Overdiagnosis of Pulmonary Embolism by Pulmonary CT Angiography. AJR Am J Roentgenol. 2015;205:271-277. [PMID: 26204274 DOI: 10.2214/ajr.14.13938]

Emergency Ultrasound Unveils Intermediate-High Risk Saddle Pulmonary Embolism with Extensive Bilateral Clot Burden, Masquerading as Micturition Syncope: A Case Report

BACKGROUND

Isolated syncope as the manifestation of pulmonary embolism (PE) is a rare and diagnostically challenging presentation that often leads to delayed or missed diagnosis, increasing morbidity and mortality. In spite of emphasizing cardiovascular etiologies of syncope, current guidelines offer essentially no guidance in establishing a diagnostic workup for PE in these patients. By performing bedside echocardiography, emergency physicians can accurately identify concerning features suggestive of PE in patients with syncope.

CASE REPORT

A 78-year-old man, receiving ertapenem via a peripherally inserted central catheter for treatment of extended spectrum β-lactamase urinary tract infection, presented to the emergency department for isolated syncope with collapse while urinating. Arriving asymptomatic with normal vital signs and a benign physical examination, a presumptive diagnosis of micturition syncope was made. However, subtle vital sign changes on reassessment prompted performance of a point-of-care echocardiogram, which revealed signs of right heart strain. A computed tomography angiogram confirmed a saddle PE with extensive bilateral clot burden. Catheter-directed thrombectomy was performed via interventional radiology, with successful removal of pulmonary emboli. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Pulmonary embolism presenting as isolated syncope represents a daunting diagnostic dilemma, as emergency physicians may not consider it, or anchor on more benign etiologies of syncope. Although lacking sufficient sensitivity to rule out PE, point-of-care echocardiography to evaluate for signs of right heart strain can quickly and effectively point toward the diagnosis, while also assessing for other emergent cardiovascular causes of syncope. Given the lack of evidence-based guidance concerning PE presenting as syncope, bedside echocardiography should be highly considered as a part of the emergency physician's diagnostic workup, especially in patients with abnormal vital signs.

Subsegmental Pulmonary Embolism

Subsegmental pulmonary embolism (SSPE) is increasingly diagnosed with the growing use and technological advancements of multidetector computed tomography pulmonary angiography. Its diagnosis is challenging, and some presumed SSPE may actually represent imaging artifacts. Indirect evidence and results from small observational studies suggest that SSPE may be more benign than more proximal pulmonary embolism, and may thus not always require treatment. Therefore, guidelines suggest to consider a management strategy without anticoagulation in selected patients with SSPE at low risk of recurrent venous thromboembolism (VTE), in whom proximal deep vein thrombosis is excluded. Recently, a large prospective study among low-risk patients with SSPE who were left untreated showed a higher VTE recurrence risk than initially deemed acceptable by the investigators, and thus was prematurely interrupted after recruitment of 97% of the target population. However, the risk-benefit ratio of anticoagulation for low-risk patients with SSPE remains unclear, and results from randomized trials are needed to answer the question about their optimal management.

Roles of spectral dual-layer CT, D-dimer concentration, and COVID-19 pneumonia in diagnosis of pulmonary embolism

Purpose

To demonstrate advantages of spectral dual-layer computed tomography (CT) in diagnosing pulmonary embolism (PE). To compare D-dimer values in patients with PE and concomitant COVID-19 pneumonia to those in patients without PE and COVID-19 pneumonia. To compare D-dimer values in cases of minor versus extensive PE.

Methods

A monocentric retrospective study of 1500 CT pulmonary angiographies (CTPAs). Three groups of 500 consecutive examinations: 1) using conventional multidetector CT (CTC), 2) using spectral dual-layer CT (CTS), and 3) of COVID-19 pneumonia patients using spectral dual-layer CT (COV). Only patients with known D-dimer levels were enrolled in the study.

Results

Prevalence of inconclusive PE findings differed significantly between CTS and CTC (0.8 % vs. 5.4 %, p < 0.001). In all groups, D-dimer levels were significantly higher in PE positive patients than in patients without PE (CTC, 8.04 vs. 3.05 mg/L; CTS, 6.92 vs. 2.57 mg/L; COV, 10.26 vs. 2.72 mg/L, p < 0.001). There were also statistically significant differences in D-dimer values between minor and extensive PE in the groups negative for COVID-19 (CTC, 5.16 vs. 8.98 mg/L; CTS 3.52 vs. 9.27 mg/L, p < 0.001). The lowest recorded D-dimer value for proven PE in patients with COVID-19 pneumonia was 1.19 mg/L.

Conclusion

CTPAs using spectral dual-layer CT reduce the number of inconclusive PE findings. Plasma D-dimer concentration increases with extent of PE. Cut-off value of D-dimer with 100 % sensitivity for patients with COVID-19 pneumonia could be doubled to 1.0 mg/L. This threshold would have saved 110 (22 %) examinations in our cohort.

Value of computed tomography pulmonary angiography measurements in predicting 30-day mortality among patients with acute pulmonary embolism

Purpose

Late diagnosis is associated with high mortality rates in acute pulmonary embolism (PE), so early diagnosis and risk assessment are crucial. We aim to evaluate computed tomography pulmonary angiography measurements to identify relationships with 30-day mortality in patients with pulmonary embolism. This study investigated the utility of computed tomography pulmonary angiography (CTPA) measures in determining 30-day PE-related mortality and identified various echocardiographic, demographic, and clinical variables that were independently associated with short-term mortality in patients with acute PE.

Material and methods

This retrospective study examined data from July 2018 to April 2023. A total of 118 patients were included in the study. Clinical and demographic characteristics, laboratory findings, echocardiographic data, and CTPA images were retrieved from the electronic database and patient charts.

Results

The rate of 30-day mortality was 14.41%. Deceased patients were significantly older than survivors (73.53 ± 14.17 vs. 60.23 ± 17.49 years; p = 0.004), but the sex distribution was similar. In multivariable logistic regression, having received radiotherapy for malignancy, high pulmonary artery obstruction index % (> 46.2), high left pulmonary artery diameter (> 23.9 mm), and high coronary artery calcification score (> 5.5) were independently associated with mortality.

Conclusions

These results reveal specific parameters that can assist acute PE management by enabling the identification of critical events. Despite promising results in predicting short-term mortality in acute PE, further prospective cohort studies are needed to confirm the results of the present study.

