Predictors of an intermediate ventilation/perfusion lung scan in patients with suspected acute pulmonary embolism

Impact of COVID-19 on Ventilation-Perfusion (V/Q) Scans: A Comparative Analysis of Pre-COVID-19 Era V/Q Scans and Post-COVID-19 Era Perfusion Scans

Introduction The COVID-19 pandemic has profoundly impacted medical practices, including nuclear medicine. To minimize aerosol transmission risks, lung perfusion scintigraphy was preferred over traditional ventilation-perfusion (V/Q) scintigraphy during the pandemic. This study compares lung perfusion scans performed during COVID-19 with V/Q scans from the pre-COVID era. After reviewing this study, the reader will learn about V/Q scintigraphy and lung perfusion. Methods This retrospective observational study, conducted from December 2018 to July 2021, involved 868 patients - 511 in the pre-COVID era and 357 in the post-COVID era - at a single tertiary care center. The pretest probability of pulmonary embolism (PE) was determined using Wells' criteria, and data including demographics, clinical findings, and diagnostic test results (V/Q or lung perfusion scintigraphy) were collected. Results A 30% decline in lung scans was observed during the pandemic. In the pre-COVID era, 68.3% of scans had low, 27.8% had intermediate, and 3.9% had high probability for PE. During the pandemic, perfusion-only scans showed 57.3% low, 32.9% indeterminate, and 9.8% high probability for PE. Among COVID-19-positive patients, 48.9% had intermediate, and 11.1% had high probability scans. The rise in indeterminate and high-probability scans during the pandemic is attributed to COVID-19-related lung changes and hypercoagulability. Conclusion The perfusion component of lung scans is typically sufficient for evaluating acute PE. Omitting the ventilation part of the V/Q scan had minimal impact, with only a 5.1% increase in indeterminate/non-diagnostic scans using perfusion-only modified Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) criteria during the post-COVID-19 era, likely due to underlying lung parenchymal involvement in COVID-19 patients. Additionally, there was a 5.9% rise in high-probability scans, attributed to the hypercoagulability and vascular complications associated with COVID-19.

Perfusion Lung Scans During the Pandemic: COVID-19 Experience in a Large Trauma Hospital

Purpose

Material and methods

Results

Conclusion

Risk of Acute Kidney Injury after Intravenous Contrast Media Administration in Patients with Suspected Pulmonary Embolism: A Propensity-Matched Study

BACKGROUND

 Although computed tomography pulmonary angiography (CTPA) is the preferred diagnostic procedure in patients with suspected pulmonary embolism (PE), some patients undergo ventilation/perfusion (V/Q) lung scan due to concern of contrast-associated acute kidney injury (AKI).

METHODS

 The study used a cohort of 4,565 patients with suspected PE. Patients who received contrast during CTPA were compared with propensity score-matched unexposed control patients who underwent V/Q lung scanning. AKI was defined as ≥50% increase in serum creatinine during the first 72 hours after either CTPA or V/Q lung scan.

RESULTS

 Classification and regression tree analysis demonstrated that baseline creatinine was the strongest determinant of the decision to use CTPA. Propensity-score matching yielded 969 patient pairs. There were 44 AKI events (4.5%) in patients exposed to contrast media (CM) and 33 events (3.4%) in patients not exposed to CM (risk difference: 1.1%, 95% confidence interval [CI]: -0.6 to 2.9%; odds ratio [OR]: 1.39, 95% CI: 0.86-2.26; p = 0.18). Using different definitions for AKI and extending the time window for AKI diagnosis gave similar results. In a sensitivity analysis with the inverse probability weighting method, the OR for AKI in the CTPA versus V/Q scan was 1.14 (95% CI: 0.72-1.78; p = 0.58).

CONCLUSION

 Intravenous contrast material administration was not associated with an increased risk of AKI in patients with suspected PE. Given the diagnostic superiority of CTPA, these results are reassuring with regard to the use of CTPE in patients with suspected PE perceived to be at risk for AKI.

Current approach to the diagnosis of acute nonmassive pulmonary embolism

Pulmonary embolism is a common and potentially lethal disease. Given the variable presentation and associated morbidity of this condition, an accurate and efficient diagnostic algorithm is required. Clinical pretest probability serves as the root of any diagnostic approach. We, thus, review several clinical decision rules that may help standardize this determination. Using a review of the literature, the accuracy, predictive values, and likelihood ratios for several diagnostic tests are described. The combination of these tests, based on the pretest probability of disease, can be used in a Bayesian fashion to make accurate treatment decisions. A completely noninvasive diagnostic algorithm for patients presenting with suspected acute pulmonary embolism is proposed.

Pulmonary embolism in the elderly: a review on clinical, instrumental and laboratory presentation

Objective

Diagnosis of pulmonary embolism (PE) remains difficult and is often missed in the elderly due to nonspecific and atypical presentation. Diagnostic algorithms able to rule out PE and validated in young adult patients may have reduced applicability in elderly patients, which increases the number of diagnostic tools use and costs. The aim of the present study was to analyze the reported clinical presentation of PE in patients aged 65 and more.

Materials and Methods

Prospective and retrospective English language studies dealing with the clinical, instrumental and laboratory aspects of PE in patients more than 65 and published after January 1987 and indexed in MEDLINE using keywords as pulmonary embolism, elderly, old, venous thromboembolism (VTE) in the title, abstract or text, were reviewed.

Results

Dyspnea (range 59%–91.5%), tachypnea (46%–74%), tachycardia (29%–76%), and chest pain (26%–57%) represented the most common clinical symptoms and signs. Bed rest was the most frequent risk factor for VTE (15%–67%); deep vein thrombosis was detected in 15%–50% of cases. Sinus tachycardia, right bundle branch block, and ST-T abnormalities were the most frequent ECG findings. Abnormalities of chest X-ray varied (less than 50% in one-half of the studies and more than 70% in the other one-half). Arterial blood gas analysis revealed severe hypoxemia and mild hypocapnia as the main findings. D-Dimer was higher than cut-off in 100% of patients in 75% of studies. Clinical usefulness of D-Dimer measurement decreases with age, although the strategies based on D-Dimer seem to be cost-effective at least until 80 years.

Conclusion

Despite limitations due to pooling data of heterogeneous studies, our review could contribute to the knowledge of the presentation of PE in the elderly with its diagnostic difficulties. A diagnostic strategy based on reviewed data is proposed.

Evidence-based Practice in Radiology: Steps 3 and 4—Appraise and Apply Diagnostic Radiology Literature

Several paradigms for evidence-based practice (EBP) exist. One model proposes that specialist academic centers should primarily construct valid guidelines for various topics in medicine (top-down model). An alternative model integrates "the best research evidence with clinical expertise and patient values" (bottom-up model). Whereas the former model inherently implies a central specialized process, the latter implies that practitioners working in nonspecialist centers can learn and implement a standardized set of tools with which to ask a question, search and appraise the literature, and then apply best current evidence in a local setting. This article focuses on appraising the literature and applying retrieved results and is part of a series on EBP in radiology. This article describes a clinical scenario in which a new respirologist at a hospital requests indirect computed tomographic (CT) venography as part of a work-up of a patient with a high pretest probability for pulmonary embolism and a positive d-dimer test result. Many controversies surround the technique of indirect CT venography, and difficult topics such as this are ideally suited to the tools of EBP. This article will describe how to approach such a scenario.