RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates

Computed tomography pulmonary angiogram ordering, adherence to decision rules and yield in the emergency department: An observational study

OBJECTIVE

Pulmonary embolism (PE) frequently requires diagnosis through CT pulmonary angiogram (CTPA). Appropriate application of evidence-based clinical decision tools can reduce unnecessary CTPAs. This study assessed adherence to and the efficacy of various aspects of the Queensland Health suspected PE diagnostic pathway, including Wells score, PE rule out criteria (PERC) and age-adjusted D-dimer interpretation.

METHODS

Retrospective study of CTPAs ordered from 1 January to 30 April 2023 in a tertiary and urban ED in Southeast Queensland. Data on clinical variables, D-dimer and CTPA results were collected through medical record and radiology database review. Descriptive analyses were used to determine adherence to Queensland guidelines and performance of D-dimer interpretation tools (including comparison of age-adjusted PE with a new pre-test probability [PTP]-based model using D-dimer cut-off <1000 ng/mL for Wells score ≤4 and 500 ng/mL for Wells score 4.5-6).

RESULTS

A total of 573 CTPAs were available for analysis with a 12.4% (95% confidence interval 10.0-15.4) diagnostic yield. Stratification by Wells score showed yields of 4.0%, 18.5% and 41% for low-, moderate- and high-risk patients, respectively. Twenty-five patients with low-PTP who received CTPA could have been excluded with the PERC rule. Age-adjusted D-dimer interpretation may have prevented 26 CTPAs with no false negatives, whereas PTP approach may have prevented 128 CTPAs with four false negatives.

CONCLUSION

Guideline adherence can be improved, and adherence to existing clinical decision tools may reduce unnecessary CTPA ordering and increase diagnostic yield. The use of the age-adjusted D-dimer had good sensitivity, whereas the new PTP approach will require further prospective research.

Preemptive anticoagulation of pulmonary embolism

BACKGROUND

Pulmonary embolism (PE) is a life-threatening disease where preemptive anticoagulation is recommended by guidelines for patients with intermediate to high pretest risk of PE.

AIMS

The primary objective of our study was to describe the use of preemptive anticoagulation from the emergency department (ED) or inpatient wards stratified by risk assessment score.

METHODS

We performed a retrospective observational cohort study of consecutive patients undergoing computed tomography pulmonary angiography (CTPA) for investigation of PE. Patients were classified as either ED patients or hospital ward patients based on where the CTPA was requested. The pretest risk of PE was calculated using the Revised Geneva Score (RGS) and patients were divided into low and intermediate to high risk.

RESULTS

A total of 392 consecutive patients who underwent CTPA at Monash Health were reviewed. There were 108 (27.6%) patients who were categorised as low risk (RGS 0-3) and 284 (72.4%) categorised as intermediate to high risk (RGS >3). There were 29 (7.4%) patients overall who received preemptive anticoagulation. Diagnostic yield of CTPA in the ED was low, with only four of 144 (2.8%) CTPA scans positive for PE. The yield of CTPA was higher in ward patients, with 63 of 248 (25.4%) being diagnostic of PE.

CONCLUSIONS

The use of preemptive anticoagulation for suspected PE was uncommon and was not influenced by the pretest probability of PE as determined by a validated clinical prediction tool. This may reflect concerns regarding haemorrhagic complications without any clear evidence of benefit. Diagnostic yield of CTPA performed in the ED was low.

Diagnostic Yield, Radiation Exposure, and the Role of Clinical Decision Rules to Limit Computed Tomographic Pulmonary Angiography-Associated Complications

OBJECTIVES

Computed tomographic pulmonary angiography (CT-PA) is associated with significant cost, contrast, and radiation exposure. Clinical decision rules (CDRs) reduce the need for diagnostic imaging; however, their utility in the medical intensive care unit (MICU) remains unknown. We explored the diagnostic yield and complications associated with CT-PA (radiation exposure and contrast-induced acute kidney injury [AKI]) while investigating the efficacy of CDRs to reduce unnecessary testing.

METHODS

All CT-PAs performed in an academic MICU for 4 years were retrospectively reviewed. The Wells and revised Geneva scores (CDRs) and radiation dose per CT-PA were calculated, and the incidence of post-CT-PA AKI was recorded.

RESULTS

A total of 439 studies were analyzed; the diagnostic yield was 11% (48 PEs). Positive CT-PAs were associated with a higher Wells score (5.8 versus 3.2, P < 0.001), but similar revised Geneva scores (6.4 versus 6.0, P = 0.32). A Wells score of ≥4 had a positive likelihood ratio of 2.1 with a negative predictive value of 98.2. More than half (88.9%) of patients with a Wells score of ≤4 developed an AKI, with 55.6% of those having recovery of renal function.

CONCLUSIONS

There is overutilization of CT-PA in the MICU. The Wells score retains its negative predictive value in critically ill adult patients and may aid to limit radiation exposure and contrast-induced AKI in MICU.

