tomography (CT) and magnetic resonance imaging (MRI) scans and has been generously used for years. There are only a few scientific publications that have systematically evaluated the impact of this contrast-enhancing technique over noncontrast enhancing techniques.

RADIOLOGICAL STANDARD

According to these publications and our clinical experiences, there are far more indications to use non-contrast-enhancing techniques as they are used in clinical practice. The most important requirement to renounce the use of a contrast agent is sufficient clinical information and differentiated justified indication. The present review shows useful non-contrast-enhanced examination techniques for neuroradiology, musculoskeletal system, lymphatic system, and thorax, including the hearth, abdomen and breasts.

CLINICAL RECOMMENDATIONS

Good indications for non-contrast imaging are generally follow-ups. In cerebral related questions, like in traumatic or atraumatic emergencies, transient ischemic attacks, minor stroke diagnostic, dementia and in follow-ups of multiple sclerosis, there is usually no need for contrast agent. Examinations of the musculoskeletal systems and follow-up examinations of the lymphatic system can generally be done without a contrast agent. There is no major loss of value in CT and MRI scans of the thorax by examining without contrast. The value of using a contrast agent in the abdomen is far less than expected. Up to now use of a contrast agent is essential in evaluating questions related to vessels or angiomatous tissue and in breast MRI.

Altered Mental Status in ICU Patients: Diagnostic Yield of Noncontrast Head CT for Abnormal and Communicable Findings

OBJECTIVE

To evaluate the diagnostic yield of noncontrast head CT for acute communicable findings in ICU patients specifically scanned for altered mental status.

DESIGN

Retrospective observational cohort study.

SETTING

University Hospital Neuroscience, Medical, and Surgical ICUs.

PATIENTS

ICU patients with new-onset altered mental status.

INTERVENTION

Noncontrast head CT.

MEASUREMENTS AND MAIN RESULTS

Reports on head CTs from two university hospitals performed for the sole indication of altered mental status in ICU patients between July 2011 and June 2013 were reviewed for 1) acute (new or worsening) hemorrhage, 2) mass effect/herniation, 3) infarction, and 4) hydrocephalus. Subgroup analyses of positive findings were performed by 1) ICU group type, 2) age, and 3) race. A total of 2,486 head CTs were performed in 1,357 patients whose age ranged from 14 to 116 years (median, 59; mean, 57.6 ± 16). Acute communicable findings in at least one of four categories were present in 22.8% (566/2,486) of examinations, with hydrocephalus being most common (11.5% [286/2,486]). The frequency of any acute communicable findings in neuroscience, medical, and surgical ICUs was 28.6% (471/1,648), 9.8% (43/440), and 13.1% (52/398), respectively. Neuroscience ICU head CTs had significantly higher rates of acute communicable findings in all categories, except for acute infarction, compared with the other two ICUs (p < 0.001). Acute hydrocephalus (13.6% vs 7.4%; p < 0.001) and mass effect (6.7% vs 4.3%; p = 0.01) were more common in patients less than 65 years. For other acute categories, no significant difference was noted by age. There was no significant difference in the likelihood of a positive examination by race.

CONCLUSIONS

Almost one in four head CTs in a university ICU patient population performed for primary indication of altered mental status yields abnormal communicable findings. In this patient population, utilization management barriers to examination ordering should be minimized.