CT pulmonary angiography: increasingly diagnosing less severe pulmonary emboli

Diagnostic Yield, Radiation Exposure, and the Role of Clinical Decision Rules to Limit Computed Tomographic Pulmonary Angiography-Associated Complications

OBJECTIVES

Computed tomographic pulmonary angiography (CT-PA) is associated with significant cost, contrast, and radiation exposure. Clinical decision rules (CDRs) reduce the need for diagnostic imaging; however, their utility in the medical intensive care unit (MICU) remains unknown. We explored the diagnostic yield and complications associated with CT-PA (radiation exposure and contrast-induced acute kidney injury [AKI]) while investigating the efficacy of CDRs to reduce unnecessary testing.

METHODS

All CT-PAs performed in an academic MICU for 4 years were retrospectively reviewed. The Wells and revised Geneva scores (CDRs) and radiation dose per CT-PA were calculated, and the incidence of post-CT-PA AKI was recorded.

RESULTS

A total of 439 studies were analyzed; the diagnostic yield was 11% (48 PEs). Positive CT-PAs were associated with a higher Wells score (5.8 versus 3.2, P < 0.001), but similar revised Geneva scores (6.4 versus 6.0, P = 0.32). A Wells score of ≥4 had a positive likelihood ratio of 2.1 with a negative predictive value of 98.2. More than half (88.9%) of patients with a Wells score of ≤4 developed an AKI, with 55.6% of those having recovery of renal function.

CONCLUSIONS

There is overutilization of CT-PA in the MICU. The Wells score retains its negative predictive value in critically ill adult patients and may aid to limit radiation exposure and contrast-induced AKI in MICU.

Comparison of international guideline recommendations for the diagnosis of pulmonary embolism

Pulmonary embolism is one of the leading causes of death due to cardiovascular disease. Timely diagnosis is crucial, but challenging, as the clinical presentation of pulmonary embolism is unspecific and easily mistaken for other common medical emergencies. Clinical prediction rules and D-dimer measurement allow stratification of patients into groups of expected prevalence and are key elements in adequate selection of patients for diagnostic imaging; however, the strengths and weaknesses of the multiple proposed prediction rules, when to measure D-dimer, and which cutoff to apply might be elusive to a significant proportion of physicians. 13 international guidelines authored by medical societies or expert author groups provide recommendations on facets of the diagnostic investigations in suspected pulmonary embolism, some of which are hallmarked by pronounced heterogeneity. This Review summarises key recommendations of each guideline, considers the most recent evidence on the topic, compares guideline recommendations on each facet of the diagnosis of pulmonary embolism, and provides a synthesis on the most common recommendations.

Bibliometric Analysis of Diagnostic Yield of CT Pulmonary Angiogram (CTPA) in the Diagnosis of Pulmonary Embolism (PE)

CT pulmonary angiography (CTPA) is the investigation of choice for diagnosing pulmonary embolism (PE). Due to the speed and ease of performing the CTPA scans, more clinicians are becoming overly reliant on them, even for patients without strong suspicion of PE. We conducted a bibliometric analysis on the PubMed database from 1990 to 2022 to investigate the literature on the diagnostic yield of CTPA in the diagnosis of PE. A total of 166 articles were published in 98 journals. The number of publications has steadily increased since 2010 and peaked in 2020. Authors from 24 countries contributed to these publications, with the overwhelming majority emanating from United States of America, totaling 66 articles. The authors' contributions were relatively well spread out, with the top four authors publishing the highest number of articles at six each. When we investigated the collaboration between the authors, we found limited multinational and multi-institutional collaborations on this topic. Therefore, more multinational and multi-institutional collaborations will be valuable in future studies. In conclusion, this bibliometric analysis summarizes the literature on diagnostic yield of CTPA in the diagnosis of PE and sheds light on the future pathway that researchers and institutions can focus on.

Diagnostic Yield of CT Pulmonary Angiogram in the Diagnosis of Pulmonary Embolism and Its Predictive Factors

Introduction Computed tomography pulmonary angiography (CTPA) is the reference investigation of choice to diagnose pulmonary embolism (PE). Nevertheless, the use of CTPA should be weighed against its risks, such as radiation and contrast-induced nephropathy. We aim to assess the yield of CTPA in diagnosing PE at a tertiary centre in Malaysia. We also identify predictive factors associated with the yield of CTPA in this cohort. Methods This was a cross-sectional study involving all patients who had had CTPA done at Hospital Tengku Ampuan Afzan, Kuantan, Malaysia, from January 1, 2021, to November 30, 2021. All patients' records were retrieved and reviewed. CTPA images were retrieved from the Radiology Information System (RIS) and Picture Archiving and Communication System (PACS). They were double-reviewed by the authors, with the initial reports redacted from reporting radiologists to prevent reporting bias. The predictive factors were determined using simple logistic regression and multiple logistic regression. Results A total of 351 CTPAs were reviewed, of which 93 were found to be positive for PE, giving rise to an overall CTPA yield of 26.5%. Upon simple logistic regression, factors such as gender, discipline, history of trauma, presence of COVID-19 infection, and pneumonia were found to be associated with positive CTPA. Upon multiple logistic regression, male patients were found to have a higher chance of positive CTPA results. On the other hand, patients with COVID-19 infection and pneumonia have a lower chance of positive results in CTPA. Conclusion The yield of CTPA in diagnosing PE at our institution was acceptable at 26.5%. Upon multiple logistic regression, patients with COVID-19 infection and pneumonia were more likely to have a negative CTPA result, highlighting the need for clinicians to be more prudent in requesting CTPAs in these patients.

Evaluation of lung perfusion by using lung perfusion SPECT and lung CT with breathing synchronization software

Background

Lung perfusion using 99mTc-macroaggregated albumin single-photon emission computed tomography (SPECT) and lung computed tomography (CT) is a useful modality for identifying patients with pulmonary artery embolism. However, conformity between SPECT and CT at the bottom of the lung is generally low. This study aims to investigate the progression of conformity between lung perfusion SPECT and lung CT using a breathing synchronization software.

