D-dimer levels to exclude pulmonary embolism and reduce the need for CT angiography in COVID-19 in an outpatient population

OBJECTIVES

Emerging results indicate that, in COVID-19, thromboembolic complications contribute to the high mortality and morbidity. Previous research showed that the prevalence of pulmonary embolism (PE) is between 25-50% in COVID-19 patients, however, most of these reports are based on data from patients with severe pneumonia, treated in intensive care units.

MATERIALS AND METHODS

We conducted a retrospective, single-center, observational study to estimate the prevalence of PE in COVID-19 patients who underwent CT angiography and to identify the most important predictors. Adult outpatients with COVID-19, who presented at our COVID Outpatient Clinic between 1st and 31st of March in 2021 and underwent CTA examination were included in this study. Multiple linear regression analysis was used to identify predictors of PE in COVID-19 patients. The predictors were: age, gender, disease duration, CT severity index and log-transformed quantitative D-dimer (logQDDIM) value.

RESULTS

843 COVID-19 patients were included into the study. 82.56% (693 patients) of the infected patients had a pulmonary CTA examination and D-dimer levels (mean age: 59.82 years ± 15.66). 7.61% (53 patients) of the patients had PE. 2.02% (14 patients) of the patients had main branch or lobar PE. The multiple regression analysis found that only logQDDIM was a significant predictor. A logQDDIM cut-off value of 0.0169 (1.0171 ug/ml serum D-dimer) predicted PE with 99% sensitivity (p<0.0001, degree-of-freedom = 570, AUC = 0.72).

CONCLUSIONS

We demonstrated in a large cohort of COVID-19 patients that a cut-off value of QDDIM of 1ug/ml can exclude pulmonary embolism in an outpatient setting, implicating that QDDIM might potentially supersede CTA as a screening approach in COVID-19 outpatient clinics.

Feasibility of monitoring the resolution of acute pulmonary embolism with non-contrast-enhanced magnetic resonance imaging at one day, one week, one, three, and six months

BACKGROUND

Pulmonary embolism (PE) is a common cause of death with an incidence of approximately 1-2 cases per 1000 inhabitants in Europe and the United States. Treatment for PE is the administration of anticoagulants for at least three months.

PURPOSE

To assess the feasibility of following the resolution rate of PE over time using repeated imaging with a non-contrast-enhanced magnetic resonance imaging (MRI) protocol.

MATERIAL AND METHODS

Patients (n = 18) diagnosed with acute PE via computed tomography pulmonary angiography (CTPA) underwent non-contrast-enhanced MRI at two tertiary hospitals. The first MRI was performed within 36 h of CTPA, with follow-up at one week, one, three, and six months. The MRI sequence used was a non-contrast-enhanced standard two-dimensional steady-state free precession under free-breathing and without respiratory or cardiac gating. All MRI scans were then compared to the initial CTPA. The emboli were assessed visually for location and size, and clot burden was calculated using the Qanadli score.

RESULTS

MRI revealed complete resolution in seven cases at one week, in five cases at one month, and in three cases at three months. The most significant resolution of emboli occurred within the first few weeks, with only 10% of the diagnosed emboli persisting at the one-month examination.

CONCLUSION

The use of MRI imparts the ability to visualize PE without radiation and thus allows multiple examinations to be made, for example in studies investigating the resolution of PE or the evaluation of drug effect in clinical trials.

Reproducibility of pulmonary magnetic resonance angiography in adults with muco-obstructive pulmonary disease

BACKGROUND

Recent studies support magnetic resonance angiography (MRA) as a diagnostic tool for pulmonary arterial disease.

PURPOSE

To determine MRA image quality and reproducibility, and the dependence of MRA image quality and reproducibility on disease severity in patients with chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF).

MATERIAL AND METHODS

Twenty patients with COPD (mean age 66.5 ± 8.9 years; FEV1% = 42.0 ± 13.3%) and 15 with CF (mean age 29.3 ± 9.3 years; FEV1% = 66.6 ± 15.8%) underwent morpho-functional chest magnetic resonance imaging (MRI) including time-resolved MRA twice one month apart (MRI1, MRI2), and COPD patients underwent non-contrast computed tomography (CT). Image quality was assessed visually using standardized subjective 5-point scales. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were measured by regions of interest. Disease severity was determined by spirometry, a well-evaluated chest MRI score, and by computational CT emphysema index (EI) for COPD.

RESULTS

Subjective image quality was diagnostic for all MRA at MRI1 and MRI2 (mean score = 4.7 ± 0.6). CNR and SNR were 4 43.8 ± 8.7 and 50.5 ± 8.7, respectively. Neither image quality score nor CNR or SNR correlated with FEV1% or chest MRI score for COPD and CF (r = 0.239-0.248). CNR and SNR did not change from MRI1 to MRI2 (P = 0.434-0.995). Further, insignificant differences in CNR and SNR between MRA at MRI1 and MRI2 did not correlate with FEV1% nor chest MRI score in COPD and CF (r = -0.238-0.183), nor with EI in COPD (r = 0.100-0.111).

CONCLUSION

MRA achieved diagnostic quality in COPD and CF patients and was highly reproducible irrespective of disease severity. This supports MRA as a robust alternative to CT in patients with underlying muco-obstructive lung disease.

Clinical controversies in the management of acute pulmonary embolism: evaluation of four important but controversial aspects of acute pulmonary embolism management that are still subject of debate and research

INTRODUCTION

Acute pulmonary embolism (PE) is a disease with a broad spectrum of clinical presentations. While some patients can be treated at home or may even be left untreated, other patients require an aggressive approach with reperfusion treatment.