Bibliometric Analysis of Diagnostic Yield of CT Pulmonary Angiogram (CTPA) in the Diagnosis of Pulmonary Embolism (PE)

CT pulmonary angiography (CTPA) is the investigation of choice for diagnosing pulmonary embolism (PE). Due to the speed and ease of performing the CTPA scans, more clinicians are becoming overly reliant on them, even for patients without strong suspicion of PE. We conducted a bibliometric analysis on the PubMed database from 1990 to 2022 to investigate the literature on the diagnostic yield of CTPA in the diagnosis of PE. A total of 166 articles were published in 98 journals. The number of publications has steadily increased since 2010 and peaked in 2020. Authors from 24 countries contributed to these publications, with the overwhelming majority emanating from United States of America, totaling 66 articles. The authors' contributions were relatively well spread out, with the top four authors publishing the highest number of articles at six each. When we investigated the collaboration between the authors, we found limited multinational and multi-institutional collaborations on this topic. Therefore, more multinational and multi-institutional collaborations will be valuable in future studies. In conclusion, this bibliometric analysis summarizes the literature on diagnostic yield of CTPA in the diagnosis of PE and sheds light on the future pathway that researchers and institutions can focus on.

Diagnostic Yield of CT Pulmonary Angiogram in the Diagnosis of Pulmonary Embolism and Its Predictive Factors

Introduction Computed tomography pulmonary angiography (CTPA) is the reference investigation of choice to diagnose pulmonary embolism (PE). Nevertheless, the use of CTPA should be weighed against its risks, such as radiation and contrast-induced nephropathy. We aim to assess the yield of CTPA in diagnosing PE at a tertiary centre in Malaysia. We also identify predictive factors associated with the yield of CTPA in this cohort. Methods This was a cross-sectional study involving all patients who had had CTPA done at Hospital Tengku Ampuan Afzan, Kuantan, Malaysia, from January 1, 2021, to November 30, 2021. All patients' records were retrieved and reviewed. CTPA images were retrieved from the Radiology Information System (RIS) and Picture Archiving and Communication System (PACS). They were double-reviewed by the authors, with the initial reports redacted from reporting radiologists to prevent reporting bias. The predictive factors were determined using simple logistic regression and multiple logistic regression. Results A total of 351 CTPAs were reviewed, of which 93 were found to be positive for PE, giving rise to an overall CTPA yield of 26.5%. Upon simple logistic regression, factors such as gender, discipline, history of trauma, presence of COVID-19 infection, and pneumonia were found to be associated with positive CTPA. Upon multiple logistic regression, male patients were found to have a higher chance of positive CTPA results. On the other hand, patients with COVID-19 infection and pneumonia have a lower chance of positive results in CTPA. Conclusion The yield of CTPA in diagnosing PE at our institution was acceptable at 26.5%. Upon multiple logistic regression, patients with COVID-19 infection and pneumonia were more likely to have a negative CTPA result, highlighting the need for clinicians to be more prudent in requesting CTPAs in these patients.

How Tasmanian Emergency Departments 'Choose Wisely' When Investigating Suspected Pulmonary Embolism

Overuse of computed tomography pulmonary angiograms (CTPAs) for diagnosis of pulmonary embolism (PE) has been recognised as an issue for over ten years, with Choosing Wisely Australia recommending that CTPAs only be ordered if indicated by a clinical practice guideline (CPG). This study aimed to explore the use of evidence-based practice within regional Tasmanian emergency departments in relation to CTPA orders by determining whether CTPAs were ordered in accordance with validated CPGs. We conducted a retrospective medical record review of all patients who underwent CTPA across all public emergency departments in Tasmania between 1 August 2018 and 31 December 2019 inclusive. Data from 2758 CTPAs across four emergency departments were included. PE was reported in 343 (12.4%) of CTPAs conducted, with yield ranging from 8.2% to 16.1% between the four sites. Overall, 52.1% of participants had neither a CPG documented, nor a D-dimer conducted before their scan. A CPG was documented before 11.8% of scans, while D-dimer was conducted before 43% of CTPAs. The findings presented in this study indicate that Tasmanian emergency departments are not consistently 'Choosing Wisely' when investigating PE. Further research is required to identify explanations for these findings.

Deep Learning-Based Algorithm for Automatic Detection of Pulmonary Embolism in Chest CT Angiograms

Purpose: Since the prompt recognition of acute pulmonary embolism (PE) and the immediate initiation of treatment can significantly reduce the risk of death, we developed a deep learning (DL)-based application aimed to automatically detect PEs on chest computed tomography angiograms (CTAs) and alert radiologists for an urgent interpretation. Convolutional neural networks (CNNs) were used to design the application. The associated algorithm used a hybrid 3D/2D UNet topology. The training phase was performed on datasets adequately distributed in terms of vendors, patient age, slice thickness, and kVp. The objective of this study was to validate the performance of the algorithm in detecting suspected PEs on CTAs. Methods: The validation dataset included 387 anonymized real-world chest CTAs from multiple clinical sites (228 U.S. cities). The data were acquired on 41 different scanner models from five different scanner makers. The ground truth (presence or absence of PE on CTA images) was established by three independent U.S. board-certified radiologists. Results: The algorithm correctly identified 170 of 186 exams positive for PE (sensitivity 91.4% [95% CI: 86.4–95.0%]) and 184 of 201 exams negative for PE (specificity 91.5% [95% CI: 86.8–95.0%]), leading to an accuracy of 91.5%. False negative cases were either chronic PEs or PEs at the limit of subsegmental arteries and close to partial volume effect artifacts. Most of the false positive findings were due to contrast agent-related fluid artifacts, pulmonary veins, and lymph nodes. Conclusions: The DL-based algorithm has a high degree of diagnostic accuracy with balanced sensitivity and specificity for the detection of PE on CTAs.

