Safety of ruling out acute pulmonary embolism by normal computed tomography pulmonary angiography in patients with an indication for computed tomography: systematic review and meta-analysis

Role of recombinant human granulocyte colony-stimulating factor in development of cancer-associated venous thromboembolism in lung cancer patients who undergo chemotherapy

Background

The role of recombinant human granulocyte colony-stimulating factor (rhG-CSF), especially the long-acting factor in the development of cancer-associated venous thromboembolism (VTE) in lung cancer patients who undergo chemotherapy has been understudied, although the use of rhG-CSF has been reported to be associated with an increased risk of VTE.

Methods

We retrospectively reviewed 1,673 lung cancer patients who underwent hospitalized chemotherapy. We performed propensity score matching to offset confounding factors related to cancer-associated VTE development and classified the patients into short-acting (N = 273), long-acting (N = 273), and no rhG-CSF (N = 273) groups. The primary outcome was cumulative cancer-associated VTE development three months after all cycles of chemotherapy.

Results

The overall VTE incidence in the short-acting, long-acting, and no rhG-CSF groups was 5.5%, 10.3%, and 2.2%, respectively (P <0.001). The VTE incidence in the long-acting rhG-CSF group was higher than that in the short-acting (P = 0.039) and no rhG-CSF groups (P <0.001). The VTE incidence in the short-acting rhG-CSF group was higher than that in the no rhG-CSF group (P = 0.045). The use of rhG-CSF (hazard ratio [HR] 2.337; 95% confidence interval [CI] [1.236-5.251], P = 0.006) was positively correlated with VTE development among all patients, whereas the use of long-acting rhG-CSF (HR 1.917, 95% CI [1.138-4.359]; P = 0.016), was positively correlated with VTE development in patients receiving rhG-CSF.

Conclusion

The use of rhG-CSF, especially long-acting rhG-CSF, increases the risk of cancer-associated VTE development compared to no rhG-CSF use in lung cancer patients who undergo hospitalized chemotherapy.

Clinical predictors of pulmonary embolism for inpatients: are computed tomography pulmonary angiograms being requested appropriately?

BACKGROUND

The heterogeneity of inpatient pulmonary embolism (PE) presentations may lead to computed tomography pulmonary angiograms (CTPA) being over-requested. Current clinical predictors for PE, including Wells criteria and Pulmonary Embolism Rule-out Criteria (PERC), have predominantly focussed on outpatient and emergency department populations.

AIM

To determine the clinical indicators for ordering inpatient CTPA and the predictors of positive scans for PE.

METHODS

Consecutive inpatient CTPA (performed >24 h after admission) from January 2017 to December 2017 were retrospectively reviewed. Variables including baseline characteristics, vital signs and risk factors for PE were extracted.

RESULTS

A total of 312 CTPA was reviewed (average patient age 67 years; 46% male) and 36 CTPA were positive for PE (11.5%). The average time to inpatient CTPA request was 7 days. Clinical indicators associated with positive scans were hypoxia (odds ratio (OR) 2.4; 95% confidence interval (CI) 1.1-5.6), tachypnoea (OR 2.5; 95% CI 1.2-6.0), recent surgery or immobilisation (OR 2.7; 95% CI 1.2-6.4), S1Q3T3 pattern on electrocardiogram (ECG; OR 7.2; 95% CI 1.4-35.7) and right bundle branch block pattern on ECG (OR 4.7; 95% CI 1.6-13.1). Hypotension, fever and malignancy were not significant. Both PERC and Wells criteria had poor positive predictive value (12% and 27% respectively), but the negative predictive value for PERC and Wells was 100% and 95.8% respectively.

CONCLUSION

Inpatient CTPA appear to be over-requested and can potentially be rationalised based on a combination of clinical predictors and Wells criteria and/or PERC rule. Further prospective studies are needed to develop accurate clinical decision tools targeted towards inpatients.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Computerised clinical decision support system for the diagnosis of pulmonary thromboembolism: a preclinical pilot study

BACKGROUND

Recommendations for the diagnosis of pulmonary embolism are available for healthcare providers. Yet, real practice data show existing gaps in the translation of evidence-based recommendations. This is a study to assess the effect of a computerised decision support system (CDSS) with an enhanced design based on best practices in content and reasoning representation for the diagnosis of pulmonary embolism.

DESIGN

Randomised preclinical pilot study of paper-based clinical scenarios in the diagnosis of pulmonary embolism. Participants were clinicians (n=30) from three levels of experience: medical students, residents and physicians. Participants were randomised to two interventions for the diagnosis of pulmonary embolism: a didactic lecture versus a decision tree via a CDSS. The primary outcome of diagnostic pathway concordance (derived as a ratio of the number of correct diagnostic decision steps divided by the ideal number of diagnostic decision steps in diagnostic algorithms) was measured at baseline (five clinical scenarios) and after either intervention for a total of 10 clinical scenarios.

RESULTS

The mean of diagnostic pathway concordance improved in both study groups: baseline mean=0.73, post mean for the CDSS group=0.90 (p<0.001, 95% CI 0.10-0.24); baseline mean=0.71, post mean for didactic lecture group=0.85 (p<0.001, 95% CI 0.07-0.2). There was no statistically significant difference between the two study groups or between the three levels of participants.

INTERPRETATION

A computerised decision support system designed for both content and reasoning visualisation can improve clinicians' diagnostic decision-making.

Machine learning with D-dimer in the risk stratification for pulmonary embolism: a derivation and internal validation study

AIM

To develop a machine learning model to predict the diagnosis of pulmonary embolism (PE).

METHODS AND RESULTS

We undertook a derivation and internal validation study to develop a risk prediction model for use in patients being investigated for possible PE. The machine learning technique, generalized logistic regression using elastic net, was chosen following an assessment of seven machine learning techniques and on the basis that it optimized the area under the receiver operator characteristic curve (AUC) and Brier score. Models were developed both with and without the addition of D-dimer. A total of 3347 patients were included in the study of whom, 219 (6.5%) had PE. Four clinical variables (O2 saturation, previous deep venous thrombosis or PE, immobilization or surgery, and alternative diagnosis equal or more likely than PE) plus D-dimer contributed to the machine learning models. The addition of D-dimer improved the AUC by 0.16 (95% confidence interval 0.13-0.19), from 0.73 to 0.89 (0.87-0.91) and decreased the Brier score by 14% (10-18%). More could be ruled out with a higher positive likelihood ratio than by the Wells score combined with D-dimer, revised Geneva score combined with D-dimer, or the Pulmonary Embolism Rule-out Criteria score. Machine learning with D-dimer maintained a low-false-negative rate at a true-negative rate of nearly 53%, which was better performance than any of the other alternatives.

