Negative Computed Tomography Pulmonary Angiography Research Articles

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.

The demographic, clinical, and medical manifestations of pulmonary thromboembolism development in COVID-19

BackgroundSince the emergence of coronavirus disease 2019 (COVID-19), various clinical manifestations ranging from asymptomatic to severe, life-threatening courses have been presented. It is well known that COVID-19 patients are at an increased risk of pulmonary thromboembolism (PTE) development; however, the associated demographic, medical, and clinical factors for developing PTE remain unknown. The current study aimed to assess the characteristics of patients with PTE.MethodsThis case-control study was derived from an ongoing population-based investigation of hospitalized patients with COVID-19 pneumonia. The case group included 99 patients with PTE confirmed by computed tomography pulmonary angiography (CTPA), and the controls (N=132) were age-matched patients selected from the PTE-suspected patients with a negative CTPA. The demographic, medical, and clinical characteristics of the study population were entered into the study checklist and compared. A logistic regression test was used to determine the factors associated with PTE development.ResultsAmong the 13,099 admitted patients, 690 (5.26%) were suspected of having PTE according to their clinical manifestations. CTPA was performed for suspected cases, and PTE was confirmed in 132 patients (19.13%). Logistic regression assessments revealed that male gender (OR, 2.39; 95%CI, 1.38‒4.13), decreased oxygen saturation (OR, 2.33; 95%CI, 1.27‒4.26), and lower hemoglobin (OR, 0.83, 0.95), and albumin (OR, 0.31; 95%CI, 0.18‒0.53) levels were associated with PTE development.ConclusionPTE was confirmed in one-fifth of suspected patients who underwent CTPA imaging. Male sex, decreased oxygen saturation, and lower levels of hemoglobin and albumin were independent predictors of PTE in patients with COVID-19 pneumonia.

Determinants of time-to-disposition in patients who underwent CT for pulmonary embolism: a retrospective study

BackgroundPulmonary embolism (PE) is a common life-threatening medical emergency that needs prompt diagnosis and management. Providing urgent care is a key determinant of quality in the emergency department (ED) and time-based targets have been implemented to reduce length of stay and overcrowding. The study aimed to determine factors that are associated with having a time-to-disposition of less than 4 h in patients with suspected PE who underwent computed tomography pulmonary angiography (CT-PA) to confirm the diagnosis.MethodsAfter obtaining approval from the ethics committee, we conducted a retrospective observational study by examining CT-PA scans that was performed to rule out PE in all adult patients presenting at the ED between January 2018 and December 2019. Demographic information and clinical information, as well as arrival and disposition times were collected from electronic health records. Multivariable regression analysis was used to identify the independent factors associated with meeting the 4-h target in the ED.ResultsIn total, the study involved 232 patients (76 men and 156 women). The median length of stay in the ED was 5.2 h and the 4-h target was achieved in 37% of patients. Multivariable logistic regression analysis revealed that a positive CT-PA scan for PE was independently associated with meeting the four-hour target in the ED (odds ratio [OR]: 2.2; 95% CI: 1.1–4.8). Furthermore, Hemoptysis was the only clinical symptom that served as an independent factor associated with meeting the 4-h target in the ED (OR: 10.4; 95% CI: 1.2–90.8).ConclusionDespite the lower number of staff and higher volume of patients on weekends, patients who presented on weekends had shorter stays and were more likely to meet the 4-h target. Careful clinical assessment, prior to requesting a CT-PA scan, is crucial, since negative CT-PA scans may be associated with failure to meet the 4-h target.

Performance of a 3D convolutional neural network in the detection of hypoperfusion at CT pulmonary angiography in patients with chronic pulmonary embolism: a feasibility study