Raising the D-dimer threshold for ruling out pulmonary embolism: A single-site, observational study with a historical comparison

OBJECTIVE

The objective of this study was to assess the impact of introduction of a new pulmonary embolism (PE) diagnostic guideline with a raised D-dimer threshold.

METHODS

This is a single-site, observational, cohort study with a historical comparison. The new guideline raised the D-dimer threshold to 1000 ng/mL for most patients with a Wells' score of 4 or less. Patients investigated for PE with a D-dimer level and/or definitive imaging in 6-month periods before and after the introduction of the guideline were eligible. Patients with D-dimers of 500-1000 ng/mL were prospectively followed up at 3 months for missed PE.

RESULTS

During the pre-intervention period, 688 patients were investigated for PE, 366 (53.2%) received definitive imaging and 39 PE were diagnosed (5.7% overall, 10.7% of those imaged). For the 121 patients with D-dimers ≥500 and <1000 ng/mL, 87 (71.9%) were imaged with 7 (5.8%) having a PE diagnosed. Post intervention there were 930 patients, of which 426 (45.8%) received definitive chest imaging and there were 50 patients with PE diagnosed (5.4% overall, 11.7% of those imaged). For the 185 patients with D-dimers ≥500 and <1000 ng/mL, 60 (32.4%) were imaged with 5 (2.7%) having PE diagnosed. No cases of missed PE were identified at 3 months.

CONCLUSION

The introduction of the new guideline was associated with a reduction in overall imaging rates without evidence of missed PE. Further evaluation in other settings is recommended.

Computed Tomography Angiography for Detection of Pulmonary Embolism in Western Australia Shows Increasing Use with Decreasing Diagnostic Yield

(1) Background: Pulmonary embolism (PE) can be fatal. Computed tomography pulmonary angiography (CTPA) can accurately diagnose PE, but it should be used only when reasonable pre-test probability exists. Overtesting with CTPA exposes patients to excess ionizing radiation and contrast media, while PE overdiagnosis leads to the treatment of small emboli unlikely to cause harm. This study assessed trends in CTPA use and diagnostic yield. We also assessed trends in PE hospitalizations and mortality to indicate PE severity. (2) Methods: Analysis of Western Australian linked administrative data for 2003-2015 including hospitalizations, emergency department (ED) attendances, and CTPA performed at hospitals. Age-sex standardized trends were calculated for CTPA use, PE hospitalizations, and mortality (as a proxy for severity). Logistic regression assessed diagnostic yield of CTPA following unplanned ED presentations. (3) Results: CTPA use increased from 3.3 per 10,000 person-years in 2003 (95% CI 3.0-3.6) to 17.1 per 10,000 person-years (16.5-17.7) in 2015. Diagnostic yield of CTPA increased from 12.7% in 2003 to 17.4% in 2005, declining to 12.2% in 2015 (p = 0.049). PE hospitalizations increased from 3.8 per 10,000 (3.5-4.1) in 2003 to 5.2 per 10,000 (4.8-5.5) in 2015. Mortality remained constant at 0.50 per 10,000 (0.39-0.62) in 2003 and 0.42 per 10,000 (0.32-0.51) in 2015. (4) Conclusions: CTPA increased from 2003 to 2015, while diagnostic yield decreased, potentially indicating overtesting. PE mortality remained constant despite increasing hospitalizations, likely indicating a higher proportion of less severe cases. As treatment can be harmful, this could represent overdiagnosis.

Use of Computed Tomography Pulmonary Angiography in Emergency Departments: A Literature Review

Computed tomography pulmonary angiography (CTPA) has become the most widely used technique for diagnosis or exclusion of a pulmonary embolism (PE). It has been suggested that overuse of this imaging type may be prevalent, especially in emergency departments (EDs). The purpose of this literature review was to explore the use of CTPAs in EDs worldwide. A review following PRISMA guidelines was completed, with research published between September 2010 and August 2020 included. Five key topics emerged: use of CTPAs; explanations for overuse; use of D-dimer; variability in ordering practices between clinicians; and strategies to reduce overuse. This review found that CTPAs continue to be overused in EDs, leading to superfluous risks to patients. Published studies identify that while clinical practice guidelines (CPGs) have a strong effect on reducing unnecessary CTPAs with no significantly increased risk of missed diagnosis, the adoption of these tools by ED clinicians has remained low. This literature review highlights the need for further research into why CTPAs continue to be overused within EDs and why clinicians are hesitant to use CPGs in the clinical setting. Moreover, investigations into other potential strategies that may combat the overuse of this diagnostic tool are essential to reduce potential harm.

Automated detection of pulmonary embolism from CT-angiograms using deep learning

Background

The aim of this study was to develop and evaluate a deep neural network model in the automated detection of pulmonary embolism (PE) from computed tomography pulmonary angiograms (CTPAs) using only weakly labelled training data.

Methods

We developed a deep neural network model consisting of two parts: a convolutional neural network architecture called InceptionResNet V2 and a long-short term memory network to process whole CTPA stacks as sequences of slices. Two versions of the model were created using either chest X-rays (Model A) or natural images (Model B) as pre-training data. We retrospectively collected 600 CTPAs to use in training and validation and 200 CTPAs to use in testing. CTPAs were annotated only with binary labels on both stack- and slice-based levels. Performance of the models was evaluated with ROC and precision–recall curves, specificity, sensitivity, accuracy, as well as positive and negative predictive values.