Methods

Among 95 consecutive patients who underwent lung perfusion SPECT and lung CT within 14 days because of suspected pulmonary embolism between June 2019 and August 2020 in department of cardiovascular medicine, we identified 28 patients (73 ± 10 years) who had normal pulmonary artery on contrast lung CT. We compared lung volumes calculated using lung perfusion SPECT and lung CT as gold standard. Visual conformity between lung SPECT and lung CT was scored 0–4 (0: 0–25%, 1: 25–50%, 2: 50–75%, 3: 75–90%, 4: > 90%) by two specialists in nuclear medicine and assessed.

Results

The lung volume calculated from lung CT was 3749 ± 788 ml. The lung volume calculated from lung perfusion SPECT without using the breathing synchronization software was 3091 ± 610 ml. There was a significant difference between the lung volume calculated from CT and SPECT without using the breathing synchronization software (P < 0.01). The lung volume calculated from lung perfusion SPECT using the breathing synchronization software was 3435 ± 686 ml, and there was no significant difference between the lung volume calculated from CT and SPECT using the breathing synchronization software. The visual score improved with the use of breathing synchronization software (without software; 1.9 ± 0.6 vs. with software; 3.4 ± 0.7, P < 0.001).

Conclusion

This study demonstrated that the breathing synchronization software could improve conformity between lung perfusion SPECT and lung CT.

Computed Tomography Pulmonary Angiography Utilization in the Emergency Department During the COVID-19 Pandemic

PURPOSE

To determine if computed tomography pulmonary angiography (CTPA) ordering increased significantly during the COVID-19 pandemic in an emergency department (ED) setting; if positive findings for pulmonary embolism (PE) increased to the same degree; and whether COVID-positive patients have a higher incidence of PE than COVID-negative patients at ED presentation.

MATERIALS AND METHODS

We conducted a retrospective review of CTPA performed in our ED between June and December in 2019 and 2020. We collected data on patient demographics, symptoms, COVID-19 status, lab and imaging results, and risk factors for PE. We used a Wilcoxon rank sum to analyze quantitative variables and χ2 or Fisher test for categorical variables. We used logistic regression to identify predictive factors for PE.

RESULTS

CTPA ordering increased from 432 studies in 2019 to 699 in 2020 (+61.8%, P<0.0001), but detection rates for PE remained stable (11.3% vs. 10.2%, P=0.61). In 2020, 10 of 91 COVID-positive patients undergoing CTPA had positive studies. On regression analysis, COVID-19 was not a significant predictor of PE at ED presentation (odds ratio 1.029, 95% confidence interval: 0.959-1.103). COVID-positive patients were more likely to have nondiagnostic imaging (7.7% vs. 2.5% [COVID-negative] and 0.8% [not tested], P=0.007).

CONCLUSIONS

While CTPA ordering increased significantly during the pandemic, our positivity rate remained stable, suggesting that this increase was appropriate. COVID-positive patients who underwent CTPA in the ED did not have a higher incidence of PE than other patients. Clinicians should use clinical judgment to weigh the likelihood of PE against the risk of nondiagnostic results when determining whether to expose COVID-positive patients to high-dose radiation and contrast with CTPA on initial presentation.

The use of computed tomography in the management of injury in tertiary emergency departments in Western Australia: Evidence of overtesting?

BACKGROUND

This study investigated trends in computed tomography (CT) utilization across different triage categories of injury presentations to tertiary emergency departments (EDs) and associations with diagnostic yield measured by injury severity, hospitalization and length of stay (LOS), and mortality.

METHODS

A total of 411,155 injury-related ED presentations extracted from linked records from Western Australia from 2004 to 2015 were included in the retrospective study. The use of CT scanning and diagnostic yield measured by rate of diagnosis with severe injury, hospitalizations and LOS, and mortality were captured annually for injury-related ED presentations. Multivariable regression models were used to calculate the annual adjusted rate of CT scanning for injury presentations and hospitalizations across triage categories, diagnosis with severe injury, LOS, and mortality. The significance of changes observed was compared among patients with CT imaging relative to those without CT.

RESULTS

While the number of ED presentations with injury increased by 65% from 2004 to 2015, the use of CT scanning in these presentations increased by 176%. The largest increase in CT use was among ED presentations triaged as semi-/nonurgent (+256%). Injury presentations with CT, compared to those without, had a higher rate of diagnosis with moderate/severe injury and hospitalization but no difference in LOS and mortality. The probability/rate observed in the outcomes of interest had a greater decrease over time in those with CT scanning compared with those without CT scanning across triage categories.

CONCLUSIONS

The reduction in diagnostic yield in terms of injury severity and hospitalization found in our study might indicate a shift toward overtesting using CT in ED for injury or a higher use of CT to assist in the management of injuries. This helps health care policymakers consider whether the current increase in CT use meets the desired levels of quality and efficient care.

Diagnosing pulmonary thromboembolism: Concerns and controversies

Pulmonary thromboembolism (PTE) is an important cause of mortality/morbidity even today despite advancement in clinical understanding as well as diagnostic facilities. Clinical diagnosis of PTE is often challenging because of nonspecific sign/symptoms. Adherence to clinical decision-making protocols and appropriate use of diagnostic modalities like computed tomography pulmonary angiography can resolve the diagnostic dilemma in most cases and help in the overall management of PTE. This article deals with various concerns as well as controversies surrounding accurate diagnosis of PTE as on date.

Present Limitations of Artificial Intelligence in the Emergency Setting - Performance Study of a Commercial, Computer-Aided Detection Algorithm for Pulmonary Embolism

PURPOSE

 Since artificial intelligence is transitioning from an experimental stage to clinical implementation, the aim of our study was to evaluate the performance of a commercial, computer-aided detection algorithm of computed tomography pulmonary angiograms regarding the presence of pulmonary embolism in the emergency room.

