Diagnosis and management of subsegmental pulmonary embolism

Diagnosis of acute pulmonary embolism: when photon-counting-detector CT replaces energy-integrating-detector CT in daily routine

PURPOSE

To compare the diagnostic approach of acute pulmonary embolism (PE) with photon-counting-detector CT (PCD-CT) and energy-integrating-detector CT (EID-CT).

MATERIALS AND METHODS

Two cohorts underwent CT angiographic examinations with EID-CT (Group 1; n = 158) and PCD-CT (Group 2; n = 172), (b) with two options in Group 1, dual energy (Group 1a) or single energy (Group 1b) and a single option in Group 2 (spectral imaging with single source).

RESULTS

In Group 2, all patients benefited from spectral imaging, only accessible to 105 patients (66.5%) in Group 1, with a mean acquisition time significantly shorter (0.9 ± 0.1 s vs 4.0 ± 0 .3 s; p < 0.001) and mean values of CTDIvol and DLP reduced by 46.3% and 47.7%, respectively. Comparing the quality of 70 keV (Group 2) and averaged (Group 1a) images: (a) the mean attenuation within pulmonary arteries did not differ (p = 0.13); (b) the image noise was significantly higher (p < 0.001) in Group 2 with no difference in subjective image noise (p = 0.29); and (c) 89% of examinations were devoid of artifacts in Group 2 vs 28.6% in Group 1a. The percentage of diagnostic examinations was 95.2% (100/105; Group 1a), 100% (53/53; Group 1b), and 95.3% (164/172; Group 2). There were 4.8% (5/105; Group 1a) and 4.7% (8/172; Group 2) of non-diagnostic examinations, mainly due to the suboptimal quality of vascular opacification with the restoration of a diagnostic image quality on low-energy images.

CONCLUSION

Compared to EID-CT, morphology and perfusion imaging were available in all patients scanned with PCD-CT, with the radiation dose reduced by 48%.

CLINICAL RELEVANCE STATEMENT

PCD-CT enables scanning patients with the advantages of both spectral imaging, including high-quality morphologic imaging and lung perfusion for all patients, and fast scanning-a combination that is not simultaneously accessible with EID-CT while reducing the radiation dose by almost 50%.

An overview of systematic reviews on imaging tests for diagnosis of pulmonary embolism applying different network meta-analytic methods

PURPOSE

This study aimed to apply different methods of diagnostic test accuracy network meta-analysis (DTA-NMA) for studies reporting results of five imaging tests for the diagnosis of suspected pulmonary embolism (PE): pulmonary angiography (PA), computed tomography angiography (CTPA), magnetic resonance angiography (MRA), planar ventilation/perfusion (V/Q) scintigraphy and single-photon emission computed tomography ventilation/perfusion (SPECT V/Q).

METHODS

We searched four databases (MEDLINE [via PubMed], Cochrane CENTRAL, Scopus, and Epistemonikos) from inception until June 2, 2022 to identify systematic reviews (SRs) describing diagnostic accuracy of PA, CTPA, MRA, V/Q scan and SPECT V/Q for suspected PE. Study-level data were extracted and pooled using a hierarchical summary receiver operating characteristic (HSROC) meta-regression approach and two DTA-NMA models to compare accuracy estimates of different imaging tests. Risk of bias was assessed using the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies-2) tool and certainty of evidence using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) framework.

RESULTS

We identified 13 SRs, synthesizing data from 33 primary studies and for four imaging tests (PA, CTPA, MRA and V/Q scan). The HSROC meta-regression model using PA as the reference standard showed that MRA had the best overall diagnostic performance with sensitivity of 0.93 (95% confidence interval [CI]: 0.76, 1.00) and specificity of 0.94 (95% CI: 0.84, 0.99). However, DTA-NMA models indicated that V/Q scan had the highest sensitivity, while CTPA was most specific.

CONCLUSION

Selecting a different DTA-NMA method to assess multiple diagnostic tests can affect estimates of diagnostic accuracy. There is no established method, but the choice depends on the data and familiarity with Bayesian statistics.

The value of distinguishing patients with isolated subsegmental pulmonary embolism presenting to two tertiary hospitals in Australia: an observational study

Isolated-subsegmental-pulmonary-embolism (SSPE) is increasingly diagnosed with the use of computed-tomography-pulmonary-angiogram (CTPA). There remains clinical equipoise for management of SSPE with previous studies not accounting for frailty while determining clinical outcomes. Clinical outcomes among patients with isolated SSPE were compared with those with a more proximal PE after accounting for frailty and other risk-factors. This study included all patients with a positive CTPA for pulmonary embolism (PE) admitted between 2017 and 2021 to two Australian-tertiary-hospitals. Frailty was determined by use of the hospital-frailty-risk-score (HFRS). Competing-risk-analysis and Cox-proportional hazard models determined the cumulative-risk of VTE and mortality within 3 months and 1 year of index PE event after adjustment for frailty and other variables. Of 334 patients with positive CTPA for PE, 111 (33.2%) had isolated-SSPE. The mean (SD) age was 64.3 (17.7) years, 50.9% were males and 9.6% were frail. The risk of recurrent VTE within 3-months (0.9% vs. 1.8%, P = 0.458) and within 1-year of follow-up (2.7% vs. 6.3%, P = 0.126) did not differ significantly between patients with isolated SSPE and those with more proximal PE. After adjusted analyses, the cumulative-incidence of recurrent VTE was not different among patients with isolated SSPE within 1 year of index event [subdistribution-hazard-ratio (HR) 0.84, 95% CI 0.19 to 3.60]. Similarly, mortality within 1 year of index event was also not different between the two groups (aHR 1.72, 95% CI 0.92-3.23). The prevalence of SSPE was 33.2% and even after adjustment for frailty these patients had no different clinical outcomes than those with proximal PE.

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.

Novel Approaches to Imaging the Pulmonary Vasculature and Right Heart

There is an increased appreciation for the importance of the right heart and pulmonary circulation in several disease states across the spectrum of pulmonary hypertension and left heart failure. However, assessment of the structure and function of the right heart and pulmonary circulation can be challenging, due to the complex geometry of the right ventricle, comorbid pulmonary airways and parenchymal disease, and the overlap of hemodynamic abnormalities with left heart failure. Several new and evolving imaging modalities interrogate the right heart and pulmonary circulation with greater diagnostic precision. Echocardiographic approaches such as speckle-tracking and 3-dimensional imaging provide detailed assessments of regional systolic and diastolic function and volumetric assessments. Magnetic resonance approaches can provide high-resolution views of cardiac structure/function, tissue characterization, and perfusion through the pulmonary vasculature. Molecular imaging with positron emission tomography allows an assessment of specific pathobiologically relevant targets in the right heart and pulmonary circulation. Machine learning analysis of high-resolution computed tomographic lung scans permits quantitative morphometry of the lung circulation without intravenous contrast. Inhaled magnetic resonance imaging probes, such as hyperpolarized 129Xe magnetic resonance imaging, report on pulmonary gas exchange and pulmonary capillary hemodynamics. These approaches provide important information on right ventricular structure and function along with perfusion through the pulmonary circulation. At this time, the majority of these developing technologies have yet to be clinically validated, with few studies demonstrating the utility of these imaging biomarkers for diagnosis or monitoring disease. These technologies hold promise for earlier diagnosis and noninvasive monitoring of right heart failure and pulmonary hypertension that will aid in preclinical studies, enhance patient selection and provide surrogate end points in clinical trials, and ultimately improve bedside care.