POCUS for Thrombus: Emphasizing the Importance of Initial Point-of-Care Ultrasound in the Management of Pulmonary Thromboembolism

Pulmonary embolism (PE) constitutes a substantial health burden among individuals in the United States. It ranks as the third most common cause of cardiovascular death aside from stroke and myocardial infarction. Diagnostic errors are common with PE as patients can present with non-specific symptoms or could be completely asymptomatic with PE being an incidental finding. Diagnostic errors can result in missed or late diagnosis of PE, which, in turn, increases health care costs, morbidity, and mortality rates. Hence, early diagnosis is crucial. Computed tomography pulmonary angiography (CTPA) remains the gold standard in PE diagnosis, despite exposure to high doses of radiation. Point-of-care ultrasound (POCUS) is an underutilized, non-invasive technique that aids in the early diagnosis of PE and can safely reduce the radiation from CTPA in cases where contraindication exists. POCUS has been shown to have a high sensitivity and specificity for early diagnosis of PE.

Evidence for overdiagnosis in noncancer conditions was assessed: a metaepidemiological study using the 'Fair Umpire' framework

OBJECTIVES

To evaluate the strength of the evidence for, and the extent of, overdiagnosis in noncancer conditions.

STUDY DESIGN AND SETTING

We systematically searched for studies investigating overdiagnosis in noncancer conditions. Using the 'Fair Umpire' framework to assess the evidence that cases diagnosed by one diagnostic strategy but not by another may be overdiagnosed, two reviewers independently identified whether a Fair Umpire-a disease-specific clinical outcome, a test result or risk factor that can determine whether an additional case does or does not have disease-was present. Disease-specific clinical outcomes provide the strongest evidence for overdiagnosis, follow-up or concurrent tests provide weaker evidence, and risk factors provide only weak evidence. Studies without a Fair Umpire provide the weakest evidence of overdiagnosis.

RESULTS

Of 132 studies, 47 (36%) did not include a Fair Umpire to adjudicate additional diagnoses. When present, the most common Umpire was a single test or risk factor (32% of studies), with disease-specific clinical outcome Umpires used in only 21% of studies. Estimates of overdiagnosis included 43-45% of screen-detected acute abdominal aneurysms, 54% of cases of acute kidney injury, and 77% of cases of oligohydramnios in pregnancy.

CONCLUSION

Much of the current evidence for overdiagnosis in noncancer conditions is weak. Application of the framework can guide development of robust studies to detect and estimate overdiagnosis in noncancer conditions, ultimately informing evidence-based policies to reduce it.

Sex differences in guideline-consistent diagnostic testing for acute pulmonary embolism among adult emergency department patients aged 18-49

BACKGROUND

Pulmonary embolism (PE) is a frequent diagnostic consideration in emergency department (ED) patients, yet diagnosis is challenging because symptoms of PE are nonspecific. Guidelines recommend the use of clinical decision tools to increase efficiency and avoid harms from overtesting, including D-dimer screening in patients not at high risk for PE. Women undergo testing for PE more often than men yet have a lower yield from testing. Our study objective was to determine whether patient sex influenced the odds of received guideline-consistent care.

METHODS

We performed a retrospective cohort study at two large U.S. academic EDs from January 1, 2016, to December 31, 2018. Nonpregnant patients aged 18-49 years were included if they presented with chest pain, shortness of breath, hemoptysis, or syncope and underwent testing for PE with D-dimer or imaging. Demographic and clinical data were exported from the electronic medical record (EMR). Pretest risk scores were calculated using manually abstracted EMR data. Diagnostic testing was then compared with recommended testing based on pretest risk. The primary outcome was receipt of guideline-consistent care, which required an elevated screening D-dimer prior to imaging in all non-high-risk patients.

RESULTS

We studied 1991 discrete patient encounters; 37% (735) of patients were male and 63% (1256) were female. Baseline characteristics, including revised Geneva scores, were similar between sexes. Female patients were more likely to receive guideline-consistent care (70% [874/1256] female vs. 63% [463/735] male, p < 0.01) and less likely to be diagnosed with PE (3.1% [39/1256] female vs. 5.3% [39/735] male, p < 0.05). The most common guideline deviation in both sexes was obtaining imaging without a screening D-dimer in a non-high-risk patient (75% [287/382] female vs. 75% [205/272] male).

CONCLUSIONS

In this cohort, females were more likely than males to receive care consistent with current guidelines and less likely to be diagnosed with PE.

[Expert Opinion Questionnaire About Chest CT Scan Using A Negative Pressure Isolation Strecher in COVID-19 Patients: Image Quality and Infection Risk]

PURPOSE

To survey perceptions of certified physicians on the protocol of chest CT in patients with coronavirus (COVID-19) using a negative pressure isolation stretcher (NPIS).

MATERIALS AND METHODS

This study collected questionnaire responses from a total of 27 certified physicians who had previously performed chest CT with NPIS in COVID-19 isolation hospitals.

RESULTS

The nine surveyed hospitals performed an average of 116 chest CT examinations with NPIS each year. Of these, an average of 24 cases (21%) were contrast chest CT. Of the 9 pulmonologists we surveyed, 5 (56%) agreed that patients who showed abnormalities in serum D-dimer required contrast chest CT. All 9 surveyed radiologists agreed that the image quality of the chest CT with NPIS was sufficient for CT image interpretation regarding pneumonia or pulmonary embolism. Furthermore, in our 9 surveyed infectionologists, 5 (56%) agreed that a risk of secondary infection in the CT room after temporary opening of NPIS could be prevented through a process of disinfection.

CONCLUSION

Experienced physicians considered that the effects of NIPS on chest CT image quality was minimal in patients with COVID-19, and the risk of CT room contamination was easily controlled.

Retrospective batch analysis to evaluate the diagnostic accuracy of a clinically deployed AI algorithm for the detection of acute pulmonary embolism on CTPA

PURPOSE

To generate and extend the evidence on the clinical validity of an artificial intelligence (AI) algorithm to detect acute pulmonary embolism (PE) on CT pulmonary angiography (CTPA) of patients suspected of PE and to evaluate the possibility of reducing the risk of missed findings in clinical practice with AI-assisted reporting.

METHODS

Consecutive CTPA scan data of 3316 patients referred because of suspected PE between 24-2-2018 and 31-12-2020 were retrospectively analysed by a CE-certified and FDA-approved AI algorithm. The output of the AI was compared with the attending radiologists' report. To define the reference standard, discordant findings were independently evaluated by two readers. In case of disagreement, an experienced cardiothoracic radiologist adjudicated.

RESULTS

According to the reference standard, PE was present in 717 patients (21.6%). PE was missed by the AI in 23 patients, while the attending radiologist missed 60 PE. The AI detected 2 false positives and the attending radiologist 9. The sensitivity for the detection of PE by the AI algorithm was significantly higher compared to the radiology report (96.8% vs. 91.6%, p < 0.001). Specificity of the AI was also significantly higher (99.9% vs. 99.7%, p = 0.035). NPV and PPV of the AI were also significantly higher than the radiology report.