MATERIALS AND METHODS

 This retrospective study includes all pulmonary computed tomography angiogram studies performed in a large emergency department over a period of 36 months that were analyzed by two radiologists experienced in emergency radiology to set a reference standard. Original reports and computer-aided detection results were compared regarding the detection of lobar, segmental, and subsegmental pulmonary embolism. All computer-aided detection findings were analyzed concerning the underlying pathology. False-positive findings were correlated to the contrast-to-noise ratio.

RESULTS

 Expert reading revealed pulmonary embolism in 182 of 1229 patients (49 % men, 10-97 years) with a total of 504 emboli. The computer-aided detection algorithm reported 3331 findings, including 258 (8 %) true-positive findings and 3073 (92 %) false-positive findings. Computer-aided detection analysis showed a sensitivity of 47 % (95 %CI: 33-61 %) on the lobar level and 50 % (95 %CI 43-56 %) on the subsegmental level. On average, there were 2.25 false-positive findings per study (median 2, range 0-25). There was no significant correlation between the number of false-positive findings and the contrast-to-noise ratio (Spearman's Rank Correlation Coefficient = 0.09). Soft tissue (61.0 %) and pulmonary veins (24.1 %) were the most common underlying reasons for false-positive findings.

CONCLUSION

 Applied to a population at a large emergency room, the tested commercial computer-aided detection algorithm faced relevant performance challenges that need to be addressed in future development projects.

KEY POINTS

  · Computed tomography pulmonary angiograms are frequently acquired in emergency radiology.. · Computer-aided detection algorithms (CADs) can support image analysis.. · CADs face challenges regarding false-positive and false-negative findings.. · Radiologists using CADs need to be aware of these limitations.. · Further software improvements are necessary ahead of implementation in the daily routine..

CITATION FORMAT

· Müller-Peltzer K, Kretzschmar L, Negrão de Figueiredo G et al. Present Limitations of Artificial Intelligence in the Emergency Setting - Performance Study of a Commercial, Computer-Aided Detection Algorithm for Pulmonary Embolism. Fortschr Röntgenstr 2021; DOI: 10.1055/a-1515-2923.

Factors Affecting Radiation Dose in Computed Tomography Angiograms for Pulmonary Embolism: A Retrospective Cohort Study

Objectives

Computed tomography pulmonary angiogram (CTPA) is one of the most commonly ordered and frequently overused tests. The purpose of this study was to evaluate the mean radiation dose to patients getting CTPA and to identify factors that are associated with higher dose.

Material and Methods

This institutionally approved retrospective study included all patients who had a CTPA to rule out acute pulmonary embolism between 2016 and 2018 in a tertiary care center. Patient data (age, sex, body mass index [BMI], and patient location), CT scanner type, image reconstruction methodology, and radiation dose parameters (dose-length product [DLP]) were recorded. Effective dose estimates were obtained by multiplying DLP by conversion coefficient (0.014 mSv•mGy^-1•cm^-1). Multivariate logistic regression analysis was performed to determine the factors affecting the radiation dose.

Results

There were 2342 patients (1099 men and 1243 women) with a mean age of 58.1 years (range 0.2-104.4 years) and BMI of 31.3 kg/m² (range 12-91.5 kg/m²). The mean effective radiation dose was 5.512 mSv (median - 4.27 mSv; range 0.1-43.0 mSv). Patient factors, including BMI >25 kg/m², male sex, age >18 years, and intensive care unit (ICU) location, were associated with significantly higher dose (P < 0.05). CT scanning using third generation dual-source scanner with model-based iterative reconstruction (IR) had significantly lower dose (mean: 4.90 mSv) versus single-source (64-slice) scanner with filtered back projection (mean: 9.29 mSv, P < 0.001).

Conclusion

Patients with high BMI and ICU referrals are associated with high CT radiation dose. They are most likely to benefit by scanning on newer generation scanner using advance model-based IR techniques.

Investigation of pulmonary embolism in patients with chest pain in the emergency department: a retrospective multicenter study

INTRODUCTION

Chest pain is a common main complaint in the emergency department. Among its associated differential diagnoses, pulmonary embolism remains a key concern for the clinician. There are no clear recommendations on which patients should have a formal workup for pulmonary embolism diagnosis. The objective of this study was to determine the proportion of patients with chest pain who were investigated for pulmonary embolism diagnosis and to determine the clinical profile of these patients.

METHODS

This was a retrospective multicenter study conducted in three French Emergency Departments. We included all patients who presented to these centers for chest pain during a 2-month period. The primary outcome was the initiation of pulmonary embolism workup. We also aimed to find factors associated with this outcome.

RESULTS

We included 881 patients with a main complaint of chest pain. Mean age was 50 years and 481 (56%) were men. A total of 263 patients (30%, 95% confidence interval 27-33%) had a formal pulmonary embolism workup, and pulmonary embolism was ultimately diagnosed in 7 cases (prevalence of 2.6%, 95% confidence interval 1.1-5.3%). Five factors were identified as independently associated with a workup for pulmonary embolism diagnosis: female sex, young age, no ischemic heart disease, recent flight and associated dyspnea.

CONCLUSION

Among patients presenting to emergency department with chest pain, 30% had a workup for pulmonary embolism. We report five clinical variables independently associated with a higher probability of pulmonary embolism workup in our sample.

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.

Comparison of the age-adjusted and clinical probability-adjusted D-dimer to exclude pulmonary embolism in the ED

BACKGROUND

Diagnosing pulmonary embolism (PE) in the emergency department (ED) can be challenging because its signs and symptoms are non-specific.

OBJECTIVE

We compared the efficacy and safety of using age-adjusted D-dimer interpretation, clinical probability-adjusted D-dimer interpretation and standard D-dimer approach to exclude PE in ED patients.