BackgroundChronic pulmonary embolism (CPE) is a life-threatening disease easily misdiagnosed on computed tomography. We investigated a three-dimensional convolutional neural network (CNN) algorithm for detecting hypoperfusion in CPE from computed tomography pulmonary angiography (CTPA).MethodsPreoperative CTPA of 25 patients with CPE and 25 without pulmonary embolism were selected. We applied a 48%–12%–40% training-validation-testing split (12 positive and 12 negative CTPA volumes for training, 3 positives and 3 negatives for validation, 10 positives and 10 negatives for testing). The median number of axial images per CTPA was 335 (min–max, 111–570). Expert manual segmentations were used as training and testing targets. The CNN output was compared to a method in which a Hounsfield unit (HU) threshold was used to detect hypoperfusion. Receiver operating characteristic area under the curve (AUC) and Matthew correlation coefficient (MCC) were calculated with their 95% confidence interval (CI).ResultsThe predicted segmentations of CNN showed AUC 0.87 (95% CI 0.82–0.91), those of HU-threshold method 0.79 (95% CI 0.74–0.84). The optimal global threshold values were CNN output probability ≥ 0.37 and ≤ -850 HU. Using these values, MCC was 0.46 (95% CI 0.29–0.59) for CNN and 0.35 (95% CI 0.18–0.48) for HU-threshold method (average difference in MCC in the bootstrap samples 0.11 (95% CI 0.05–0.16). A high CNN prediction probability was a strong predictor of CPE.ConclusionsWe proposed a deep learning method for detecting hypoperfusion in CPE from CTPA. This model may help evaluating disease extent and supporting treatment planning.

Serial markers of coagulation and inflammation and the occurrence of clinical pulmonary thromboembolism in mechanically ventilated patients with SARS-CoV-2 infection; the prospective Maastricht intensive care COVID cohort

BackgroundThe incidence of pulmonary thromboembolism is high in SARS-CoV-2 patients admitted to the Intensive Care. Elevated biomarkers of coagulation (fibrinogen and D-dimer) and inflammation (c-reactive protein (CRP) and ferritin) are associated with poor outcome in SARS-CoV-2. Whether the time-course of fibrinogen, D-dimer, CRP and ferritin is associated with the occurrence of pulmonary thromboembolism in SARS-CoV-2 patients is unknown. We hypothesise that patients on mechanical ventilation with SARS-CoV-2 infection and clinical pulmonary thromboembolism have lower concentrations of fibrinogen and higher D-dimer, CRP, and ferritin concentrations over time compared to patients without a clinical pulmonary thromboembolism.MethodsIn a prospective study, fibrinogen, D-dimer, CRP and ferritin were measured daily. Clinical suspected pulmonary thromboembolism was either confirmed or excluded based on computed tomography pulmonary angiography (CTPA) or by transthoracic ultrasound (TTU) (i.e., right-sided cardiac thrombus). In addition, patients who received therapy with recombinant tissue plasminogen activator were included when clinical instability in suspected pulmonary thromboembolism did not allow CTPA. Serial data were analysed using a mixed-effects linear regression model, and models were adjusted for known risk factors (age, sex, APACHE-II score, body mass index), biomarkers of coagulation and inflammation, and anticoagulants.ResultsThirty-one patients were considered to suffer from pulmonary thromboembolism ((positive CTPA (n = 27), TTU positive (n = 1), therapy with recombinant tissue plasminogen activator (n = 3)), and eight patients with negative CTPA were included. After adjustment for known risk factors and anticoagulants, patients with, compared to those without, clinical pulmonary thromboembolism had lower average fibrinogen concentration of − 0.9 g/L (95% CI: − 1.6 – − 0.1) and lower average ferritin concentration of − 1045 μg/L (95% CI: − 1983 – − 106) over time. D-dimer and CRP average concentration did not significantly differ, 561 μg/L (− 6212–7334) and 27 mg/L (− 32–86) respectively. Ferritin lost statistical significance, both in sensitivity analysis and after adjustment for fibrinogen and D-dimer.ConclusionLower average concentrations of fibrinogen over time were associated with the presence of clinical pulmonary thromboembolism in patients at the Intensive Care, whereas D-dimer, CRP and ferritin were not. Lower concentrations over time may indicate the consumption of fibrinogen related to thrombus formation in the pulmonary vessels.