Risk for Recurrent Venous Thromboembolism in Patients With Subsegmental Pulmonary Embolism Managed Without Anticoagulation : A Multicenter Prospective Cohort Study

BACKGROUND

The incidence of pulmonary embolism has been increasing, but its case-fatality rate is decreasing, suggesting a lesser severity of illness. The clinical importance of patients with pulmonary embolism isolated to the subsegmental vessels is unknown.

OBJECTIVE

To determine the rate of recurrent venous thromboembolism in patients with subsegmental pulmonary embolism managed without anticoagulation.

DESIGN

Multicenter prospective cohort study. (ClinicalTrials.gov: NCT01455818).

SETTING

Eighteen sites between February 2011 and February 2021.

PATIENTS

Patients with isolated subsegmental pulmonary embolism.

INTERVENTION

At diagnosis, patients underwent bilateral lower-extremity venous ultrasonography, which was repeated 1 week later if results were negative. Patients without deep venous thrombosis did not receive anticoagulant therapy.

MEASUREMENTS

The primary outcome was recurrent venous thromboembolism during the 90-day follow-up period.

RESULTS

Recruitment was stopped prematurely because the predefined stopping rule was met after 292 of a projected 300 patients were enrolled. Of the 266 patients included in the primary analysis, the primary outcome occurred in 8 patients, for a cumulative incidence of 3.1% (95% CI, 1.6% to 6.1%) over the 90-day follow-up. The incidence of recurrent venous thromboembolism was 2.1% (CI, 0.8% to 5.5%) and 5.7% (CI, 2.2% to 14.4%) over the 90-day follow-up in patients with single and multiple isolated subsegmental pulmonary embolism, respectively. No patients had a fatal recurrent pulmonary embolism.

LIMITATION

The study was restricted to patients with low-risk subsegmental pulmonary embolism.

CONCLUSION

Overall, patients with subsegmental pulmonary embolism who did not have proximal deep venous thrombosis had a higher-than-expected rate of recurrent venous thromboembolism.

PRIMARY FUNDING SOURCE

Heart and Stroke Foundation of Canada and French Ministry of Health Programme Hospitalier de Recherche Clinique.

CT pulmonary angiography appropriateness in a single emergency department: does the use of revised Geneva score matter?

PURPOSE

To assess the percentage of computed tomography pulmonary angiography (CTPA) procedures that could have been avoided by methodical application of the Revised Geneva Score (RGS) coupled with age-adjusted D-dimer cut-offs rather than only clinical judgment in Emergency Department patients with suspected pulmonary embolism (PE).

MATERIAL AND METHODS

Between November 2019 and May 2020, 437 patients with suspected PE based on symptoms and D-dimer test were included in this study. All patients underwent to CTPA. For each patient, we retrospectively calculated the age-adjusted D-dimer cut-offs and the RGS in the original version. Finally, CT images were retrospectively reviewed, and the presence of PE was recorded.

RESULTS

In total, 43 (9.84%) CTPA could have been avoided by use of RGS coupled with age-adjusted D-dimer cut-offs. Prevalence of PE was 14.87%. From the analysis of 43 inappropriate CTPA, 24 (55.81%) of patients did not show any thoracic signs, two (4.65%) of patients had PE, and the remaining patients had alternative thoracic findings.

CONCLUSION

The study showed good prevalence of PE diagnoses in our department using only physician assessment, although 9.84% CTPA could have been avoided by methodical application of RGS coupled with age-adjusted D-dimer cut-offs.

Frequency of computed tomography abnormalities in patients with chronic thromboembolic pulmonary hypertension: a comparative study between lung perfusion scan and computed tomography pulmonary angiography

Introduction

Chronic thromboembolic pulmonary hypertension (CTEPH) is one of the leading causes of pulmonary hypertension. Diagnosis of CTEPH can be established using various imaging techniques, including ventilation-perfusion scintigraphy (VQ) and multidetector computed tomography pulmonary angiography (CTPA). The aim of this study was to determine the frequency of direct pulmonary vascular, parenchymal lung, and cardiac abnormalities on CTPA in patients with CTEPH and to compare the diagnostic accuracy of both VQ scan CTPA in detecting CTEPH.

Methods

We retrospectively included 54 patients who had been referred for pulmonary hypertension service (20 males, 34 females). All patients had VQ scan and CTPA within 15 days and underwent pulmonary artery endarterectomy (PEA) thereafter. VQ scans were reported according to modified PIOPED (Prospective Investigation of Pulmonary Embolism Diagnosis) criteria. CTPA was considered as diagnostic for CTEPH if it showed presence of thrombus, webs, stenosis, or perfusion lung abnormalities.

Results

The mean age of the study population was 41±10 years. The mean pulmonary artery pressure was 53±13 mmHg. Fifty-three out of 54 patients in the study population had high probability VQ scan and one patient had intermediate probability. CTPA was suggestive of CTEPH in all patients. The most frequent CTPA findings in the central pulmonary arteries and peripheral arteries were presence of thrombotic materials, abnormal vessel tapering and abrupt vessels-cut off (76% vs 65%, 67% vs 48%, and 48% vs 22%), respectively. The mosaic lung perfusion was present in 78% of the patients, and various cardiac morphology abnormalities were present and most common was abnormal right to left ventricle ratio (69%).

Conclusion

Our findings indicate that both VQ scan and CTPA are highly sensitive for the detection of CTEPH confirmed by PEA. Most CTEPH patients had several pulmonary vascular, parenchymal lung and cardiac abnormalities. There was no sign with 100% sensitivity on CTPA for CTEPH detection.

Variabilities in Reference Standard by Radiologists and Performance Assessment in Detection of Pulmonary Embolism in CT Pulmonary Angiography

Annotating lesion locations by radiologists' manual marking is a key step to provide reference standard for the training and testing of a computer-aided detection system by supervised machine learning. Inter-reader variability is not uncommon in readings even by expert radiologists. This study evaluated the variability of the radiologist-identified pulmonary emboli (PEs) to demonstrate the importance of improving the reliability of the reference standard by a multi-step process for performance evaluation. In an initial reading of 40 CTPA PE cases, two experienced thoracic radiologists independently marked the PE locations. For markings from the two radiologists that did not agree, each radiologist re-read the cases independently to assess the discordant markings. Finally, for markings that still disagreed after the second reading, the two radiologists read together to reach a consensus. The variability of radiologists was evaluated by analyzing the agreement between two radiologists. For the 40 cases, 475 and 514 PEs were identified by radiologists R1 and R2 in the initial independent readings, respectively. For a total of 545 marks by the two radiologists, 81.5% (444/545) of the marks agreed but 101 marks in 36 cases differed. After consensus, 65 (64.4%) and 36 (35.6%) of the 101 marks were determined to be true PEs and false positives (FPs), respectively. Of these, 48 and 17 were false negatives (FNs) and 14 and 22 were FPs by R1 and R2, respectively. Our study demonstrated that there is substantial variability in reference standards provided by radiologists, which impacts the performance assessment of a lesion detection system. Combination of multiple radiologists' readings and consensus is needed to improve the reliability of a reference standard.