DESIGN/METHODS

We performed a health records review at two emergency departments over a two-year period. We reviewed all cases where patients had a D-dimer ordered to test for PE or underwent CT or VQ scanning for PE. PE was considered to be present during the emergency department visit if PE was diagnosed on CT or VQ (subsegmental level or above), or if the patient was subsequently found to have PE or deep vein thrombosis during the next 30 days. We applied the three D-dimer approaches to the low and moderate probability patients. The primary outcome was exclusion of PE with each rule. Secondary objective was to estimate the negative predictive value (NPV) for each rule.

RESULTS

1163 emergency patients were tested for PE and 1075 patients were eligible for inclusion in our analysis. PE was excluded in 70.4% (95% CI 67.6-73.0%), 80.3% (95% CI 77.9-82.6%) and 68.9%; (95% CI 65.7-71.3%) with the age-adjusted, clinical probability-adjusted and standard D-dimer approach. The NPVs were 99.7% (95% CI 99.0-99.9%), 99.1% (95% CI 98.3-99.5%) and 100% (95% CI 99.4-100.0%) respectively.

CONCLUSION

The clinical probability-adjusted rule appears to exclude PE in a greater proportion of patients, with a very small reduction in the negative predictive value.

The Patient Safety Indicator Perioperative Pulmonary Embolism or Deep Vein Thrombosis: Is there associated surveillance bias in the Veterans Health Administration?

BACKGROUND

Studies disagree whether surveillance bias is associated with perioperative venous thromboembolism (VTE) performance measures. A prior VA study used a chart-based outcome; no studies have used the fully specified administrative data-based AHRQ Patient Safety Indicator, PSI-12, as their primary outcome. If surveillance bias were present, we hypothesized that inpatient surveillance rates would be associated with higher PSI-12 rates, but with lower post-discharge VTE rates.

METHODS

Using VA data, we examined Pearson correlations between hospital-level VTE imaging rates and risk-adjusted PSI-12 rates and post-discharge VTE rates. To determine the robustness of findings, we conducted several sensitivity analyses.

RESULTS

Hospital imaging rates were positively correlated with both PSI-12 (r = 0.24, p = 0.01) and post-discharge VTE rates (r = 0.16, p = 0.09). Sensitivity analyses yielded similar findings.

CONCLUSIONS

Like the prior VA study, we found no evidence of PSI-12-related surveillance bias. Given the use of PSI-12 in nationwide measurement, these findings warrant replication using similar methods in the non-VA setting.

Impact of Patient Affect on Physician Estimate of Probability of Serious Illness and Test Ordering

PURPOSE

The authors hypothesize patient facial affect may influence clinician pretest probability (PTP) estimate of cardiopulmonary emergency (CPE) and desire to order a computerized tomographic pulmonary angiogram (CTPA).

METHOD

This prospective study was conducted at three Indiana University-affiliated hospitals in two parts: collecting videos of patients undergoing CTPA for suspected acute pulmonary embolism watching a humorous video (August 2014-April 2015) and presenting the medical histories and videos to clinicians to determine the impact of patient facial affect on physicians' PTP estimate of CPE and desire to order a CTPA (June-November 2015). Patient outcomes were adjudicated as CPE+ or CPE- by three independent reviewers. Physicians completed a standardized test of facial affect recognition, read standardized medical histories, then viewed videos of the patients' faces. Clinicians marked their PTP estimate of CPE and desire for a CTPA before and after seeing the video on a visual analog scale (VAS).

RESULTS

Fifty physicians completed all 73 videos. Seeing the patient's face produced a > 10% absolute change in PTP estimate of CPE in 1,204/3,650 (33%) cases and desire for a CTPA in 1,095/3,650 (30%) cases. The mean area under the receiver operating characteristic curve for CPE estimate was 0.55 ± 0.15, and the change in CPE VAS was negatively correlated with physicians' standardized test scores (r = -0.23).

CONCLUSIONS

Clinicians may use patients' faces to make clinically important inferences about presence of serious illness and need for diagnostic testing. However, these inferences may fail to align with actual patient outcomes.

Pulmonary Embolism Testing Among Emergency Department Patients Who Are Pulmonary Embolism Rule-out Criteria Negative

OBJECTIVE

Previous studies have demonstrated that rates of pulmonary embolism (PE) testing have increased without a concomitant decrease in PE-related mortality. The Pulmonary Embolism Rule-out Criteria (PERC) intend to reduce testing for PE in the emergency department (ED) by identifying low-risk patients ("PERC-negative") who do not require D-dimer, computed tomography pulmonary angiogram (CTPA), or ventilation/perfusion (VQ) scan for PE. This study assesses PE testing rates among PERC-negative patients presenting to an urban academic ED.

METHODS

We prospectively enrolled a convenience sample of ED patients with chest pain and/or shortness of breath presenting between June 2010 and December 2015. We recorded baseline variables at the time of ED presentation, information on testing performed in the ED, and the diagnosis of acute PE during the ED visit. We classified patients as PERC-positive or PERC-negative utilizing baseline variables and clinical characteristics.

RESULTS

Of the 3,024 study patients, 54.8% (95% confidence interval = 53%-56.5%) were female and the mean age was 51.7 (51.1-52.3) years. A total of 17.5% (16.2%-18.9%) of study patients were PERC-negative and 33.7% (32%-35.4%) of all patients underwent testing for PE. A total of 25.5% (22%-29.4%) of PERC-negative patients had PE testing compared to 35.4% (33.6%-37.3%) of PERC-positive patients (p < 0.001). A total of 7.2% (5.3%-9.7%) of PERC-negative patients had advanced imaging without a D-dimer compared to 19.2% (17.8%-20.8%) of PERC-positive patients (p < 0.001). In multivariate analysis, factors associated with PE testing in PERC-negative patients included age, white non-Hispanic race/ethnicity, pleuritic chest pain, and a complaint of both chest pain and shortness of breath. Two PERC-negative patients (0.4%) were diagnosed with an acute PE in the ED compared to 2.2% of PERC-positive patients (p = 0.008). The overall testing yield for PE was 1.6% (0.4%-9.2%) among PERC-negative patients versus 6.3% (4.9%-8.1%) among PERC-positive patients (p = 0.017).