Results

Both models performed well on both stack- and slice-based levels. On the stack-based level, Model A reached specificity and sensitivity of 93.5% and 86.6%, respectively, outperforming Model B slightly (specificity 90.7% and sensitivity 83.5%). However, the difference between their ROC AUC scores was not statistically significant (0.94 vs 0.91, p = 0.07).

Conclusions

We show that a deep learning model trained with a relatively small, weakly annotated dataset can achieve excellent performance results in detecting PE from CTPAs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-022-00763-z.

Clinical and radiological characteristics of acute pulmonary embolus in relation to 28-day and 6-month mortality

Background

Patients with acute pulmonary embolism (PE) exhibit a wide spectrum of clinical and laboratory features when presenting to hospital and pathophysiologic mechanisms differentiating low-risk and high-risk PE are poorly understood.

Objectives

To investigate the prognostic value of clinical, laboratory and radiological information that is available within routine tests undertaken for patients with acute PE.

Methods

Electronic patient records (EPR) of patients who underwent Computed Tomography Pulmonary Angiogram (CTPA) scan for the investigation of acute PE during 6-month period (01.01.2016–30.06.2016) were examined. Data was gathered from EPR for patients that met inclusion criteria and all CTPA scans were re-evaluated. Biochemical thresholds of low-grade and high-grade inflammation, serum CRP >10mg/L and >150mg/L and serum albumin concentrations <35g/L and <25 g/L, were combined in the Glasgow Prognostic Score (GPS) and peri-operative Glasgow Prognostic Score (poGPS) respectively. Neutrophil Lymphocyte ratio (NLR) was also calculated. Pulmonary Embolus Severity Index score was calculated.

Results

Of the total CTPA reports (n = 2129) examined, 245 patients were eligible for inclusion. Of these, 20 (8%) patients had died at 28-days and 43 (18%) at 6-months. Of the 197 non-cancer related presentations, 28-day and 6-month mortality were 3% and 8% respectively. Of the 48 cancer related presentations, 28-day and 6-month mortality were 29% and 58% respectively. On univariate analysis, age ≥65 years (p<0.01), PESI score ≥100(p = <0.001), NLR ≥3(p<0.001) and Coronary Artery Calcification (CAC) score ≥ 6 (p<0.001) were associated with higher 28-day and 6-month mortality. PESI score ≥100 (OR 5.2, 95% CI: 1.1, 24.2, P <0.05), poGPS ≥1 (OR 2.5, 95% CI: 1.2–5.0, P = 0.01) and NLR ≥3 (OR 3.7, 95% CI: 1.0–3.4, P <0.05) remained independently associated with 28-day mortality. On multivariate binary logistic regression analysis of factors associated with 6-month mortality, PESI score ≥100 (OR 6.2, 95% CI: 2.3–17.0, p<0.001) and coronary artery calcification score ≥6 (OR 2.3, 95% CI: 1.1–4.8, p = 0.030) remained independently associated with death at 6-months. When patients who had an underlying cancer diagnosis were excluded from the analysis only GPS≥1 remained independently associated with 6-month mortality (OR 5.0, 95% CI 1.2–22.0, p<0.05).

Conclusion

PESI score >100, poGPS≥1, NLR ≥3 and CAC score ≥6 were associated with 28-day and 6-month mortality. PESI score ≥100, poGPS≥1 and NLR ≥3 remained independently associated with 28-day mortality. PESI score ≥100 and CAC score ≥6 remained independently associated with 6-month mortality. When patients with underlying cancer were excluded from the analysis, GPS≥1 remained independently associated with 6-month mortality. The role of the systemic inflammatory response (SIR) in determining treatment and prognosis requires further study. Routine reporting of CAC scores in CTPA scans for acute PE may have a role in aiding clinical decision-making regarding treatment and prognosis.

Investigation and management of pulmonary embolism 1: a probability-based approach

Pulmonary embolism remains a common and potentially deadly disease, despite advances in diagnostic imaging, treatment and prevention. Managing pulmonary embolism requires a multifactorial approach involving risk stratification, determining appropriate diagnostics and selecting individualised therapy. This article reviews the pathophysiology, risk factors, clinical presentation, diagnostic evaluation and therapeutic management and early outpatient management of pulmonary embolism. The second part summarises pulmonary embolism in the setting of pregnancy, COVID-19, recurrent disease and chronic thromboembolic pulmonary hypertension.

Recommended D-Dimer Use in Suspected Pulmonary Embolism Is Insufficient to Curb the Long-Term Overutilization of CT Pulmonary Angiography

PURPOSE

The aim of this study was to determine whether the authors' emergency medicine department has seen a significant change in CT pulmonary angiography (CTPA) utilization or positive rates for pulmonary embolism (PE) over a 10-year period for the 2 years before and 8 years after the implementation of patient population-specific D-dimer recommendations.

METHODS

A retrospective chart review was performed among all patients belonging to a geographically isolated health maintenance organization who underwent CTPA for the evaluation of acute PE in the emergency department between 2010 and 2019. The positive rate for acute PE among these studies was calculated and stratified by serum D-dimer value collected within 48 hours previously.

RESULTS

A total of 6,013 CT pulmonary angiographic studies were reviewed, of which 40.2% had serum D-dimer ≥ 1.0 μg/mL (positive rate 10.6%), 42.5% did not have serum D-dimer drawn (positive rate 7.3%), and 17.2% had serum D-dimer < 1.0 μg/mL (positive rate 0.6%). There was a significant increase in positivity on CTPA in 2012 with the health group's formal recommendation of a D-dimer cutoff of 1.0 μg/mL. This improvement also corresponded with fewer orders for CTPA after a negative D-dimer result. However, in the following years, CTPA utilization and percentage positivity were found to be reverting to the prerecommendation statistics.