AREAS COVERED

(1) Advanced reperfusion treatment in hemodynamically stable acute PE patients considered to be at high risk of decompensation and death, (2) the treatment of subsegmental pulmonary embolism, (3) outpatient treatment for hemodynamically stable PE patients with signs of right ventricle (RV) dysfunction, and (4) the optimal approach to identify and treatpost-PE syndrome.

EXPERT OPINION

Outside clinical trials, hemodynamically stable acute PE patients should not be treated with primary reperfusion therapy. Thrombolysis and/or catheter-directed therapy are only to be considered as rescue treatment. Subsegmental PE can be left untreated in selected low-risk patients, after proximal deep vein thrombosis has been ruled out. Patients with an sPESI or Hestia score of 0 criteria can be treated at home, independent of the presence of RV overload. Finally, health-care providers should be aware of post-PE syndrome and diagnose chronic thromboembolic pulmonary disease (CTEPD) as early as possible. Persistently symptomatic patients without CTEPD benefit from exercise training and cardiopulmonary rehabilitation.

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.

Comparing ‘clinical hunch’ against clinical decision support systems (PERC rule, wells score, revised Geneva score and YEARS criteria) in the diagnosis of acute pulmonary embolism

Background

Pulmonary embolism (PE) is a common and potentially life-threatening condition. Since it is considered a ‘do not miss’ diagnosis, PE tends to be over-investigated beyond the evidence-based clinical decision support systems (CDSS), which in turn subjects patients to unnecessary radiation and contrast agent exposure with no apparent benefits in terms of outcome.

The purpose of this study was to evaluate the yield of ‘clinical hunch’ (gestalt) and four CDSS: the PERC Rule, Wells score, revised Geneva score, and Years criteria.

Methods

A review was conducted on the Electronic Medical Records (EMR) of 1566 patients from the Emergency Department at a tertiary teaching hospital who underwent CTPA from the 1st of January 2018 to the 31st of December 2019. The scores for the four CDSS were calculated retrospectively from the EMR data. We considered that a CTPA had been ordered on a clinical hunch when there was no mention of CDSS in the EMR, and no D-dimer test. A bypass of CDSS was confirmed when any step of the diagnostic algorithms was not followed.

Results

Of the total 1566 patients who underwent CTPA, 265 (17%) were positive for PE. The diagnosis yield from the five decision groups (clinical hunch and four CDSS) was as follows—clinical hunch, 15%; PERC rule, 18% (6% when bypassed); Wells score, 19% (11% when bypassed); revised Geneva score, 26% (13% when bypassed); and YEARS criteria, 18% (6% when bypassed).

Conclusion

Clinicians should trust the evidence-based clinical decision support systems in line with the international guidelines to diagnose PE.

Using barium as an internal radioprotective shield for pregnant patients undergoing CT pulmonary angiography: A retrospective study

PURPOSE

The purpose of our retrospective study was to assess the effect of barium sulfate contrast medium on radiation dose and diagnostic quality of CT Pulmonary Angiography (CTPA) in an in-vivo study of pregnant patients.

METHODS

Our retrospective study included 33 pregnant patients who underwent CTPA to exclude pulmonary embolism. The patients received oral 40% w/v barium solution just prior to the acquisition of their planning radiograph. All CTPA were performed on 64-slice, single-source CT scanners with AEC with noise index = 28.62-31.64 and the allowed mA range of 100-450. However, only 5/33 patients had mA modulation (AEC 100-450 mA range), while 28/33 patients had mA maxed out at the set maximum mA of 450 over the entire scan range. We recorded CTDIvol (mGy), DLP (mGy.cm) and scan length. The same information was recorded in weight-and scanner-matched, non-pregnant patients. Statistical tests included descriptive data (median and interquartile range) and Mann-Whitney test.

RESULTS

There were no significant differences in CTDIvol and DLP between the barium and control group patients (p > 0.1). The median mA below the diaphragm was significantly higher in each patient with barium compared to the weight and scanner-matched patient without barium. Evaluation of lung and subsegmental lower lobe pulmonary arteries was limited in 85% barium group. Due to thin prospective section thickness (1.25 mm), most patients were scanned at maximum allowed mA for AEC.

CONCLUSION

Use of AEC with thick barium in pregnant patients undergoing CTPA as an internal radioprotective shield produces counterproductive artifacts and tube current increments.

Influence of using recommended radiological criteria on MDCT-angiography diagnosis of single isolated subsegmental pulmonary embolism

OBJECTIVES

We assessed the rate of false-positive diagnoses of MDCT-pulmonary angiography (MDCT-A) in patients with single isolated subsegmental pulmonary embolism (SISSPE).

METHODS

All patients who underwent MDCT-A between 2006 and 2017 for ruling out acute pulmonary embolism (PE) and received an initial diagnosis of SISSPE were included. The MDCT-A of these patients were reviewed retrospectively by four experienced thoracic radiologists, who applied radiological criteria recommended by the American College of Chest Physicians Antithrombotic Guidelines (ACCP 2016) for the diagnosis of SISSPE. Data extracted from medical records were history of venous thromboembolism (VTE), alternative diagnoses, other diagnostic studies for VTE, anticoagulation, bleeding complications, and VTE over the following 3 months.