CONCLUSION

In an academic ED, a significant proportion of PERC-negative patients underwent testing for PE, including CT or VQ scan without D-dimer risk stratification. Future areas of research may include evaluating factors that lead clinicians to pursue PE testing in PERC-negative patients and implementing clinical pathways to minimize practice variability among these patients.

The Economic Value of Hybrid Single-photon Emission Computed Tomography With Computed Tomography Imaging in Pulmonary Embolism Diagnosis

Objective

The objective was to quantify the potential economic value of single‐photon emission computed tomography (SPECT) with computed tomography (CT; SPECT/CT) versus CT pulmonary angiography (CTPA), ventilation–perfusion (V/Q) planar scintigraphy, and V/Q SPECT imaging modalities for diagnosing suspected pulmonary embolism (PE) patients in an emergency setting.

Methods

An Excel‐based simulation model was developed to compare SPECT/CT versus the alternate scanning technologies from a payer's perspective. Clinical endpoints (diagnosis, treatment, complications, and mortality) and their corresponding cost data (2016 USD) were obtained by performing a best evidence review of the published literature. Studies were pooled and parameters were weighted by sample size. Outcomes measured included differences in 1) excess costs, 2) total costs, and 3) lives lost per annum between SPECT/CT and the other imaging modalities. One‐way (±25%) sensitivity and three scenario analyses were performed to gauge the robustness of the results.

Results

For every 1,000 suspected PE patients undergoing imaging, expected annual economic burden by modality was found to be 3.2 million (SPECT/CT), 3.8 million (CTPA), 5.8 million (planar), and 3.6 million (SPECT) USD, with a switch to SPECT/CT technology yielding per‐patient‐per‐month cost savings of $51.80 (vs. CTPA), $213.80 (vs. planar), and $36.30 (vs. SPECT), respectively. The model calculated that the incremental number of lives saved with SPECT/CT was six (vs. CTPA) and three (vs. planar). Utilizing SPECT/CT as the initial imaging modality for workup of acute PE was also expected to save $994,777 (vs. CTPA), $2,852,014 (vs. planar), and $435,038 (vs. SPECT) in “potentially avoidable”’ excess costs per annum for a payer or health plan.

Conclusion

Compared to the currently available scanning technologies for diagnosing suspected PE, SPECT/CT appears to confer superior economic value, primarily via improved sensitivity and specificity and low nondiagnostic rates. In turn, the improved diagnostic accuracy accords this modality the lowest ratio of expenses attributable to potentially avoidable complications, misdiagnosis, and underdiagnosis.

Increased Computed Tomography Utilization in the Emergency Department and Its Association with Hospital Admission

Introduction

Our goal was to investigate trends in computed tomography (CT) utilization in emergency departments (EDs) and its association with hospitalization.

Methods

We conducted an analysis of an administrative claims database of U.S. privately insured and Medicare Advantage enrollees. We identified ED visits from 2005 through 2013 and assessed for CT use, associated factors, and hospitalization after CT, along with patient demographics. We used both descriptive methods and regression models adjusted for year, age, sex, race, geographic region, and Hwang comorbidity score to explore associations among CT use, year, demographic characteristics, and hospitalization.

Results

We identified 33,144,233 ED visits; 5,901,603 (17.8%) involved CT. Over time, CT use during ED visits increased 59.9%. CT use increased in all age groups but decreased in children since 2010. In propensity-matching analysis, odds of hospitalization increased with age, comorbidities, male sex, and CT use (odds ratio, 2.38). Odds of hospitalization over time decreased more quickly for patients with CT.

Conclusion

CT utilization in the ED has increased significantly from 2005 through 2013. For children, CT use after 2010 decreased, indicating caution about CT use. Male sex, older age, and higher number of comorbidities were predictors of CT in the ED. Over time, odds of hospitalization decreased more quickly for patients with CT.

Identification of Pulmonary Hypertension Caused by Left-Sided Heart Disease (World Health Organization Group 2) Based on Cardiac Chamber Volumes Derived From Chest CT Imaging

BACKGROUND

Evaluations of patients with pulmonary hypertension (PH) commonly include chest CT imaging. We hypothesized that cardiac chamber volumes calculated from the same CT scans can yield additional information to distinguish PH related to left-sided heart disease (World Health Organization group 2) from other PH subtypes.

METHODS

Patients who had PH confirmed by right heart catheterization and contrast-enhanced chest CT studies were enrolled in this retrospective multicenter study. Cardiac chamber volumes were calculated using automated segmentation software and compared between group 2 and non-group 2 patients with PH.

RESULTS

This study included 114 patients with PH, 27 (24%) of whom were classified as group 2 based on their pulmonary capillary wedge pressure. Patients with group 2 PH exhibited significantly larger median left atrial (LA) volumes (118 mL vs 63 mL; P < .001), larger median left ventricular (LV) volumes (90 mL vs 76 mL; P = .02), and smaller median right ventricular (RV) volumes (173 mL vs 210 mL; P = .005) than did non-group 2 patients. On multivariate analysis adjusted for age, sex, and mean pulmonary arterial pressure, group 2 PH was significantly associated with larger median LA and LV volumes (P < .001 and P = .008, respectively) and decreased volume ratios of RA/LA, RV/LV, and RV/LA (P = .001, P = .004, and P < .001, respectively). Enlarged LA volumes demonstrated a high discriminatory ability for group 2 PH (area under the curve, 0.92; 95% CI, 0.870-0.968).