CONCLUSIONS

The failure to mandate the use of serum D-dimer with a higher threshold value for patients who are to undergo CTPA for possible PE has resulted in poor lasting compliance despite promising early results. A firmer approach is likely necessary to yield positive long-term outcomes.

Advances in the Management of Acute Venous Thromboembolism and New Therapeutic Agents

Important advances in the understanding and management of venous thromboembolism (VTE) have enhanced our ability to diagnose, prevent, and treat VTE. In this narrative review, we discuss how recent advances in the understanding and management of VTE are changing practice, highlight ongoing unmet needs in VTE management, and outline how novel therapeutic targets with little or no influence on hemostasis may help address these unmet needs.

To scan or not to scan - D-dimers and computed tomography pulmonary angiography in the era of COVID-19

The COVID-19 pandemic has had many ramifications on healthcare delivery and practice. As part of this, utilising biomarkers to risk stratify patients has become increasingly popular. During the COVID-19 pandemic the use of D-dimer has increased due to the evidence of COVID-19 induced thrombo-embolic disease. We evaluated the use of D-dimer on all hospital admissions during the peak of the pandemic and evaluated its sensitivity in diagnosing pulmonary embolic disease (PE). Patients without COVID-19 infection were as likely to have evidence of PE as their COVID-positive counterparts. However, the sensitivity of a D-dimer was higher in COVID-positive patients at a lower D-dimer level (>1,500 μg/L, sensitivity 81%, specificity 70%) than in those without clinical, immunological or radiological evidence of COVID-19 infection (D-dimer >2,000 μg/L, sensitivity 80%, specificity 76%). These data suggest higher D-dimer thresholds should be considered for the exclusion of pulmonary emboli.

Utilization of serum D-dimer assays prior to computed tomography pulmonary angiography scans in the diagnosis of pulmonary embolism among emergency department physicians: a retrospective observational study

Background

A variety of evidence-based algorithms and decision rules using D-Dimer testing have been proposed as instruments to allow physicians to safely rule out a pulmonary embolism (PE) in low-risk patients.

Objective

To describe the prevalence of D-Dimer utilization among emergency department (ED) physicians and its impact on positive yields and utilization rates of Computed Tomography Pulmonary Angiography (CTPA).

Methods

Data was collected on all CTPA studies ordered by ED physicians at three sites during a 2-year period. Using a chi-square test, we compared the diagnostic yield for those patients who had a D-Dimer prior to their CTPA and those who did not. Secondary analysis was done to examine the impact of D-Dimer testing prior to CTPA on individual physician diagnostic yield or utilization rate.

Results

A total of 2811 CTPAs were included in the analysis. Of these, 964 CTPAs (34.3%) were ordered without a D-Dimer, and 343 (18.7%) underwent a CTPA despite a negative D-Dimer. Those CTPAs preceded by a D-Dimer showed no significant difference in positive yields when compared to those ordered without a D-Dimer (9.9% versus 11.3%, p = 0.26). At the individual physician level, no statistically significant relationship was found between D-Dimer utilization and CTPA utilization rate or diagnostic yield.

Conclusion

This study provides evidence of suboptimal adherence to guidelines in terms of D-Dimer screening prior to CTPA, and forgoing CTPAs in patients with negative D-Dimers. However, the lack of a positive impact of D-Dimer testing on either CTPA diagnostic yield or utilization rate is indicative of issues relating to the high false-positive rates associated with D-Dimer screening.

Symptomatic subsegmental versus more central pulmonary embolism: Clinical outcomes during anticoagulation

BACKGROUND

The optimal therapy of patients with acute subsegmental pulmonary embolism (PE) is controversial.

METHODS

We used the RIETE (Registro Informatizado Enfermedad TromboEmbólica) database to compare the rate of symptomatic PE recurrences during anticoagulation in patients with subsegmental, segmental, or more central PEs.

RESULTS

Among 15 963 patients with a first episode of symptomatic PE, 834 (5.2%) had subsegmental PE, 3797 (24%) segmental, and 11 332 (71%) more central PE. Most patients in all subgroups received initial therapy with low-molecular-weight heparin, and then most switched to vitamin K antagonists. Median duration of therapy was 179, 185, and 204 days, respectively. During anticoagulation, 183 patients developed PE recurrences, 131 developed deep vein thrombosis (DVT), 543 bled, and 1718 died (fatal PE, 135). The rate of PE recurrences was twofold higher in patients with subsegmental PE than in those with segmental (hazard ratio [HR], 2.13; 95% confidence interval [CI], 1.16-3.85) or more central PE (HR, 1.89; 95% CI, 1.12-3.13). On multivariable analysis, patients with subsegmental PE had a higher risk for PE recurrences than those with central PE (adjusted HR, 1.75; 95% CI, 1.02-3.03). After stratifying patients with subsegmental PE according to ultrasound imaging in the lower limbs, the rate of PE recurrences was similar in patients with DVT, in patients without DVT, and in those with no ultrasound imaging.

CONCLUSIONS

Our study reveals that the risk for PE recurrences in patients with segmental PE is not lower than in those with more central PE, thus suggesting that the risk of PE recurrences is not influenced by the anatomic location of PE.

