Variation in emergency department use of computed tomography for investigation of acute aortic dissection

Diagnosis and management of acute aortic dissection in the emergency department

Acute aortic dissection is often misdiagnosed as a result of its atypical presentations. It affects 4000 patients a year in the UK of all ages, not just older patients, with increasing numbers of cases expected in the future because of the ageing population. Dissection of the aortic wall leads to sudden, severe pain, and commonly end-organ symptoms which must be recognised. Acute aortic dissection can be challenging to diagnose in the emergency department because of the multitude of possible presentations and the need for selective testing with Computed Tomography Angiography (CTA). Clinicians often miss acute aortic dissection because it is not considered in the differential diagnosis, and the challenge lies in identifying acute aortic dissection in a sea of complaints of chest, back and abdominal pain. There are several ways to improve diagnosis, including awareness campaigns, better education about patients in which to consider acute aortic dissection, and improved detection strategies including which patients should receive CTA. Clinical decision tools and biomarkers could help, but further research is required and is a research focus in emergency medicine. Once diagnosed, blood pressure control, analgesia and urgent surgery or transfer to enable this to occur with minimal delay is required.

Diagnosis of Acute Aortic Syndrome in the Emergency Department (DAShED) study: an observational cohort study of people attending the emergency department with symptoms consistent with acute aortic syndrome

BACKGROUND

The diagnosis of acute aortic syndrome (AAS) is commonly delayed or missed in the ED. We describe characteristics of ED attendances with symptoms potentially associated with AAS, diagnostic performance of clinical decision tools (CDTs) and physicians and yield of CT aorta angiogram (CTA).

METHODS

This was a multicentre observational cohort study of adults attending 27 UK EDs between 26 September 2022 and 30 November 2022, with potential AAS symptoms: chest, back or abdominal pain, syncope or symptoms related to malperfusion. Patients were preferably identified prospectively, but retrospective recruitment was also permitted. Anonymised, routinely collected patient data including components of CDTs, was abstracted. Clinicians treating prospectively identified patients were asked to record their perceived likelihood of AAS, prior to any confirmatory testing. Reference standard was radiological or operative confirmation of AAS. 30-day electronic patient record follow-up evaluated whether a subsequent diagnosis of AAS had been made and mortality.

RESULTS

5548 patients presented, with a median age of 55 years (IQR 37-72; n=5539). 14 (0.3%; n=5353) had confirmed AAS. 10/1046 (1.0%) patients in whom the ED clinician thought AAS was possible had AAS. 5/147 (3.4%) patients in whom AAS was considered the most likely diagnosis had AAS. 2/3319 (0.06%) patients in whom AAS was considered not possible did have AAS. 540 (10%; n=5446) patients underwent CT, of which 407 were CTA (7%). 30-day follow-up did not reveal any missed AAS diagnoses. AUROC (area under the receiver operating characteristic) curve for ED clinician AAS likelihood rating was 0.958 (95% CI 0.933 to 0.983, n=4006) and for individual CDTs were: Aortic Dissection Detection Risk Score (ADD-RS) 0.674 (95% CI 0.508 to 0.839, n=4989), AORTAs 0.689 (95% CI 0.527 to 0.852, n=5132), Canadian 0.818 (95% CI 0.686 to 0.951, n=5180) and Sheffield 0.628 (95% CI 0.467 to 0.788, n=5092).

CONCLUSION

Only 0.3% of patients presenting with potential AAS symptoms had AAS but 7% underwent CTA. CDTs incorporating clinician gestalt appear to be most promising, but further prospective work is needed, including evaluation of the role of D-dimer.

TRIAL REGISTRATION NUMBER

NCT05582967; NCT05582967.

Can you accurately rule out acute aortic syndrome by restricting imaging of the aorta to the area of the patient's pain?