CONCLUSION

A machine learning model outperformed traditional risk scores for the risk stratification of PE in the emergency department. However, external validation is needed.

COVID-19 and venous thromboembolism: Known and unknown for imaging decisions

As we continue to fight against the current coronavirus disease-2019 (COVID-19) pandemic, healthcare professionals across the globe are trying to answer questions surrounding how to best help patients with the up-to-date available science while awaiting the development of new therapies and mass vaccination. Since early in the pandemic, studies indicated a heightened risk of venous thromboembolism (VTE) in COVID-19 infected patients. There have been differing expert opinions about how to assess pretest probability of VTE in this patient population. This has been partly due to the high prevalence of respiratory failure in this patient population and the use of D-dimer as a prognostic test which is also frequently elevated in patients with COVID-19 in absence of VTE. Some experts have argued for an approach similar to usual care with testing if clinical suspicion is high enough. Some have argued for more routine screening at different points of care. Others have even suggested empiric therapeutic anti-coagulation in moderate to severely ill COVID-19 patients. In the following article, we review and summarize the most current literature in hopes of assisting clinicians in decision making and guidance for when to be concerned for VTE in COVID-19 patients. We also discuss research gaps and share pathways currently being used within our institution.

High-risk pulmonary embolism with out-of-hospital cardiac arrest: Acute multidisciplinary approach leading to surgical embolectomy with good clinical outcome

Percutaneous pulmonary angiography may be used for early diagnosis of pulmonary embolism in the hemodynamic unstable patient. Pulmonary embolectomy is an effective treatment option in patients with acute high-risk pulmonary embolism.

Pulmonary embolism: update on management and controversies

Pulmonary embolism is a common and potentially fatal cardiovascular disorder that must be promptly diagnosed and treated. The diagnosis, risk assessment, and management of pulmonary embolism have evolved with a better understanding of efficient use of diagnostic and therapeutic options. The use of either clinical probability adjusted or age adjusted D-dimer interpretation has led to a reduction in diagnostic imaging to exclude pulmonary embolism. Direct oral anticoagulation therapies are safe, effective, and convenient treatments for most patients with acute venous thromboembolism, with a lower risk of bleeding than vitamin K antagonists. These oral therapeutic options have opened up opportunities for safe outpatient management of pulmonary embolism in selected patients. Recent clinical trials exploring the use of systemic thrombolysis in intermediate to high risk pulmonary embolism suggest that this therapy should be reserved for patients with evidence of hemodynamic compromise. The role of low dose systemic or catheter directed thrombolysis in other patient subgroups is uncertain. After a diagnosis of pulmonary embolism, all patients should be assessed for risk of recurrent venous thromboembolism to guide duration of anticoagulation. Patients with a venous thromboembolism associated with a strong, transient, provoking risk factor can safely discontinue anticoagulation after three months of treatment. Patients with an ongoing strong risk factor, such as cancer, or unprovoked events are at increased risk of recurrent events and should be considered for extended treatment. The use of a risk prediction score can help to identify patients with unprovoked venous thromboembolism who can benefit from extended duration therapy. Despite major advances in the management of pulmonary embolism, up to half of patients report chronic functional limitations. Such patients should be screened for chronic thromboembolic pulmonary hypertension, but only a small proportion will have this as the explanation of their symptoms. In the remaining patients, future studies are needed to understand the pathophysiology and explore interventions to improve quality of life.

Investigation and diagnostic imaging of suspected pulmonary embolism during pregnancy and the puerperium: A review of the literature

Pulmonary embolism (PE) is a leading cause of maternal mortality with women at increased risk of PE during pregnancy and the early postpartum period. Clinical assessment of suspected PE during pregnancy is challenging as signs and symptoms associated with PE overlap with physiological changes of pregnancy. Clinical tests and rules commonly used to assess pre-test probability of PE were historically not well validated in the pregnant population. The challenges of clinical assessment in the pregnant and postpartum population result in a lowered threshold for diagnostic imaging. Computed tomographic pulmonary angiography (CTPA) and nuclear medicine lung scintigraphy or ventilation/perfusion (V/Q) scans are the main types of diagnostic imaging for suspected PE. Both methods are associated with small levels of ionising radiation exposure to mother and foetus. Accuracy of the diagnostic imaging tests is paramount. Haemodynamic changes of pregnancy, including increased heart rate, increased blood volume and altered flow velocity in the pulmonary arteries, may influence the quality of imaging. This comprehensive review examines the literature and evidence for the investigation and diagnostic imaging of suspected pulmonary embolism during pregnancy with CTPA and V/Q. Clinical decision-making tools, biomarkers and diagnostic imaging during pregnancy and postpartum will be considered with a focus on diagnostic accuracy and yield, radiation dose exposure (maternal-foetal) and protocol modifications. Current practice guideline recommendations and recent literature on diagnostic pathways are also presented.

Pulmonary embolism: update on diagnosis and management

Pulmonary embolism (PE) is a potentially life-threatening condition, mandating urgent diagnosis and treatment. The symptoms of PE may be non-specific; diagnosis therefore relies on a clinical assessment and objective diagnostic testing. A clinical decision rule can determine the pre-test probability of PE. If PE is "unlikely", refer for a D-dimer test. If the D-dimer result is normal, PE can be excluded. If D-dimer levels are increased, refer for chest imaging. If PE is "likely", refer for chest imaging. Imaging with computed tomography pulmonary angiogram is accurate and preferred for diagnosing PE, but may detect asymptomatic PE of uncertain clinical significance. Imaging with ventilation-perfusion (VQ) scan is associated with lower radiation exposure than computed tomography pulmonary angiogram, and may be preferred in younger patients and pregnancy. A low probability or high probability VQ scan is helpful for ruling out or confirming PE, respectively; however, an intermediate probability VQ scan requires further investigation. The direct oral anticoagulants have expanded the anticoagulation options for PE. These are the preferred anticoagulant for most patients with PE because they are associated with a lower risk of bleeding, and have the practical advantages of fixed dosage, no need for routine monitoring, and fewer drug interactions compared with vitamin K antagonists. Initial parenteral treatment is required before dabigatran and edoxaban.