Is computed tomographic pulmonary angiography justified in all patients with suspected pulmonary embolism – tertiary multidisciplinary hospital perspective

Abstract Background According to 2019 ESC guidelines for management in patients with the pulmonary embolism (PE), the computed tomographic pulmonary angiography (CTPA) is the diagnostic method of choice in suspected high-risk PE defined as patients with hemodynamic instability. In stable cases, it is recommended to assess the pre-test probability of the PE. However, CTPA with its great accuracy and wide availability in most medical centers is used as often to confirm as to exclude the diagnosis in PE suspected patients, despite the fact that it is linked with the risk of radiation and iodine-containing contrast exposure. Purpose The aim of the study was to assess the validity of CTPA use in patients with suspected PE form the perspective of multidisciplinary clinical center. Methods We retrospectively analyzed the data of from 52,474 hospitalized patients between 01.2018 and 12.2019. A total of 261 (0.5%) consecutive patients with suspected PE (in the emergency department or during hospitalization) were included into the study. Due to suspicion of PE all patients underwent the CTPA. In this group, we analyzed all available clinical data, results of laboratory and diagnostic tests (before and after CTPA) including estimated glomerular filtration rate (eGFR), creatinine level, transthoracic echocardiography (TTE) and planar ventilation/perfusion (lung scintigraphy) scan (V/Q SPECT) if performed. Results The CTPA confirmed PE in 28.9% of patients. The most common final diagnoses, established in the group with negative CTPA result, include heart failure (33.9%), pneumonia (14.4%) exacerbation of chronic obstructive pulmonary disease or asthma (9.3%) and acute coronary syndrome (5.9%). Acute PE was the cause of in-hospital death in 2.4% of patients and the rate of all cause in-hospital death was 11.4%. In 54.2% of patients we observed the eGFR decline and creatinine level increase, meeting the criteria of the acute contrast-induced nephropathy in 33 of them of them (19.8%). In the group with excluded PE, mean eGFR before CTPA was 70.9ml/min/1.73m2 with the decline to mean 60.4ml/min/1.73m2 during the hospitalization (p<0.01). In patients with negative CTPA result and the worsening of the renal function mean eGFR decline was 17.8ml/min/1.73m2 (p<0.01) and mean creatinine level increase was 38.6μmol/l (p<0.01). CONSLUSIONS The initial data collected show the overuse of CTPA in suspected PE, as the diagnosis was confirmed in less than one-third of them. Although CTPA allows to exclude or confirm PE unambiguously, its use is associated with risk of acute contrast-induced nephropathy. Additionally, in patients with exacerbation of heart failure established as final diagnosis after excluding PE, intensive diuretic treatment is crucial and may cause further accompanying renal function worsening. Therefore, optimizing the diagnostic pathway in patients with suspected PE into less aggravating procedures such as TTE or V/Q SPECT is justifiable. Funding Acknowledgement Type of funding source: None

DETERMINANTS FOR POSITIVE COMPUTED TOMOGRAPHY PULMONARY ANGIOGRAPHY (CTPA) IN DIAGNOSING PULMONARY EMBOLISM IN NORTHEAST STATE OF PENINSULAR MALAYSIA

Background: This study was conducted to estimate the annual proportion of positive computed tomography pulmonary angiography (CTPA) in diagnosing pulmonary embolism and determine its socio-demographic and clinical determinants. Materials and Methods: CTPA datasets of 431 patients from 2014 to 2017 were analysed retrospectively to estimate the annual proportion of cases with pulmonary embolism in Kelantan, a northeast state of peninsular Malaysia. Comparative cross-sectional study between positive and negative CTPA cases among 388 randomly selected patients that fulfilled the inclusion criteria was conducted to determine associated factors for positive CTPA finding. Descriptive statistics, simple and multiple logistic regressions were used for data analysis. Result: The annual proportion of positive CTPA cases ranged from 25.2% to 33.3%. The mean age of patients with positive CTPA finding was 50.32 years old and majority of positive CTPA patients were male (67.0 %), cigarette smoker (67.0 %), non-hypertensive (58.9%) and had high Well’s score (74.5%). Older age, male gender and high Wells score were the significant determinants for positive CTPA findings with an adjusted odds ratio (aOR) of 1.03 (95% confidence interval (CI): 1.01-1.05; p = 0.004), 5.42 (95% CI: 2.31-12.68; p < 0.001), and 13.45 (95% CI: 6.93-26.11; p < 0.001), respectively. Conclusion: Patients with older age, male gender and high Wells score were more likely to get positive CTPA finding. These significant determinants might help clinicians in preventing unnecessary CTPA examination, thus unjustified radiation to the patient can be avoided.