BACKGROUND

Acute aortic syndrome (AAS) is a life-threatening condition necessitating timely and accurate diagnosis for appropriate treatment. Currently, the only way to rule out the diagnosis is advanced imaging. The most accessible is computed tomography of the entire aorta. Most scans are negative, exposing patients to radiation, increased time in the emergency department (ED), and non-significant incidental findings. This study investigated whether restricting imaging to the area of aortic-related pain accurately rules out AAS.

METHODS

A health records review was conducted on consecutive cases from three academic EDs between 2015 and 2020. Data were extracted and verified from multiple sources. Participants included adults diagnosed with AAS based on radiological evidence. The diagnostic performance of the restricted imaging strategy was assessed; sensitivity and likelihood ratios with 95% confidence intervals were calculated.

RESULTS

Data from 149 cases of AAS were collected, with the majority presenting with chest pain (46%) or abdominal pain (24%). The restricted imaging strategy demonstrated a sensitivity of 96% (95% CI 91.4-98.5%) in ruling out AAS. In a subset of patients with systolic blood pressure > 90 mmHg and without aortic aneurysm/repair (n = 86), the sensitivity was 100% (95% CI 96-100%).

CONCLUSION

Restricting imaging to the area of pain in hemodynamically stable patients without known aortic aneurysm provides a highly sensitive approach to ruling out AAS.

Review article: Accuracy of emergency physician performed point-of-care ultrasound of the thoracic aorta: A systematic review and narrative synthesis of the literature

Point-of-care ultrasound (POCUS) is becoming ubiquitous in emergency medicine. POCUS for abdominal aortic aneurysm is well established in practice. The thoracic aorta can also be assessed by POCUS for dissection and aneurysm and transthoracic echocardiography is endorsed by international guidelines as an initial test for thoracic aortic pathologies. A systematic search of Ovid Medline, PubMed, EMBASE, SCOPUS and Web of Science from January 2000 to August 2022 identified four studies evaluating diagnostic accuracy of emergency physician POCUS for thoracic aortic dissection (TAD) and five studies for thoracic aortic aneurysm (TAA). Study designs were heterogeneous including differing diagnostic criteria for aortic pathology. Convenience recruitment was frequent in prospective studies. Sensitivity and specificity ranges for studies of TAD were 41-91% and 94-100%, respectively when an intimal flap was seen. Sensitivity and specificity ranges for studies of thoracic aorta dilation >40 mm were 50-100% and 93-100%, respectively; for >45 mm ranges were 64-65% and 95-99%. Literature review identified that POCUS is specific for TAD and TAA. POCUS reduces the time to diagnosis of thoracic aortic pathology; however, it remains insensitive and cannot be recommended as a stand-alone rule-out test. We suggest that detection of thoracic aorta dilation >40 mm by POCUS at any site increases the suspicion of serious aortic pathology. Studies incorporating algorithmic use of POCUS, Aortic Dissection Detection Risk Score and D-dimer as decision tools are promising and may improve current ED practices. Further research is warranted in this rapidly evolving field.

Why do emergency department clinicians miss acute aortic syndrome? A case series and descriptive analysis

Objectives: To understand why the diagnosis of AAS is missed in the ED, and to characterise the presenting features of cases in which a diagnosis of AAS was missed. Methods: A retrospective case series cohort study was performed, identifying and analysing cases where AAS was misdiagnosed in three UK EDs between 1st January 2011 and 31st December 2020. Results: 43 cases were included, 22 of which were type A aortic dissections. The most common incorrect presumed diagnoses made were acute coronary syndrome (28%), pulmonary embolism (12%) and ‘non-specific chest pain’ (12%). In 31 cases (72%) there was no evidence from the notes that the clinician had considered AAS in the differential diagnosis. In 10 cases (23%), AAS was considered, but the clinician was falsely reassured by atypical or resolved symptoms, clinical examination, or normal chest x-ray. Conclusions: ED clinicians may miss AAS by not considering it as a possibility, being falsely reassured by atypical or resolved symptoms, or mistaking it for other more common conditions.  Further prospective work is necessary to establish the role of diagnostic aids and biomarkers in UK EDs.