CONCLUSION

The AI algorithm showed a significantly higher diagnostic accuracy for the detection of PE on CTPA compared to the report of the attending radiologist. This finding indicates that missed positive findings could be prevented with the implementation of AI-assisted reporting in daily clinical practice.

CRITICAL RELEVANCE STATEMENT

Missed positive findings on CTPA of patients suspected of pulmonary embolism can be prevented with the implementation of AI-assisted care.

KEY POINTS

The AI algorithm showed excellent diagnostic accuracy detecting PE on CTPA. Accuracy of the AI was significantly higher compared to the attending radiologist. Highest diagnostic accuracy can likely be achieved by radiologists supported by AI. Our results indicate that implementation of AI-assisted reporting could reduce the number of missed positive findings.

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.

Developing Validated Tools to Identify Pulmonary Embolism in Electronic Databases: Rationale and Design of the PE-EHR+ Study

BACKGROUND

 Contemporary pulmonary embolism (PE) research, in many cases, relies on data from electronic health records (EHRs) and administrative databases that use International Classification of Diseases (ICD) codes. Natural language processing (NLP) tools can be used for automated chart review and patient identification. However, there remains uncertainty with the validity of ICD-10 codes or NLP algorithms for patient identification.

METHODS

 The PE-EHR+ study has been designed to validate ICD-10 codes as Principal Discharge Diagnosis, or Secondary Discharge Diagnoses, as well as NLP tools set out in prior studies to identify patients with PE within EHRs. Manual chart review by two independent abstractors by predefined criteria will be the reference standard. Sensitivity, specificity, and positive and negative predictive values will be determined. We will assess the discriminatory function of code subgroups for intermediate- and high-risk PE. In addition, accuracy of NLP algorithms to identify PE from radiology reports will be assessed.

RESULTS

 A total of 1,734 patients from the Mass General Brigham health system have been identified. These include 578 with ICD-10 Principal Discharge Diagnosis codes for PE, 578 with codes in the secondary position, and 578 without PE codes during the index hospitalization. Patients within each group were selected randomly from the entire pool of patients at the Mass General Brigham health system. A smaller subset of patients will also be identified from the Yale-New Haven Health System. Data validation and analyses will be forthcoming.

CONCLUSIONS

 The PE-EHR+ study will help validate efficient tools for identification of patients with PE in EHRs, improving the reliability of efficient observational studies or randomized trials of patients with PE using electronic databases.

Assessment of the Utilization of Validated Diagnostic Predictive Tools and D-Dimer in the Evaluation of Pulmonary Embolism: A Single-Center Retrospective Cohort Study from a Public Hospital in New York City

INTRODUCTION

A significant increase in the use of computed tomography with pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism (PE) has been observed in the past twenty years. We aimed to investigate whether the validated diagnostic predictive tools and D-dimers were adequately utilized in a large public hospital in New York City.

METHODS

We conducted a retrospective review of patients who underwent CTPA for the specific indication of ruling out PE over a period of one year. Two independent reviewers, blinded to each other and to the CTPA and D-dimer results, estimated the clinical probability (CP) of PE using Well's score, the YEARS algorithm, and the revised Geneva score. Patients were classified based on the presence or absence of PE in the CTPA.

RESULTS

A total of 917 patients were included in the analysis (median age: 57 years, female: 59%). The clinical probability of PE was considered low by both independent reviewers in 563 (61.4%), 487 (55%), and 184 (20.1%) patients based on Well's score, the YEARS algorithm, and the revised Geneva score, respectively. D-dimer testing was conducted in less than half of the patients who were deemed to have low CP for PE by both independent reviewers. Using a D-dimer cut-off of <500 ng/mL or the age-adjusted cut-off in patients with a low CP of PE would have missed only a small number of mainly subsegmental PE. All three tools, when combined with D-dimer < 500 ng/mL or <age-adjusted cut-off, yielded a NPV of > 95%.

CONCLUSION

All three validated diagnostic predictive tools were found to have significant diagnostic value in ruling out PE when combined with a D-dimer cut-off of <500 ng/mL or the age-adjusted cut-off. Excessive use of CTPA was likely secondary to suboptimal use of diagnostic predictive tools.

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.

How to Combat Over-Testing for Patients Suspected of Pulmonary Embolism: A Narrative Review

The diagnosis of PE remains difficult in 2023 because the signs and symptoms are not sensible nor specific. The consequences of potential diagnostic errors can be dramatic, whether by default or by excess. Furthermore, the achievement of a simple diagnostic strategy, based on clinical probability assessment, D-dimer measurement and computed tomography pulmonary angiography (CTPA) leads to a new challenge for PE diagnosis: over-testing. Indeed, since the 2000s, the wide availability of CTPA resulted in a major increase in investigations with a mod I confirm erate increase in PE diagnosis, without any notable improvement in patient outcomes. Quite the contrary, the complications of anticoagulation for PE increased significantly, and the long-term consequences of imaging diagnostic radiation is an important concern, especially the risk of breast cancer for young women. As a result, several strategies have been proposed to fight over-testing. They are mostly based on defining a subgroup of patients for whom no specific exam should be required to rule-out PE and adjusting the D-dimer cutoff to allow the exclusion of PE without performing CTPA. This narrative review presents the advantages and limitations of these different strategies as well as the perspective in PE diagnosis.

In Situ Pulmonary Arterial Thrombosis-Literature Review and Clinical Significance of a Distinct Entity

Filling defects identified in the pulmonary arterial tree are commonly presumed to represent an embolic phenomenon originating from thrombi formed in remote veins, particularly lower-extremity deep venous thrombosis (DVT). However, accumulating evidence supports an underappreciated cause for pulmonary arterial thrombosis (PAT), namely, de novo thrombogenesis-where thrombosis arises within the pulmonary arteries in the absence of DVT. Although historically underrecognized, in situ PAT has become of heightened importance with the emergence of SARS-CoV-2 infection. In situ PAT is attributed to endothelial dysfunction, systemic inflammation, and acute lung injury, and has been described in a range of conditions including COVID-19, trauma, acute chest syndrome in sickle cell disease, pulmonary infections, and severe pulmonary arterial hypertension. The distinction between pulmonary embolus and in situ PAT may have important implications regarding management decisions and clinical outcomes. In this review, we summarize the pathophysiology, imaging appearances, and management of in situ PAT in various clinical situations. This understanding will promote optimal tailored treatment strategies for this increasingly recognized entity.