Relationship between Thrombosis Risk Factors, Clinical Symptoms, and Laboratory Findings with Pulmonary Embolism Diagnosis; a Cross-Sectional Study.

Pulmonary embolism (PE) is a potentially life threatening disease, accurate and timely diagnosis of which is still a challenge that physicians face. This study was designed with the aim of evaluating the relationship between thrombosis risk factors, clinical symptoms, and laboratory findings with the presence or absence of PE. The present retrospective cross-sectional study was performed on patients with suspected pulmonary embolism who were hospitalized in different departments of Shohadaye Tajrish Hospital, Tehran, Iran, during 1 year. All patients underwent computed tomography pulmonary angiography (CTPA) and then thrombosis risk factors, clinical symptoms, and laboratory findings of confirmed PE cases with CTPA were compared with others. 188 patients with the mean age of 61.91 ± 18.25 (20 - 101) years were studied (54.8% male). Based on Wells' score, 32 (17.2%) patients were in the low risk group, 145 (78.0%) were in the moderate risk group, and 9 (4.8%) patients were classified in the high risk group for developing PE. CTPA findings confirmed PE diagnosis for 60 (31.7%) patients (6.7% high risk, 75.0% moderate risk, 18.3% low risk). D-dimer test was only ordered for 27 patients, 25 (92.6%) of which were positive. Among the patients with positive D-dimer, 18 (72.0%) cases had negative CTPA. Inactivity (57.4%), hypertension (32.8%), and history of cancer (29.5%) were the most common risk factors of thrombosis in patients with PE. In addition, shortness of breath (60.1%) and tachypnea (11.1%) were the most common clinical findings among patients with PE. There was no significant difference between the patients with PE diagnosis and others regarding mean age (p = 0.560), sex distribution (p = 0.438), and type of thrombosis risk factors (p > 0.05), hospitalization department (p = 0.757), Wells' score (p = 0.665), electrocardiography findings, or blood gas analyses. Although attention to thrombosis risk factors, clinical symptoms, and laboratory findings, can be helpful in screening patients with suspected PE, considering the ability of CT scan in confirming or ruling out other possible differential diagnoses, it seems that a revision should be done to lower the threshold of ordering this diagnostic modality for suspected cases.

Diagnosis of Pulmonary Embolism During Pregnancy: A Multicenter Prospective Management Outcome Study.

Data on the optimal diagnostic management of pregnant women with suspected pulmonary embolism (PE) are limited, and guidelines provide inconsistent recommendations on use of diagnostic tests. To prospectively validate a diagnostic strategy in pregnant women with suspected PE. Multicenter, multinational, prospective diagnostic management outcome study involving pretest clinical probability assessment, high-sensitivity D-dimer testing, bilateral lower limb compression ultrasonography (CUS), and computed tomography pulmonary angiography (CTPA). (ClinicalTrials.gov: NCT00740454). 11 centers in France and Switzerland between August 2008 and July 2016. Pregnant women with clinically suspected PE in emergency departments. Pulmonary embolism was excluded in patients with a low or intermediate pretest clinical probability and a negative D-dimer result. All others underwent lower limb CUS and, if results were negative, CTPA. A ventilation-perfusion (V/Q) scan was done if CTPA results were inconclusive. Pulmonary embolism was excluded if results of the diagnostic work-up were negative, and untreated pregnant women had clinical follow-up at 3 months. The primary outcome was the rate of adjudicated venous thromboembolic events during the 3-month follow-up. 441 women were assessed for eligibility, and 395 were included in the study. Among these, PE was diagnosed in 28 (7.1%) (proximal deep venous thrombosis found on ultrasonography [n= 7], positive CTPA result [n= 19], and high-probability V/Q scan [n= 2]) and excluded in 367 (clinical probability and negative D-dimer result [n= 46], negative CTPA result [n= 290], normal or low-probability V/Q scan [n= 17], and other reason [n= 14]). Twenty-two women received extended anticoagulation during follow-up, mainly for previous venous thromboembolic disease. The rate of symptomatic venous thromboembolic events was 0.0% (95% CI, 0.0% to 1.0%) among untreated women after exclusion of PE on the basis of negative results on the diagnostic work-up. There were several protocol deviations, reflecting the difficulty of performing studies in pregnant women with suspected PE. A diagnostic strategy based on assessment of clinical probability, D-dimer measurement, CUS, and CTPA can safely rule out PE in pregnant women. Swiss National Foundation for Scientific Research, Groupe d'Etude de la Thrombose de Bretagne Occidentale, and International Society on Thrombosis and Haemostasis.