Routine Use of a Pocket-Sized Handheld Echoscopic Device Plus a Biomarker by Emergency Medicine Residents with an Early Screening Algorithm for Suspected Type A Acute Aortic Syndrome

(1) Background: The early screening strategy for type A acute aortic syndrome (A-AAS) patients has always been challenging. (2) Methods: From September 2020-31 March 2022, 179 consecutive patients with suspected A-AAS were retrospectively reviewed. We assessed the diagnostic value of the use of handheld echocardiographic devices (PHHEs) by emergency medicine (EM) residents either alone or in combination with serum acidic calponin in this patient group. (3) Results: The direct sign of PHHE had a specificity (SP) of 97.7%. The sign of ascending aortic dilatation showed SE = 77.6%, SP = 68.5%, PPV = 48.1% and NPV = 89%. SE, SP, PPV and NPV of a positive PHHE direct sign were 55.6%, 100%, 100% and 71.4% in 19 hypotension/shock patients with suspected A-AAS, respectively. The area under curve (AUC) of acidic calponin combined with an ascending aorta diameter >40 mm was 0.927, with an SE and SP of 83.7% and 89.2%, respectively. These two combined indicators significantly improved the diagnostic efficiency of A-AAS compared with either of them alone (p = 0.017; standard error 0.016, Z value 2.39; p = 0.001, standard error 0.028, Z value 3.29). (4) Conclusion: EM resident-performed PHHE was highly indicative of A-AAS in patients presenting with shock or hypotension. An ascending aorta diameter > 40 mm combined with acidic calponin demonstrated acceptable diagnostic accuracy as a rapid first-line triage tool to identify patients with suspected A-AAS.

Epidemiology, mortality and miss rate of acute aortic syndrome in Ontario, Canada: a population-based study

INTRODUCTION

Acute aortic syndrome (AAS) is a life-threatening emergency. It describes three distinct diagnoses: acute aortic dissection, acute intramural hematoma and penetrating atherosclerotic ulcer. There are currently no accurate estimates for incidence, mortality or misdiagnosis. Our objectives were to determine the incidence, mortality and miss rate of acute aortic syndrome in the emergency department (ED).

METHODS

A population-based retrospective cohort study of anonymously linked data for residents of Ontario, Canada, was carried out. Incident cases of acute aortic syndrome were identified between 2003 and 2018 using a validated algorithm based on ICD-10 codes and death. Incidence (number of cases/population of Ontario), mortality, and miss rate were calculated. Miss rate was defined as when a patient was seen in the ED within 14 days prior to an acute aortic syndrome diagnosis with a presenting complaint consistent with acute aortic syndrome.

RESULTS

There were 1299 cases of acute aortic syndrome over the study period [age mean (SD) 68.03 ± 14.70; female (n = 500, 38.5%); rural areas (n = 111, 8.6%)]. The overall annual incidence for acute aortic syndrome was 0.61 per 100,000. One year mortality decreased from 47.4 to 29.1%. ED mortality was 14.9%. In the 14 days prior to diagnosis 12.5% of patients were seen in the ED with a presentation consistent with acute aortic syndrome.

CONCLUSIONS

Annual incidence of acute aortic syndrome was found to be lower than other population-based studies. Also, the burden of mortality is seen in the ED. Education initiatives should focus on the identification of acute aortic syndrome in the ED to address mortality and miss rate.

Trends in computed tomography aortography and acute aortic syndrome in an emergency department within Aotearoa New Zealand

OBJECTIVE

Acute aortic syndrome (AAS) comprises a triad of life-threatening aortic conditions that are difficult to diagnose because of their non-specific clinical presentations. Contrast-enhanced computed tomography aortography (CTA) has a high sensitivity and specificity for these conditions. However, under- and over-investigation of patients with suspected AAS using CTA carries significant risk. The aim of the present study was to evaluate the diagnostic imaging practices of CTA use for patients presenting to an ED with suspected AAS.