New guidelines from the Thrombosis and Haemostasis Society of Australia and New Zealand for the diagnosis and management of venous thromboembolism

INTRODUCTION

Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is the third most common cardiovascular disease and, globally, more than an estimated 10 million people have it yearly. It is a chronic and recurrent disease. The symptoms of VTE are non-specific and the diagnosis should actively be sought once considered. The mainstay of VTE treatment is anticoagulation, with few patients requiring additional intervention. A working group of experts in the area recently completed an evidence-based guideline for the diagnosis and management of DVT and PE on behalf of the Thrombosis and Haemostasis Society of Australia and New Zealand (www.thanz.org.au/resources/thanz-guidelines).

MAIN RECOMMENDATIONS

The diagnosis of VTE should be established with imaging; it may be excluded by the use of clinical prediction rules combined with D-dimer testing. Proximal DVT or PE caused by a major surgery or trauma that is no longer present should be treated with anticoagulant therapy for 3 months. Proximal DVT or PE that is unprovoked or associated with a transient risk factor (non-surgical) should be treated with anticoagulant therapy for 3-6 months. Proximal DVT or PE that is recurrent (two or more) and provoked by active cancer or antiphospholipid syndrome should receive extended anticoagulation. Distal DVT caused by a major provoking factor that is no longer present should be treated with anticoagulant therapy for 6 weeks. For patients continuing with extended anticoagulant therapy, either therapeutic or low dose direct oral anticoagulants can be prescribed and is preferred over warfarin in the absence of contraindications. Routine thrombophilia testing is not indicated. Thrombolysis or a suitable alternative is indicated for massive (haemodynamically unstable) PE.

CHANGES IN MANAGEMENT AS A RESULT OF THE GUIDELINE

Most patients with acute VTE should be treated with a factor Xa inhibitor and be assessed for extended anticoagulation.

Portable Ventilation/Perfusion Scanning is Useful for Evaluating Clinically Significant Pulmonary Embolism in the ICU Despite Abnormal Chest Radiography

OBJECTIVE

Computed tomography angiography is limited in the intensive care unit (ICU) due to renal insufficiency, hemodynamic instability, and difficulty transporting unstable patients. A portable ventilation/perfusion (V/Q) scan can be used. However, it is commonly believed that an abnormal chest radiograph can result in a nondiagnostic scan. In this retrospective study, we demonstrate that portable V/Q scans can be helpful in ruling in or out clinically significant pulmonary embolism (PE) despite an abnormal chest x-ray in the ICU.

DESIGN

Two physicians conducted chart reviews and original V/Q reports. A staff radiologist, with 40 years of experience, rated chest x-ray abnormalities using predetermined criteria.

SETTING

The study was conducted in the ICU.

PATIENTS

The first 100 consecutive patients with suspected PE who underwent a portable V/Q scan.

INTERVENTIONS

Those with a portable V/Q scan.

RESULTS

A normal baseline chest radiograph was found in only 6% of patients. Fifty-three percent had moderate, 24% had severe, and 10% had very-severe radiographic abnormalities. Despite the abnormal x-rays, 88% of the V/Q scans were low probability for a PE despite an average abnormal radiograph rating of moderate. A high-probability V/Q for PE was diagnosed in 3% of the population despite chest x-ray ratings of moderate to severe. Six patients had their empiric anticoagulation discontinued after obtaining the results of the V/Q scan, and no anticoagulation was started for PE after a low-probability V/Q scan.

CONCLUSION

Despite the large percentage of moderate-to-severe x-ray abnormalities, PE can still be diagnosed (high-probability scan) in the ICU with a portable V/Q scan. Although low-probability scans do not rule out acute PE, it appeared less likely that any patient with a low-probability V/Q scan had severe hypoxemia or hemodynamic instability due to a significant PE, which was useful to clinicians and allowed them to either stop or not start anticoagulation.

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.

Outcomes following a negative computed tomography pulmonary angiography according to pulmonary embolism prevalence: a meta-analysis of the management outcome studies

Essentials Computed tomographic pulmonary angiography (CTPA) is used to exclude pulmonary embolism. This meta-analysis explores the occurrence of venous thromboembolic events (VTE) after a CTPA. Occurrence of VTE after a negative CTPA is ˜8% in study subgroups with a prevalence of PE ≥ 40%. CTPA may be insufficient to safely rule out VTE as a stand-alone diagnostic test for this subgroup.

SUMMARY

Background Outcome studies have reported the safety of computed tomographic pulmonary angiography (CTPA) as a stand-alone imaging technique to rule out pulmonary embolism (PE). Whether this can be applied to all clinical probabilities remains controversial. Objectives We performed a meta-analysis to determine the proportion of patients with venous thromboembolic events (VTE) despite a negative CTPA according to pretest PE prevalence. Methods We searched MEDLINE, EMBASE and the Cochrane Library (January 1990 to May 2017) for outcome studies recruiting patients with suspected PE using CTPA as a diagnostic strategy. The primary outcome was the cumulative occurrence of VTE at 3 months following a negative CTPA. Results Twenty-two different studies were identified. VTE was confirmed in 2.4% of patients (95% CI, 1.3-3.8%) either at the time of the index event or in the 3 months follow-up. Subgroup analyses suggested that the cumulative occurrence of VTE was related to pretest prevalence of PE, as VTE occurred in 1.8% (95% CI, 0.5-3.7%), 1.4% (95% CI, 0.7-2.3%), 1.0% (95% CI, 0.5-1.8%) and 8.1% (95% CI, 3.5-14.5%) of subgroups of patients with a PE prevalence < 20%, 20-29%, 30-39% and ≥ 40%, respectively. This was further confirmed using meta-regression analysis. Conclusions The negative predictive value of CTPA for VTE varies according to pretest prevalence of PE, and is likely to be insufficient to safely rule out VTE as a stand-alone diagnostic test amongst patients at the highest pretest probability of VTE. Prospective studies are required to validate the appropriate diagnostic algorithm for this subgroup of patients.

Sex-specific performance of pre-imaging diagnostic algorithms for pulmonary embolism

Essentials Decision rules for pulmonary embolism are used indiscriminately despite possible sex-differences. Various pre-imaging diagnostic algorithms have been investigated in several prospective studies. When analysed at an individual patient data level the algorithms perform similarly in both sexes. Estrogen use and male sex were associated with a higher prevalence in suspected pulmonary embolism.