RESULTS

Of 3839 patients undergoing MDCT-A, PE was found in 1021 (26.6%) and SISSPE in 59 (1.5% overall and 5.8% of all patients with PE). An alternative diagnosis to PE was made on the basis of CT in 33 (55.9%) patients. Forty-one (69.5%) patients received anticoagulants, and major life-threatening bleeding complications occurred in 2, with one death. Recurrent PE was not documented in any patient with SISSPE. In the retrospective assessment of the 59 cases of SISSPE, 21 were negative for PE, with a false-positive rate of 35.6% (21/59); so the percentage of SISSPE cases after the revision was 3.7% of all patients with PE; 11 of these 21 patients received anticoagulation.

CONCLUSIONS

Radiologists should be aware of the high rate of false-positives when making the diagnosis of SISSPE on MDCT-A without using strict diagnostic criteria. Misdiagnosis exposes patients to unnecessary anticoagulation.

KEY POINTS

• Radiologist should be aware of the high rate of false-positive diagnoses of single isolated subsegmental pulmonary embolism (SISSPE) in MDCT-pulmonary angiography (MDCT-A) performed for ruling out pulmonary embolism. • Misdiagnosis of SISSPE in MDCT-A can be reduced by using strict diagnostic radiological criteria recommended by the American College of Chest Physicians Antithrombotic Guidelines. • Unnecessary anticoagulation therapy with potential severe bleeding complications may result from misdiagnosis of SISSPE.

Effect of a Diagnostic Strategy Using an Elevated and Age-Adjusted D-Dimer Threshold on Thromboembolic Events in Emergency Department Patients With Suspected Pulmonary Embolism: A Randomized Clinical Trial

IMPORTANCE

Uncontrolled studies suggest that pulmonary embolism (PE) can be safely ruled out using the YEARS rule, a diagnostic strategy that uses varying D-dimer thresholds.

OBJECTIVE

To prospectively validate the safety of a strategy that combines the YEARS rule with the pulmonary embolism rule-out criteria (PERC) rule and an age-adjusted D-dimer threshold.

DESIGN, SETTINGS, AND PARTICIPANTS

A cluster-randomized, crossover, noninferiority trial in 18 emergency departments (EDs) in France and Spain. Patients (N = 1414) who had a low clinical risk of PE not excluded by the PERC rule or a subjective clinical intermediate risk of PE were included from October 2019 to June 2020, and followed up until October 2020.

INTERVENTIONS

Each center was randomized for the sequence of intervention periods. In the intervention period (726 patients), PE was excluded without chest imaging in patients with no YEARS criteria and a D-dimer level less than 1000 ng/mL and in patients with 1 or more YEARS criteria and a D-dimer level less than the age-adjusted threshold (500 ng/mL if age <50 years or age in years × 10 in patients ≥50 years). In the control period (688 patients), PE was excluded without chest imaging if the D-dimer level was less than the age-adjusted threshold.

MAIN OUTCOMES AND MEASURES

The primary end point was venous thromboembolism (VTE) at 3 months. The noninferiority margin was set at 1.35%. There were 8 secondary end points, including chest imaging, ED length of stay, hospital admission, nonindicated anticoagulation treatment, all-cause death, and all-cause readmission at 3 months.

RESULTS

Of the 1414 included patients (mean age, 55 years; 58% female), 1217 (86%) were analyzed in the per-protocol analysis. PE was diagnosed in the ED in 100 patients (7.1%). At 3 months, VTE was diagnosed in 1 patient in the intervention group (0.15% [95% CI, 0.0% to 0.86%]) vs 5 patients in the control group (0.80% [95% CI, 0.26% to 1.86%]) (adjusted difference, -0.64% [1-sided 97.5% CI, -∞ to 0.21%], within the noninferiority margin). Of the 6 analyzed secondary end points, only 2 showed a statistically significant difference in the intervention group compared with the control group: chest imaging (30.4% vs 40.0%; adjusted difference, -8.7% [95% CI, -13.8% to -3.5%]) and ED median length of stay (6 hours [IQR, 4 to 8 hours] vs 6 hours [IQR, 5 to 9 hours]; adjusted difference, -1.6 hours [95% CI, -2.3 to -0.9]).

CONCLUSIONS AND RELEVANCE

Among ED patients with suspected PE, the use of the YEARS rule combined with the age-adjusted D-dimer threshold in PERC-positive patients, compared with a conventional diagnostic strategy, did not result in an inferior rate of thromboembolic events.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04032769.

Clinical and angiopulmonographic association in pulmonary embolism

Aim. To detect the effect of the feature of the pulmonary vascular obstruction on the clinical manifestations of pulmonary embolism (PE). Materials and methods. The 127 patients with PE were included in this study. PE verified with multidetector computed tomography with pulmonary angiography. Among them were 57 patients with high-risk PE, and 39 patients with intermediate-risk PE and 31 patients with low-risk PE. The pulmonary artery obstruction index and the obstruction level were determined. Results. The mean values of the pulmonary artery obstruction index in high and intermediate risk patients were 42.5%, and in low risk patients 12.5% (p0.001). The trunk or main branches obstruction was in 80.7% of high-risk PE patients, the main or lobar branches obstruction in 92.3% of intermediate-risk patients and lobar or segmental branches obstruction in 93.5% of low-risk patients. Pulmonary infarction was detected in 89.2% of patients with the segmental branches obstruction and with another level of obstruction in 28.0% of patients only (p0.001). Conclusion. The hemodynamic disorder in pulmonary embolism associate with the pulmonary artery obstruction index of more than 30%. The development of obstructive shock is associated with the pulmonary artery trunk obstruction, and the development of pulmonary infarction associated with the segmental branches obstruction.