METHODS

All atraumatic thoracic CTAs performed on patients aged ≥15 years old with suspected AAS who presented to Auckland City Hospital between 2009 and 2019 were included. Outcomes of interest were the annual ED and population incidences of AAS, and the rate of CTAs performed.

RESULTS

A total of 1646 CTAs were included. There were 135 (8.2%) cases of at least one AAS diagnosis and 220 (13.4%) cases where an alternative diagnosis was made. The population-adjusted number of AAS diagnoses remained relatively stable over the study period, with a mean annual AAS incidence of 19.6 (95% confidence interval 9.9-33.7) per 100 000 patients, and 3.2 (95% confidence interval 1.6-5.4) per 100 000 population. The number of ED presentations increased during the study period, along with the population-adjusted rate of CTAs performed, from approximately 150 per 100 000 patients (2009) to 350 per 100 000 patients (2019).

CONCLUSIONS

Thoracic CTA use for investigating suspected AAS in our ED has recently increased. However, the annual incidence of AAS did not increase over the same period, but was higher than reported in overseas institutions.

Variation in CTA evaluation of ED patients suspected of aortic dissection

PURPOSE

This study was performed to investigate the variation in CTA imaging for AoD in an ED to determine if limiting the scanned region to the chest can effectively rule-out AoD without delaying care.

METHODS

A retrospective chart review was performed for all patients belonging to a geographically isolated health maintenance organization who underwent CTA evaluation for possible acute AoD in the emergency department between 2016 and 2020. We evaluated for the regions included in the CTA, the presence of an acute AoD, and clinical outcomes. For those who were ruled-out of an AoD with a CTA limited to the chest, we investigated clinical follow-up up to 6 months after their initial presentation.

RESULTS

Over the study period, there were 1143 CT scans ordered by ED physicians to evaluate for AoD in patients without a history of AoD. Only 23.0% of screening studies were of the chest only. There were 29 acute AoDs diagnosed (14 type A and 15 type B) making for a prevalence of 2.5%. Only one patient with an acute AoD detected on a chest-only CTA required farther imaging, which did not delay clinical care. No patients ruled-out for acute AoD with a chest-only CTA had a return ED visit or repeat CTA within 6 months diagnosing a missed AoD. There were no AoDs limited to the abdominal aorta that would have been missed on a chest-only study.

CONCLUSION

In patients in the ED with suspected new acute AoD, a CTA limited to the chest can effectively evaluate the condition without delaying care in this integrated healthcare system with 24/7 CT availability.

Can D-Dimer in Low-Risk Patients Exclude Aortic Dissection in the Emergency Department?

BACKGROUND

Aortic dissection (AD) is a challenging diagnosis associated with severe mortality. However, acute AD is a rare clinical entity and can be overevaluated in the emergency department. D-dimer, both alone and in combination with the Aortic Dissection Detection Risk Score (ADD-RS), has been studied as a tool to evaluate for AD.

CLINICAL QUESTION

Can a negative D-dimer in low-risk patients exclude AD in the emergency department?

EVIDENCE REVIEW

Retrieved studies included three systematic review and meta-analyses and two prospective cohort studies. D-dimer was found to be highly sensitive for acute AD, with a sensitivity of 98.0%. The ADD-RS was also highly sensitive (95.7%) for AD. Two meta-analyses reported a combination of a negative D-dimer and ADD-RS < 1 to have a pooled sensitivity of 99.9% and 100% for acute aortic syndrome.

CONCLUSIONS

Neither D-dimer nor the ADD-RS alone provides adequate sensitivity to exclude acute AD. However, a negative D-dimer combined with an ADD-RS < 1 is likely sufficient to rule out AD. Even with these findings, physicians must place clinical judgment above laboratory testing or scoring systems when deciding whether to pursue a diagnosis of acute AD.