SUMMARY

Background In patients suspected of pulmonary embolism (PE), clinical decision rules are combined with D-dimer testing to rule out PE, avoiding the need for imaging in those at low risk. Despite sex differences in several aspects of the disease, including its diagnosis, these algorithms are used indiscriminately in women and men. Objectives To compare the performance, defined as efficiency and failure rate, of three pre-imaging diagnostic algorithms for PE between women and men: the Wells rule with fixed or with age-adjusted D-dimer cut-off, and a recently validated algorithm (YEARS). A secondary aim was to determine the sex-specific prevalence of PE. Methods Individual patient data were obtained from six studies using the Wells rule (fixed D-dimer, n = 5; age adjusted, n = 1) and from one study using the YEARS algorithm. All studies prospectively enrolled consecutive patients with suspected PE. Main outcomes were efficiency (proportion of patients in which the algorithm ruled out PE without imaging) and failure rate (proportion of patients with PE not detected by the algorithm). Outcomes were estimated using (multilevel) logistic regression models. Results The main outcomes showed no sex differences in any of the separate algorithms. With all three, the prevalence of PE was lower in women (OR, 0.66, 0.68 and 0.74). In women, estrogen use, adjusted for age, was associated with lower efficiency and higher prevalence and D-dimer levels. Conclusions The investigated pre-imaging diagnostic algorithms for patients suspected of PE show no sex differences in performance. Male sex and estrogen use are both associated with a higher probability of having the disease.

Safety of multidetector computed tomography pulmonary angiography to exclude pulmonary embolism in patients with a likely pretest clinical probability

Essentials Safety of computed tomography (CTPA) to exclude pulmonary embolism (PE) in all patients is debated. We analysed the outcome of PE-likely outpatients left untreated after negative CTPA alone. The 3-month venous thromboembolic risk in these patients was very low (0.6%; 95% CI 0.2-2.3). Multidetector CTPA alone safely excludes PE in patients with likely clinical probability.

SUMMARY

Background In patients with suspected pulmonary embolism (PE) classified as having a likely or high pretest clinical probability, the need to perform additional testing after a negative multidetector computed tomography pulmonary angiography (CTPA) finding remains a matter of debate. Objectives To assess the safety of excluding PE by CTPA without additional imaging in patients with a likely pretest probability of PE. Patients/Methods We retrospectively analyzed patients included in two multicenter management outcome studies that assessed diagnostic algorithms for PE diagnosis. Results Two thousand five hundred and twenty-two outpatients with suspected PE were available for analysis. Of these 2522 patients, 845 had a likely clinical probability as assessed by use of the simplified revised Geneva score. Of all of these patients, 314 had the diagnosis of PE excluded by a negative CTPA finding alone without additional testing, and were left without anticoagulant treatment and followed up for 3 months. Two patients presented with a venous thromboembolism (VTE) during follow-up. Therefore, the 3-month VTE risk in likely-probability patients after a negative CTPA finding alone was 2/314 (0.6%; 95% confidence interval [CI] 0.2-2.3%). Conclusions In outpatients with suspected PE and a likely clinical probability as assessed by use of the simplified revised Geneva score, CTPA alone seems to be able to safely exclude PE, with a low 3-month VTE rate, which is similar to the VTE rate following the gold standard, i.e. pulmonary angiography.

Simplified diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study

BACKGROUND

Validated diagnostic algorithms in patients with suspected pulmonary embolism are often not used correctly or only benefit subgroups of patients, leading to overuse of computed tomography pulmonary angiography (CTPA). The YEARS clinical decision rule that incorporates differential D-dimer cutoff values at presentation, has been developed to be fast, to be compatible with clinical practice, and to reduce the number of CTPA investigations in all age groups. We aimed to prospectively evaluate this novel and simplified diagnostic algorithm for suspected acute pulmonary embolism.

METHODS

We did a prospective, multicentre, cohort study in 12 hospitals in the Netherlands, including consecutive patients with suspected pulmonary embolism between Oct 5, 2013, to July 9, 2015. Patients were managed by simultaneous assessment of the YEARS clinical decision rule, consisting of three items (clinical signs of deep vein thrombosis, haemoptysis, and whether pulmonary embolism is the most likely diagnosis), and D-dimer concentrations. In patients without YEARS items and D-dimer less than 1000 ng/mL, or in patients with one or more YEARS items and D-dimer less than 500 ng/mL, pulmonary embolism was considered excluded. All other patients had CTPA. The primary outcome was the number of independently adjudicated events of venous thromboembolism during 3 months of follow-up after pulmonary embolism was excluded, and the secondary outcome was the number of required CTPA compared with the Wells' diagnostic algorithm. For the primary outcome regarding the safety of the diagnostic strategy, we used a per-protocol approach. For the secondary outcome regarding the efficiency of the diagnostic strategy, we used an intention-to-diagnose approach. This trial is registered with the Netherlands Trial Registry, number NTR4193.

FINDINGS

3616 consecutive patients with clinically suspected pulmonary embolism were screened, of whom 151 (4%) were excluded. The remaining 3465 patients were assessed of whom 456 (13%) were diagnosed with pulmonary embolism at baseline. Of the 2946 patients (85%) in whom pulmonary embolism was ruled out at baseline and remained untreated, 18 patients were diagnosed with symptomatic venous thromboembolism during 3-month follow-up (0·61%, 95% CI 0·36-0·96) of whom six had fatal pulmonary embolism (0·20%, 0·07-0·44). CTPA was not indicated in 1651 (48%) patients with the YEARS algorithm compared with 1174 (34%) patients, if Wells' rule and fixed D-dimer threshold of less than 500 ng/mL would have been applied, a difference of 14% (95% CI 12-16).

INTERPRETATION

In our study pulmonary embolism was safely excluded by the YEARS diagnostic algorithm in patients with suspected pulmonary embolism. The main advantage of the YEARS algorithm in our patients is the absolute 14% decrease of CTPA examinations in all ages and across several relevant subgroups.

FUNDING

This study was supported by unrestricted grants from the participating hospitals.

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.