American Society of Hematology 2021 guidelines for management of venous thromboembolism: prevention and treatment in patients with cancer

BACKGROUND

Venous thromboembolism (VTE) is a common complication among patients with cancer. Patients with cancer and VTE are at a markedly increased risk for morbidity and mortality.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in their decisions about the prevention and treatment of VTE in patients with cancer.

METHODS

ASH formed a multidisciplinary guideline panel balanced to minimize potential bias from conflicts of interest. The guideline development process was supported by updated or new systematic evidence reviews. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess evidence and make recommendations.

RESULTS

Recommendations address mechanical and pharmacological prophylaxis in hospitalized medical patients with cancer, those undergoing a surgical procedure, and ambulatory patients receiving cancer chemotherapy. The recommendations also address the use of anticoagulation for the initial, short-term, and long-term treatment of VTE in patients with cancer.

CONCLUSIONS

Strong recommendations include not using thromboprophylaxis in ambulatory patients receiving cancer chemotherapy at low risk of VTE and to use low-molecular-weight heparin (LMWH) for initial treatment of VTE in patients with cancer. Conditional recommendations include using thromboprophylaxis in hospitalized medical patients with cancer, LMWH or fondaparinux for surgical patients with cancer, LMWH or direct oral anticoagulants (DOAC) in ambulatory patients with cancer receiving systemic therapy at high risk of VTE and LMWH or DOAC for initial treatment of VTE, DOAC for the short-term treatment of VTE, and LMWH or DOAC for the long-term treatment of VTE in patients with cancer.

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.

Clinical Surveillance vs. Anticoagulation For low-risk patiEnts with isolated SubSegmental Pulmonary Embolism: protocol for a multicentre randomised placebo-controlled non-inferiority trial (SAFE-SSPE)

INTRODUCTION

The clinical significance of subsegmental pulmonary embolism (SSPE) is currently unclear. Although growing evidence from observational studies suggests that withholding anticoagulant treatment may be a safe option in selected patients with isolated SSPE, most patients with this condition receive anticoagulant treatment, which is associated with a 90-day risk of recurrent venous thromboembolism (VTE) of 0.8% and major bleeding of up to 5%. Given the ongoing controversy concerning the risk-benefit ratio of anticoagulation for isolated SSPE and the lack of evidence from randomised-controlled studies, the aim of this clinical trial is to evaluate the efficacy and safety of clinical surveillance without anticoagulation in low-risk patients with isolated SSPE.

METHODS AND ANALYSIS

SAFE-SSPE (Surveillance vs. Anticoagulation For low-risk patiEnts with isolated SubSegmental Pulmonary Embolism, a multicentre randomised placebo-controlled non-inferiority trial) is an international, multicentre, placebo-controlled, double-blind, parallel-group non-inferiority trial conducted in Switzerland, the Netherlands and Canada. Low-risk patients with isolated SSPE are randomised to receive clinical surveillance with either placebo (no anticoagulation) or anticoagulant treatment with rivaroxaban. All patients undergo bilateral whole-leg compression ultrasonography to exclude concomitant deep vein thrombosis before enrolment. Patients are followed for 90 days. The primary outcome is symptomatic recurrent VTE (efficacy). The secondary outcomes include clinically significant bleeding and all-cause mortality (safety). The ancillary outcomes are health-related quality of life, functional status and medical resource utilisation.

ETHICS AND DISSEMINATION

The local ethics committees in Switzerland have approved this protocol. Submission to the Ethical Committees in the Netherlands and Canada is underway. The results of this trial will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT04263038.

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.

Adverse Events and Mortality in Anticoagulated Patients with Different Categories of Pulmonary Embolism

Objective

To determine whether the pulmonary embolism (PE) categories of massive, submassive, PE with no right ventricle dysfunction (NRVD), and subsegmental only (SSO) adequately predict clinical outcome.

Methods

Patients treated for acute PE (March 1, 2013, through July 31, 2019) were followed forward prospectively to compare venous thromboembolism (VTE) recurrence, all-cause mortality, major bleeding, and clinically relevant nonmajor bleeding (CRNMB) across 4 PE categories.

Results

Of 2703 patients with VTE, 1188 (44%) had PE, of which 1021 (85.9%) completed at least 3 months of therapy or had clinical outcomes precluding further treatment (27 with massive, 217 submassive, 557 NRVD, and 220 SSO PE). One patient with massive, 8 with submassive, 23 with NRVD, and 5 with SSO PE had recurrent VTE (3.90, 5.33, 5.36, and 3.66 per 100 person-years, respectively; P=.84). There were 3 deaths in massive, 27 in submassive, 140 in NRVD, and 34 in SSO PE groups (11.59, 17.37, 31.74, and 24.74 per 100 person-years, respectively; P=.02); when adjusted for cancer, the relationship was no longer significant (P=.27). One patient with massive, 5 with submassive, 22 with NRVD, and 5 with SSO PE had major bleeding (3.90, 3.31, 5.24, and 3.75 per 100 person-years, respectively; P=.66). Similar cumulative rates for CRNMB were observed (P=.87). Three-month rates of VTE recurrence, death, major bleeding, and CRNMB did not differ by PE category.

Conclusion

In the setting of anticoagulation therapy with maximal standardization and evidence-based practice, there is no evidence of a difference between PE categories and outcomes.

Trial Registration

clinicaltrials.gov Identifier: NCT03504007.

Anticoagulant treatment for subsegmental pulmonary embolism

BACKGROUND

Acute pulmonary embolism (PE) is a common cause of death, accounting for 50,000 to 200,000 deaths annually. It is the third most common cause of mortality among the cardiovascular diseases, after coronary artery disease and stroke. The advent of multi-detector computed tomographic pulmonary angiography (CTPA) has allowed better assessment of PE regarding visualisation of the peripheral pulmonary arteries, increasing its rate of diagnosis. More cases of peripheral PEs, such as isolated subsegmental PE (SSPE) and incidental PE, have thereby been identified. These two conditions are usually found in patients with few or none of the classic PE symptoms such as haemoptysis or pleuritic pain, acute dyspnoea or circulatory collapse. However, in patients with reduced cardiopulmonary reserve, classic PE symptoms can be found with isolated SSPEs. Incidental SSPE is found casually in asymptomatic patients, usually by diagnostic imaging performed for other reasons (for example routine CT for cancer staging in oncology patients). Traditionally, all PEs are anticoagulated in a similar manner independent of their location, or number and size of the thrombi. It has been suggested that many patients with SSPE may be treated without benefit, increasing adverse events by a possible unnecessary use of anticoagulants. Patients with isolated SSPE, or incidental PE, may have a more benign clinical presentation compared to those with proximal PEs. However, the clinical significance in patients, and their prognosis, needs to be studied to evaluate whether anticoagulation therapy is required. This is the second update of the Cochrane systematic review published in 2014.

OBJECTIVES

To assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and AMED databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 26 November 2019. We also undertook reference checking to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials of anticoagulation therapy versus control in patients with SSPE or incidental SSPE.

DATA COLLECTION AND ANALYSIS

Two review authors inspected all citations identified to ensure reliable assessment. If relevant studies were identified, we planned for two review authors to independently extract data and to assess the methodological quality of identified trials using the criteria recommended in the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We did not identify any studies that met the inclusion criteria.