Acute pulmonary embolism: appropriateness of emergency department management according to clinical guidelines

BACKGROUND AND AIMS

To evaluate the frequency of acute pulmonary embolism, the use of clinical probability scores, and the appropriateness of the management of patients for whom computed tomography angiography (CTA) was requested from the emergency department for suspected acute pulmonary embolism.

MATERIALS AND METHODS

This was a retrospective observational study of CTA studies requested from the emergency department to rule out acute pulmonary embolism. We analyzed clinical variables and the explicit use of clinical probability scores. We determined the appropriateness of management according to the Wells Score and Geneva Score and the simplified versions of these two scores, calculated retrospectively.

RESULTS

We included 534 patients (52.8% women; mean age, 73 years). The frequency of acute pulmonary embolism was 23.0% and the Wells Score was explicitly used in 15.2%. The appropriateness of the management varied depending on the clinical probability score used to assess it (54.5%-75.8%) and on whether the standard D-dimer or age-adjusted D-dimer was used.

CONCLUSIONS

The failure to use the Wells Scores in all cases does not necessarily imply inappropriate management, and the performance of global clinical judgment can be similar to that of clinical probability scores; however, specific studies are necessary to confirm this hypothesis.

Predictors of Overtesting in Pulmonary Embolism Diagnosis

BACKGROUND

The benefits of computed tomography pulmonary angiography (CTPA) for pulmonary embolism (PE) diagnosis must be weighed against its risks, radiation-induced malignancy, and contrast-induced nephropathy. Appropriate use of CTPA can be assessed by monitoring yield, the percentage of tests positive for PE. We identify factors that are associated low CTPA yield, which may predict overtesting.

METHODS

This was a retrospective cohort study of six emergency departments between June 2014 and February 2017. The electronic health record was queried for CTPAs ordered for adult patients in the emergency department. We assessed the following patient factors: age, gender, body mass index, number of comorbidities, race, and ethnicity, provider factors: type (resident, fellow, attending, physician assistant) and environment factors: test time of day, season of visit, and crowdedness of the department.

RESULTS

A total of 14,782 CTPAs were reviewed, of which 1366 were found to be positive for PE, resulting in an overall CTPA yield of 9.24%. Provider type was not associated with a difference in yield. Testing was less likely to be positive in younger patients, females, those with lower body mass indexes and those identifying as Asian or Hispanic. Testing was also less likely to be positive when ordered during the overnight shift and during the winter and spring seasons.

CONCLUSION

Our study identified several patient and environmental factors associated with low CTPA yield suggesting potential targets for overtesting. Targeting education and clinical decision support to assist providers in these circumstances may meaningfully improve yields.

Outcomes of Multidetector Computed Tomography Pulmonary Angiography in Pregnant and Postpartum Women With Suspected Pulmonary Embolism

PURPOSE

Verify whether there is a difference in likelihood of developing pulmonary embolism (PE) between pregnant women, nonpregnant women of reproductive age, and postpartum (up to 6 weeks) women, by comparing their outcomes on computed tomography pulmonary angiography (CTPA) done for suspicion of PE.

MATERIALS AND METHODS

Retrospective cohort study of 1463 CTPA done for suspicion of PE in females of reproductive age (18-40 years), nonpregnant, pregnant (antepartum), and postpartum, from 2 tertiary-care academic hospitals between October 2006 and September 2015. Primary outcome was diagnosis of PE on imaging. Additional assessment was made of technical adequacy of the studies and method of delivery for the postpartum cohort (vaginal vs caesarean birth). Twenty-nine technically nondiagnostic studies were excluded. The effect of any potential variable on PE status was tested using univariate logistic regression. Subgroup analysis was performed after excluding patients with independent risk factors for PE.

RESULTS

The rate of CTPA positive for PE was less among pregnant patients compared to early postpartum and nonpregnant women of similar age, 2.9% vs 11.5% and 10.3%, respectively. Pregnancy was associated with statistically significant decreased odds ratio of developing a PE on CTPA, 0.23 (0.09-0.89), P value = .004. After excluding patients with additional independent risk factors for PE, there was no statistically significant odds ratio association between presence of PE on CTPA and pregnancy 0.41 (0.13-1.34), P value = .14.

CONCLUSION

Rate of CTPA positive for PE in pregnant women was lower than in nonpregnant and early postpartum women. Pregnancy was statistically significantly less likely to be associated with positive PE on a CTPA study. The common perception that pregnancy (antepartum state) is associated with an increased risk of PE may require a thorough critical reappraisal.

Pulmonary embolism rule out: positivity and factors affecting the yield of CT angiography

OBJECTIVE

CT pulmonary angiography (CTPA) is one of the most commonly ordered CT imaging tests. It is often believed to be overutilised with few recent studies showing a yield of less than 2%. This study aimed to determine the overall positivity rate of CTPA examinations and understand the factors that affect the yield of the CTPA examination.

METHODS

We retrospectively analysed 2713 patients who received the CTPA exam between 2016 and 2018. Type of study ordered (CTPA chest or CTPA chest with abdomen and pelvis CT), patient location (emergency department (ED), outpatient, inpatient, intensive care unit (ICU)) and patient characteristics-age, sex and body mass index (BMI) were recorded. A logistic regression analysis was performed to determine what factors affect the positivity rate of CT scans for pulmonary embolism (PE).