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.

Primary diagnosis of pulmonary embolism with unenhanced MRI for patients not eligible for CTPA: Clinical outcome

Purpose

To follow up the clinical outcome of patients with suspected pulmonary embolism (PE), in those only imaged using unenhanced, free-breathing magnetic resonance imaging (MRI).

Methods and materials

Fifty-seven patients aged 29-99 years (mean 70, SD 18) that could not undergo Computed Tomography Pulmonary Angiography (CTPA) were offered alternative imaging diagnostics in parallel with ongoing methodological studies validating MRI vs CTPA. Contraindications included renal failure (n = 44), severe iodine contrast allergy (n = 10), pregnancy (n = 2) and radioactive iodine therapy (n = 1). The unenhanced MRI protocol was based on free-breathing, steady-state free precession with no cardiac or respiratory gating. Retrospective review of the electronic medical record (EMR) was made of 0-12 months post-imaging and was collected during 2012-2018.

Results

All 57 MRIs were of diagnostic quality and 12 pulmonary embolisms were diagnosed. Of the 57 patients, 44 were already on, or had started anticoagulation therapy due to clinical suspicion of PE. Four of the patients were put on anticoagulation after the positive MRI and 13 were taken off anticoagulation after a negative MRI report. Other diagnoses reported (considering dyspnea) were pleural effusion (n = 24), consolidation (n = 12) and pericardial effusion (n = 2). One patient had a deep vein thrombosis (DVT) within three months of our negative MRI result and then had a stroke within one year. Another patient suffered a stroke within three months of being diagnosed (by MRI) with PE and given anticoagulation as treatment.

Conclusions

Our method supported or altered clinical decision-making and treatment in this cohort. A diagnostic tool for PE without intravenous contrast agent or radiation is of great benefit for certain patients.

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.

Computed Tomography Pulmonary Angiography during Pregnancy: Radiation Dose of Commonly Used Protocols and the Effect of Scan Length Optimization

Objective

To evaluate the radiation dose for pregnant women and fetuses undergoing commonly used computed tomography of the pulmonary arteries (CTPA) scan protocols and subsequently evaluate the simulated effect of an optimized scan length.

Materials and Methods

A total of 120 CTPA datasets were acquired using four distinctive scan protocols, with 30 patients per protocol. These datasets were mapped to Cristy phantoms in order to simulate pregnancy and to assess the effect of an effective radiation dose (in mSv) in the first, second, or third trimester of pregnancy, including a simulation of fetal dose in second and third trimesters. The investigated scan protocols involved a 64-slice helical scan at 120 kVp, a high-pitch dual source acquisition at 100 kVp, a dual-energy acquisition at 80/140 kVp, and an automated-kV-selection, high pitch helical scan at a reference kV of 100 kV_ref. The effective dose for women and fetuses was simulated before and after scan length adaptation. The original images were interpreted before and after scan length adaptations to evaluate potentially missed diagnoses.

Results

Large inter-scanner and inter-protocol variations were found; application of the latest technology decreased the dose for non-pregnant women by 69% (7.0–2.2 mSv). Individual scan length optimization proved safe and effective, decreasing the fetal dose by 76–83%. Nineteen (16%) cases of pulmonary embolism were diagnosed and, after scan length optimization, none were missed.

Conclusion

Careful CTPA scan protocol selection and additional optimization of scan length may result in significant radiation dose reduction for a pregnant patient and her fetus, whilst maintaining diagnostic confidence.

Histological validation of pulmonary infarction detected with contrast-enhanced ultrasound in patients with negative computed tomography pulmonary angiogram: A case series

OBJECTIVE

The purpose of this case series is to evaluate the diagnostic potential of contrast-enhanced ultrasound (CEUS) in patients with clinically suspected pulmonary embolism (PE), suspicious pleural lesions, and negative computed tomography pulmonary angiogram (CTPA).

PATIENTS/METHODS

Between January 2017 and January 2018, we examined patients with an intermediate or a high-risk Wells score and a negative CTPA with lung B-mode ultrasound (LUS). In a total of six patients, pleural defects were identified and further examined by CEUS. Nonenhancing lesions or those with inhomogeneous enhancement were considered to be suspicious for an embolic event and biopsied for histological validation. The data analysis was retrospective.

RESULTS

In LUS, the lesions had an average size of 2.4 cm (range 2-3 cm). Five were hypoechoic and one was complex. The shape was wedge shaped (n = 5) or round (n = 1), and the number was solitary (n = 4) or multiple (n = 2) with dorsobasal localization (n = 6). Three lesions were nonenhancing, and three had an inhomogeneous enhancement with areas with complete absence of enhancement. The histological examination showed pulmonary infarction in all six cases, and in one patient also cells of a lung carcinoma.

CONCLUSION

Our case series demonstrates the diagnostic potential of CEUS for detecting peripheral pulmonary infarction in patients with clinically suspected PE and negative CTPA scan regarding PE. A histological validation or a narrow follow-up might be warranted in some cases.

Computed tomography pulmonary angiography using high-pitch dual-source scanner technology

Objectives:

To compare use of ultra-fast high-pitch dual-source free-breathing computed tomography pulmonary angiogram (CTPA) with conventional standard-pitch single-source breath-hold CTPA.