AUTHORS' CONCLUSIONS

There is no evidence from randomised controlled trials to assess the effectiveness and safety of anticoagulation therapy versus control in patients with isolated subsegmental pulmonary embolism (SSPE) or incidental SSPE. Well-conducted research is required before informed practice decisions can be made.

Comparison of acquisition protocols for ventilation/perfusion SPECT-a Monte Carlo study

One of the most commonly used imaging techniques for diagnosing pulmonary embolism (PE) is ventilation/perfusion (V/P) scintigraphy. The aim of this study was to evaluate the performance of the currently used imaging protocols for V/P single photon emission computed tomography (V/P SPECT) at two nuclear medicine department sites and to investigate the effect of altering important protocol parameters. The Monte Carlo technique was used to simulate 4D digital phantoms with perfusion defects. Six imaging protocols were included in the study and a total of 72 digital patients were simulated. Six dually trained radiologists/nuclear medicine physicians reviewed the images and reported all perfusion mismatch findings. The radiologists also visually graded the image quality. No statistically significant differences in diagnostic performance were found between the studied protocols, but visual grading analysis pointed out one protocol as significantly superior to four of the other protocols. Considering the study results, we have decided to harmonize our clinical protocols for imaging patients with suspected PE. The administered Technegas and macro aggregated albumin activities have been altered, a low energy all purpose collimator is used instead of a low energy high resolution collimator and the acquisition times have been lowered.

Clinical presentation and outcomes in elderly patients with symptomatic isolated subsegmental pulmonary embolism

OBJECTIVES

Data are limited on clinical presentation and outcomes in elderly patients with acute symptomatic isolated subsegmental pulmonary embolism (SSPE). We compared clinical presentation, risk factors, processes of care, and outcomes between elderly patients with SSPE and patients with more proximal pulmonary embolism (PE).

METHODS

We prospectively followed 578 patients aged ≥65 years with acute symptomatic isolated SSPE or proximal PE in a multicentre Swiss cohort study. We compared quality of life at three months using the PEmb-QoL, and examined the independent association between localization of PE and clinical outcomes (recurrent venous thromboembolism [VTE], overall mortality) using regression models with adjustment for potential confounders.

RESULTS

Overall, 11% of patients had isolated SSPE. Patients with SSPE were less likely to have a pulse ≥110/min (3% vs. 13%), but more likely to have active cancer (28% vs. 15%) and to receive outpatient care (11% vs. 4%) than patients with proximal PE. Virtually all patients (98%) with SSPE received anticoagulants. Quality of life did not differ between the groups at 3 months. No patient with SSPE vs. seven patients with proximal PE died from the index PE event. No significant difference was observed for the 3-year cumulative incidence of recurrent VTE (7% vs. 12%) and death (29% vs. 20%). After adjustment, SSPE was not associated with a lower risk of clinical outcomes than proximal PE.

CONCLUSIONS

Clinical presentation and incidences of adverse outcomes did not differ significantly between elderly patients with SSPE or proximal PE, although the power to detect differences might have been limited given the small number of events. Thus, our study does not provide evidence that unselected, elderly patients with SSPE have a more benign clinical course.

Radiologist Performance in the Detection of Pulmonary Embolism: Features that Favor Correct Interpretation and Risk Factors for Errors

PURPOSE

This study aimed to assess the factors contributing toward accurate detection and erroneous interpretation of pulmonary embolism (PE).

MATERIALS AND METHODS

Over 13 months, all computed tomography pulmonary angiography studies were retrospectively rereviewed by a chest radiologist. Two additional chest radiologists assessed cases with disagreement between the first interpretation and rereview. The number, extent, and location of PE and specialty training, experience, time of study, kV, resident prelim, use of iterative reconstruction, signal to noise ratio (SNR), and reports describing the study as "limited" were recorded. Parametric and nonparametric statistical testing was performed (significance P<0.05).

RESULTS

Of 2555 computed tomography pulmonary angiography cases assessed, there were 230 true positive (170 multiple, 60 single PE), 2271 true negative, 35 false-negative (15 multiple and 20 single PE), and 19 false-positive studies. The overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy of radiologists was 86.8%, 99.2%, 92.4%, 98.5%, and 97.9%. Sensitivity for the detection of multiple and central PE was significantly higher than the detection of single and peripheral PE, respectively (P<0.01 for both). The sensitivity of thoracic radiologists (91.7%) was higher than nonthoracic (82.8%) and reached significance for single PE (89.2% vs. 61.4%, P<0.02). Errors were more likely in cases with lower SNR (P=0.04) and those described as limited (P<0.001). Misses occurred more frequently in the upper lobe posterior and lower lobe lateral segments and subsegments (P=0.038).

CONCLUSIONS

The accuracy for PE detection is high, but errors are more likely in studies with single PE interpreted by nonthoracic radiologists, especially when located in certain segments and in cases with low SNR or described as limited.

Diagnostic Accuracy Studies

The medical community often assumes that the tests we use to diagnose various diseases are accurate, safe, and effective. However, the study designs traditionally used to determine whether such a diagnostic test is indeed accurate, safe, and effective are often at a higher risk of bias and are of lower methodological quality than those evaluating efficacy of therapeutic interventions. Several designs can be used to study diagnostic tests such as diagnostic accuracy cross-sectional studies, diagnostic accuracy case-control studies, and diagnostic accuracy comparative studies. Clinicians, researchers, and policy-makers may wish to consider moving toward higher quality study designs when studying new diagnostic modalities prior to their implementation in routine practice and diagnostic randomized trials are one such alternative.

Incidence, mortality and bleeding rates associated with pulmonary embolism in England between 1997 and 2015

BACKGROUND

Improvements in availability and accuracy of diagnostic testing in pulmonary embolism (PE) in the last 20 years have more recently been paralleled by the introduction of additional anticoagulation agents and treatment strategies. These developments are likely to shape potentially important changes in PE incidence, associated mortality and treatment complications.

METHODS

We investigated trends in PE incidence, PE-related mortality and bleeding risk by analysing Hospital Episodes Statistics for England.

RESULTS

Between 1997 and 2015, 464,046 patients (53.9% female) were hospitalized with PE in England. The annual number of hospitalizations with an associated diagnosis of PE more than doubled over this period (24,366 in 1998 vs. 53,108 in 2014), with a corresponding increase in PE hospitalization rate (50.2 to 97.8 per 100,000 population/year), evident in all age categories. Mortality at 1 and 3 months decreased over the study period and was significantly associated with age, treatment era and comorbidities. The risk of bleeding resulting in hospitalization or death within 3 and 12 months after the index PE admission increased over the study period (4.3%/5.1% for 1998-2004 versus 6.1%/7.2% for 2010-2014, p < 0.001 for both comparisons).

CONCLUSIONS

The incidence of PE doubled in England between 1997 and 2015, likely attributable to raised awareness and ability to diagnose less severe cases. While PE-associated mortality decreased, there was an increase in bleeding risk. Renewed efforts directed at reducing the incidence of bleeding, including consideration of anticoagulation regimens and investigation of anticoagulation requirement in patients with low-risk features, are needed.