Development and Validation of a Simplified Probability Assessment Score Integrated With Age-Adjusted d-Dimer for Diagnosis of Acute Aortic Syndromes

Background

When acute aortic syndromes (AASs) are suspected, pretest clinical probability assessment and d‐dimer (DD) testing are diagnostic options allowing standardized care. Guidelines suggest use of a 12‐item/3‐category score (aortic dissection detection) and a DD cutoff of 500 ng/mL. However, a simplified assessment tool and a more specific DD cutoff could be advantageous.

Methods and Results

In a prospective derivation cohort (n=1848), 6 items identified by logistic regression (thoracic aortic aneurysm, severe pain, sudden pain, pulse deficit, neurologic deficit, hypotension), composed a simplified score (AORTAs) assigning 2 points to hypotension and 1 to the other items. AORTAs≤1 and ≥2 defined low and high clinical probability, respectively. Age‐adjusted DD was calculated as years/age × 10 ng/mL (minimum 500). The AORTAs score and AORTAs≤1/age‐adjusted DD rule were validated in 2 patient cohorts: a high‐prevalence retrospective cohort (n=1035; 22% AASs) and a low‐prevalence prospective cohort (n=447; 11% AASs) subjected to 30‐day follow‐up. The AUC of the AORTAs score was 0.729 versus 0.697 of the aortic dissection detection score (P=0.005). AORTAs score assessment reclassified 16.6% to 25.1% of patients, with significant net reclassification improvement of 10.3% to 32.7% for AASs and −8.6 to −17% for alternative diagnoses. In both cohorts, AORTAs≥2 had superior sensitivity and slightly lower specificity than aortic dissection detection ≥2. In the prospective validation cohort, AORTAs≤1/age‐adjusted DD had a sensitivity of 100%, a specificity of 48.6%, and an efficiency of 43.3%.

Conclusions

AORTAs is a simplified score with increased sensitivity, improved AAS classification, and minor trade‐off in specificity, amenable to integration with age‐adjusted DD for diagnostic rule‐out.

A simple intervention to reduce your chance of missing an acute aortic dissection

INTRODUCTION

Acute aortic dissection (AAD) is a time sensitive, difficult to diagnose, aortic emergency. We sought to explore the quality of history taking in AAD and assess its impact on misdiagnosis.

METHODS

We studied a retrospective cohort of patients >18 years old who presented to two tertiary care emergency departments from January 1st 2004 - December 31st 2012 and were diagnosed with an acute aortic dissection (AAD) on CT, MRI or TEE. Trained reviewers' extracted data using a standardized data collection form. The definitions of 5 pain characteristics - character, onset, duration, quality, and radiation were defined a priori.

RESULTS

Data were collected for 194 cases of acute aortic dissection with a mean age of 65(SD 14.1) and 66.7% male, 34(17.6%) missed on initial presentation. Only 20(14.8%) patients were asked all 5 questions. The most common initial incorrect diagnosis were acute coronary syndrome (16, 47%), pulmonary embolism (5, 14.7%) and stroke (4, 11.7%). If <2 questions were asked 1 in 5 cases were missed, 4 times greater than if >2 were asked (P < 0.01).

CONCLUSION

Clinicians should ask and document the character, onset, duration, radiation and severity of pain in any patient presenting with chest, abdominal or flank pain. A focused history still remains the keystone to reducing misdiagnosis.

Integration of transthoracic focused cardiac ultrasound in the diagnostic algorithm for suspected acute aortic syndromes

AIMS

The diagnosis of acute aortic syndromes (AASs) is challenging and requires integrated strategies. Transthoracic focused cardiac ultrasound (FoCUS) is endorsed by guidelines as a first-line/triage tool allowing rapid bedside assessment of the aorta. However, the performance of FoCUS in the European Society of Cardiology-recommended workup of AASs awaits validation.

