The yield of chest X-ray or ultra-low-dose chest-CT in emergency department patients suspected of pulmonary infection without respiratory symptoms or signs

The diagnostic utility of computed tomography scans performed for febrile neutropenia in a single centre

BACKGROUND

Computed tomography (CT) imaging has become a first line investigation for most cases of febrile neutropenia (FN) which can be the only sign of infection in oncology patients undergoing active chemotherapy and bone marrow transplants. The utility of routine non-targeted imaging remains unclear.

OBJECTIVE

To assess and compare the diagnostic rate between targeted, non-targeted and pan-scan CT in identifying an acute source of infection in adult oncology patients with FN.

MATERIALS AND METHODS

A retrospective observational study was conducted between February 2019 and March 2023 on 417 consecutive CT examinations for the clinical indication of source identification in FN. Scans were noted for the anatomical regions that were imaged and reports were classified as positive, negative or equivocal for infection. Pre-existing pathology was also noted. Results were tabulated and statistical analyses for comparison between groups of scans was performed using chi-square test.

RESULTS

All targeted regional scans had statistically significant difference in positive rate compared to non-targeted scans of the respective region; chest (Χ²(1)=18.11, P<.001); sinus (Χ²(1)=15.36, P<.001); abdomen and pelvis (Χ²(1)=5.95, P=.01). Pneumonia (41.3 %) was much more likely to be the diagnosis compared to sinusitis (16.2 %) in concomitant CT chest to sinus examinations (Χ²(1)=45.3, P<.001). Pan-scans had a higher incidence of positive diagnosis compared to all-targeted scans (Χ²(1)=4.91, P=.03) but when compared to higher yield targeted scans (abdomen and chest), there was no statistical difference (Χ²(1)=2.43, P=.12). 20/54 patients had pan-scans despite having localising symptoms.

CONCLUSION

Imaging guided by presenting signs and symptoms can help to reduce unnecessary imaging and promote more judicious use of non-targeted and pan-scan CT in current practices.

Computed tomography in patients with sepsis presenting to the emergency department: exploring its role in light of patient outcomes

OBJECTIVES

This study aimed to explore the role of CT in septic patients presenting to the emergency department (ED).

MATERIALS AND METHODS

We performed a retrospective secondary analysis of 192 septic patients from a prospective observational study, i.e., the "LIFE POC" study. Sepsis was diagnosed in accordance with the Sepsis-3 definition. Clinical and radiological data were collected from the hospital administration and radiological systems. Information on mortality and morbidity was collected. Time-to-CT between CT scan and sepsis diagnosis (ttCTsd) was calculated. Diagnostic accuracy was assessed with the final sepsis source as reference standard. The reference standard was established through the treating team of the patient based on all available clinical, imaging, and microbiological data.

RESULTS

Sixty-two of 192 patients underwent a CT examination for sepsis focus detection. The final septic source was identified by CT in 69.4% (n = 43). CT detected septic foci with 81.1% sensitivity (95% CI, 68.0-90.6%) and 55.6% specificity (95% CI, 21.2-86.3%). Patients with short versus long ttCTsd did not differ in terms of mortality (16.1%, n = 5 vs 9.7, n = 3; p = 0.449), length of hospital stay (median 16 d, IQR 9 d 12 h-23 d 18 h vs median 13 d, IQR 10 d 00 h-24 d 00 h; p = 0.863), or duration of intensive care (median 3d 12 h, IQR 2 d 6 h-7 d 18 h vs median 5d, IQR 2 d-11 d; p = 0.800).

CONCLUSIONS

Our findings show a high sensitivity of CT in ED patients with sepsis, confirming its relevance in guiding treatment decisions. The low specificity suggests that a negative CT requires further ancillary diagnostic tests for focus detection. The timing of CT did not affect morbidity or mortality outcomes.

CLINICAL RELEVANCE STATEMENT

In patients with sepsis who present to the ED, CT can be used to identify infectious foci on the basis of clinical suspicion, but should not be used as a rule-out test. Scientific evidence for the optimal timing of CT beyond clinical decision-making is currently missing, as potential mortality benefits are clouded by differences in clinical severity at the time of ED presentation.