Venous thromboembolism: Past, present and future

Venous thromboembolism (VTE), the third most frequent acute cardiovascular syndrome, is associated with a considerable disease burden which continues to grow along with the longer life expectancy of the population worldwide. In the past century, parenteral heparin prophylaxis was established for hospitalised patients at elevated risk of VTE. More recently, non-vitamin K antagonist oral anticoagulants (NOACs) with a direct inhibiting effect on factor Xa or thrombin, underwent extensive testing in clinical trials and have been approved for patients undergoing hip or knee replacement. Clinical investigation is ongoing in further areas of thromboprophylaxis, including medical prophylaxis in patients and high-risk situations in the outpatient setting. The diagnostic approach to suspected VTE is now based on advanced imaging techniques and robust diagnostic algorithms which ensure high sensitivity and specificity. Nevertheless, the role of clinical, or pre-test, probability assessment remains crucial to avoid overdiagnosis and treatment errors. Advances in reperfusion strategies, along progressive establishment of the NOACs as the new standard of anticoagulation treatment, have simplified the management of VTE, improving outcomes and particularly safety. While new molecular targets for anticoagulation are being investigated in the quest to further reduce bleeding risk, adjusting the initial regimen to the patient's risk and finding the optimal duration of anticoagulation after an index VTE event will be some of the top priorities in the years to come. Importantly, and in parallel to new drugs and technical advances in imaging, incentives such as hospital accreditation and funding based on evidence-based practice need to be implemented to increase guideline adherence.

Is a normal computed tomography pulmonary angiography safe to rule out acute pulmonary embolism in patients with a likely clinical probability? A patient-level meta-analysis

A normal computed tomography pulmonary angiography (CTPA) remains a controversial criterion for ruling out acute pulmonary embolism (PE) in patients with a likely clinical probability. We set out to determine the risk of VTE and fatal PE after a normal CTPA in this patient category and compare these risk to those after a normal pulmonary angiogram of 1.7 % (95 %CI 1.0-2.7 %) and 0.3 % (95 %CI 0.02-0.7 %). A patient-level meta-analysis from 4 prospective diagnostic management studies that sequentially applied the Wells rule, D-dimer tests and CTPA to consecutive patients with clinically suspected acute PE. The primary outcome was the 3-month VTE incidence after a normal CTPA. A total of 6,148 patients were included with an overall PE prevalence of 24 %. The 3-month VTE incidence in all 4,421 patients in whom PE was excluded at baseline was 1.2 % (95 %CI 0.48-2.6) and the risk of fatal PE was 0.11 % (95 %CI 0.02-0.70). In patients with a likely clinical probability the 3-month incidences of VTE and fatal PE were 2.0 % (95 %CI 1.0-4.1 %) and 0.48 % (95 %CI 0.20-1.1 %) after a normal CTPA. The 3-month incidence of VTE was 6.3 % (95 %CI 3.0-12) in patients with a Wells rule >6 points. In conclusion, this study suggests that a normal CTPA may be considered as a valid diagnostic criterion to rule out PE in the majority of patients with a likely clinical probability, although the risk of VTE is higher in subgroups such as patients with a Wells rule >6 points for which a closer follow-up should be considered.

Clinical application of the Innovance D-dimer assay in the diagnosis of acute pulmonary thromboembolism

Patients with acute pulmonary thromboembolism (APTE) have a high short-term mortality rate. The current study aimed to investigate the use of D-dimer in the diagnosis of APTE in suspected APTE patients. All suspected APTE patients were classified into diagnosis or control groups according to the results of a computed tomography pulmonary angiogram. Mann-Whitney U and Kruskal-Wallis H tests were used to evaluate the association between D-dimer values and APTE. Area under the curve (AUC) values and the Youden Index were used to determine D-dimer cut-off levels for the prediction of APTE. The data of 112 suspected APTE patients (54.8% women; mean age, 70.5 years) were analyzed prospectively. There were no significant differences in age (74.5 vs. 73.5 years, P=0.538) or gender distribution (female ratio 56.5 vs. 53.0%, P=0.847) between the diagnosis and control groups. The incidence of symptoms including dyspnea (67.4 vs. 33.3%; P<0.01), chest distress (47.8 vs. 25.8%; P<0.05) and elevated D-dimer (8.49 vs. 0.97 mg/l; P<0.001) were significantly higher in patients with APTE compared with the control group. D-dimer values >3.32 mg/l fibrinogen equivalent units (FEU) were indicative of APTE and the Youden Index was 0.69. The maximum AUC was 0.87 (95% CI: 0.79-0.92), the sensitivity and specificity were 89.13 and 80.30%, respectively, the positive and negative likelihood ratios were 4.53 and 0.14, respectively, and the positive and negative predictive values were 75.90 and 91.40%, respectively. A D-dimer value <0.60 mg/l FEU was the optimal threshold for excluding APTE diagnosis, with a sensitivity of 100.0% and a specificity of 28.79%. The positive and negative likelihood ratios were 1.40 and 0.00, respectively, and the positive and negative predictive values were 49.50 and 100.00%, respectively. Thus, D-dimer levels, combined with clinical assessment, yield high sensitivity and specificity in diagnosing APTE.

Imaging for the exclusion of pulmonary embolism in pregnancy

BACKGROUND

Pulmonary embolism is a leading cause of pregnancy-related death. An accurate diagnosis in pregnant patients is crucial to prevent untreated pulmonary embolism as well as unnecessary anticoagulant treatment and future preventive measures. Applied imaging techniques might perform differently in these younger patients with less comorbidity and altered physiology, who largely have been excluded from diagnostic studies.

OBJECTIVES

To determine the diagnostic accuracy of computed tomography pulmonary angiography (CTPA), lung scintigraphy and magnetic resonance angiography (MRA) for the diagnosis of pulmonary embolism during pregnancy.

SEARCH METHODS

We searched MEDLINE and Embase until July 2015. We used included studies as seeds in citations searches and in 'find similar' functions and searched reference lists. We approached experts in the field to help us identify non-indexed studies.

SELECTION CRITERIA

We included consecutive series of pregnant patients suspected of pulmonary embolism who had undergone one of the index tests (computed tomography (CT) pulmonary angiography, lung scintigraphy or MRA) and clinical follow-up or pulmonary angiography as a reference test.

DATA COLLECTION AND ANALYSIS

Two review authors performed data extraction and quality assessment. We contacted investigators of potentially eligible studies to obtain missing information. In the primary analysis, we regarded inconclusive index test results as a negative reference test, and treatment for pulmonary embolism after an inconclusive index test as a positive reference test.

MAIN RESULTS

We included 11 studies (four CTPA, five lung scintigraphy, two both) with a total of 695 CTPA and 665 lung scintigraphy results. Lung scintigraphy was applied by different techniques. No MRA studies matched our inclusion criteria.Overall, risk of bias and concerns regarding applicability were high in all studies as judged in light of the review research question, as was heterogeneity in study methods. We did not undertake meta-analysis. All studies used clinical follow-up as a reference standard, none in a manner that enabled reliable identification of false positives. Sensitivity and negative predictive value were therefore the only valid test accuracy measures.The median negative predictive value for CTPA was 100% (range 96% to 100%). Median sensitivity was 83% (range 0% to 100%).The median negative predictive value for lung scintigraphy was 100% (range 99% to 100%). Median sensitivity was 100% (range 0% to 100%).The median frequency of inconclusive results was 5.9% (range 0.9% to 36%) for CTPA and 4.0% (range 0% to 23%) for lung scintigraphy. The overall median prevalence of pulmonary embolism was 3.3% (range 0.0% to 8.7%).