METHODS AND RESULTS

This was a prespecified subanalysis of the ADvISED multicentre prospective study. Patients with suspected AAS underwent FoCUS for detection of direct/indirect signs of AAS. Clinical probability assessment was performed with the aortic dissection detection risk score (ADD-RS). Case adjudication was based on advanced imaging, surgery, autopsy, or 14-day follow-up. An AAS was diagnosed in 146 (17.4%) of 839 patients. Presence of direct FoCUS signs had a sensitivity and specificity of 45.2% [95% confidence interval (CI) 37-53.6%] and 97.4% (95% CI 95.9-98.4%), while presence of any FoCUS sign had a sensitivity and specificity of 89% (95% CI 82.8-93.6%) and 74.5% (95% CI 71-77.7%) for AAS. The additive value of FoCUS was most evident within low clinical probability (ADD-RS ≤1). Herein, direct FoCUS signs were identified in 40 (4.8%) patients (P < 0.001), including 29 with AAS. ADD-RS ≤1 plus negative FoCUS for AAS rule-out had a sensitivity of 93.8% (95% CI 88.6-97.1%) and a failure rate of 1.9% (95% CI 0.9-3.6%). Addition of negative D-dimer led to a failure rate of 0% (95% CI 0-1.2%).

CONCLUSION

FoCUS has additive value in the workup of AASs. Direct FoCUS signs can rapidly identify patients requiring advanced imaging despite low clinical probability. In integrated bundles, negative FoCUS is useful for rule-out of AASs.

Systematic Review of Aortic Dissection Detection Risk Score Plus D-dimer for Diagnostic Rule-out Of Suspected Acute Aortic Syndromes

OBJECTIVES

In patients at low clinical probability of acute aortic syndromes (AASs), decision on advanced aortic imaging is cumbersome. Integration of the aortic dissection detection risk score (ADD-RS) with D-dimer (DD) provides a potential pipeline for standardized diagnostic rule-out. We systematically reviewed and summarized supporting data.

METHODS

Cross-sectional studies assessing integration of ADD-RS with DD for diagnosis of AASs were identified on MEDLINE, EMBASE and Web Of Science databases. Two reviewers independently screened articles, assessed quality, and extracted data. The quality of design and reporting was evaluated with the QUADAS-2 and STARD tools. Individual patient data were obtained, to allow analysis of both conventional (500 ng/mL) and age-adjusted (DD_age-adj ) DD cutoffs. Data were summarized for four diagnostic strategies combining ADD-RS = 0 or ≤ 1, with DD < 500 ng/mL or < DD_age-adj . The statistical heterogeneity of the diagnostic variables was estimated with Higgins' I² . Pooled values were calculated for variables showing nonsignificant heterogeneity.

RESULTS

After screening of 680 studies, four articles (including a total of 3,804 patients) met inclusion criteria. One prospective study provided a low risk of bias/applicability concerns, while methodologic limitations were found in the other three retrospective studies. Statistical heterogeneity was negligible for sensitivity and negative likelihood ratio (LR) values and significant for specificity and positive LR values of all diagnostic strategies. Pooled sensitivity was 99.9% (95% confidence interval [CI] = 99.3% to 100%, I²  = 0) for ADD-RS = 0 and DD < 500 ng/mL or < DD_age-adj , 98.9% (95% CI = 97.9% to 99.9%, I²  = 0) for ADD-RS ≤ 1 and DD < 500 ng/mL, and 97.6% (95% CI = 96.3% to 98.9%, I²  = 0) for ADD-RS ≤ 1 and DD < DD_age-adj .

CONCLUSIONS

Despite methodologic limitations, integration of ADD-RS = 0 or ≤ 1 with DD < 500 ng/mL shows negligible heterogeneity and consistently high sensitivity across studies, thus supporting reliability for diagnostic rule-out of AASs. Data supporting ADD-RS = 0 plus DD_age-adj appear preliminary and require further scrutiny.