Lower prevalence of subsegmental pulmonary embolism after application of the YEARS diagnostic algorithm

The rate of identified isolated subsegmental pulmonary embolism (ssPE) has doubled with advances in computed tomography pulmonary angiography (CTPA) technology, but its clinical relevance is debated. The YEARS diagnostic algorithm was shown to safely reduce the number of required CTPAs in the diagnostic management of PE. We hypothesized that the higher threshold for performing CTPA in YEARS was associated with a lower prevalence of ssPE compared to the conventional diagnostic algorithm. We compared 2291 consecutive patients with suspected PE managed according to YEARS to 3306 consecutive control patients managed according to the Wells score for the prevalence of isolated ssPE. In the YEARS cohort, 52% were managed without CTPA, 12% had pulmonary embolism (PE) of which 10% were isolated ssPE, and the 3‐month diagnostic failure rate was 0·35%. In the control cohort, 32% were managed without CTPA, 20% had PE of which 16% were isolated ssPE, and the 3‐month failure rate was 0·73%. The isolated ssPE prevalence was significantly lower in YEARS (absolute difference 6·2% (95% confidence interval [CI] 1·4–10), Odds Ratio 0·58 (95% CI 0·37–0·90). In conclusion, YEARS is associated with a lower prevalence of isolated ssPE, due to reduction in CTPAs by the higher D‐dimer threshold. This was however not associated with a higher risk of recurrent VTE during follow‐up.

Systematic Review and Meta-analysis of Outcomes of Patients With Subsegmental Pulmonary Embolism With and Without Anticoagulation Treatment

BACKGROUND

This systematic review addresses the controversy over the decision to anticoagulate patients with subsegmental pulmonary embolism (SSPE).

METHODS

We searched Ovid MEDLINE, PubMed, Embase, the Cochrane Library, Scopus, Web of Science, ClinicalTrials.gov, Google Scholar, and bibliographies in March 2017. Two authors reviewed and retained papers with symptomatic patients who underwent computerized tomographic pulmonary angiography and had sufficient information to determine SSPE; decision to treat (or not) with systemic anticoagulation; and outcomes of bleeding, venous thromboembolism (VTE) recurrence, and death. Papers were assessed for selection and publication bias and heterogeneity, with Eggers and the inconsistency indexes (I² ).

RESULTS

From 1,512 papers screened, we included 14 studies comprising 15,563 patients for full-length review and analysis. Pooled data demonstrated I²  = 99% with an Eggers p < 0.001, suggesting significant publication bias. The pooled prevalence of SSPE was 4.6% (95% confidence interval [CI] = 1.8%-8.5%). The frequency of bleeding in SSPE patients treated with anticoagulation (n = 589) was 8.1% (95% CI = 2.8%-15.8%), with no available bleeding data in untreated patients (n = 126). The frequency of VTE recurrence within 90 days was 5.3% (95% CI = 1.6%-10.9%) for treated versus 3.9% (95% CI = 4.8%-13.4%) for untreated, while the frequency of death was 2.1% (95% CI = 3.4%-5.2%) for treated versus 3.0% (95% CI = 2.8%-8.6%) for untreated.

CONCLUSION

This systematic review highlights the lack of any clinical trial to make a clear inference about harm or benefit of anticoagulation for SSPE. Comparison of pooled data from uncontrolled outcome studies shows no increase in VTE recurrence or death rates for patients who were not anticoagulated. These data suggest clinical equipoise for decision to anticoagulate or not anticoagulate patients with SSPE. However, this inference is limited by small numbers, imprecision, and the lack of a controlled clinical trial.

Magnetic resonance angiography for the primary diagnosis of pulmonary embolism: A review from the international workshop for pulmonary functional imaging

Pulmonary contrast enhanced magnetic resonance angiography (CE-MRA) is useful for the primary diagnosis of pulmonary embolism (PE). Many sites have chosen not to use CE-MRA as a first line of diagnostic tool for PE because of the speed and higher efficacy of computerized tomographic angiography (CTA). In this review, we discuss the strengths and weaknesses of CE-MRA and the appropriate imaging scenarios for the primary diagnosis of PE derived from our unique multi-institutional experience in this area. The optimal patient for this test has a low to intermediate suspicion for PE based on clinical decision rules. Patients in extremis are not candidates for this test. Younger women (< 35 years of age) and patients with iodinated contrast allergies are best served by using this modality We discuss the history of the use of this test, recent technical innovations, artifacts, direct and indirect findings for PE, ancillary findings, and the effectiveness (patient outcomes) of CE-MRA for the exclusion of PE. Current outcomes data shows that CE-MRA and NM V/Q scans are effective alternative tests to CTA for the primary diagnosis of PE.

Does my patient have a pulmonary embolism? The Wells vs. PISA 2 rule in orthopedic patients

The diagnosis of venous thromboembolism is difficult in the postoperative setting because signs such as hypoxemia, leg pain, and swelling are so common. CTPA can also detect subsegmental PE (SSPE), of which the clinical significance has been widely debated. Clinical decision rules (CDR), such as the Wells and PISA 2, have been developed to identify symptomatic patients at low risk for PE who could forgo imaging. We performed this study in order to (1) compare the performance of the Wells and PISA 2 CDR in orthopedic patients; (2) compare CDR scores in patients with subsegmental PE (SSPE) versus larger clots; and (3) identify variables that improve performance of the Wells in orthopedic patients. This retrospective cohort study included all orthopedic surgery patients that underwent computerized tomographic pulmonary angiography at a single institution from 1/1/13 to 12/31/14 and had data to calculate both Wells and PISA 2 scores. CDR sensitivity, specificity and c-statistics were calculated. Multivariable logistic regression was used to identify variables that improved CDR performance. 402 patients were included in the study. The Wells rule (cutoff > 4) had sensitivity 74% and specificity 45%. PISA 2 (cutoff 0.6) had sensitivity 90% and specificity 11%. The Wells performed better than PISA 2: c-statistic 0.60 vs. 0.50; p = 0.007. The mean Wells score was 5.20 ± 1.68 for patients with SSPE and 5.41 ± 1.86 for patients with larger clots. Adding the variables prior smoking and varicose veins improved the performance of the Wells rule (c-statistic 0.66 vs. 0.60, p = 0.008). The Wells rule (cutoff > 4) performs better than PISA 2 in orthopedic patients. Neither can distinguish patients with SSPE from those with larger clots. Although adding past smoking and varicose veins to the Wells improves its performance, this requires validation in other populations.

Diagnosis of acute pulmonary embolism

Advances in the management of patients with suspected pulmonary embolism (PE) have improved diagnostic accuracy and made management algorithms safer, easier to use, and well standardized. These diagnostic algorithms are mainly based on the assessment of clinical pretest probability, D-dimer measurement, and imaging tests-predominantly computed tomography pulmonary angiography. These diagnostic algorithms allow safe and cost-effective diagnosis for most patients with suspected PE. In this review, we summarize signs and symptoms of PE, current existing evidence for PE diagnosis, and focus on the challenge of diagnosing PE in special patient populations, such as pregnant women, or patients with a prior VTE. We also discuss novel imaging tests for PE diagnosis and highlight some of the additional challenges that might require adjustments to current diagnostic strategies, such as the reduced clinical suspicion threshold, resulting in a lower proportion of PE among suspected patients as well as the overdiagnosis of subsegmental PE.

Is it safe to withhold long-term anticoagulation therapy in patients with small pulmonary emboli diagnosed by SPECT scintigraphy?