Clinical Significance and Outcome in Patients with Asymptomatic Versus Symptomatic Subsegmental Pulmonary Embolism

The clinical significance and optimal therapy of patients with subsegmental pulmonary embolism (SSPE) remain controversial. We used the data in the RIETE Registry to compare the baseline characteristics, treatment, and outcomes during anticoagulation and after its discontinuation in patients with asymptomatic vs. symptomatic SSPE. From January 2009 to September 2022, there were 2135 patients with a first episode of SSPE, of whom 160 (7.5%) were asymptomatic. Most patients in both subgroups received anticoagulant therapy (97% vs. 99.4%, respectively). During anticoagulation, 14 patients developed symptomatic pulmonary embolism (PE) recurrences, 28 lower-limb deep vein thrombosis (DVT), 54 bled, and 242 died. The patients with asymptomatic SSPE had similar rates of symptomatic PE recurrences (hazard ratio (HR): 2.46; 95% CI: 0.37-9.74), DVT (HR: 0.53; 95% CI: 0.03-2.80), or major bleeding (HR: 0.85; 95% CI: 0.21-2.42) to those with symptomatic SSPE, but had a higher mortality rate (HR: 1.59; 95% CI: 1.25-2.94). The rate of major bleeding outweighed the rate of PE recurrences (54 major bleeds vs. 14 PE recurrences), and the rate of fatal bleeds outweighed the rate of fatal PE recurrences (12 vs. 6 deaths). After discontinuing anticoagulation, the patients with asymptomatic SSPE had a similar rate of PE recurrences (HR: 1.27; 95% CI: 0.20-4.55) and a non-significantly higher mortality rate (HR: 2.06; 95% CI: 0.92-4.10). The patients with asymptomatic SSPE had similar rates of PE recurrences to those with symptomatic SSPE, during and after discontinuing anticoagulation. The unexpectedly higher rate of major bleeding than recurrences highlights the need for randomized trials to find the best management.

Imaging in the Intensive Care Unit

Radiology plays an important role in the management of the most seriously ill patients in the hospital. Over the years, continued advances in imaging technology have contributed to an improvement in patient care. However, even with such advances, the portable chest radiograph (CXR) remains one of the most commonly requested radiographic examinations. While they provide valuable information, CXRs remain relatively insensitive at revealing abnormalities and are often nonspecific. Chest computed tomography (CT) can display findings that are occult on CXR and is particularly useful at identifying and characterizing pleural effusions, detecting barotrauma including small pneumothoraces, distinguishing pneumonia from atelectasis, and revealing unsuspected or additional abnormalities which could result in increased morbidity and mortality if left untreated. CT pulmonary angiography is the modality of choice in the evaluation of pulmonary emboli which can complicate the hospital course of the ICU patient. This article will provide guidance for interpretation of CXR and thoracic CT images, discuss some of the invasive devices routinely used, and review the radiologic manifestations of common pathologic disease states encountered in ICU patients. In addition, imaging findings and complications of more specific clinical scenarios in which the incidence has increased in the ICU setting, such as patients who are immunocompromised, have interstitial lung disease, or COVID-19, will also be discussed. Communication between the radiologist and intensivist, particularly on complicated cases, is important to help increase diagnostic accuracy and leads to an improvement in the management of the most critically ill patients.

Diagnosing Pulmonary Embolism With Computed Tomography Pulmonary Angiography: Diagnostic Accuracy of a Reduced Scan Range

PURPOSE

Computed tomography pulmonary angiography (CT-PA) is frequently used in the diagnostic workup of pulmonary embolism (PE), even in highly radiosensitive patient populations. This study aims to assess CT-PA with reduced z -axis coverage (compared with a standard scan range covering the entire lung) for its sensitivity for detecting PE and its potential to reduce the radiation dose.

MATERIALS AND METHODS

We retrospectively analyzed 602 consecutive CT-PA scans with definite or possible PE reported. A reduced scan range was defined based on the topogram, where the cranial slice was set at the top of the aortic arch and the caudal slice at the top of the lower hemidiaphragm. Locations of emboli in relation to the reduced scan range were recorded.

RESULTS

We included 513 CT-PA scans with definite acute PE in statistical analysis. Patients' median age was 66 (52 to 77) years, 46% were female. Median dose length product was 270.8 (111.3 to 503.9) mGy*cm. Comparing the original and reduced scan ranges, the mean scan length was significantly reduced by 48.0±8.6% (26.8±3.0 vs. 13.9±2.6 cm, P <0.001). Single emboli outside the reduced range in addition to emboli within were found in 15 scans (2.9%), while only 1 scan (0.2%) had an embolus outside the reduced range and none within it. The resulting sensitivity of CT-PA with reduced scan range was 99.81% (95% confidence interval: 98.74%-99.99%) for detecting any PE.

CONCLUSION

A reduced scan length in CT-PA, as defined above, would substantially decrease radiation dose while maintaining diagnostic accuracy for detecting PE.

Evaluation of the appropriate use of chest CT-Scans in the diagnosis of hospitalized patients in shiraz teaching hospitals, Southern Iran

PURPOSE

During recent years, overuse of medical imaging especially computed tomography has become a serious concern. We evaluated the suitable usage of chest computed tomography (CT)-scan, in patients hospitalized in emergency and medical wards of two teaching hospitals of Shiraz University of Medical Science.

METHODS

Medical records of 216 patients admitted in two major teaching hospitals (Namazi and Shahid Faghihi), who had undergone chest radiography and at least one type of chest CT were investigated. The clinical and paraclinical manifestations were independently presented to three pulmonologists and their opinion regarding the necessity and type of CT prescription were documented. Also, the patient's history was presented to an expert chest radiologist and asked to rate the appropriateness of chest CT according to American colleague of radiologist (ACR) criteria.

RESULTS

In 127 cases (59%), at least 2 out of 3 pulmonologists had the same opinion on the necessity of performing CT scan regardless of CT scan type, in 89 cases (41%) the same CT type and in 38 (17.5%) cases other CT type was supposed. Based on ACR criteria, of total prescribed CTs, 49.5% were "usually not appropriate" and 31.5% of cases were "usually appropriate". Among 109 pulmonary CT angiography, 54 (49.5%) was usually not appropriate base on ACR criteria, which was the most frequent inappropriate requested CT type.

CONCLUSION

Considering the high rates of inappropriate utilization of chest CT scan in our teaching hospitals, implementation of the standard guideline at a different level and consulting with a pulmonologist, may prevent unnecessary chest CTs prescription and reduce harm to patients and the health system.