AUTHORS' CONCLUSIONS

Both CTPA and lung scintigraphy seem appropriate for exclusion of pulmonary embolism during pregnancy. However, the quality of the evidence mandates cautious adoption of this conclusion. Important limitations included poor reference standards, necessary assumptions in the analysis regarding inconclusive test results and the inherent inability of included studies to identify false positives. It is unclear which test has the highest accuracy. There is a need for direct comparisons between diagnostic methods, including MR, in prospective randomized diagnostic studies.

Unenhanced and Contrast-Enhanced MR Angiography and Perfusion Imaging for Suspected Pulmonary Thromboembolism

OBJECTIVE

This article discusses the basics of unenhanced MR angiography (MRA) and MR venography (MRV), time-resolved contrast-enhanced (CE) MRA and dynamic first-pass CE perfusion MRI, and unenhanced and CE MRV, in addition to assessing the clinical relevance of these techniques for evaluating patients with suspected pulmonary thromboembolism and deep venous thrombosis.

CONCLUSION

Since the 1990s, the efficacy of MRA or MRV and dynamic perfusion MRI for patients with suspected pulmonary thromboembolism and deep venous thrombosis has been evaluated. On the basis of the results of single-center trials, comprehensive MRI protocols, including pulmonary unenhanced and CE MRA, perfusion MRI, and MRV, promise to be safe and time effective for assessing patients with suspected pulmonary thromboembolism, although future multicenter trials are required to assess the real clinical value of MRI.

The role of computed tomography in the diagnosis of acute and chronic pulmonary embolism

Pulmonary embolism (PE) is a potentially life threatening condition requiring adequate diagnosis and treatment. Computed tomography pulmonary angiography (CTPA) is excellent for including and excluding PE, therefore CT is the first-choice diagnostic imaging technique in patients suspected of having acute PE. Due to its wide availability and low invasiveness, CTPA tends to be overused. Correct implementation of clinical decision rules in diagnostic workup for PE improves adequate use of CT. Also, CT adds prognostic value by evaluating right ventricular (RV) function. CT-assessed RV dysfunction and to lesser extent central emboli location predicts PE-related mortality in normotensive and hypotensive patients, while PE embolic obstruction index has limited prognostic value. Simple RV/left ventricular (LV) diameter ratio measures >1.0 already predict risk for adverse outcome, whereas ratios <1.0 can safely exclude adverse outcome. Consequently, assessing the RV/LV diameter ratio may help identify patients who are potential candidates for treatment at home instead of treatment in the hospital. A minority of patients develop chronic thromboembolic pulmonary hypertension (CTEPH) following acute PE, which is a life-threatening condition that can be diagnosed by CT. In proximal CTEPH, involving the more central pulmonary arteries, thrombectomy usually results in good outcome in terms of both functional status and long-term survival rate. CT is becoming the imaging method of choice for diagnosing CTEPH as it can identify patients who may benefit from thrombectomy. New CT developments such as distensibility measurements and dual-energy or subtraction techniques may further refine diagnosis and prognosis for improved patient care.

Current and future perspectives in imaging of venous thromboembolism

Several thrombus imaging techniques for the diagnosis of venous thromboembolism (VTE) are available. The most prevalent forms of VTE are deep vein thrombosis of the lower extremities and pulmonary embolism. However, VTE may also occur at unusual sites such as deep veins of the upper extremity and the splanchnic and cerebral veins. Currently, the imaging techniques most widely used in clinical practice are compression ultrasonography and computed tomography (CT) pulmonary angiography. Moreover, single-photon emission CT, CT venography, positron emission tomography, and different magnetic resonance imaging (MRI) techniques, including magnetic resonance direct thrombus imaging, have been evaluated in clinical studies. This review provides an overview of the technique, diagnostic accuracy and potential pitfalls of these established and emerging imaging modalities for the different sites of venous thromboembolism.

Individually tailored contrast enhancement in CT pulmonary angiography

OBJECTIVE

The purpose was to evaluate individually shaped contrast media (CM) delivery in CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE).

METHODS

100 consecutive emergency patients with clinical suspicion of PE were evaluated. High-pitch CTPA was performed on a second-generation dual-source CT using the following parameters: 100 kV, 200-250 mAsref, rotation time 0.28 s, 128 × 0.6 mm col. and image reconstruction 1.0/0.8 mm (B30f). Group 1 (n = 50) then received a fixed CM bolus (300 = mgI ml(-1), volume = 90 ml and flow rate = 6 ml s(-1)); Group 2 (n = 50) received a body weight-adapted CM bolus determined by dedicated contrast injection software. For analysis, groups were further subdivided into low-weight (40-75 kg) and high-weight (76-117 kg) groups. Technical image quality was graded using a four-point Likert scale (1 = non-diagnostic; 2 = diagnostic; 3 = good and 4 = excellent image quality) at the level of the pulmonary trunk and pulmonary arteries. Objective image quality analysis was performed by measuring contrast enhancement in Hounsfield units (HU) at the same levels. Attenuation levels > 180 HU were considered diagnostic.

RESULTS

All examinations were graded as diagnostic at each level. The individual minimum pulmonary attenuation was 184 and 270 HU for Group 1 and 2, respectively. Mean attenuation was as follows: Group 1: 475 ± 105 HU (40-75 kg) and 402 ± 115 HU (76-117 kg), p < 0.03. Group 2: 424 ± 76 HU (40-75 kg) and 418 ± 100 HU (76-117 kg), p = 0.8. For Group 2, CM volumes were: 55 ± 5 ml (40-75 kg) and 66 ± 5 ml (76-117 kg), leading to 16-51% CM reduction.

CONCLUSION

Even under emergency conditions, individualized CM protocols can provide diagnostic and robust image quality in CTPA for PE with a substantial reduction of CM volume for lower weight patients, compared with a fixed CM protocol.

ADVANCES IN KNOWLEDGE

CM volume can substantially be reduced by using individualized CM protocols in CT angiography for PE without compromising the diagnostic image quality.