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

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

Ruling out Pulmonary Embolism in Patients with High Pretest Probability.

IntroductionThe American College of Emergency Physicians guidelines recommend more aggressive workup beyond imaging alone in patients with a high pretest probability (PTP) of pulmonary embolism (PE). However, the ability of multiple tests to safely rule out PE in high PTP patients is not known. We sought to measure the ability of negative computed tomography pulmonary angiography (CTPA) along with negative D-dimer to rule out PE in these high-risk patients.MethodsWe analyzed data from a previous prospective observational study conducted in 12 emergency departments (ED). Wells score criteria were entered by providers before final PE testing. PE was diagnosed by imaging on the index ED visit, or within 45 days, demonstrating either PE or deep vein thrombosis (DVT), or if the patient died of PE during the 45-day, follow-up period. Testing threshold was set at 1.8%.ResultsA total of 7,940 patients were enrolled and tested for PE, and 257 had high PTP (Wells >6). Sixteen of these high-risk patients had negative CTPA and negative D-dimer, of whom two were positive for PE (12.5% [95% confidence interval {2.2%–40.0%}]). One of these patients had a DVT on CT venogram and the other was diagnosed at follow-up.ConclusionOur analysis suggests that in patients with high PTP of PE, neither negative CTPA by itself nor a negative CTPA plus a negative D-dimer are sufficient to rule out PE. More aggressive workup strategies may be required for these patients.

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

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

Use of Computed Tomography Pulmonary Angiography for Suspected Pulmonary Embolism in Patients with Malignancy- a Single Center Experience

Background: Pulmonary embolism (PE) is a potentially lethal condition commonly suspected in patients with malignancy. Computed Tomography Pulmonary Angiography (CTPA) is increasingly used in the diagnosis of PE, and guidelines have incorporated various screening tools including the Modified Geneva and Wells criteria to facilitate exclusion of pulmonary embolism. There is an increased risk of venous thromboembolism in patients with active malignancy and therefore an increased suspicion in patients who present to the emergency department (ED) with concerning symptoms.Methods: This is a retrospective analysis at a single tertiary care institution. All patients initially diagnosed with an active malignancy since 2005 and underwent a CTPA between January 2010 and October 2015 were reviewed. Patients were excluded if the CTPA was performed in the setting of trauma, a history of benign malignancy, or if the diagnosis of malignancy was made subsequent to the CTPA. Data collected included patient demographics, clinical presentation, type of malignancy and treatment regimen received. The modified Geneva and Wells criteria were applied to all patients independent from the initial ED risk assessment for a PE.Results: There were 796 patient records reviewed, of which 162 patients met inclusion criteria. Out of these 162 patients, only 8 (4.9%) were found to have a pulmonary embolism. All patients with a positive CTPA had an intermediate risk per the Geneva criteria while only 62.5% had an intermediate risk per the Wells criteria. Of the 154 patients with a negative CTPA, 71.5% and 78.7% had an intermediate risk; 22.5% and 18.7% were classified as low risk based on Wells and Geneva criteria, respectively. The median age of patients was 59 years old, and the majority were male (58%). The most common malignancies in which a CTPA was ordered were lung cancer (27.7%) followed by breast cancer (14.9%) and prostate cancer (6.8%). Despite a negative CTPA, 82 out of 154 patients (53%) were admitted to the hospital.Conclusion: Pulmonary embolism is commonly associated with and frequently suspected in patients with active malignancy. The incidence of PE over a 5-year period in oncology patients was 5% in our emergency department. In total, 18.7% to 22.5% of patients could have avoided a CTPA if scoring was based on the Wells or Geneva criteria. Based on the review at our institution, the modified Geneva and Wells criteria are not adequate, and a new tool needs to be developed for risk stratification for the diagnosis of PE specifically in patients with active malignancy. DisclosuresNo relevant conflicts of interest to declare.