Current use of D-dimer for the exclusion of venous thrombosis in hospitalized patients

D-dimer assay’s utility for excluding venous thromboembolism (VTE) in hospitalized patients is debatable. We aimed to assess the current use of D-dimer as a diagnostic tool for excluding VTE in hospitalized patients and examine a mandatory age-adjusted D-dimer (AADD) threshold for diagnostic imaging. Retrospective cohort study between 2014 to 2019 that included patients from medical and surgical wards with a positive AADD result drawn during their hospitalization. The outcomes were determining a D-dimer threshold requiring further evaluation and assessing the prognostic value of D-dimer in predicting clinically relevant VTE in hospitalized patients. The cohort included 354 patients, 56% of them underwent definitive diagnostic imaging, and 7.6% were diagnosed with VTE after a positive AADD within 90 days of follow-up. Mortality rates were higher in patients diagnosed with VTE (33.3% vs. 15.9%, p = 0.03). Patients with pneumonia and other infectious etiologies were less likely to be further evaluated by definitive imaging (p = 0.001). Patients with a respiratory complaint (p = 0.02), chest pain (p < 0.001), or leg swelling (p = 0.01) were more likely to undergo diagnostic imaging. Patients with D-dimer levels > X2 the AADD were at increased risk of VTE [OR 3.87 (1.45–10.27)]. At 90 days of follow-up, no excess mortality was observed for patients without diagnostic evaluation following elevated AADD. D-dimer may be used in hospitalized patients to exclude VTE using the traditional AADD thresholds, with a high negative predictive value. D-dimer levels > X2 the AADD usually mandates further diagnostic imaging, while lower levels, probably do not require additional workup, with a sensitivity of almost 80% and no excess mortality.

ERS International Congress 2021: highlights from the Pulmonary Vascular Diseases Assembly

This article aims to summarise the latest research presented at the virtual 2021 European Respiratory Society (ERS) International Congress in the field of pulmonary vascular disease. In light of the current guidelines and proceedings, knowledge gaps are addressed and the newest findings of the various forms of pulmonary hypertension as well as key points on pulmonary embolism are discussed.

Despite the comprehensive coverage of the guidelines for pulmonary embolism at previous conferences, discussions about controversies in the diagnosis and treatment of this condition in specific cases were debated and are addressed in the first section of this article.

We then report on an interesting pro–con debate about the current classification of pulmonary hypertension.

We further report on presentations on Group 3 pulmonary hypertension, with research exploring pathogenesis, phenotyping, diagnosis and treatment; important contributions on the diagnosis of post-capillary pulmonary hypertension are also included.

Finally, we summarise the latest evidence presented on pulmonary vascular disease and COVID-19 and a statement on the new imaging guidelines for pulmonary vascular disease from the Fleischner Society.

This article summarises communications from #ERSCongress 2021 on pulmonary embolism diagnosis and treatment, PAH and CTEPH during the COVID-19 pandemic and beyond, novelties in post-capillary PH and in PH associated with respiratory diseaseshttps://bit.ly/3ASDO21

Dual-energy CT in pulmonary vascular disease

Dual-energy CT (DECT) imaging is a technique that extends the capabilities of CT beyond that of established densitometric evaluations. CT pulmonary angiography (CTPA) performed with dual-energy technique benefits from both the availability of low kVp CT data and also the concurrent ability to quantify iodine enhancement in the lung parenchyma. Parenchymal enhancement, presented as pulmonary perfused blood volume maps, may be considered as a surrogate of pulmonary perfusion. These distinct capabilities have led to new opportunities in the evaluation of pulmonary vascular diseases. Dual-energy CTPA offers the potential for improvements in pulmonary emboli detection, diagnostic confidence, and most notably severity stratification. Furthermore, the appreciated insights of pulmonary vascular physiology conferred by DECT have resulted in increased use for the assessment of pulmonary hypertension, with particular utility in the subset of patients with chronic thromboembolic pulmonary hypertension. With the increasing availability of dual energy-capable CT systems, dual energy CTPA is becoming a standard-of-care protocol for CTPA acquisition in acute PE. Furthermore, qualitative and quantitative pulmonary vascular DECT data heralds promise for the technique as a "one-stop shop" for diagnosis and surveillance assessment in patients with pulmonary hypertension. This review explores the current application, clinical value, and limitations of DECT imaging in acute and chronic pulmonary vascular conditions. It should be noted that certain manufacturers and investigators prefer alternative terms, such as spectral or multi-energy CT imaging. In this review, the term dual energy is utilised, although readers can consider these terms synonymous for purposes of the principles explained.

Developing and validating natural language processing algorithms for radiology reports compared to ICD-10 codes for identifying venous thromboembolism in hospitalized medical patients

BACKGROUND

Identifying venous thromboembolism (VTE) from large clinical and administrative databases is important for research and quality improvement.

OBJECTIVE

To develop and validate natural language processing (NLP) algorithms to identify VTE from radiology reports among general internal medicine (GIM) inpatients.

METHODS

This cross-sectional study included GIM hospitalizations between April 1, 2010 and March 31, 2017 at 5 hospitals in Toronto, Ontario, Canada. We developed NLP algorithms to identify pulmonary embolism (PE) and deep venous thrombosis (DVT) from radiologist reports of thoracic computed tomography (CT), extremity compression ultrasound (US), and nuclear ventilation-perfusion (VQ) scans in a training dataset of 1551 hospitalizations. We compared the accuracy of our NLP algorithms, the previously-published "simpleNLP" tool, and administrative discharge diagnosis codes (ICD-10-CA) for PE and DVT to the "gold standard" manual review in a separate random sample of 4000 GIM hospitalizations.

RESULTS

Our NLP algorithms were highly accurate for identifying DVT from US, with sensitivity 0.94, positive predictive value (PPV) 0.90, and Area Under the Receiver-Operating-Characteristic Curve (AUC) 0.96; and in identifying PE from CT, with sensitivity 0.91, PPV 0.89, and AUC 0.96. Administrative diagnosis codes and the simple NLP tool were less accurate for DVT (ICD-10-CA sensitivity 0.63, PPV 0.43, AUC 0.81; simpleNLP sensitivity 0.41, PPV 0.36, AUC 0.66) and PE (ICD-10-CA sensitivity 0.83, PPV 0.70, AUC 0.91; simpleNLP sensitivity 0.89, PPV 0.62, AUC 0.92).

CONCLUSIONS

Administrative diagnosis codes are unreliable in identifying VTE in hospitalized patients. We developed highly accurate NLP algorithms to identify VTE from radiology reports in a multicentre sample and have made the algorithms freely available to the academic community with a user-friendly tool (https://lks-chart.github.io/CHARTextract-docs/08-downloads/rulesets.html#venous-thromboembolism-vte-rulesets).