RESULTS

With 296 positive test results, the overall CTPA positivity was 10.9%. Male sex was associated with higher CTPA positivity, gender difference was maximum in 18-year to 35-year age group. Overweight and obese patients had significantly higher positivity as compared with BMI<25 (p<0.05). Higher positivity rate was seen in the BMI 25-40 group (11.9%) as compared with BMI>40 (10.1%) (p<0.05). Significant difference (p<0.001) was also found in CTPA examination yield from ICU (15.3%) versus inpatients (other than ICU) (12.4%) versus ED (9.6%), and outpatients (8.5%). The difference in CTPA yield based on the type of CT order (CTPA chest vs CTPA chest with CT abdomen and pelvis), patient's age and sex was not significant.

CONCLUSION

CTPA yield of 10.9% in this study is comparable to acceptable positivity rate for the USA and is higher than recent studies showing positivity of <2%. Patient characteristics like obesity and ICU or inpatient location are associated with higher rate of CT positivity.

Higher Imaging Yield When Clinical Decision Support Is Used

OBJECTIVE

Increased utilization of CT pulmonary angiography (CTPA) for the evaluation of pulmonary embolism has been associated with decreasing diagnostic yields and rising concerns about the harms of unnecessary testing. The objective of this study was to determine whether clinical decision support (CDS) use would be associated with increased imaging yields after controlling for selection bias.

METHODS

We performed a retrospective cohort study in the emergency departments of two tertiary care hospitals of all CTPAs performed between August 2015 and September 2018. Providers ordering a CTPA are routed to an optional CDS tool, which allows them to use Wells' Criteria for pulmonary embolism. After propensity score matching, CTPA yield was calculated for the CDS-use and CDS-dismissal groups and stratified by provider type.

RESULTS

A total of 7,367 CTPAs were ordered during the study period. Of those, providers used the CDS tool in 2,568 (35%) cases and did not use the tool in 4,799 (65%) of cases. After propensity score matching, CTPA yield was 11.99% in the CDS-use group and 8.70% in the CDS-dismissal group (P < .001). Attending physicians, residents, and physician assistant CDS users demonstrated a 56.5% (P = .006), 38.7% (P = .01), and 16.7% (P = .03) increased yield compared with those who dismissed the tool, respectively.

DISCUSSION

Diagnostic yield was 38% higher for CTPAs when the provider used the CDS tool, after controlling for selection bias. Yields were higher for every provider type. Further research is needed to discover successful strategies to increase provider use of these important tools.

Epidemiology and diagnosis of pulmonary embolism in lung cancer patients: is there a role for age adjusted D-dimers cutoff?

Our knowledge about the incidence of pulmonary embolism (PE) and the performance of age adjusted D-dimers (Dd) cutoff amongst patients with lung cancer (LC) and suspected PE, remains limited. We retrospectively analyzed all clinically suspected patients who underwent computed tomography pulmonary angiography (CTPA) in a tertiary hospital during a 19 month period. Cancer diagnosis was established using ICD10 code. Eligible for Dd analysis were those tested up to 24 h prior to the scan. We analyzed 2549 patients (54.6% males, median age 68.8 years, IQR 57-78), 15.8% had active LC and 5.4% other cancers (oC), while 70% were scanned in the Emergency Department (ED) and the rest during hospitalization. Overall incidence of PE was 16%. LC, but not oC, increased significantly the risk for PE (OR 1.58, 95% CI 1.21-2.06). LC patients were less likely to have bilateral (aOR 0.16, 95% CI 0.07-0.4) or central PE (aOR 0.2, 95% CI 0.09-0.48). Amongst those diagnosed with PE in the ED, LC increased all-cause inhospital mortality (aOR 6.7, 95% CI 2.64-16.95). When age adjusted instead of conventional Dd cutoff was used for ruling out PE in the ED, specificity for LC patients increased (10.16% vs 3.91%) without false negative tests (negative likelihood ratio-NLR = 0). A higher cutoff of 1.13 mg/l raised specificity to 28.9%, with only one case missed (sensitivity: 97.4%, NLR: 0.09, 95% CI 0.01-0.64). LC increases the risk for PE and adversely affects prognosis. Age adjusted and probably an even higher, "LC adjusted" Dd cutoff, could increase the specificity of the test without compromising its sensitivity.

Radionuclide lung scans for suspected acute pulmonary embolism: Single photon emission computed tomography (SPECT) or hybrid SPECT/CT?

INTRODUCTION

Hybrid single photon emission computed tomography (SPECT) with CT (SPECT/CT) may improve diagnostic accuracy in suspected acute pulmonary embolism, but further research is needed. We evaluated whether the use of attenuation correction and/or the depiction of lung pathology with hybrid SPECT/CT could significantly reduce potentially false-positive ventilation-perfusion (VQ) SPECT studies or obviate the need for a ventilation study.

METHODS

Two specialists (S1 and S2) reviewed prospectively acquired VQ SPECT/CT in 165 patients. Studies were reported using standard criteria and compared to VQ SPECT and Q SPECT/CT.