Background

The need for anticoagulation therapy (AC) in patients with subsegmental pulmonary embolism (SSPE) diagnosed by computed tomography of the pulmonary arteries (CTPA) has been questioned, as these patients run low risk for recurrent venous thromboembolism (VTE) during 3 months of follow-up. Whether this applies also to patients with small PE diagnosed with pulmonary scintigraphy has not yet been evaluated, however.

Methods

We therefore retrospectively evaluated 54 patients (mean age 62 ± 19 years, 36 [67 %] women) with small PE diagnosed by ventilation/perfusion singe photon emission computed tomography (V/P SPECT) who did not receive conventional long-term AC.

Results

More than half of our patients (36[67 %]) received less than 48 h of AC, 11 (20 %) patients were treated for 2–14 days, and 7 (13 %) for 15–30 days. The majority (28 [52 %]) of our patients had a non-low simplified pulmonary emboli severity index (S-PESI), and 7 (13 %) had malignancy. D-dimer was negative in 18 (33 %), positive in 10 (19 %), and not analyzed in 28 (52 %) patients. Phlebography of the lower extremities had been performed with negative result in one patient.

During 90 days of follow up no deaths or PE occurred. Seven patients were readmitted to hospital, whereof two (2/54 [4 %]) were diagnosed with deep venous thrombosis (DVT) necessitating AC therapy.

Conclusion

In conclusion, withholding longterm AC therapy in patients with SSPE diagnosed by V/P SPECT resulted in 4 % risk for recurrence of VTE during 90 days of follow up, and can therefore currently not be recommended.

Historical Evolution of Imaging Techniques for the Evaluation of Pulmonary Embolism

As we celebrate the 100th anniversary of the founding of the Radiological Society of North America (RSNA), it seems fitting to look back at the major accomplishments of the radiology community in the diagnosis of pulmonary embolism. Few diseases have so consistently captured the attention of the medical community. Since the first description of pulmonary embolism by Virchow in the 1850s, clinicians have struggled to reach a timely diagnosis of this common condition because of its nonspecific and often confusing clinical picture. As imaging tests started to gain importance in the 1900s, the approach to diagnosing pulmonary embolism also began to change. Rapid improvements in angiography, ventilation-perfusion imaging, and cross-sectional imaging modalities such as computed tomography (CT) and magnetic resonance imaging have constantly forced health care professionals to rethink how they diagnose pulmonary embolism. Needless to say, the way pulmonary embolism is diagnosed today is distinctly different from how it was diagnosed in Virchow's era; and imaging, particularly CT, now forms the cornerstone of diagnostic evaluation. Currently, radiology offers a variety of tests that are fast and accurate and can provide anatomic and functional information, thus allowing early diagnosis and triage of cases. This review provides a historical journey into the evolution of these imaging tests and highlights some of the major breakthroughs achieved by the radiology community and RSNA in this process. Also highlighted are areas of ongoing research and development in this field of imaging as radiologists seek to combat some of the newer challenges faced by modern medicine, such as rising health care costs and radiation dose hazards.

Diagnostic Value of Dual-Source Computerized Tomography Combined with Perfusion Imaging for Peripheral Pulmonary Embolism

BACKGROUND

Pulmonary embolism has become the third most common cardiovascular disease, which can seriously harm human health.

OBJECTIVES

To investigate the diagnostic value of dual-source computerized tomography (CT) and perfusion imaging for peripheral pulmonary embolism.

PATIENTS AND METHODS

Thirty-two patients with suspected pulmonary embolism underwent dual-source CT exams. To compare the ability of pulmonary embolism detection software (PED) with CT pulmonary angiography (CTPA) in determining the presence, numbers, and locations of pulmonary emboli, the subsequent images were reviewed by two radiologists using both imaging modalities. Also, the diagnostic consistency between PED and CTPA images and dual-energy pulmonary perfusion imaging (DEPI) for segmental pulmonary embolism was compared.

RESULTS

CTPA images revealed 50 (7.81%) segmental and 56 (4.38%) sub-segmental pulmonary embolisms, while the PED images showed 68 (10.63%) segmental and 94 (7.34%) sub-segmental pulmonary embolisms. Thus, the detection rate on PED images for peripheral pulmonary embolism was significantly higher than that of the CTPA images (P < 0.05). There was good consistency for diagnosing segmental pulmonary embolism between PED and CTPA and DEPI (kappa = 0.85). The sensitivity and specificity of DEPI images for the diagnosis of pulmonary embolism were 91.7% and 97.5%, respectively.

CONCLUSION

PED software of dual-source CT combined with perfusion imaging can significantly improve the detection rate of peripheral pulmonary embolism.

Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report

BACKGROUND

We update recommendations on 12 topics that were in the 9th edition of these guidelines, and address 3 new topics.

METHODS

We generate strong (Grade 1) and weak (Grade 2) recommendations based on high- (Grade A), moderate- (Grade B), and low- (Grade C) quality evidence.

RESULTS

For VTE and no cancer, as long-term anticoagulant therapy, we suggest dabigatran (Grade 2B), rivaroxaban (Grade 2B), apixaban (Grade 2B), or edoxaban (Grade 2B) over vitamin K antagonist (VKA) therapy, and suggest VKA therapy over low-molecular-weight heparin (LMWH; Grade 2C). For VTE and cancer, we suggest LMWH over VKA (Grade 2B), dabigatran (Grade 2C), rivaroxaban (Grade 2C), apixaban (Grade 2C), or edoxaban (Grade 2C). We have not changed recommendations for who should stop anticoagulation at 3 months or receive extended therapy. For VTE treated with anticoagulants, we recommend against an inferior vena cava filter (Grade 1B). For DVT, we suggest not using compression stockings routinely to prevent PTS (Grade 2B). For subsegmental pulmonary embolism and no proximal DVT, we suggest clinical surveillance over anticoagulation with a low risk of recurrent VTE (Grade 2C), and anticoagulation over clinical surveillance with a high risk (Grade 2C). We suggest thrombolytic therapy for pulmonary embolism with hypotension (Grade 2B), and systemic therapy over catheter-directed thrombolysis (Grade 2C). For recurrent VTE on a non-LMWH anticoagulant, we suggest LMWH (Grade 2C); for recurrent VTE on LMWH, we suggest increasing the LMWH dose (Grade 2C).

CONCLUSIONS

Of 54 recommendations included in the 30 statements, 20 were strong and none was based on high-quality evidence, highlighting the need for further research.

Subsegmental pulmonary embolism: A narrative review

Through the introduction of computed tomography pulmonary angiography (CTPA) for diagnosis of the pulmonary embolism (PE), the high sensitivity of this diagnostic tool led to detecting peripheral filling defects as small as 2-3mm, termed as subsegmental pulmonary embolism (SSPE). However, despite these substantial increases in diagnosis of small pulmonary embolism, there are minimal changes in mortality. Moreover, SSPE patients generally are hemodynamically stable with mild clinical presentation, lower serum level of biomarkers, lower incidence of associated proximal DVTs and less frequent echocardiographic changes compared to the patients with emboli located in more central pulmonary arteries. However, the pros and cons of anticoagulant therapy versus non-treating, monitoring protocol and exact long term outcome of these patients are still unclear. In this article we review existing evidence and provide an overview of what is known about the diagnosis and management of subsegmental pulmonary embolism.