Challenges in Managing Isolated Subsegmental Pulmonary Embolism

This commentary explores the clinical conundrums arising when caring for patients with acute pulmonary embolism isolated to the subsegmental pulmonary arteries. We discuss ways to confirm the radiologic diagnosis, how to distinguish patients for whom anticoagulation is indicated from those who are eligible for structured surveillance without anticoagulation, what surveillance entails, and why ensuring continuity of care matters. We report a case from our own experience that illustrates these decision-making crossroads and highlights the importance of cross-disciplinary collaboration. Because the evidence in the literature is currently weak and indirect, we draw on expert opinion in US and European guidelines, a recent statement from a multidisciplinary consensus panel, and several ongoing well-designed clinical trials. This discussion will help clinicians better manage the spectrum of patients who present with isolated subsegmental embolism.

Serial use of existing clinical decisions aids can reduce computed tomography pulmonary angiography for pulmonary embolism

Pulmonary embolism (PE) remains a diagnostic challenge in emergency medicine. Clinical decision aids (CDAs) like the Pulmonary Embolism Rule-Out Criteria (PERC) are sensitive but poorly specific; serial CDA use may improve specificity. The goal of this before-and-after study was to determine if serial use of existing CDAs in a novel diagnostic algorithm safely decreases the use of CT pulmonary angiograms (CTPA). This was a retrospective before-and-after study conducted at an urban ED with 105,000 annual visits. Our algorithm uses PERC, Wells' score, and D-dimer in series, before moving to CTPA. The algorithm was introduced in January, 2017. Use of CDAs and D-dimer in the 24 months pre- and 12 months post-intervention were obtained by chart review. The algorithm's effect on CTPA ordering was assessed by comparing volume 5 years pre- and 3 years post-intervention, adjusted for ED volume. Mean CTPAs per 1000 adult ED visits was 11.1 in the 5 pre-intervention years and 9.9 in the 3 post-intervention years (p < 0.0001). Use of PERC, Wells' score and D-dimer increased from 1.1%, 1.1%, and 28% to 8.8% (p = 0.0002) 8.1% (p = 0.0005), and 35% (p = 0.0066), respectively. Pre-intervention, there were six potentially missed PEs compared to three in the post-intervention period. Introduction of our serial CDA diagnostic algorithm was associated with increased use of CDAs and D-dimer and reduced CTPA rate without an apparent increase in the number of missed PEs. Prospective validation is needed to confirm these results.

Radiologic mimics of pulmonary embolism

The diagnosis of pulmonary embolism (PE) is often made more challenging by the presence of diseases that can mimic thromboembolic disease. There is no specific or sensitive constellation of clinical signs or symptoms that can be used to diagnose PE. Ventilation/perfusion scans can have false-positive findings related to mediastinal conditions that can compress the pulmonary arteries, and pulmonary hemorrhage can resemble PE on V/Q scanning with potentially devastating consequences if anticoagulation is started. CT-scan related issues l eading to potential false-positive diagnoses range from inadequate imaging technique, to systemic-pulmonary shunting, to non-thrombotic occlusion of pulmonary arteries by tumor, septic emboli, and emboli of fat, air, and foreign material, as well as vasculitic processes. Careful assessment of the patient and consideration of these potential mimickers is imperative to correct diagnosis of this potentially life-threatening condition.

Derivation and Validation of a 4-Level Clinical Pretest Probability Score for Suspected Pulmonary Embolism to Safely Decrease Imaging Testing

Importance

In patients with suspected pulmonary embolism (PE), overuse of diagnostic imaging is an important point of concern.

Objective

To derive and validate a 4-level pretest probability rule (4-Level Pulmonary Embolism Clinical Probability Score [4PEPS]) that makes it possible to rule out PE solely on clinical criteria and optimized D-dimer measurement to safely decrease imaging testing for suspected PE.

Design, Setting, and Participants

This study included consecutive outpatients suspected of having PE from US and European emergency departments. Individual data from 3 merged management studies (n = 11 114; overall prevalence of PE, 11%) were used for the derivation cohort and internal validation cohort. The external validation cohorts were taken from 2 independent studies, the first with a high PE prevalence (n = 1548; prevalence, 21.5%) and the second with a moderate PE prevalence (n = 1669; prevalence, 11.7%). A prior definition of pretest probability target values to achieve a posttest probability less than 2% was used on the basis of the negative likelihood ratios of D-dimer. Data were collected from January 2003 to April 2016, and data were analyzed from June 2018 to August 2019.

Main Outcomes and Measures

The rate of PE diagnosed during the initial workup or during follow-up and the rate of imaging testing.

Results

Of the 5588 patients in the derivation cohort, 3441 (61.8%) were female, and the mean (SD) age was 52 (18.5) years. The 4PEPS comprises 13 clinical variables scored from -2 to 5. It results in the following strategy: (1) very low probability of PE if 4PEPS is less than 0: PE ruled out without testing; (2) low probability of PE if 4PEPS is 0 to 5: PE ruled out if D-dimer level is less than 1.0 μg/mL; (3) moderate probability of PE if 4PEPS is 6 to 12: PE ruled out if D-dimer level is less than the age-adjusted cutoff value; (4) high probability of PE if 4PEPS is greater than 12: PE ruled out by imaging without preceding D-dimer test. In the first and the second external validation cohorts, the area under the receiver operator characteristic curves were 0.79 (95% CI, 0.76 to 0.82) and 0.78 (95% CI, 0.74 to 0.81), respectively. The false-negative testing rates if the 4PEPS strategy had been applied were 0.71% (95% CI, 0.37 to 1.23) and 0.89% (95% CI, 0.53 to 1.49), respectively. The absolute reductions in imaging testing were -22% (95% CI, -26 to -19) and -19% (95% CI, -22 to -16) in the first and second external validation cohorts, respectively. The 4PEPS strategy compared favorably with all recent strategies in terms of imaging testing.

Conclusions and Relevance

The 4PEPS strategy may lead to a substantial and safe reduction in imaging testing for patients with suspected PE. It should now be tested in a formal outcome study.

Clinical characteristics, management, and outcome of incidental pulmonary embolism in cancer patients

Incidental pulmonary embolisms (IPEs) are common in cancer patients. Examining the characteristics and outcomes of IPEs in cancer patients can help to ensure proper management, promoting better outcomes. To determine the clinical characteristics, management, and outcomes of IPEs for cancer patients, we conducted a 1:2 ratio case-control study and identified all consecutive patients with IPE who visited the emergency department at The University of Texas MD Anderson Cancer Center between 1 January 2006 and 1 January 2016. Each IPE case was matched with 2 controls using a propensity score obtained using logistic regression for IPE status with other factors affecting overall survival. A total of 904 confirmed cases were included in the analysis. IPE frequently occurred during the first year after cancer diagnosis (odds ratio [OR], 2.79; 95% confidence interval [95% CI], 2.37-3.29; P < .001). Patients receiving cytotoxic chemotherapy had a nearly threefold greater risk of developing IPE (OR, 2.87; 95% CI, 2.42-3.40; P < .001). In-hospital mortality was 1.9%. The 7- and 30-day mortality rates among the cases were 1.8% and 9.9%, respectively, which was significantly higher than in the control groups: 0.2% and 3.1%, respectively (P < .001). IPE was associated with reduced overall survival (hazard ratio [HR], 1.93; 95% CI, 1.74-2.14; P < .001). Concurrent incidental venous thromboembolism was identified in 189 of the patients (20.9%) and was also associated with reduced overall survival (HR, 1.65; 95% CI, 1.21-2.25; P = .001). Our results show that IPE events are associated with poor outcomes in cancer patients. Proper management plans similar to those of symptomatic pulmonary embolisms are essential.