Methods:

This retrospective comparative study was conducted in Radiology Department at King Fahad Military Medical Complex Dhahran, Saudi Arabia from July 2016 to December 2017. Patients (N=130) were divided into 2 groups, each having 65 consecutive patients; Group-1 (single-source CT) and Group-2 (dual-source CT). Previously treated pulmonary embolism cases, pregnant patients and those with incomplete data were excluded. Image quality was subjectively assessed by 2 readers for adequacy of contrast opacification and pulmonary vessel outline, and presence of artifacts (breathing motion, cardiac pulsation, and contrast related). Scan acquisition times and radiation doses were also compared. Chi-square and t-test were used to determine association.

Results:

Improved image quality (optimal studies without artifacts 91%) was seen in Group-2 compared to Group-1 (optimal studies without artifacts 75.4%). Also, reduced scan time (1-2 sec.) and radiation dose (mean dose length product (DLP)-248 mGy-cm) were observed in Group-2 compared to Group-1 (scan time- 6.5 sec, mean DLP-375). Results were found significant (p<0.05).

Conclusion:

High-pitch dual-source CT with free-breathing yields better image quality, reduces image acquisition time and radiation doses.

Venous Thromboembolism in Neurocritical Care Patients

BACKGROUND

Venous thromboembolism (VTE) is a potentially life-threatening complication among critically ill patients. Neurocritical care patients are presumed to be at high risk for VTE; however, data regarding risk factors in this population are limited. We designed this study to evaluate the frequency, risk factors, and clinical impact of VTE in neurocritical care patients.

METHODS

We obtained data from the electronic medical record of all adult patients admitted to neurological intensive care unit (NICU) at Henry Ford Hospital between January 2015 and March 2018. Venous thromboembolism was defined as deep vein thrombosis, pulmonary embolism, or both diagnosed by Doppler, chest computed tomography (CT) angiography or ventilation-perfusion scan >24 hours after admission. Patients with ICU length of stay <24 hours or who received therapeutic anticoagulants or were diagnosed with VTE within 24 hours of admission were excluded.

RESULTS

Among 2188 consecutive NICU patients, 63 (2.9%) developed VTE. Prophylactic anticoagulant use was similar in patients with and without VTE (95% vs 92%; P = .482). Venous thromboembolism was associated with higher mortality (24% vs 13%, P = .019), and longer ICU (12 [interquartile range, IQR 5-23] vs 3 [IQR 2-8] days, P < .001) and hospital (22 [IQR 15-36] vs 8 [IQR 5-15] days, P < .001) length of stay. In a multivariable analysis, potentially modifiable predictors of VTE included central venous catheterization (odds ratio [OR] 3.01; 95% confidence interval [CI], 1.69-5.38; P < .001) and longer duration of immobilization (Braden activity score <3, OR 1.07 per day; 95% CI, 1.05-1.09; P < .001). Nonmodifiable predictors included higher International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) scores (which accounts for age >60, prior VTE, cancer and thrombophilia; OR 1.66; 95% CI, 1.40-1.97; P < .001) and body mass index (OR 1.05; 95% CI, 1.01-1.08; P = .007).

CONCLUSIONS

Despite chemoprophylaxis, VTE still occurred in 2.9% of neurocritical care patients. Longer duration of immobilization and central venous catheterization are potentially modifiable risk factors for VTE in critically ill neurological patients.

The problem of under-diagnosis and over-diagnosis of pulmonary embolism

Pulmonary embolism (PE) is an increasingly recognised condition which is associated with significant morbidity and mortality. Despite the better awareness of this serious condition, the diagnosis is still overlooked in many cases with sometimes fatal consequences. Under-diagnosis may be due to several reasons including reliance on non-specific 'classic' symptoms, belief that bedside measurements will likely be abnormal in the setting of acute PE, and confounding factors like co-existent cardiorespiratory diseases or being in an intensive care unit, where the diagnosis may not be considered. At the same time, incidental diagnosis of PE is occurring more often due to frequent use of imaging investigations alongside advancements in CT technology, and dilemma exists as to whether the chance finding of PE requires anticoagulation, especially when identified only at the subsegmental level. This article reviews these two issues of under-diagnosis and over-diagnosis of PE in the current era.

Overdiagnosis of pulmonary embolism: definition, causes and implications

Overuse of computed tomography pulmonary angiography to diagnose pulmonary embolism in people who have only a low pre-test probability of pulmonary embolism has received significant attention in the past. The issue of overdiagnosis of pulmonary embolism, a potential consequence of overtesting, has been less explored. The term “overdiagnosis”, used in a narrow sense, describes a correct (true positive) diagnosis in a person but without any associated harm. The aim of this review is to summarise literature on the topic of overdiagnosis of pulmonary embolism and translate this epidemiological concept into the clinical practice of respiratory professionals. The review concludes that the location of pulmonary embolism at a subsegmental level, rather than whether a diagnosis was made incidentally or following an investigation for suspected pulmonary embolism, is the best predictor for situations in which anticoagulation may not be necessary. In the absence of strong evidence of the optimal management of subsegmental pulmonary embolism, treatment decisions should be made case by case, taking into account the patient's situation and preference.

A suggested definition of overdiagnosis of pulmonary embolism: a diagnosis of pulmonary embolism that, if left untreated, would not lead to more harm than if it were treated with anticoagulation therapy, independent of symptomshttp://ow.ly/wgAK30nr5IV

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.