Recent developments in the diagnosis and treatment of pulmonary embolism

Due to the nonspecific symptoms of the condition, a diagnosis of acute pulmonary embolism (PE) is frequently considered. However, PE will only be confirmed in 10-20% of patients. Because the imaging test of choice, computed tomography pulmonary angiography (CTPA), is costly and associated with radiation exposure and other complications, a validated diagnostic algorithm consisting of a clinical decision rule and D-dimer test should be used to safely exclude PE in 20-30% of patients without the need for CTPA. Recently, the age-adjusted D-dimer threshold has been validated, and this has increased the proportion of patients at older age in whom PE can be excluded without CTPA. Initial therapeutic management of PE depends on the risk of short-term PE-related mortality. Haemodynamically unstable patients should be closely monitored and receive thrombolytic therapy unless contraindicated because of an unacceptably high bleeding risk, whereas patients with low-risk PE may be safely discharged early from hospital or receive only outpatient treatment. The PESI score and Hestia decision rule are available to select patients in whom early discharge or outpatient treatment will be safe, although the safety of these strategies should be confirmed in additional studies. Standard PE therapy consists of low molecular weight heparin (LMWH) followed by vitamin K antagonists (VKAs). Recently, several nonvitamin K-dependent oral anticoagulants have been shown to be as effective as LMWH/VKAs, and maybe safer. Determining the optimal duration of treatment for a first unprovoked PE remains a challenge, although clinical prediction rules for estimating the risk of recurrence of venous thromboembolism and anticoagulation-associated haemorrhage are under investigation. Using these prediction rules may lead to both more standardized and more individualized long-term treatment of PE.

Multidetector computed tomographic pulmonary angiography in patients with a high clinical probability of pulmonary embolism

ESSENTIALS: When high probability of pulmonary embolism (PE), sensitivity of computed tomography (CT) is unclear. We investigated the sensitivity of multidetector CT among 134 patients with a high probability of PE. A normal CT alone may not safely exclude PE in patients with a high clinical pretest probability. In patients with no clear alternative diagnosis after CTPA, further testing should be strongly considered.

BACKGROUND

Whether patients with a negative multidetector computed tomographic pulmonary angiography (CTPA) result and a high clinical pretest probability of pulmonary embolism (PE) should be further investigated is controversial.

METHODS

This was a prospective investigation of the sensitivity of multidetector CTPA among patients with a priori clinical assessment of a high probability of PE according to the Wells criteria. Among patients with a negative CTPA result, the diagnosis of PE required at least one of the following conditions: ventilation/perfusion lung scan showing a high probability of PE in a patient with no history of PE, abnormal findings on venous ultrasonography in a patient without previous deep vein thrombosis at that site, or the occurrence of venous thromboembolism (VTE) in a 3-month follow-up period after anticoagulation was withheld because of a negative multidetector CTPA result.

RESULTS

We identified 498 patients with a priori clinical assessment of a high probability of PE and a completed CTPA study. CTPA excluded PE in 134 patients; in these patients, the pooled incidence of VTE was 5.2% (seven of 134 patients; 95% confidence interval [CI] 1.5-9.0). Five patients had VTEs that were confirmed by an additional imaging test despite a negative CTPA result (five of 48 patients; 10.4%; 95% CI 1.8-19.1), and two patients had objectively confirmed VTEs that occurred during clinical follow-up of at least 3 months (two of 86 patients; 2.3%; 95% CI 0-5.5). None of the patients had a fatal PE during follow-up.

CONCLUSIONS

A normal multidetector CTPA result alone may not safely exclude PE in patients with a high clinical pretest probability.

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.

Current challenges in diagnostic imaging of venous thromboembolism

Because the clinical diagnosis of deep-vein thrombosis and pulmonary embolism is nonspecific, integrated diagnostic approaches for patients with suspected venous thromboembolism have been developed over the years, involving both non-invasive bedside tools (clinical decision rules and D-dimer blood tests) for patients with low pretest probability and diagnostic techniques (compression ultrasound for deep-vein thrombosis and computed tomography pulmonary angiography for pulmonary embolism) for those with a high pretest probability. This combination has led to standardized diagnostic algorithms with proven safety for excluding venous thrombotic disease. At the same time, it has become apparent that, as a result of the natural history of venous thrombosis, there are special patient populations in which the current standard diagnostic algorithms are not sufficient. In this review, we present 3 evidence-based patient cases to underline recent developments in the imaging diagnosis of venous thromboembolism.

Prevalence and clinical significance of extravascular incidental findings in patients undergoing CT cervico-cerebral angiography

INTRODUCTION

CT cervico-cerebral angiography (CTCCA) is now the first line diagnostic imaging modality for the majority of vascular pathologies of the head and neck with diagnostic value comparable to or better than traditional angiographic techniques. The aim of this study was to assess the prevalence, clinical significance and management of extravascular incidental findings detected on CTCCA.

MATERIALS AND METHODS

A retrospective review of the CTCCA reports of 302 consecutive patients from 2009 to 2013 was undertaken. Extravascular incidental findings were classified, according to an adaptation of the CT colonography data and reporting system (CRADS), as EV1-EV4. EV1=no incidental findings, EV2=clinically insignificant incidental finding, EV3=incidental finding of intermediate clinical significance, EV4=highly clinically significant finding. Follow up of the electronic medical records of patients with EV3 or EV4 findings was undertaken to determine subsequent management.

RESULTS

Potentially clinically significant findings were demonstrated in 14.2% of patients with 8.6% of patients having a highly clinically significant finding. 4 incidental findings were confirmed to be malignant lesions and 5 required acute intervention. In addition 19% of patients with highly clinically significant incidental findings did not receive appropriate follow up.

DISCUSSION

This study has demonstrated the presence of clinically important incidental findings in a significant proportion of patients undergoing CTCCA with a significant minority of these patients not receiving follow up. A standardised method of reporting incidental findings, such as that used in this paper, would aid radiologists and referring physicians in recording and communicating these findings.

Triage for suspected acute Pulmonary Embolism: Think before opening Pandora's Box

This is a review of the current strengths and weaknesses of the various imaging modalities available for the diagnosis of suspected non-massive Pulmonary Embolism (PE). Without careful consideration for the clinical presentation, and the timely application of clinical decision support (CDS) methodology, the current overutilization of imaging resources for this disease will continue. For a patient with a low clinical risk profile and a negative D-dimer there is no reason to consider further workup with imaging; as the negative predictive value in this scenario is the same as imaging. While the current efficacy and effectiveness data support the continued use of Computed Tomographic angiography (CTA) as the imaging golden standard for the diagnosis of PE; this test does have the unintended consequences of radiation exposure, possible overdiagnosis and overuse. There is a persistent lack of appreciation on the part of ordering physicians for the effectiveness of the alternatives to CTA (ventilation-perfusion imaging and contrast enhanced magnetic resonance angiography) in these patients. Careful use of standardized protocols for patient triage and the application of CDS will allow for a better use of imaging resources.