Risk of pulmonary embolism after a prior negative CT pulmonary angiogram

ContextWith increasing utilization of computed tomography pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism (PE), many patients undergo repeat CTs. ObjectiveThe aim of this study is to identify the rate of positive subsequent CTPAs after an initial negative CTPA and whether there is a risk-free period after a negative CTPA. MethodsWe evaluated 318 patients with at least 1 subsequent CTPA after an initial negative CTPA, with 786 total CTPAs. We also evaluated a control group of 200 unselected CTPAs. ResultsThe positive rate in the repeat group was 7% at the first repeat CTPA and 10% per-patient within 1000 days. The positive rate in the control group was 9% (P= not significant). No risk-free period was seen, with a positive rate of 5% within 2 weeks after a negative CTPA. The number of prior negative CTPAs showed a trend towards decreasing rate of the subsequent CTPA being positive, but this did not meet statistical significance. DiscussionThere is no risk-free period after an initial negative CTPA, and therefore, patients with clinical suspicion of PE should be rescanned even after a recent negative study. Even patients with multiple negative prior CTPAs have a measurable risk of subsequent PE. Established clinical prediction scoring systems must be used to triage the patients who need CTPAs.

Ventilation/Perfusion SPECT lung scintigraphy and computed tomography pulmonary angiography in patients with clinical suspicion of pulmonary embolism

The aim was to compare ventilation/perfusion SPECT lung scintigraphy (V/Q-SPECT) and computed tomography pulmonary angiography (CTPA) in patients with suspicion of pulmonary embolism (PE). Material and methodsThis prospectively designed study included 53 patients with intermediate or high clinical probability of PE. A V/Q-SPECT and CTPA was performed on all patients. The V/Q-SPECT was interpreted according to the European Association of Nuclear Medicine and Molecular Imaging (EANMMI) guidelines. CTPA was reported as positive, negative, or indeterminate. ResultsCTPA was positive in 22 cases, negative in 28, and indeterminate in 3. V/Q-SPECT was positive in 27 cases, negative in 24, and non-diagnostic in 2. In the 22 with positive CTPA, V/Q-SPECT was positive in 18, negative in 3, and non-diagnostic in 1. In the 28 with negative CTPA, V/Q-SPECT was positive in 8, negative in 19, and non-diagnostic in 1. In the 3 with indeterminate CTPA, V/Q-SPECT was positive in 1 and negative in 2. In the 2 non-diagnostic cases V/Q-SPECT, CTPA was positive in 1 and negative in one. In the 10 high clinical probabilities, CTPA and V/Q-SPECT were positive in 7, negative in 2, and in 1, CTPA was positive and V/Q-SPECT negative. In the 38 intermediate probability group, CTPA and V/Q-SPECT were positive in 11, negative in 17, with CTPA negative and V/Q-SPECT positive in 8, and in 2 CTPA was positive and V/Q-SPECT negative. The results show that V/Q-SPECT detected PE in 5 patients more than CTPA. ConclusionOur results show a 77% concordance of both techniques. Overall V/Q-SPECT detected PE in 18% more patients than CTPA in the intermediate group. Both techniques have a complementary role when a diagnosis cannot be made with one of them.