Spectral Detector Computed Tomography Pulmonary Angiography: Improved Diagnostic Assessment and Automated Estimation of Window Settings Angiography of Pulmonary Arteries From Novel Spectral Detector Computed Tomography Provides Improved Image Quality if Settings are Adjusted

OBJECTIVE

This study aimed to evaluate image quality (IQ) of virtual monoenergetic images (VMIs) from novel spectral detector computed tomography angiography of the pulmonary arteries and to identify appropriate window settings for each kiloelectron volt level.

MATERIALS

Forty consecutive patients were included in this institutional review board-approved, Health Insurance Portability and Accountability Act-compliant study.Signal- and contrast-to-noise ratios were calculated within the pulmonary trunk, and pulmonary/lobar/segmental arteries were calculated. The IQ and diagnostic certainty were rated by 2 radiologists on 5-point scales. In addition, they recorded appropriate window settings (center/width) that were linearly modeled against attenuation within the pulmonary trunk to generate generable results.

RESULTS

Signal- and contrast-to-noise ratios, IQ, and diagnostic certainty are significantly increased in low-kiloelectron volt VMIs (≤60 keV). Interrater agreement was excellent (ĸ = 0.89). We developed 2 linear models (R: 0.91-0.97 and R: 0.43-0.91, respectively, P ≤ 0.01), that suggest appropriate window settings.

CONCLUSIONS

The VMIs from spectral detector computed tomography improve objective and subjective IQ in angiography of the pulmonary arteries, if window settings are adjusted; they can be automatically estimated using reported linear models.

Pulmonary microvascular remodeling in chronic thrombo-embolic pulmonary hypertension

Pulmonary vascular remodeling in pulmonary arterial hypertension involves perturbations in the nitric oxide (NO) and endothelin-1 (ET-1) pathways. However, the implications of pulmonary vascular remodeling and these pathways remain unclear in chronic thrombo-embolic pulmonary hypertension (CTEPH). The objective of the present study was to characterize changes in microvascular morphology and function, focussing on the ET-1 and NO pathways, in a CTEPH swine model. Swine were chronically instrumented and received up to five pulmonary embolizations by microsphere infusion, whereas endothelial dysfunction was induced by daily administration of the endothelial NO synthase inhibitor N^ω-nitro-l-arginine methyl ester until 2 wk before the end of study. Swine were subjected to exercise, and the pulmonary vasculature was investigated by hemodynamic, histological, quantitative PCR, and myograph experiments. In swine with CTEPH, the increased right-ventricular afterload, decreased cardiac index, and mild ventilation-perfusion-mismatch were exacerbated during exercise. Pulmonary microvascular remodeling was evidenced by increased muscularization, which was accompanied by an increased maximal vasoconstriction. Although ET-1-induced vasoconstriction was increased in CTEPH pulmonary small arteries, the ET-1 sensitivity was decreased. Moreover, the contribution of the ET_A receptor to ET-1 vasoconstriction was increased, whereas the contribution of the ET_B receptor was decreased and the contribution of Rho-kinase was lost. A reduction in endogenous NO production was compensated in part by a decreased phosphodiesterase 5 (PDE5) activity resulting in an apparent increased NO sensitivity in CTEPH pulmonary small arteries. These findings suggest that pulmonary microvascular remodeling with a reduced activity of PDE5 and Rho-kinase may contribute to the lack of therapeutic efficacy of PDE5 inhibitors and Rho-kinase inhibitors in CTEPH.

Can the use of an age-adjusted D-dimer cut-off value help in our diagnosis of suspected pulmonary embolism?

Safe exclusion of pulmonary embolism (PE) is a common problem in acute medicine. Common care pathways usually involve the use of a pre-test probability score with a D-dimer test to aid clinical decision-making. Unfortunately, the specificity of many D-dimer assays decreases with age. This study investigates the role of an age-adjusted D-dimer of 5 x patient's age when the conventional cut-off of the assay is 230 ng/mL. Data was collected retrospectively over a 12-month period from patients who went on to have either computed tomography pulmonary angiography (CTPA) or pulmonary ventilation/perfusion (V/Q) imaging. D-dimers in patients with low or moderate Wells score were analysed for both conventional and age-adjusted cut-offs. The use of an adjusted D-dimer showed a sensitivity of 0.97 (95% CI 0.9-1.0) while the specificity increased from 0.07 (95% CI 0.04-0.11) for the conventional cut-off to 0.32 (95% CI 0.27-0.38) for the age-adjusted cut-off. Using a 5 x patient's age-adjusted D-dimer cut-off is both safe and showed an increased specificity comparable to those published previously on other D-dimer assays.

Pulmonary Embolism in Ischemic Stroke

Silent pulmonary embolism (PE) may be associated with acute ischemic stroke (AIS). We identified 10 patients from 3,132 unique patients (3,431 CT scans). We retrospectively examined CT angiogram of patients with AIS to determine the frequency of concurrent PE in AIS. The period prevalence of PE was 0.32. Seven patients had concurrent PE, whereas three had PE diagnosed 2 days after their AIS presentation. We suspected paradoxical embolism via patent foramen ovale as the cause of stroke in three patients and thrombophilia in four patients. Seven patients had poor outcome including four deaths. CT angiogram stroke protocol images from aortic arch to vertex allows visualization of upper pulmonary arteries and PE detection in AIS.

D-dimer levels in VTE patients with distal and proximal clots

OBJECTIVES

There is growing evidence that venous thromboembolism (VTE) patients with distal clots (distal calf deep vein thrombosis [DVT] and sub-segmental pulmonary embolism [PE]) may not routinely benefit from anticoagulation. We compared the D-dimer levels in VTE patients with distal and proximal clots.