Canadian Society of Thoracic Radiology/Canadian Association of Radiologists Best Practice Guidance for Investigation of Acute Pulmonary Embolism, Part 2: Technical Issues and Interpretation Pitfalls

The investigation of acute pulmonary embolism is a common task for radiologists in Canada. Technical image quality and reporting quality must be excellent; pulmonary embolism is a life-threatening disease that should not be missed but overdiagnosis and unnecessary treatment should be avoided. The most frequently performed imaging investigation, computed tomography pulmonary angiogram (CTPA), can be limited by poor pulmonary arterial opacification, technical artifacts and interpretative errors. Image quality can be affected by patient factors (such as body habitus, motion artifact and cardiac output), intravenous (IV) contrast protocols (including the timing, rate and volume of IV contrast administration) and common physics artifacts (including beam hardening). Mimics of acute pulmonary embolism can be seen in normal anatomic structures, disease in non-vascular structures and pulmonary artery filling defects not related to acute pulmonary emboli. Understanding these pitfalls can help mitigate error, improve diagnostic quality and optimize patient outcomes. Dual energy computed tomography holds promise to improve imaging diagnosis, particularly in clinical scenarios where routine CTPA may be problematic, including patients with impaired renal function and patients with altered cardiac anatomy.

A critical analysis of 57 cases of Hughes-Stovin syndrome (HSS). A report by the HSS International Study Group (HSSISG)

BACKGROUND

Hughes-Stovin syndrome (HSS) is a systemic disease characterized by widespread vascular thrombosis and pulmonary vasculitis with serious morbidity and mortality. The HSS International Study Group is a multidisciplinary taskforce aiming to study HSS, in order to generate consensus recommendations regarding diagnosis and treatment.

METHODS

We included 57 published cases of HSS (43 males) and collected data regarding: clinical presentation, associated complications, hemoptysis severity, laboratory and computed tomography pulmonary angiography (CTPA) findings, treatment modalities and cause of death.

RESULTS

At initial presentation, DVT was observed in 29(33.3 %), thrombophlebitis in 3(5.3%), hemoptysis in 24(42.1%), and diplopia and seizures in 1 patient each. During the course of disease, DVT occurred in 48(84.2%) patients, and superficial thrombophlebitis was observed in 29(50.9%). Hemoptysis occurred in 53(93.0%) patients and was fatal in 12(21.1%). Pulmonary artery (PA) aneurysms (PAAs) were bilateral in 53(93%) patients. PAA were located within the main PA in 11(19.3%), lobar in 50(87.7%), interlobar in 13(22.8%) and segmental in 42(73.7%). Fatal outcomes were more common in patients with inferior vena cava thrombosis (p = 0.039) and ruptured PAAs (p < 0.001). Death was less common in patients treated with corticosteroids (p < 0.001), cyclophosphamide (p < 0.008), azathioprine (p < 0.008), combined immune modulators (p < 0.001). No patients had uveitis; 6(10.5%) had genital ulcers and 11(19.3%) had oral ulcers.

CONCLUSIONS

HSS may lead to serious morbidity and mortality if left untreated. PAAs, adherent in-situ thrombosis and aneurysmal wall enhancement are characteristic CTPA signs of HSS pulmonary vasculitis. Combined immune modulators contribute to favorable outcomes.

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.

The Positive Rate of Pulmonary Embolism by CT Pulmonary Angiography Is High in an Emergency Department, Even in Low-Risk or Young Patients

OBJECTIVE

The clinical presentation of pulmonary embolism (PE) can be various and misleading. We analyzed patients with suspicion of PE and subsequently performed computed tomography pulmonary angiography (CTPA) in an emergency department of Internal Medicine, focusing on patient groups in which PE might be underestimated in the emergency setting, such as young patients and patients with low clinical probability.

MATERIAL AND METHODS

In 2016 and 2017, all patients receiving a CTPA for investigation of PE were retrospectively evaluated for clinical parameters (age, symptoms, and vital parameters) and D-dimers. The Wells score was calculated.

RESULTS

CTPA was performed in 323 patients (158 female and 165 male; mean age 62 years). The leading symptoms for admission were dyspnea or chest pain; 62% showed intermediate or high risk for PE, calculated by applying the Wells score. In 123 (38%) of all patients, a PE was proved and pathologic age-adjusted D-dimers were found in 97.6%. Thirty of 121 (25%) patients with low risk according to Wells score had a PE. Deep vein thrombosis was verified in 67/123 (55%) patients; 43% (15/35) of all suspicions for PE in patients <40 years were positive with 4/15 (26%), showing a central PE. Younger patients (<40 years) with PE presented more often with tachycardia or tachypnea and chest pain or dyspnea than elderly patients with PE.

CONCLUSION

CTPA frequently proves a PE in patients with suspicion of PE in an emergency department of Internal Medicine. If PE is suspected and CTPA performed accordingly, the presence of PE is quite common even in low-risk patient groups (Wells score) or in young patients <40 years with chest pain or dyspnea.

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.

Exhaled breath condensate in acute pulmonary embolism; a porcine study of effect of condensing temperature and feasibility of protein analysis by mass spectrometry

INTRODUCTION

The search for diagnostic biomarkers for pulmonary embolism (PE) has mainly been focused on blood samples. Exhaled breath condensate (EBC) is a possible source for biomarkers specific for chronic lung diseases and cancer, yet no previous studies have investigated the potential of EBC for diagnosis of PE. The protein content in the EBC is very low, and efficient condensing of the EBC is important in order to obtain high quality samples for protein analysis. We investigated if advanced proteomic techniques in a porcine model of acute intermediate-high-risk PE was feasible using two different condensing temperatures for EBC collection.

METHODS

Seven pigs were anaesthetized and intubated. EBC was collected one hour after intubation. Two autologous emboli were induced through the right external jugular vein. Two hours after the emboli were administered, EBC was collected again. Condensing temperature was either -21 °C or -80 °C. Nano liquid chromatography - tandem mass spectrometry (nLC-MS/MS) was used to identify and quantify proteins of the EBC.