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

ESSENTIALS: When high probability of pulmonary embolism (PE), sensitivity of computed tomography (CT) is unclear. We investigated the sensitivity of multidetector CT among 134 patients with a high probability of PE. A normal CT alone may not safely exclude PE in patients with a high clinical pretest probability. In patients with no clear alternative diagnosis after CTPA, further testing should be strongly considered. Whether patients with a negative multidetector computed tomographic pulmonary angiography (CTPA) result and a high clinical pretest probability of pulmonary embolism (PE) should be further investigated is controversial. This was a prospective investigation of the sensitivity of multidetector CTPA among patients with a priori clinical assessment of a high probability of PE according to the Wells criteria. Among patients with a negative CTPA result, the diagnosis of PE required at least one of the following conditions: ventilation/perfusion lung scan showing a high probability of PE in a patient with no history of PE, abnormal findings on venous ultrasonography in a patient without previous deep vein thrombosis at that site, or the occurrence of venous thromboembolism (VTE) in a 3-month follow-up period after anticoagulation was withheld because of a negative multidetector CTPA result. We identified 498 patients with a priori clinical assessment of a high probability of PE and a completed CTPA study. CTPA excluded PE in 134 patients; in these patients, the pooled incidence of VTE was 5.2% (seven of 134 patients; 95% confidence interval [CI] 1.5-9.0). Five patients had VTEs that were confirmed by an additional imaging test despite a negative CTPA result (five of 48 patients; 10.4%; 95% CI 1.8-19.1), and two patients had objectively confirmed VTEs that occurred during clinical follow-up of at least 3 months (two of 86 patients; 2.3%; 95% CI 0-5.5). None of the patients had a fatal PE during follow-up. A normal multidetector CTPA result alone may not safely exclude PE in patients with a high clinical pretest probability.

The prevalence of pulmonary embolism among patients suffering from acute exacerbations of chronic obstructive pulmonary disease.

The clinical diagnosis of acute pulmonary embolism (PE) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) is often difficult due to the similarity in the presenting symptoms of the two conditions. The purpose of this study was to determine the prevalence of PE in patients with acute exacerbation of COPD. Forty-nine consecutive patients admitted to our medical center for acute exacerbation of COPD were investigated for PE (whether or not clinically suspected), following a standardized algorithm based on D-dimer testing and computed tomography pulmonary angiography (CTPA). PE was ruled out by a D-dimer value <500 μg/L in 20 (41 %) patients and by negative CTPA in 40 (82 %). PE was confirmed in 9 patients. The prevalence of PE was 18 %. One patient with normal D-dimer had PE. Presenting symptoms and signs were similar between patients who did and did not have PE. PE was detected in 18 % of COPD patients who were hospitalized for an acute exacerbation. This finding supports the systematic evaluation of PE in hospitalized COPD exacerbated patients.

MR imaging in pulmonary embolism: does it have a future?

In most centers, computed tomography (CT) pulmonary angiography (CTPA) is the first-choice imaging test for diagnosing acute pulmonary embolism (PE). However, CT may be undesirable, contraindicated or inconclusive. In such cases, the usual alternatives include scintigraphy and magnetic resonance (MR) imaging. Scintigraphy is better validated and is discussed extensively in this issue therefore some consideration of MR is warranted. Despite the acknowledged imperfections of scintigraphy, MR imaging has failed to compete with it in most centers. Past publications on MR imaging in PE have revealed variable (but usually mediocre) diagnostic accuracy, and a high rate of non-diagnostic examinations due to motion artifacts or poor enhancement. In addition, MR is not always easily available and it can be very difficult to perform an MR study when the patient is acutely ill and dyspneic. Research in MR imaging continues, however, and recent data should make it possible to assess whether technical progress with MR has made the technique more competitive with respect to scintigraphy or even CTPA. A 2013 publication evaluated four MR techniques in 277 patients with a CTPA reference standard [1]. The MR techniques included: unenhanced free-breathing as well as breath-hold-ECG-gated techniques and contrast-enhanced perfusion and MR angiography (MRA). The sensitivity of the best MR sequence (corresponding to the better reading between those of two expert radiologists) did not exceed 90 %. With the observed disease prevalence of 37.5 %, the negative predictive values for this sequence ranged from 87 to 91 % and for other sequences were as low as 80 %. However, up to 50 % of contrast-enhanced MRA studies were technically inadequate (30 % due to artifacts, 20 % due to poor enhancement). If we consider inconclusive studies as negative tests, the sensitivity drops to 44 % and the negative predictive value to 74 %. If we exclude inconclusive studies, the diagnostic yield is unacceptably low. On the other hand, if a test with this sensitivity was applied to a population with a 10 % disease prevalence (which is common in many USA emergency departments), 30 % or more of the positive tests would be false positive. Importantly, the MR perfusion sequences had negative predictive values of less than 85 %, therefore a negative MR perfusion examination could not rule out PE in the same way that negative pulmonary scintigraphy has been proven to do. These results are comparable to some of the less good data obtained with pulmonary scintigraphy. Why then should one consider MR as an alternative to CT, rather than simply using nuclear medicine? We think the most persuasive reason is the flexibility offered by multiple MR techniques. When PE is highly probable clinically (70–80 % pretest probability), a negative CTPA is insufficient to exclude PE (the post-test probability remains about 30 %). At this point MR can be used as a problem-solving test, in addition to examine the pulmonary arteries; indeed, contrastenhanced MR can obtain indirect venography to evaluate for deep venous thrombosis. If this, too, is negative, then PE is less likely, but if it is positive, venous thromboembolism is documented. Indirect venography can also be F. Sardanelli (&) Department of Biomedical Sciences for Health, IRCCS Policlinico San Donato, Unit of Radiology, Universita degli Studi di Milano, Via Morandi 30, San Donato Milanese, 20097 Milan, Italy e-mail: francesco.sardanelli@unimi.it