Overdiagnosis of Pulmonary Embolism by Pulmonary CT Angiography

OBJECTIVE

The purpose of this study is to evaluate the rate of overdiagnosis of pulmonary embolism (PE) by pulmonary CT angiography (CTA) in a tertiary-care university hospital.

MATERIALS AND METHODS

This study is a retrospective review of all pulmonary CTA examinations performed in a tertiary-care university hospital over a 12-month period. Studies originally reported as positive for PE were retrospectively reinterpreted by three subspecialty chest radiologists with more than 10 years' experience. A pulmonary CTA was considered negative for PE when all three chest radiologists were in agreement that the pulmonary CTA study was negative for PE. The location and potential causes for PE overdiagnosis were recorded.

RESULTS

A total of 937 pulmonary CTA studies were performed over the study period. PE was diagnosed in the initial report in 174 of these cases (18.6%). There was discordance between the chest radiologists and the original radiologist in 45 of 174 (25.9%) cases. Discordance occurred more often where the original reported PE was solitary (46.2% of reported solitary PEs were considered negative on retrospective review) and located in a segmental or subsegmental pulmonary artery (26.8% of segmental and 59.4% of subsegmental PE diagnoses were considered negative on retrospective review). The most common cause of diagnostic difficulty was breathing motion artifact, followed by beam-hardening artifact.

CONCLUSION

In routine clinical practice, PEs diagnosed by pulmonary CTA are frequently overdiagnosed, when compared with the consensus opinion of a panel of expert chest radiologists. Improvements in the quality of pulmonary CTA examination and increased familiarity with potential diagnostic pitfalls in pulmonary CTA are recommended to minimize misdiagnosis of PE.

Multidetector computed tomography pulmonary angiography in childhood acute pulmonary embolism

Pulmonary embolism is a life-threatening condition affecting people of all ages. Multidetector row CT pulmonary angiography has improved the imaging of pulmonary embolism in both adults and children and is now regarded as the routine modality for detection of pulmonary embolism. Advanced CT pulmonary angiography techniques developed in recent years, such as dual-energy CT, have been applied as a one-stop modality for pulmonary embolism diagnosis in children, as they can simultaneously provide anatomical and functional information. We discuss CT pulmonary angiography techniques, common and uncommon findings of pulmonary embolism in both conventional and dual-energy CT pulmonary angiography, and radiation dose considerations.

Management and outcomes of single subsegmental pulmonary embolus: a retrospective audit at North Shore Hospital, New Zealand

BACKGROUND

It is unknown whether filling defects in subsegmental arteries on multidetector computed tomography pulmonary angiography correlate with clinically relevant subsegmental pulmonary embolism (PE) on pulmonary angiography. Current guidelines do not differentiate between PE in segmental and subsegmental vessels, and many patients receive at least 3 months anticoagulation. The strategy employed at North Shore Hospital in haemodynamically stable patients with single subsegmental PE is to perform bilateral lower leg compression ultrasound (CUS). Anticoagulation is withheld if CUS is negative; a bilateral CUS is repeated in 7-10 days.

AIM

The aim of this retrospective audit was to ensure our current management strategy is safe.

METHODS

All diagnoses of single subsegmental PE between June 2005 and June 2013 were included. The primary outcome was the rate of venous thromboembolism (VTE) recurrence within 3 months of single subsegmental PE diagnosis. Secondary outcomes were rates of major/minor bleeding and all-cause mortality.

RESULTS

Thirty-two patients were included - 20 were treated with anticoagulation; 12 were managed with observation/serial bilateral lower limb CUS. None of the patients in either group had VTE recurrence by 3 months. No bleeding episodes were observed in the observation group; there was a 10% major bleeding rate (n = 2) in the treatment group. One death occurred in each group, neither of which was attributed to VTE.

CONCLUSION

Withholding anticoagulation in patients with single subsegmental PE and negative serial bilateral CUS appears to be a safe and effective management strategy, with a low risk of VTE recurrence.

Derivation of a screening tool to identify patients with right ventricular dysfunction or tricuspid regurgitation after negative computerized tomographic pulmonary angiography of the chest

Many dyspneic patients who undergo computerized tomographic pulmonary angiography (CTPA) for presumed acute pulmonary embolism (PE) have no identified cause for their dyspnea yet have persistent symptoms, leading to more CTPA scanning. Right ventricular (RV) dysfunction or overload can signal treatable causes of dyspnea. We report the rate of isolated RV dysfunction or overload after negative CTPA and derive a clinical decision rule (CDR). We performed secondary analysis of a multicenter study of diagnostic accuracy for PE. Inclusion required persistent dyspnea and no PE. Echocardiography was ordered at clinician discretion. A characterization of isolated RV dysfunction or overload required normal left ventricular function and RV hypokinesis, or estimated RV systolic pressure of at least 40 mmHg. The CDR was derived from bivariate analysis of 97 candidate variables, followed by multivariate logistic regression. Of 647 patients, 431 had no PE and persistent dyspnea, and 184 (43%) of these 431 had echocardiography ordered. Of these, 64 patients (35% [95% confidence interval (CI): 28%-42%]) had isolated RV dysfunction or overload, and these patients were significantly more likely to have a repeat CTPA within 90 days (P = .02, [Formula: see text] test). From univariate analysis, 4 variables predicted isolated RV dysfunction: complete right bundle branch block, normal CTPA scan, active malignancy, and CTPA with infiltrate, the last negatively. Logistic regression found only normal CTPA scanning significant. The final rule (persistent dyspnea + normal CTPA scan) had a positive predictive value of 53% (95% CI: 37%-69%). We conclude that a simple CDR consisting of persistent dyspnea plus a normal CTPA scan predicts a high probability of isolated RV dysfunction or overload on echocardiography.

Wells Score and Poor Outcomes Among Adult Patients With Subsegmental Pulmonary Embolism

Introduction:

Since the introduction of computed tomography pulmonary angiography, isolated subsegmental pulmonary embolism has become a commonly recognized clinical problem, but its clinical relevance remains unclear. The objective of the present study was to evaluate the extent to which the simplified Wells score discriminates between patients with varying levels of risk of complications after presenting with subsegmental pulmonary embolism.

Materials and Methods:

Retrospective cohort study. Patients included had subsegmental pulmonary embolism (1 or multiple emboli limited to subsegmental arteries). Primary explanatory variable was the simplified Wells score, categorized as high (>4) or low (≤4). The primary outcome was time to death or new venous thromboembolism. Kaplan-Meier techniques and Cox regression analysis were used to compare the survival experience of patients with high versus low Wells score with and without adjustment for active malignancy, age, Charlson score, previous venous thromboembolism, and previous major surgery in the last 30 days.

Main Results:

Seventy-nine patients with subsegmental pulmonary embolism were included. Patients with a high Wells score had a 4-fold increased risk of the composite outcome (hazard ratio = 4.2, 95% confidence interval [CI] = 2.0-8.9, P < .001). Other covariates significantly associated with increased risk in univariate analyses included active malignancy, a low serum albumin, and an increased Charlson score. In multivariate Cox regression analyses adjusting for these other factors, a high Wells score remained significant (hazard ratio 5.5, 95% CI 2.4-12.6, P < .001).