CONCLUSIONS

Volumetric analysis of the cardiac chambers from nongated chest CT scans, particularly with findings of an enlarged left atrium, exhibited high discriminatory ability for identifying patients with PH due to left-sided heart disease.

Clinical and echocardiographic findings of patients with suspected acute pulmonary thromboembolism who underwent computed tomography pulmonary angiography

Background:

The aim of the study was to determine the correlation between clinical and echocardiographic findings and risk factors of patients with suspected acute pulmonary thromboembolism (PTE) who underwent computed tomography pulmonary angiography (CTPA).

Materials and Methods:

In this cross-sectional study, 310 hospitalized patients aged >18 years with high clinical suspicion of PTE referred to imaging center of our hospital from different wards for CTPA were enrolled. The frequency of different clinical presentations, risk factors, items of Wells’ criteria, and echocardiographic findings was compared in patients with and without PTE, which have been diagnosed according to the CTPA results.

Results:

PTE was diagnosed in 53 (17.1%) of patients with suspected PTE. From clinical manifestations, tachypnea, pleuritic chest pain, and edema of lower extremities were significantly more frequent among patients with PTE (P < 0.05). Major surgery was the risk factor which was significantly more prevalent among patients with PTE (P < 0.05). Frequency of all criteria of Wells’ criteria, except hemoptysis, was significantly higher in patients with PTE (P < 0.05). The frequency of all studied echocardiographic variables was significantly higher in patients with PTE (P < 0.05).

Conclusion:

It is suggested that we could use the results of this study for utilizing the diagnostic process of PTE in patients with highly clinical suspicion of PTE and providing more validated decision. Using the results of this study, we could identify high-risk patients and made appropriate risk assessment for better management of patients with suspected PTE as well as reduce the rate of unnecessary CTPA and its related adverse consequences.

RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates

INTRODUCTION

Overuse of CT Pulmonary Angiograms (CTPA) for diagnosing pulmonary embolism (PE), particularly in Emergency Departments (ED), is considered problematic. Marked variations in positive CTPA rates are reported, with American 4-10% yields driving most concerns. Higher resolution CTPA may increase sub-segmental PE (SSPE) diagnoses, which may be up to 40% false positive. Excessive use and false positives could increase harm vs. benefit. These issues have not been systematically examined outside America.

AIMS

To describe current yield variation and CTPA utilisation in Australasian ED, exploring potential factors correlated with variation.

METHODS

A retrospective multi-centre review of consecutive ED-ordered CTPA using standard radiology reports. ED CTPA report data were inputted onto preformatted data-sheets. The primary outcome was site level yield, analysed both intra-site and against a nominated 15.3% yield. Factors potentially associated with yield were assessed for correlation.

RESULTS

Fourteen radiology departments (15 ED) provided 7077 CTPA data (94% ≥64-slice CT); PE were reported in 1028 (yield 14.6% (95%CI 13.8-15.4%; range 9.3-25.3%; site variation p <0.0001) with four sites significantly below and one above the 15.3% target. Admissions, CTPA usage, PE diagnosis rates and size of PE were uncorrelated with yield. Large PE (≥lobar) were 55% (CI: 52.1-58.2%) and SSPE 8.8% (CI: 7.1-10.5%) of positive scans. CTPA usage (0.2-1.5% adult attendances) was correlated (p<0.006) with PE diagnosis but not SSPE: large PE proportions.

DISCUSSION/ CONCLUSIONS

We found significant intra-site CTPA yield variation within Australasia. Yield was not clearly correlated with CTPA usage or increased small PE rates. Both SSPE and large PE rates were similar to higher yield historical cohorts. CTPA use was considerably below USA 2.5-3% rates. Higher CTPA utilisation was positively correlated with PE diagnoses, but without evidence of increased proportions of small PE. This suggests that increased diagnoses seem to be of clinically relevant sized PE.

PERC rule to exclude the diagnosis of pulmonary embolism in emergency low-risk patients: study protocol for the PROPER randomized controlled study

BACKGROUND

The diagnosis of Pulmonary Embolism (PE) in the emergency department (ED) is crucial. As emergency physicians fear missing this potential life-threatening condition, PE tends to be over-investigated, exposing patients to unnecessary risks and uncertain benefit in terms of outcome. The Pulmonary Embolism Rule-out Criteria (PERC) is an eight-item block of clinical criteria that can identify patients who can safely be discharged from the ED without further investigation for PE. The endorsement of this rule could markedly reduce the number of irradiative imaging studies, ED length of stay, and rate of adverse events resulting from both diagnostic and therapeutic interventions. Several retrospective and prospective studies have shown the safety and benefits of the PERC rule for PE diagnosis in low-risk patients, but the validity of this rule is still controversial. We hypothesize that in European patients with a low gestalt clinical probability and who are PERC-negative, PE can be safely ruled out and the patient discharged without further testing.

METHODS/DESIGN

This is a controlled, cluster randomized trial, in 15 centers in France. Each center will be randomized for the sequence of intervention periods: a 6-month intervention period (PERC-based strategy) followed by a 6-month control period (usual care), or in reverse order, with 2 months of "wash-out" between the 2 periods. Adult patients presenting to the ED with a suspicion of PE and a low pre test probability estimated by clinical gestalt will be eligible. The primary outcome is the percentage of failure resulting from the diagnostic strategy, defined as diagnosed venous thromboembolic events at 3-month follow-up, among patients for whom PE has been initially ruled out.

DISCUSSION

The PERC rule has the potential to decrease the number of irradiative imaging studies in the ED, and is reported to be safe. However, no randomized study has ever validated the safety of PERC. Furthermore, some studies have challenged the safety of a PERC-based strategy to rule-out PE, especially in Europe where the prevalence of PE diagnosed in the ED is high. The PROPER study should provide high-quality evidence to settle this issue. If it confirms the safety of the PERC rule, physicians will be able to reduce the number of investigations, associated subsequent adverse events, costs, and ED length of stay for patients with a low clinical probability of PE.