Current challenges in diagnostic imaging of venous thromboembolism

Because the clinical diagnosis of deep-vein thrombosis and pulmonary embolism is nonspecific, integrated diagnostic approaches for patients with suspected venous thromboembolism have been developed over the years, involving both non-invasive bedside tools (clinical decision rules and D-dimer blood tests) for patients with low pretest probability and diagnostic techniques (compression ultrasound for deep-vein thrombosis and computed tomography pulmonary angiography for pulmonary embolism) for those with a high pretest probability. This combination has led to standardized diagnostic algorithms with proven safety for excluding venous thrombotic disease. At the same time, it has become apparent that, as a result of the natural history of venous thrombosis, there are special patient populations in which the current standard diagnostic algorithms are not sufficient. In this review, we present 3 evidence-based patient cases to underline recent developments in the imaging diagnosis of venous thromboembolism.

CT angiography in the diagnosis of cardiovascular disease: a transformation in cardiovascular CT practice

Computed tomography (CT) angiography represents the most important technical development in CT imaging and it has challenged invasive angiography in the diagnostic evaluation of cardiovascular abnormalities. Over the last decades, technological evolution in CT imaging has enabled CT angiography to become a first-line imaging modality in the diagnosis of cardiovascular disease. This review provides an overview of the diagnostic applications of CT angiography (CTA) in cardiovascular disease, with a focus on selected clinical challenges in some common cardiovascular abnormalities, which include abdominal aortic aneurysm (AAA), aortic dissection, pulmonary embolism (PE) and coronary artery disease. An evidence-based review is conducted to demonstrate how CT angiography has changed our approach in the diagnosis and management of cardiovascular disease. Radiation dose reduction strategies are also discussed to show how CT angiography can be performed in a low-dose protocol in the current clinical practice.

Performance of a diagnostic algorithm based on a prediction rule, D-dimer and CT-scan for pulmonary embolism in patients with previous venous thromboembolism. A systematic review and meta-analysis

Diagnostic management of suspected pulmonary embolism (PE) in patients with a history of venous thromboembolism (VTE) is complicated due to persistent abnormal D-dimer levels, residual embolic obstruction and higher clinical prediction rule (CPR) scores. We aimed to evaluate the safety and efficiency of the standard diagnostic algorithm consisting of a CPR, D-dimer test and computed tomography pulmonary angiography (CTPA) in this specific patient category. We performed a systematic literature search for prospective studies evaluating a diagnostic algorithm in consecutive patients with clinically suspected PE and a history of VTE. The VTE incidence rates during three-month follow-up and the number of indicated CTPAs were pooled using random effect models. Four studies concerning 1,286 patients were included with a pooled baseline PE prevalence of 36 % (95 % confidence interval [CI] 30-42). In only 217 patients (15 %; 95 %CI 11-20) PE could be excluded without CTPA. The three-month VTE incidence rate was 0.8 % (95 %CI 0.06-2.4) in patients managed without CTPA, 1.6 % (95 %CI 0.3-4.0) in patients in whom PE was excluded by CTPA and 1.4 % (95 %CI 0.6-2.7) overall. In the pooled studies, PE was safely excluded in patients with a history of VTE based on a CPR followed by a D-dimer test and/or CTPA, although the efficiency of the algorithm is relatively low compared to patients without a history of VTE.

[Practical conduct for patients with a lonely hypoxemia at rest or during exercise]

INTRODUCTION

Hypoxemia is a decrease in blood oxygen partial pressure. This work aims at presenting a practical conduct for patients with a lonely hypoxemia at rest or during exercise, defined by the absence of dyspnea at rest, obvious clinical or radiographic abnormality.

STATE OF THE ART

Diagnostic tools available to the clinician are clinical examination, CT scan, echocardiography, hyperoxia test, trans cranial ultrasound and lung scintigraphy. This work proposes a practical diagnostic approach, with a main role of chest CT.

PERSPECTIVES

Work is underway to determine more precisely the place of echocardiography for the diagnosis of intra or extra cardiac shunts.

CONCLUSIONS

The finding of a lonely hypoxemia requires careful diagnostic approach to quickly rule out potentially serious causes and not to disregard the rare causes.

Systematic review and meta-analysis of pregnant patients investigated for suspected pulmonary embolism in the emergency department

OBJECTIVES

Pregnancy causes a small increase in risk of venous thromboembolism (VTE), but a large increase in concern upon presentation to an emergency department (ED) with symptoms of pulmonary embolism (PE), which may cause physicians to employ a low test threshold. This was a systematic review with the hypothesis that symptomatic pregnant patients in the ED have a low relative risk (RR) for VTE outcome.

METHODS

Studies in all languages were identified by structured search of PubMed, EMBASE, the Cochrane library, and bibliographies in February 2014. Papers with ED patients evaluated for possible PE that included pregnancy status, and had adequate reference standards, were included. An outcome of VTE (either deep venous thrombosis [DVT] or PE) was considered disease-positive (VTE+). Papers were assessed for selection and publication bias, and heterogeneity (I(2) ). The random effects model was used if I(2)  > 24%.

RESULTS

Seventeen full-length studies of 25,339 patients were analyzed. Pooled data showed I² = 0% with a symmetrical funnel plot. Two small studies with less than 1% of all patients had evidence of selection bias. The frequency of VTE+ rate among the 506 pregnant patients was 4.1% (95% confidence interval [CI] = 2.6% to 6.0%), compared with 12.4% (95% CI = 9.0% to 16.3%) among nonpregnant patients. The pooled RR of pregnancy for VTE+ diagnosis was 0.60 (95% CI = 0.41 to 0.87). Patients in the third trimester had a RR of 0.85 (95% CI = 0.40 to 1.77), and patients of childbearing age (≤45 years) had a RR of 0.56 (95% CI = 0.34 to 0.93).

CONCLUSIONS

In the ED setting, physicians test for PE in pregnant patients at a low threshold, resulting in a low rate of VTE diagnosis and a RR of VTE that is lower than that for nonpregnant women of childbearing age who are tested for PE in the ED setting.