Prospective diagnostic accuracy study of plasma soluble ST2 for diagnosis of acute aortic syndromes

Acute aortic syndromes (AASs) are difficult to diagnose emergencies. Plasma soluble ST2 (sST2), a prognostic biomarker for heart failure, has been proposed as a diagnostic biomarker of AASs outperforming D-dimer, the current diagnostic standard. We performed a prospective diagnostic accuracy study of sST2 for AASs in the Emergency Department (ED). In 2017–2018, patients were enrolled if they had ≥1 red-flag symptoms (chest/abdominal/back pain, syncope, perfusion deficit) and a clinical suspicion of AAS. sST2 was detected with the Presage® assay. Adjudication was based on computed tomography angiography (CTA) or on diagnostic outcome inclusive of 30-day follow-up. 297 patients were enrolled, including 88 with AASs. The median age was 67 years. In 162 patients with CTA, the median sST2 level was 41.7 ng/mL (IQR 29.4–103.2) in AASs and 34.6 ng/mL (IQR 21.4–51.5) in alternative diagnoses (P = 0.005). In ROC analysis, the AUC of sST2 was 0.63, as compared to 0.82 of D-dimer (P < 0.001). Sensitivity and specificity values of sST2 associated with different cutoffs were: 95.5% and 10.8% (≥12 ng/mL), 84.1% and 29.7% (≥23.7 ng/mL), 35.2% and 85.1% (≥66.5 ng/mL). Results were similar in the full cohort. In conclusion, in patients from a European ED, plasma sST2 provided modest accuracy for diagnosis of AASs.

Integrated Use of Conventional Chest Radiography Cannot Rule Out Acute Aortic Syndromes in Emergency Department Patients at Low Clinical Probability

OBJECTIVES

Guidelines recommend chest radiography (CR) in the workup of suspected acute aortic syndromes (AASs) if the pretest clinical probability is low. However, the diagnostic impact of CR integration for the rule-in and rule-out of AASs is unknown.

METHODS

We performed a secondary analysis of the ADvISED multicenter study. Emergency department outpatients were eligible if an AAS was clinically suspected. Clinical probability was defined with the aortic dissection detection risk score (ADD-RS). CR was evaluated blindly by a radiologist, who judged on mediastinum enlargement (ME) and other signs.

RESULTS

In 2014 through 2016, a total of 1,129 patients were enrolled and 1,030 were analyzed, including 48 (4.7%) with AASs. ADD-RS/ME and ADD-RS/any CR sign (aCRs) integration were more accurate than ADD-RS alone (area under the curve = 0.8 and 0.78 vs. 0.66, p < 0.001). The sensitivity and specificity of the integrated strategies were 66.7% (95% confidence interval [CI] = 51.5% to 79.9%) and 82.5% (95% CI = 79.9% to 84.8%) for ADD-RS/ME and 68.8% (95% CI = 53.6% to 80.9%) and 76.5% (95% CI = 73.7% to 79.1%) for ADD-RS/aCRs, respectively. The sensitivity and specificity of CR per se were 54.2% (95% CI = 39.2% to 68.6%) and 92.4% (95% CI = 90.5% to 93.9%) for ME and 60.4% (95% CI = 45.3% to 74.2%) and 85.2% (95% CI = 82.9% to 87.4%) for aCRs. The agreement (κ) between attending physicians and radiologists for ME was 0.44 (95% CI = 0.35 to 0.54). ADD-RS/ME rule-in (ADD-RS ≤ 1 and ME-present, or ADD-RS > 1) applied to 204 versus 130 patients with ADD-RS > 1, including 14 with AAS and 60 false-positives (FP). ADD-RS/aCRs rule-in (ADD-RS ≤ 1 and aCRs-present, or ADD-RS > 1) applied to 264 patients, including 15 with AAS and 119 FP. ADD-RS/ME rule-out (ADD-RS ≤ 1 and ME-absent) applied to 826 (80.2%) patients, including 16 with AAS (33.3% of cases). ADD-RS/aCRs rule-out (ADD-RS ≤ 1 and aCRs-absent) applied to 766 patients (74.4%), including 15 with AAS (31.3% of cases).

CONCLUSIONS

CR integration with clinical probability assessment showed modest rule-in efficiency and insufficient sensitivity for conclusive rule-out.