TRIAL REGISTRATION

NCT02375919 .

Evaluation of Patients With Suspected Acute Pulmonary Embolism: Best Practice Advice From the Clinical Guidelines Committee of the American College of Physicians

DESCRIPTION

Pulmonary embolism (PE) can be a severe disease and is difficult to diagnose, given its nonspecific signs and symptoms. Because of this, testing patients with suspected acute PE has increased dramatically. However, the overuse of some tests, particularly computed tomography (CT) and plasma d-dimer measurement, may not improve care while potentially leading to patient harm and unnecessary expense.

METHODS

The literature search encompassed studies indexed by MEDLINE (1966-2014; English-language only) and included all clinical trials and meta-analyses on diagnostic strategies, decision rules, laboratory tests, and imaging studies for the diagnosis of PE. This document is not based on a formal systematic review, but instead seeks to provide practical advice based on the best available evidence and recent guidelines. The target audience for this paper is all clinicians; the target patient population is all adults, both inpatient and outpatient, suspected of having acute PE.

BEST PRACTICE ADVICE 1

Clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being considered.

BEST PRACTICE ADVICE 2

Clinicians should not obtain d-dimer measurements or imaging studies in patients with a low pretest probability of PE and who meet all Pulmonary Embolism Rule-Out Criteria.

BEST PRACTICE ADVICE 3

Clinicians should obtain a high-sensitivity d-dimer measurement as the initial diagnostic test in patients who have an intermediate pretest probability of PE or in patients with low pretest probability of PE who do not meet all Pulmonary Embolism Rule-Out Criteria. Clinicians should not use imaging studies as the initial test in patients who have a low or intermediate pretest probability of PE.

BEST PRACTICE ADVICE 4

Clinicians should use age-adjusted d-dimer thresholds (age × 10 ng/mL rather than a generic 500 ng/mL) in patients older than 50 years to determine whether imaging is warranted.

BEST PRACTICE ADVICE 5

Clinicians should not obtain any imaging studies in patients with a d-dimer level below the age-adjusted cutoff.

BEST PRACTICE ADVICE 6

Clinicians should obtain imaging with CT pulmonary angiography (CTPA) in patients with high pretest probability of PE. Clinicians should reserve ventilation-perfusion scans for patients who have a contraindication to CTPA or if CTPA is not available. Clinicians should not obtain a d-dimer measurement in patients with a high pretest probability of PE.

Ten years of imaging for pulmonary embolism: too many scans or the tip of an iceberg?

AIM

To examine the number and nature of investigations performed for suspected pulmonary embolism (PE) in a large teaching hospital and the change in incidence and severity of PE over a decade.

MATERIALS AND METHODS

In this retrospective study, all patients investigated for suspected PE using computed tomography pulmonary angiography (CTPA) or lung scintigraphy during 10 years to March 2012 were identified and their records reviewed. In the final year, all reportedly positive CTPA cases were reviewed and PE severity calculated, for comparison with similar historical data.

RESULTS

From 2002 to 2012, total annual investigations for suspected acute PE increased by 163% (805 to 2121). CTPA increased by 325% (475 to 2019). Detection of PE increased by 121% (193 to 426 per annum), with stable distribution of severity scores. The positive scan rate decreased from 24% to 20%. The mean age of patients being investigated for PE increased from 56 to 63 years.

CONCLUSIONS

Increased detection of PE is not due to disproportionate increase in small PEs, but to increased detection of PE of all severities. This finding supports the hypothesis that PE is more common in the general population than previously appreciated, which may represent an iceberg phenomenon of previously undetected disease.

Software-Based Hybrid Perfusion SPECT/CT Provides Diagnostic Accuracy When Other Pulmonary Embolism Imaging Is Indeterminate

PURPOSE

To investigate the diagnostic performance of perfusion single-photon emission computed tomography/computed tomography (Q-SPECT/CT) in patients suspected to have pulmonary embolism (PE) but with indeterminate computed tomographic pulmonary angiography (CTPA) or planar ventilation/perfusion (V/Q) scans.

METHODS

This retrospective study included two groups of patients. Group I consisted of 49 patients with nondiagnostic CTPA. These 49 patients underwent subsequent V/Q scans. Further Q-SPECTs were obtained in patients with indeterminate planar images and fused with existing CTPA. Group II consisted of 182 non-CTPA patients with indeterminate V/Q scans. These 182 patients underwent further Q-SPECT and separate noncontrast low-dose CT chest. Fusion Q-SPECT/CT scans were obtained through FDA-approved software and interpreted according to published criteria as positive, negative, or indeterminate for PE. Upon retrospective analyses, the final diagnosis was made using composite reference standards including all available clinical and imaging information for at least 6-month follow-up.

RESULTS

In group I patients, 1 was positive, 24 were negative, and another 24 (49 %, 24/49) were indeterminate. In the subsequent 24 Q-SPECT/CTPAs, 4 were positive, 19 were negative, and 1 was indeterminate (4.2 %, 1/24). In group II patients, 9 (4.9 %, 9/182) were indeterminate, 33 were positive, and 140 were negative. The combined nondiagnostic rate for Q-SPECT/CT was only 4.9 % (10/206). There was six false-negative and one false-positive Q-SPECT/CT examinations. The sensitivity, specificity, and positive and negative predictive value of Q-SPECT/CT were 85.7 % (36/42), 99.4 % (153/154), 97.3 % (36/37) and 96.2 % (153/159), respectively.

CONCLUSIONS

Q-SPECT/CT improves the diagnostic rate with promising accuracy in diagnosing PE that yields a satisfactory clinical verdict, especially when the CTPA and planar V/Q scan are indeterminate.

