Acute pulmonary thromboembolism in emergency room: gray-scale versus color doppler ultrasound evaluation

Diagnostic test accuracy of imaging modalities for adults with acute pulmonary embolism: A systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis aimed to evaluate the current literature on diagnostic test accuracy (DTA) of imaging modalities for adults with acute pulmonary embolism (APE).

BACKGROUND

Medical imaging plays an integral role in evaluating and managing those with APE. Guidance for imaging modality use for APE diagnosis varies due to a lack of clinical standardisation. Despite this, CTPA remains the first-line imaging modality used by clinicians.

METHODS

A literature search of PubMed, EMBASE, Trove and Mednar databases (2012-2020; English language) was performed. Studies assessing the DTA of imaging modalities for APE diagnosis were included. DTA studies methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2 tool). Results of eligible studies were pooled using random or fixed effects modelling the calculate the pooled DTA of explored imaging modalities for APE. The Higgins I² test were performed to assess between study heterogeneity.

RESULTS

10 Studies, involving 998 participants, were enrolled and pooled using the random effects model. Of the explored modalities, magnetic resonance imaging (MRI), specifically pulmonary MRI and magnetic resonance pulmonary angiography (MRPA) exhibited the highest pooled DTA. Sensitivity, specificity, negative likelihood ratio, positive likelihood ratio and diagnostic odds ratio for MRPA were 0.952 (95% CI, 0.881 to 0.987), 0.857 (95% CI, 0.637 to 0.97), 5.631 (95% CI, 2.163 to 14.659), 0.06 (95% CI, 0.007 to 0.537) and 80.310 (95% CI, 15.607 to 413.25) respectively. Based on the QUADAS-2 criteria, most studies presented low to moderate risk of bias and concern regarding applicability.

CONCLUSION

The explored ultrasound and MRI protocols which exhibit a lower radiation burden when compared to the current gold standard computed tomography pulmonary angiography (CTPA), have acceptable diagnostic accuracy for APE and can be useful in certain situations.

Diagnostic accuracy of focused deep venous, lung, cardiac and multiorgan ultrasound in suspected pulmonary embolism: a systematic review and meta-analysis

OBJECTIVE

To determine the diagnostic accuracy of point-of-care ultrasound in suspected pulmonary embolism.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, CINAHL and Cochrane library were searched on 2 July 2020 with no restrictions on the date of publication. Subject headings or subheadings combined with text words for the concepts of pulmonary embolism, ultrasound and diagnosis were used.

ELIGIBILITY CRITERIA AND DATA ANALYSIS

Eligible studies reported sensitivity and specificity of deep venous, lung, cardiac or multiorgan ultrasound in patients with suspected pulmonary embolism, using an adequate reference-test. Prospective, cross-sectional and retrospective studies were considered for eligibility. No restrictions were made on language. Studies were excluded if a control group consisted of healthy volunteers or if transesophageal or endobronchial ultrasound was used. Risk of bias was assessed using quality assessment of diagnostic accuracy studies-2. Meta-analysis of sensitivity and specificity was performed by construction of hierarchical summary receiver operator curves. I² was used to assess the study heterogeneity.

MAIN OUTCOME MEASURES

The primary outcome was overall sensitivity and specificity of reported ultrasound signs, stratified by organ approach (deep venous, lung, cardiac and multiorgan). Secondary outcomes were stratum-specific sensitivity and specificity within subgroups defined by pretest probability of pulmonary embolism.

RESULTS

6378 references were identified, and 70 studies included. The study population comprised 9664 patients with a prevalence of pulmonary embolism of 39.9% (3852/9664). Risk of bias in at least one domain was found in 98.6% (69/70) of included studies. Most frequently, 72.8% (51/70) of studies reported >24 hours between ultrasound examination and reference test or did not disclose time interval at all. Level of heterogeneity ranged from 0% to 100%. Most notable ultrasound signs were bilateral compression of femoral and popliteal veins (22 studies; 4708 patients; sensitivity 43.7% (36.3% to 51.4%); specificity 96.7% (95.4% to 97.6%)), presence of at least one hypoechoic pleural-based lesion (19 studies; 2134 patients; sensitivity 81.4% (73.2% to 87.5%); specificity 87.4% (80.9% to 91.9%)), D-sign (13 studies; 1579 patients; sensitivity 29.7% (24.6% to 35.4%); specificity 96.2% (93.1% to 98.0%)), visible right ventricular thrombus (5 studies; 995 patients; sensitivity 4.7% (2.7% to 8.1%); specificity 100% (99.0% to 100%)) and McConnell's sign (11 studies; 1480 patients; sensitivity 29.1% (20.0% to 40.1%); specificity 98.6% (96.7% to 99.4%)).

CONCLUSION

Several ultrasound signs exhibit a high specificity for pulmonary embolism, suggesting that implementation of ultrasound in the initial assessment of patients with suspected pulmonary embolism may improve the selection of patients for radiation imaging.

PROSPERO REGISTRATION NUMBER

CRD42020184313.

The "Survived Lung:" An Ultrasound Sign of "Bubbly Consolidation" Pulmonary Infarction

Since the presence of "bubbly consolidation" (central lucencies) on a multi-slice computed tomography pulmonary angiography (MCTPA) is one of the highly specific imaging appearances of infarct secondary to pulmonary embolism, we investigated the ultrasound characteristics of these infarctions. In this study, 118 patients with MCTPA diagnosis of acute pulmonary embolism were enrolled. Pulmonary infarctions were detected in 21 patients (17.7%), of which 10 (47.6%) showed the typical appearance of bubbly consolidation on MCTPA. Lung ultrasound (LUS) was performed to evaluate the characteristics of the infarcts highlighted by MCTPA. The bubbly consolidations showed a very peculiar echographic aspect represented by a triangular hypoechoic consolidation with sharp margins, the absence of air bronchograms and a mostly central roundish hyperechoic area. Air lucencies within a pulmonary infarct is hypothesized to represent the coexistence of aerated non-infarcted lung with the infarcted lung in the same lobule. The ultrasound appearance confirms this hypothesis, so we named the roundish hyperechoic area the "survived lung." This picture was found in all patients with a diagnosis of bubbly consolidation on MCTPA (100%). Χ² between MCTPA and LUS regarding the bubbly consolidation diagnosis is 17.18 (df = 1; p value = 0.00003). Bubbly consolidations show a very typical appearance on LUS. Their detection suggests further investigations (MCTPA or point-of-care multi-organ ultrasonography).