KEY POINTS

• In patients with sepsis who present to the ED, CT for focus identification has a high sensitivity and can thereby be valuable for patient management. • As the specificity is considerably lower, a thorough microbiological assessment is important in these cases. • The timing of CT did not affect morbidity and mortality outcomes in this study, which might be due to variability in clinical severity at the time of ED presentation.

[Cancer patients in the emergency department]

A growing number of patients are living with cancer or have a history of cancer leading to increasing adverse effects of treatment or disease necessitating emergency department (ED) consultation. Long-term cancer survivors are at higher risk of comorbidities causing a substantial increase in health care resource utilization. The most frequent reasons for cancer-related ED visits are dyspnea, fever, pain, gastrointestinal or neurological symptoms leading to high hospital and intensive care unit admission rates. Acute respiratory failure in cancer patients necessitates timely diagnostic testing, whereby computed tomography is superior to chest X‑ray. Delay in intensive care unit (ICU) admission or mechanical ventilation increases mortality. Febrile neutropenia is an emergency with urgent need for antibiotic treatment. Treatment of neutropenic and nonneutropenic patients with sepsis does not differ. Cardiovascular disease is now the second leading cause of long-term morbidity and mortality among cancer survivors. Immunotherapy can lead to substantial and in some patients life-threatening complications that may not easily be recognized in the ED. Cancer-specific emergencies such as leukostasis, tumorlysis or hypercalcemia rarely present to ED and require interdisciplinary care. The constantly growing cancer population is likely to increase ED utilization. Knowledge about cancer treatment and disease-associated complications is crucial for emergency physicians. Palliative care education should secure appropriate end-of-life care avoiding futile interventions.

Ultra-low-dose CT vs. chest X-ray in non-traumatic emergency department patients - a prospective randomised crossover cohort trial

Background

Ultra-low-dose CT (ULDCT) examinations of the chest at only twice the radiation dose of a chest X-ray (CXR) now offer a valuable imaging alternative to CXR. This trial prospectively compares ULDCT and CXR for the detection rate of diagnoses and their clinical relevance in a low-prevalence cohort of non-traumatic emergency department patients.

Methods

In this prospective crossover cohort trial, 294 non-traumatic emergency department patients with a clinically indicated CXR were included between May 2nd and November 26th of 2019 (www.clinicaltrials.gov: NCT03922516). All participants received both CXR and ULDCT, and were randomized into two arms with inverse reporting order. The detection rate of CXR was calculated from 'arm CXR' (n = 147; CXR first), and of ULDCT from 'arm ULDCT' (n = 147; ULDCT first). Additional information reported by the second exam in each arm was documented. From all available clinical and imaging data, expert radiologists and emergency physicians built a compound reference standard, including radiologically undetectable diagnoses, and assigned each finding to one of five clinical relevance categories for the respective patient.

Findings

Detection rates for main diagnoses by CXR and ULDCT (mean effective dose: 0.22 mSv) were 9.1% (CI [5.2, 15.5]; 11/121) and 20.1% (CI [14.2, 27.7]; 27/134; P = 0.016), respectively. As an additional imaging modality, ULDCT added 9.1% (CI [5.2, 15.5]; 11/121) of main diagnoses to prior CXRs, whereas CXRs did not add a single main diagnosis (0/134; P < 0.001). Notably, ULDCT also offered higher detection rates than CXR for all other clinical relevance categories, including findings clinically irrelevant for the respective emergency department visit with 78.5% (CI [74.0, 82.5]; 278/354) vs. 16.2% (CI [12.7, 20.3]; 58/359) as a primary modality and 68.2% (CI [63.3, 72.8]; 245/359) vs. 2.5% (CI [1.3, 4.7]; 9/354) as an additional imaging modality.

Interpretation

In non-traumatic emergency department patients, ULDCT of the chest offered more than twice the detection rate for main diagnoses compared to CXR.

Funding

The Department of Biomedical Imaging and Image-guided Therapy of Medical University of Vienna received funding from Siemens Healthineers (Erlangen, Germany) to employ two research assistants for one year.