Pulmonary Hypertension: A Nomogram Based on CT Pulmonary Angiographic Data for Prediction in Patients without Pulmonary Embolism

PURPOSE

To use cardiovascular data from computerized tomographic (CT) pulmonary angiography for facilitating the identification of pulmonary hypertension (PH) in patients without acute pulmonary embolism.

MATERIALS AND METHODS

The institutional human research committee approved this retrospective study; informed consent was waived. Patients without pulmonary embolism who underwent CT pulmonary angiography and echocardiography within 24 hours of each other between December 2008 and October 2012 were retrospectively identified. The diameters of the pulmonary artery, aorta, and right and left ventricles and the severity of reflux of contrast material were assessed. The volumes of each cardiac compartment were calculated. Doppler echocardiography served as a reference standard for PH. A prediction model for PH was built by using backward logistic regression and was presented on a nomogram. The prediction model was evaluated with 10-fold cross-validation, and a test group of patients was studied between November 2012 and June 2014.

RESULTS

The final study group included 182 patients, of whom 98 (54%) were given a diagnosis of PH on the basis echocardiographic results. Age of 67 years or older (odds ratio [OR] = 4.46), reflux grade of 3 or higher (OR = 2.63), right atrial volume of greater than or equal to 106 cm(3) (OR = 3.59), pulmonary artery diameter greater than or equal to 28 mm (OR = 2.52) and pulmonary artery diameter to aorta diameter ratio of greater than or equal to 0.86 (OR = 2.17) were independently associated with PH. The logistic model showed good discrimination ability (area under the curve = 0.844, discrimination slope = 0.359). Tenfold cross-validation showed 85.7% sensitivity, 60.7% specificity, 71.3% positive predictive value, and 76.1% negative predictive value for identification of PH, while the test group showed similar results (84.1%, 60.5%, 71.2%, and 76.7%, respectively).

CONCLUSION

Cardiovascular data derived from CT pulmonary angiography are associated with PH, and a nomogram can be created that may facilitate identification of PH after exclusion of acute pulmonary embolism.

Cost-effectiveness of quantitative pretest probability intended to reduce unnecessary medical radiation exposure in emergency department patients with chest pain and dyspnea

OBJECTIVES

Quantitative pretest probability (qPTP) incorporated into a decision support tool with advice can reduce unnecessary diagnostic testing among patients with symptoms suggestive of acute coronary syndrome (ACS) and pulmonary embolism (PE), reducing 30-day costs without an increase in 90-day adverse outcomes. This study estimates long-term (beyond 90-day) costs and outcomes associated with qPTP. The authors hypothesized that qPTP reduces lifetime costs and improves outcomes in low-risk patients with symptoms suggestive of ACS and PE.

METHODS

This was a cost-effectiveness analysis of a multicenter, randomized controlled trial of adult emergency patients with dyspnea and chest pain, in which a clinician encountering a low-risk patient with symptoms suggestive of ACS or PE conducted either the intervention (qPTP for ACS and PE with advice) or the sham (no qPTP and no advice). Effect of the intervention over a patient's lifetime was assessed using a Markov microsimulation model. Short-term costs and outcomes were from the trial; long-term outcomes and costs were from the literature. Outcomes included lifetime transition to PE, ACS, and intracranial hemorrhage (ICH); mortality from cancer, ICH, PE, ACS, renal failure, and ischemic stroke; quality-adjusted life-years (QALYs); and total medical costs compared between simulated intervention and sham groups.

RESULTS

Markov microsimulation for a 40-year-old patient receiving qPTP found lifetime cost savings of $497 for women and $528 for men, associated with small gains in QALYs (2 and 6 days, respectively) and lower rates of cancer mortality in both sexes, but a reduction in ICH only in males. Sensitivity analysis for patients aged 60 years predicted that qPTP would continue to save costs and also reduce mortality from both ICH and cancer. Use of qPTP significantly reduced the lifetime probability of PE diagnosis, with lower probability of death from PE in both sexes aged 40 to 60 years. However, use of qPTP reduced the rate of ACS diagnosis and death from ACS at age 40, but increased the death rate from ACS at age 60 for both sexes.

CONCLUSIONS

Widespread use of a combined qPTP for both ACS and PE has the potential to decrease costs by reducing diagnostic testing, while improving most long-term outcomes in emergency patients with chest pain and dyspnea.

National trends in emergency room diagnosis of pulmonary embolism, 2001-2010: a cross-sectional study

Background

Little is known about the United States diagnosis and burden of pulmonary embolism (PE) in the emergency department (ED), and their evolution over the past decade. We examined nationally representative data to evaluate factors associated with and trends in ED diagnosis of PE.

Methods

We conducted a cross-sectional study using National Hospital Ambulatory Medical Care Survey (NHAMCS) data from January 1, 2001 to December 31, 2010. We identified all ED patient visits where PE was diagnosed and corresponding demographic, hemodynamic, testing and disposition data. Analyses were performed using descriptive statistics and multivariable logistic regression.

Results

During the study period 988,000 weighted patient visits with diagnosis of PE were identified. Among patients with an ED visit, the likelihood of having a diagnosis of PE per year increased significantly from 2001 to 2010 (odds ratio [OR] 1.091, 95% confidence interval [CI] 1.034-1.152, P = 0.002 for trend) when adjusted for demographic and hospital information. In contrast, when further adjusted for the use of computed tomography (CT) among patients in the ED, the likelihood of having a diagnosis of PE per year did not change (OR 1.041, 95% CI 0.987-1.097, P = 0.14). Overall, 75.1% of patients seen with a diagnosis of PE were hemodynamically stable; 86% were admitted with an in-hospital death rate under 3%.

Conclusions

The proportion of ED visits with a diagnosis of PE increased significantly from 2001 to 2010 and this rise can be attributed in large part to the increased availability and use of CT. Most of these patients were admitted with low in-hospital mortality.