Conclusion:

High Wells score is associated with death or new venous thromboembolism during follow-up among patients with subsegmental pulmonary embolism.

Clinical trial registration:

ClinicalTrials.gov number, NCT01372514.

Pulmonary embolism: current and new treatment options

BACKGROUND

Pulmonary embolism (PE) can be a life-threatening emergency. Accurate diagnostic techniques and patient-specific management strategies are necessary to ensure favorable clinical outcomes.

METHODS

Relevant guidelines, articles, reviews, and abstracts were identified using a narrative approach in PubMed/MEDLINE, Google Scholar, clinicaltrials.gov and nice.org.uk. English-language articles published in 2000-2014 were initially identified using the search terms: novel OAC, pulmonary embolism, venous thromboembolism, diagnosis, treatment, rivaroxaban, apixaban, dabigatran, and edoxaban. The initial literature search was supported by a 'snowballing' style literature search, and relevant articles were included based on a professional judgment of relevance.

SCOPE

We discuss the diagnosis of PE and the categorization of risk for subgroups, which may assist with making treatment decisions. We review current guidance on acute and long-term treatment, possible limitations of traditional anticoagulant therapy, and the development of direct oral anticoagulants, which may significantly alter the management of patients with PE. Finally, we discuss special considerations in high-risk and hard-to-treat subpopulations that may benefit from the improved benefit-risk profile offered by these newer agents.

CONCLUSIONS

The direct oral anticoagulants may overcome several of the limitations associated with traditional anticoagulant therapy, potentially improving the standard of care for PE patients, including high-risk and hard-to-manage subgroups.

Classification of CT pulmonary angiography reports by presence, chronicity, and location of pulmonary embolism with natural language processing

In this paper we describe an efficient tool based on natural language processing for classifying the detail state of pulmonary embolism (PE) recorded in CT pulmonary angiography reports. The classification tasks include: PE present vs. absent, acute PE vs. others, central PE vs. others, and subsegmental PE vs. others. Statistical learning algorithms were trained with features extracted using the NLP tool and gold standard labels obtained via chart review from two radiologists. The areas under the receiver operating characteristic curves (AUC) for the four tasks were 0.998, 0.945, 0.987, and 0.986, respectively. We compared our classifiers with bag-of-words Naive Bayes classifiers, a standard text mining technology, which gave AUC 0.942, 0.765, 0.766, and 0.712, respectively.

An official American Thoracic Society/American College of Chest Physicians policy statement: the Choosing Wisely top five list in adult pulmonary medicine

The American Board of Internal Medicine Foundation's Choosing Wisely campaign aims to curb health-care costs and improve patient care by soliciting lists from medical societies of the top five tests or treatments in their specialty that are used too frequently and inappropriately. The American Thoracic Society (ATS) and American College of Chest Physicians created a joint task force, which produced a top five list for adult pulmonary medicine. Our top five recommendations, which were approved by the executive committees of the ATS and American College of Chest Physicians and published by Choosing Wisely in October 2013, are as follows: (1) Do not perform CT scan surveillance for evaluation of indeterminate pulmonary nodules at more frequent intervals or for a longer period of time than recommended by established guidelines; (2) do not routinely offer pharmacologic treatment with advanced vasoactive agents approved only for the management of pulmonary arterial hypertension to patients with pulmonary hypertension resulting from left heart disease or hypoxemic lung diseases (groups II or III pulmonary hypertension); (3) for patients recently discharged on supplemental home oxygen following hospitalization for an acute illness, do not renew the prescription without assessing the patient for ongoing hypoxemia; (4) do not perform chest CT angiography to evaluate for possible pulmonary embolism in patients with a low clinical probability and negative results of a highly sensitive D-dimer assay; (5) do not perform CT scan screening for lung cancer among patients at low risk for lung cancer. We hope pulmonologists will use these recommendations to stimulate frank discussions with patients about when these tests and treatments are indicated--and when they are not.

Treatment and complications in orthopaedic trauma patients with symptomatic pulmonary embolism

OBJECTIVES

The purpose of this study is to characterize the presentation, size, treatment, and complications of pulmonary embolism (PE) in a large series of orthopaedic trauma patients who developed PE after injury.

METHODS

We reviewed the records of orthopaedic trauma patients who developed a PE within 6 months of injury at 9 trauma centers and 2 tertiary care facilities.

RESULTS

There were 312 patients, 186 men and 126 women, average age 58 years. Average body mass index was 29.6, and average Injury Severity Score was 18. Seventeen percent received anticoagulation before injury, and 5% had a history of PE. After injury, 87% were placed on prophylactic anticoagulation and 68% with low-molecular weight heparin. Fifty-three percent of patients exhibited shortness of breath or chest pain. Average heart rate and O2 saturation before PE diagnosis were 110 and 94%, respectively. Thirty-nine percent had abnormal arterial blood gas, and 30% had abnormal electrocardiogram findings. Eighty-nine percent had computed tomography pulmonary angiography for diagnosis. Most clots were segmental (63%), followed by subsegmental (21%), lobar (9%), and central (7%). The most common treatment was unfractionated heparin and Coumadin (25%). Complications of anticoagulation were common: 10% had bleeding at the surgical site. Other complications of anticoagulation included gastrointestinal bleed, anemia, wound complications, death, and compartment syndrome. PE recurred in 1% of patients. Four percent died of PE within 6 months.

CONCLUSIONS

This is the first large data set to evaluate the course of PE in an orthopaedic trauma population. The complications of anticoagulation are significant and were as common in patients with lower risk clots as those with higher risk clots.

Missed pulmonary emboli on CT angiography: assessment with pulmonary embolism-computer-aided detection

OBJECTIVE

The purpose of this study is to assess the use of a pulmonary embolism (PE)- computer-aided detection (CADx) program in the detection of PE missed in clinical practice.

MATERIALS AND METHODS

Pulmonary CT angiography (CTA) studies (n = 6769) performed between January 2009 and July 2012 were retrospectively assessed by a thoracic radiologist. In studies that were positive for PE, all prior contrast-enhanced pulmonary CTA studies were reviewed. Missed PE was deemed to have occurred if PE was not described in the final interpretation. The presence, proximal extent, and number of PEs were agreed on by three thoracic radiologists. Studies with missed acute PE and available slice thickness of 2 mm or less were assessed with a prototype PE-CADx program. False-positive PE-CADx marks were analyzed. Outcomes of missed acute PEs were assessed in patients with both follow-up imaging and clinical data.

RESULTS

Fifty-three studies with overlooked acute PE met our inclusion criteria for PE-CADx assessment. The PE-CADx program identified at least one PE in 77.4% of instances (41/53). PE-CADx correctly marked at least one PE in 23 of 23 cases (100%) with multiple PEs and 18 of 30 (60%) cases with a solitary PE (p < 0.001). PE-CADx per-study sensitivity was significantly higher for segmental (65.5%) than for subsegmental (91.7%) PEs (p = 0.002). PE-CADx averaged 3.8 false-positive marks per case (range, 0-23 marks). Fourteen patients with missed PE who were not receiving anticoagulation therapy developed new PEs, including nine with an isolated subsegmental PE on the initial CT scan.

CONCLUSION

PE-CADx correctly identified 77.4% of cases of acute PE that were previously missed in clinical practice.