RESULTS

S1 and S2 recorded positive VQ SPECT in 54 (32.7%) and 42 (25.6%) cases, respectively. Hybrid SPECT/CT showed non-embolic pathology in 41 (S1) and 46 (S2) patients, but compared to VQ SPECT, neither hybrid SPECT/CT nor attenuation correction SPECT/CT had significantly fewer positive studies. Intra-observer agreement with VQ SPECT/CT was almost perfect (k = 0.91 for S1 and k = 0.95 for S2; P < 0.001), but not with Q SPECT/CT (k = 0.4 for S1 and k = 0.62 for S2; P < 0.001). Inter-observer agreement was moderate for VQ SPECT (k = 0.65) and VQ SPECT/CT (k = 0.63).

CONCLUSION

In our study, hybrid VQ SPECT/CT did not reduce the number of potentially false-positive VQ SPECT, nor did the CT obviate the need for a ventilation study. Thus, the routine use of hybrid SPECT/CT for suspected pulmonary embolism is not justified.

Retrospective Analysis of Emergency Computed Tomography Imaging Utilization at an Academic Centre: An Analysis of Clinical Indications and Outcomes

Purpose

To explore resource utilization through evaluation of computed tomography (CT) imaging trends in the emergency department by examining common indications/outcomes for imaging in this setting.

Methods

A retrospective analysis of clinical indications/outcomes for all CT imaging in 3 emergency departments over a 1-year period was conducted. Scans were divided by body part and the most common indications for each type of scan were determined. Clinical outcomes from each study were extracted from final interpretations by the reporting radiologist.

Results

A total of 4556 CT scans were performed in the emergency department over a 1-year period. A total of 3.6% of all-comers to our emergency departments underwent CT scan as part of their investigation. There were 2107 head CTs (46%), 1296 (28%) abdominal CTs, 468 (10%) CTs of the chest, 408 (9%) CTs of the neck/spine, and 101 (2%) extremity CTs performed. The most common clinical indication for performing a CT head was focal neurological defect comprising 1534 (73%) of all CT heads. Twenty-four percent of abdominal CTs were for investigation of right lower quadrant pain, followed by flank pain (19%). Chest pain and shortness of breath were the most common indications for CTs of the chest (315 [75%]) with 10% of these examinations for this indication positive for pulmonary embolism. Trauma was the most common indication for neck CTs (296 [73%]) and extremities (70 [69%]). Nil acute was the most common final interpretation in all categories (79% CT heads, 75% neck CTs, 38% abdominal CTs, 43% chest CTs).

Conclusions

Nil acute was the most common diagnosis; however, serious clinical outcomes were identified 40% of the time. Cross-sectional imaging remains an integral tool for triage and diagnosis in this environment as the cost of missing a diagnosis in this setting has a great impact on patient care.

Sickle cell disease and venous thromboembolism: A retrospective comparison of the rate of positive CT pulmonary angiography in the emergency department

BACKGROUND

Previous authors have reported an increased incidence of acute pulmonary embolism (PE) in patients with sickle cell disease (SCD) based on retrospective analysis of ICD codes. It is unknown whether patients with SCD have higher rates of positive CT pulmonary angiogram (CTPA) in the emergency department (ED).

METHODS

The institutional review board (IRB) approved this retrospective study; informed consent was waived. Between January 1, 2005 and May 31, 2015, 28 patients with SCD underwent a total of 78 CTPA studies in the ED. A control group of 75 non-SCD patients matched for age, gender and race underwent 78 consecutive CTPA studies in the emergency department. Modified Wells' (mWells') scores were calculated for each CTPA study performed. The studies for both groups were blind read by two fellowship trained body radiologists. Descriptive statistics were performed, with significance considered if p < 0.05.

RESULTS

The rate of positive CT pulmonary angiogram in patients with SCD was 6.4% (5/78), compared with 12.8% (10/78) in non-SCD matched controls. There was no significant difference in the rate of positive CTPA (p = 0.277). There was also no difference in the mean mWells' score between the two groups (2.44 for SCD vs. 1.95 for controls, p = 0.120).

CONCLUSION

SCD patients did not have a significantly different rate of acute PE when compared with matched controls undergoing CTPA in the ED.

Imaging of suspected pulmonary embolism and deep venous thrombosis in obese patients

Obesity is a growing problem around the world, and radiology departments frequently encounter difficulties related to large patient size. Diagnosis and management of suspected venous thromboembolism, in particular deep venous thrombosis (DVT) and pulmonary embolism (PE), are challenging even in some lean patients, and can become even more complicated in the setting of obesity. Many obstacles must be overcome to obtain imaging examinations in obese patients with suspected PE and/or DVT, and to ensure that these examinations are of sufficient quality to diagnose or exclude thromboembolic disease, or to establish an alternative diagnosis. Equipment limitations and technical issues both need to be acknowledged and addressed. Table weight limits and scanner sizes that readily accommodate obese and even morbidly obese patients are not in place at many clinical sites. There are also issues with image quality, which can be substantially compromised. We discuss current understanding of the effects of patient size on imaging in general and, more specifically, on the imaging modalities used for the diagnosis and treatment of DVT and PE. Emphasis will be placed on the technical parameters and protocol nuances, including contrast dosing, which are necessary to refine and optimize images for the diagnosis of DVT and PE in obese patients, while remaining cognizant of radiation exposure. More research is necessary to develop consistent high-level evidence regarding protocols to guide radiologists, and to help them effectively utilize emerging technology.

Association of Lower Diagnostic Yield With High Users of CT Pulmonary Angiogram

This study examines interphysician variability of diagnostic yield in computed tomographic pulmonary angiogram for pulmonary emboli.

Correction: RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates

[This corrects the article DOI: 10.1371/journal.pone.0166483.].