METHODS

We conducted a multinational, prospective observational study of low-to-intermediate risk adult patients presenting to the emergency department (ED) with suspected VTE. Patients were classified as distal (calf DVT or sub-segmental PE) or proximal (proximal DVT or non-sub-segmental PE) clot groups and compared with univariate and multivariate analyses.

RESULTS

Of 1752 patients with suspected DVT, 1561 (89.1%) had no DVT, 78 (4.4%) had a distal calf DVT, and 113 (6.4%) had a proximal DVT. DVT patients with proximal clots had higher D-dimer levels (3760 vs. 1670 mg/dL) than with distal clots. Sensitivity and negative predictive value (NPV) for proximal DVT at an optimal D-dimer cutoff of 5770 mg/dL were 40.7% and 52.1% respectively. Of 1834 patients with suspected PE, 1726 (94.1%) had no PE, 7 (0.4%) had isolated sub-segmental PE, and 101 (5.5%) had non-sub-segmental PE. PE patients with proximal clots had higher D-dimer levels (4170 vs. 2520 mg/dL) than those with distal clots. Sensitivity and NPV for proximal PE at an optimal D-dimer cutoff of 3499 mg/dL were 57.4% and 10.4% respectively.

CONCLUSIONS

VTE patients with proximal clots had higher D-dimer levels than patients with distal clots. However, D-dimer levels cannot be used alone to discriminate between VTE patients with distal or proximal clots.

Effect of the Pulmonary Embolism Rule-Out Criteria on Subsequent Thromboembolic Events Among Low-Risk Emergency Department Patients: The PROPER Randomized Clinical Trial

IMPORTANCE

The safety of the pulmonary embolism rule-out criteria (PERC), an 8-item block of clinical criteria aimed at ruling out pulmonary embolism (PE), has not been assessed in a randomized clinical trial.

OBJECTIVE

To prospectively validate the safety of a PERC-based strategy to rule out PE.

DESIGN, SETTING, AND PATIENTS

A crossover cluster-randomized clinical noninferiority trial in 14 emergency departments in France. Patients with a low gestalt clinical probability of PE were included from August 2015 to September 2016, and followed up until December 2016.

INTERVENTIONS

Each center was randomized for the sequence of intervention periods. In the PERC period, the diagnosis of PE was excluded with no further testing if all 8 items of the PERC rule were negative.

MAIN OUTCOMES AND MEASURES

The primary end point was the occurrence of a thromboembolic event during the 3-month follow-up period that was not initially diagnosed. The noninferiority margin was set at 1.5%. Secondary end points included the rate of computed tomographic pulmonary angiography (CTPA), median length of stay in the emergency department, and rate of hospital admission.

RESULTS

Among 1916 patients who were cluster-randomized (mean age 44 years, 980 [51%] women), 962 were assigned to the PERC group and 954 were assigned to the control group. A total of 1749 patients completed the trial. A PE was diagnosed at initial presentation in 26 patients in the control group (2.7%) vs 14 (1.5%) in the PERC group (difference, 1.3% [95% CI, -0.1% to 2.7%]; P = .052). One PE (0.1%) was diagnosed during follow-up in the PERC group vs none in the control group (difference, 0.1% [95% CI, -∞ to 0.8%]). The proportion of patients undergoing CTPA in the PERC group vs control group was 13% vs 23% (difference, -10% [95% CI, -13% to -6%]; P < .001). In the PERC group, rates were significantly reduced for the median length of emergency department stay (mean reduction, 36 minutes [95% CI, 4 to 68]) and hospital admission (difference, 3.3% [95% CI, 0.1% to 6.6%]).

CONCLUSIONS AND RELEVANCE

Among very low-risk patients with suspected PE, randomization to a PERC strategy vs conventional strategy did not result in an inferior rate of thromboembolic events over 3 months. These findings support the safety of PERC for very low-risk patients presenting to the emergency department.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02375919.

Symptomatic subsegmental pulmonary embolism: to treat or not to treat?

The introduction of computed tomographic pulmonary angiography and its recent increasing availability has led to a significant rise in its use to help clinicians diagnose acute pulmonary embolism (PE). This has led to a significant increase in the incidence of PE diagnoses. Simultaneously, the case fatality rate of acute PE has been decreasing and no significant change in its mortality has been noted, suggesting that the additional PE diagnoses are less severe and these patients might not benefit from anticoagulation therapy. This also seems to be correlated with an increase in the diagnosis of PE localized in the subsegmental pulmonary arteries (subsegmental pulmonary embolism [SSPE]). The clinical importance of SSPE is unclear. Whereas some studies have shown that it might be reasonable to manage patients with SSPE without anticoagulation, others have not. Although the current medical literature is limited, it suggests that a subgroup of patients with SSPE might be safely managed without the use of anticoagulant therapy. Current clinical practice guidelines suggest that clinicians take an individualized approach after carefully assessing the risk/benefit ratio for patients with SSPE and negative leg limb ultrasonography results. Prospective studies are ongoing and results are eagerly awaited to help tailor the management of this patient population.

Venous Thromboembolism and Pulmonary Embolism Response Teams: An Overview

Venous thromboembolism is a common disease with a wide array of signs and symptoms. It has been cited as the third leading cause of cardiovascular death, and if left untreated, it leads to death in 1 in 4 patients. Sophisticated diagnostic tools have allowed physician to become more accurate in diagnosing pulmonary embolism and deep vein thrombosis. The advent of new oral anticoagulants, the emergence of pulmonary embolism response teams, and protocols demonstrate recent achievements in the management of venous thromboembolism. The focus of this article is to discuss the treatment of venous thromboembolism.