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Introduction: High mortality associated with pulmonary embolism (PE) leads to increased concern when evaluating patients complaining of chest pain or shortness of breath in the emergency department (ED). Computed tomography pulmonary angiography (CTPA) is the test of choice for PE and is frequently employed in the ED. Our study aimed to determine how often CTPA is positive for PE, and the ultimate disposition and discharge diagnosis for patients evaluated for PE. Hypothesis: Though patients diagnosed with PE commonly need higher levels of care (intermediate care unit or intensive care unit), there is a low overall diagnostic yield for PE using CTPA, and a majority of patients are admitted with non-specific findings. Methods: We performed a retrospective cohort study of consecutive ED patients (January-June 2010) evaluated for PE in the ED using CTPA. Charts were reviewed to gather the presenting complaint, ED disposition (home vs. floor vs. higher level of care), and length of stay (LOS) for patients admitted to the hospital. For patients admitted despite a negative CTPA, we obtained final discharge diagnoses based on ICD-9 codes and physician dictations. Results: The cohort included 776 subjects (mean age 50 + 16.5 years; female 71.6%). CTPA was positive for PE in 6.6%. Of patients diagnosed with PE, 94.1% were admitted; 20.9% to a higher level of care, and 5.9% diagnosed with a PE died. All deaths occurred either in the ED or the intensive care unit (ICU); 20% of patients with PE admitted to the ICU died. The majority of patients with PE (79.1%) were admitted to the floor with average LOS 5.4 days. Despite a negative CTPA, 304 patients were admitted to the hospital; 5.3% to a higher level of care and 1.6% died. The most common admission diagnosis was non-specific chest pain (44.7%) and of these 68.4% were discharged with a similar diagnosis of “chest pain NOS”. Average LOS for patients admitted with chest pain was 1.9 days. Conclusions: The diagnostic yield of CTPA used in the ED for PE is low. Patients diagnosed with PE often need higher levels of care and have higher mortality, but the majority of patients without PE are admitted and discharged with non-specific findings after negative CTPA.

Diagnostic Imaging and Risk Stratification of Patients With Acute Pulmonary Embolism

Pulmonary embolism (PE) is the third most common acute cardiovascular disease after myocardial infarction and stroke. The prompt diagnosis, risk stratification, and treatment of patients with acute PE can reduce mortality. Multidetector row computed tomography pulmonary angiography (CTPA) is the most common study used to make the diagnosis of acute PE. CTPA may additionally identify right heart dysfunction or alternative diagnoses. There is a growing body of evidence that computed tomography signs of right heart failure predict patients at higher risk of mortality. At the same time, CTPA has about a 6-fold greater whole body effective dose than ventilation-perfusion (V/Q) scintigraphy, and a much higher dose to breast tissue in particular. V/Q scintigraphy should be considered for patients with contraindications to iodinated contrast or for patients with normal chest radiographs, especially young women. Compression ultrasonography of the proximal lower extremities, an imaging study without ionizing radiation, should be considered for patients suspected of acute PE with signs of lower extremity deep venous thrombosis or for patients with negative CTPA or V/Q scan with discordant clinical probability. This article reviews factors affecting the selection of the best imaging test for a particular patient suspected of acute PE, performance characteristics of diagnostic imaging tests, and imaging findings that correlate with higher mortality.