RESULTS

A condensing temperature of - 80 °C significantly increased the EBC volume compared with -21 °C (1.78±0.25 ml vs 0.71±0.12 ml) while the protein concentration in the EBC was unaltered. The mean protein concentration in the EBCs was 5.85±0.93 µg/ml, unaltered after PE. In total, 254 proteins were identified in the EBCs. Identified proteins included proteins of the cytoplasm, nucleus, plasma membrane and extracellular region. The protein composition did not differ according to condensing temperature.

CONCLUSION

The EBC from pigs with acute intermediate-high-risk PE contained sufficient amounts of protein for analysis by nLC-MS/MS. The proteins were from relevant cellular compartments, indicating that EBC is a possible source for biomarkers for acute PE.

Challenging anticoagulation cases: A case of incidental subsegmental pulmonary embolism in a patient with cancer

Cancer therapy and progress in quality of imaging technologies for cancer surveillance and staging are in cause for the increase incidence of smaller incidental pulmonary embolism (PE). The clinical significance of incidental subsegmental pulmonary embolism (SSPE) is hard to define, balancing between possible false positive result, hypercoagulability signal, and truly venous thromboembolism (VTE) event. Evidence for optimal management of such findings are largely extrapolated from symptomatic SSPE in non-cancer patients and from symptomatic, more proximal PE in cancer patients. Current practice guidelines vary but some suggest withholding anticoagulation in selected patients. However, most SSPEs, incidental or not, should be treated as any other cancer-associated PE due to likely similar prognosis. Choice and duration of anticoagulation are extended from existing knowledge on more proximal PE.

Improving Contrast Enhancement in Pulmonary CTA: The value of breathing maneuvers

Purpose

To investigate contrast dynamics and artifacts associated with different breathing maneuvers during pulmonary computed tomography angiography (pCTA) in a prospective randomized clinical trial.

Method

Three different breathing maneuvers (inspiration, expiration, Mueller) were randomly assigned to 146 patients receiving pCTA for suspected pulmonary embolism (PE). Contrast enhancement of central and peripheral arteries and imaging quality of lung parenchyma were compared and analyzed. Results were compared by using the analysis of variances (ANOVA) and Kruskal-Wallis-Test.

Results

Mean enhancement in the pulmonary trunk was highest during breath-hold in inspiration (293 HU, range 195-460 HU) compared to Mueller (259 HU, range 136-429 HU, p = 0022) and expiration (267 HU, range 115-376 HU). This was similar for the right pulmonary artery (inspiration 289 HU, range 173-454 HU; Mueller 250 HU, range 119-378 HU; p = 0.007; expiration 257 HU, range 114-366 HU; p = 0.032) and left pulmonary artery (inspiration 280.3 HU, range 170-462 HU; Mueller 245 HU, range 111-371 HU; p = 0.016; expiration 252 HU, range 110-371 HU).Delineation of peripheral arteries was significantly better in inspiration vs Mueller (p = 0.006) and expiration (p = 0.049). Assessment of the lung parenchyma was significantly better in inspiration vs Mueller (p = 0.013) or expiration (p < 0.001).

Conclusions

Resting inspiratory position achieved the highest enhancement levels in central and peripheral pulmonary arteries and best image quality of the pulmonary parenchyma in comparison to other breathing maneuvers. It is necessary to train the maneuver prior to the examination in order to avoid deep inspiration with the risk of suboptimal opacification of the pulmonary arteries.

Clinical and imaging profiles of pulmonary embolism: a single-institution experience

BACKGROUND

Pulmonary embolism (PE) is a common life-threatening condition with non-specific clinical presentations. The diagnosis of PE depends highly on imaging studies, which may also provide prognostic information. This study aimed to describe the clinical and imaging profiles of patients with PE, emphasizing the differences between central and peripheral PE.

METHODS

After ethics review board approval, this retrospective observational study examined the non-negative results in adult patients who underwent computed tomography pulmonary angiography (CT-PA) at our hospital between May 2016 and December 2019. Demographic and clinical information and imaging findings were collected from the electronic medical records.

RESULTS

The study included 85 cases that were identified after re-interpreting the 103 non-negative CT-PA scans. Six cases were excluded for incomplete data and 12 cases were false-positive. Central PE was found in 63.5% of the cases. Obesity was the most common risk factor seen in 37.6% of the cases. Furthermore, 9.4% of the patients had sickle cell disease, which tended to be associated with peripheral PE. There was no difference between the peripheral and central PE in most clinical and imaging parameters evaluated (P > 0.05). However, patients with isolated subsegmental PE were more likely to develop hemoptysis (P = 0.04).

CONCLUSION

This study suggests that patients with obesity and sickle cell disease constitute an important proportion of all PE cases. Furthermore, the clinical and imaging profiles in patients with peripheral PE are similar to those in patients with central PE. Future research should focus on the clinical value of peripheral PE in patients with sickle cell disease.

Diagnostic Performance of Pulmonary Embolism Imaging in Patients with History of Asthma

Asthma and pulmonary embolism (PE) can present with overlapping symptoms, and distinguishing between these 2 conditions can be challenging. Asthma may limit imaging for PE because of either worsened ventilation defects on ventilation-perfusion scanning (VQ) or increased motion artifacts on CT pulmonary angiography (CTPA). Methods: We identified adults evaluated for PE with VQ or CTPA from 2012 to 2016. Patients with chronic lung disease (other than asthma) were excluded. Studies were classified as negative, positive, or nondiagnostic. Follow-up of negative cases was reviewed to determine the rate of repeat exams (within 1 wk) and the false-negative rate (defined as diagnosis of venous thromboembolism within 90 d). Results: We reviewed 19,412 adults (aged 52 ± 18 y, 70% women) evaluated for PE (60% with VQ, 40% with CTPA); 23% had a history of asthma. Nondiagnostic results were comparable for those with and without asthma for both VQ (asthma, 3.3%; nonasthma, 3.8%; P = 0.223) and CTPA (asthma, 1.6%; nonasthma, 1.5%; P = 0.891). A history of asthma was not associated with a higher rate of repeat exams after negative imaging for VQ (asthma, 1.9%; nonasthma, 2.1%; P = 0.547) or CTPA (asthma, 0.6%; nonasthma, 0.6%; P = 0.796), nor was a history of asthma associated with a higher false-negative rate for VQ (asthma, 0.4%; nonasthma, 0.9%; P = 0.015) or CTPA (asthma, 1.9%; nonasthma 1.5%; P = 0.347). Conclusion: A history of asthma in the preceding 10 y was not associated with impaired diagnostic performance of PE imaging for either VQ or CTPA.