Contrast-enhanced pulmonary MRA for the primary diagnosis of pulmonary embolism: current state of the art and future directions

CT pulmonary angiography (CTPA) is currently considered the imaging standard of care for the diagnosis of pulmonary embolism (PE). Recent advances in contrast-enhanced pulmonary MR angiography (MRA) techniques have led to increased use of this modality for the detection of PE in the proper clinical setting. This review is intended to provide an introduction to the state-of-the-art techniques used in pulmonary MRA for the detection of PE and to discuss possible future directions for this modality. This review discusses the following issues pertinent to MRA for the diagnosis of PE: (1) the diagnostic efficacy and clinical effectiveness for pulmonary MRA relative to CTPA, (2) the different pulmonary MRA techniques used for the detection of PE, (3) guidance for building a clinical service at their institution using MRA and (4) future directions of PE MRA. Our principal aim was to show how pulmonary MRA can be used as a safe, effective modality for the diagnosis of clinically significant PE, particularly for those patients where there are concerns about ionizing radiation or contraindications/allergies to the iodinated contrast material.

Imaging of nontraumatic thoracic emergencies

PURPOSE OF REVIEW

Acute chest symptoms form an important incentive for imaging in the emergency setting. This review discusses the radiologic features of various vascular and pulmonary diseases leading to acute respiratory distress and recent developments on important emergency radiologic examinations.

RECENT FINDINGS

Recently, triple-rule-out computed tomography protocol was introduced in diagnosis of chest pain, and advancing computed tomography technology and knowledge have led to discussion on treatment of pulmonary embolism. Diffuse pulmonary opacities remain a diagnostic dilemma in the emergency setting and although imaging findings can often be nonspecific, they help in guiding toward accurate diagnosis and timely management.

SUMMARY

Though promising, triple-rule-out is not yet justified because of low incidence of additional findings compared with conventional computed tomography angiography in chest pain, but it might be suited for clinical practice in the near future. Relevance of isolated subsegmental pulmonary embolism is unknown and research on this topic is needed and on its way. We provided some key findings in differentiating diffuse pulmonary opacities and describe the additional value of chest ultrasound in this clinical dilemma. A brief sidestep to pneumothorax is made, as this is also a frequent finding in the acute dyspneic patient, as well as in patients with acute chest pain.

Imaging techniques used in the diagnostic workup of acute venous thromboembolic disease

Early diagnosis is one of the most important factors affecting the prognosis of pulmonary embolism (PE); however, the clinical presentation of PE is often very unspecific and it can simulate other diseases. For these reasons, imaging tests, especially computed tomography angiography (CTA) of the pulmonary arteries, have become the keystone in the diagnostic workup of PE. The wide availability and high diagnostic performance of pulmonary CTA has led to an increase in the number of examinations done and a consequent increase in the population's exposure to radiation and iodinated contrast material. Thus, other techniques such as scintigraphy and venous ultrasonography of the lower limbs, although less accurate, continue to be used in certain circumstances, and optimized protocols have been developed for CTA to reduce the dose of radiation (by decreasing the kilovoltage) and the dose of contrast agents. We describe the technical characteristics and interpretation of the findings for each imaging technique used to diagnose PE and discuss their advantages and limitations; this knowledge will help the best technique to be chosen for each case. Finally, we comment on some data about the increased use of CTA, its clinical repercussions, its "overuse", and doubts about its cost-effectiveness.

State-of-the-Art Pulmonary CT Angiography for Acute Pulmonary Embolism

OBJECTIVE

Pulmonary CT angiography (CTA) is the imaging modality of choice in suspected acute pulmonary embolism (PE). Current pulmonary CTA techniques involve ever lower doses of contrast medium and radiation along with advanced postprocessing applications to enhance image quality, diagnostic accuracy, and provide added value in patient management. The objective of this article is to summarize these current developments and discuss the appropriate use of state-of-the-art pulmonary CTA.

CONCLUSION

Pulmonary CTA is well established as a fast and reliable means of excluding or diagnosing PE. Continued developments in CT system hardware and postprocessing techniques will allow incremental reductions in radiation and contrast material requirements while improving image quality. Advances in risk stratification and prognostication from pulmonary CTA examinations should further refine its clinical value while minimizing the potential harm from overutilization and overdiagnosis.

Management of venous thromboembolism: an update

Venous thromboembolism (VTE), which constitutes pulmonary embolism and deep vein thrombosis, is a common disorder associated with significant morbidity and mortality. Landmark trials have shown that direct oral anticoagulants (DOACs) are as effective as conventional anticoagulation with vitamin K antagonists (VKA) in prevention of VTE recurrence and associated with less bleeding. This has paved the way for the recently published guidelines to change their recommendations in favor of DOACs in acute and long-term treatment of VTE in patients without cancer. The recommended treatment of VTE in cancer patients remains low-molecular-weight heparin. The initial management of pulmonary embolism (PE) should be directed based on established risk stratification scores. Thrombolysis is an available option for patients with hemodynamically significant PE. Recent data suggests that low-risk patients with acute PE can safely be treated as outpatients if home circumstances are adequate. There is lack of support for use of inferior vena cava filters in patients on anticoagulation. This review describes the acute, long-term, and extended treatment of VTE and recent evidence on the management of sub-segmental PE.