Acute pulmonary embolism: ancillary findings at spiral CT

Incidence and Prognostic Role of Pleural Effusion in Patients with Pulmonary Embolism: A Systematic Review and Meta-Analysis

Background: Pleural effusion is a common pulmonary embolism (PE) complication, which has been documented to increase the risk of death in PE and relate to disease progression. However, the incidence of pleural effusion varies among studies and its association with PE outcome is still unclear. This study sought to determine the pooled incidence and prognostic value of pleural effusion events in patients with PE. Methods: We systematically searched the PubMed, EMBASE, SCOPE, Web of Science, Cochrane, LILACS, CINAHL, EBSCO, AMED, and OVID databases from the inception of each database to 7 September 2022 with a restriction on human studies, to identify studies assessing the association between pleural effusion and PE including all prospective and retrospective clinical studies. An exploratory meta-analysis was performed using a random-effects model. We evaluated the heterogeneity and performed subgroup analyses. Results: The final meta-analysis included 29 studies involving 13,430 PE patients. The pooled incidence of pleural effusion in PE patients was 41.2% (95% CI: 35.7–46.6%), which tended to be unilateral (pooled incidence: 60.8%, 95% CI: 45.7–75.8%) and small (pooled incidence: 85.9%, 95% CI: 82.6–89.1%). Pooled analysis using a random-effects model (I2 = 53.2%) showed that pleural effusion was associated with an increased risk of 30-day mortality (RR 2.19, 95% CI: 1.53–3.15, p < 0.001, I2 = 67.1%) and in-hospital mortality (RR 2.39, 95% CI: 1.85–3.09, p < 0.001, I2 = 37.1%) in patients with PE. Conclusions: Our meta-analysis found that PE patients had a high incidence of pleural effusion, which was usually unilateral and small. Pleural effusion generally increases 30-day and in-hospital mortality in patients with PE, and it is recommended that physicians be aware of the risk of death from PE, especially when patients have pleural effusion. Further investigations focusing on PE with pleural effusion are warranted.

Diagnostic Accuracy of Multiple D-Dimer Cutoff Thresholds and Other Clinically Applicable Biomarkers for the Detection and Radiographic Evaluation of Pulmonary Embolism

Background: Diagnostic work-up of pulmonary embolism (PE) remains a challenge. Methods: We retrospectively studied all patients referred for computed tomography pulmonary angiography (CTPA) with suspicion of PE during a 12-month period (2018). The diagnostic accuracy of different D-dimer (Dd) cutoff thresholds for ruling out PE was evaluated. Furthermore, the association of Dd and red cell distribution width (RDW) with embolus location, CTPA findings, and patient outcome was recorded. Results: One thousand seventeen (n = 1017) patients were finally analyzed (mean age: 64.6 years (SD = 11.8), males: 549 (54%)). PE incidence was 18.7%. Central and bilateral embolism was present in 44.7% and 59.5%, respectively. Sensitivity and specificity for conventional and age-adjusted Dd cutoff was 98.2%, 7.9%, and 98.2%, 13.1%, respectively. A cutoff threshold (2.1 mg/L) with the best (64.4%) specificity was identified based on Receiver Operating Characteristics analysis. Moreover, a novel proposed Dd cutoff (0.74 mg/L) emerged with increased specificity (20.5%) and equal sensitivity (97%) compared to 0.5 mg/L, characterized by concurrent reduction (17.2%) in the number of performed CTPAs. Consolidation/atelectasis and unilateral pleural effusion were significantly associated with PE (p < 0.05, respectively). Patients with consolidation/atelectasis or intrapulmonary nodule(s)/mass on CTPA exhibited significantly greater median Dd values compared to patients without the aforementioned findings (2.34, (IQR 1.29−4.22) vs. 1.59, (IQR 0.81−2.96), and 2.39, (IQR 1.45−4.45) vs. 1.66, (IQR 0.84−3.12), p < 0.001, respectively). RDW was significantly greater in patients who died during hospitalization (p = 0.012). Conclusions: Age-adjusted Dd increased diagnostic accuracy of Dd testing without significantly decreasing the need for imaging. The proposed Dd value (0.74 mg/L) showed promise towards reducing considerably the need of CTPA. Multiple radiographic findings have been associated with increased Dd values in our study.

Analysis of Clinical and Radiological Findings in Oncology Patients Undergoing Thoracic Tomography for Suspected Pulmonary Embolism

In the present study, we aimed to compare clinical and radiological findings between patients with and without pulmonary embolism (PE) and determine possible risk factors for PE development among patients with cancer. This was a retrospective study that examined the clinical features and tomographic findings of patients with cancer who underwent thoracic tomography for suspected PE. A total of 487 cases were included in the study. Of which, 45 (9.2%) patients were found to have PE. The effect of gender on PE was found to be significant (p = 0.018). Patients with PE compared to those without PE are 2.828 times more likely to be women than men. It was determined that the probability of not having a history of coronary artery disease (CAD) was 2.930 times (p = 0.036), probability of shortness of breath was 4.153 times (p < 0.001), syncope/presyncope was 6.859 times (p = 0.007), and palpitation was 5.613 times (p = 0.040) more in those with PE compared to those without PE. The mean pulse rate per minute was significantly higher in patients with PE than in those without (p = 0.009). Ninety-one percent of patients had parenchymal abnormalities, 43.7% had mediastinal and cardiovascular abnormalities, 35.5% had pleural abnormalities, 32.9% had thoracic wall abnormalities (p = 0.109, p < 0.001, p = 0.022, p = 0.685, respectively). Our study demonstrated that patients with PE were more likely to be women, patients with a history of palpitations, shortness of breath, syncope/presyncope, and those not having a history of CAD. More comprehensive studies are required in the future to clearly identify the risk factors for PE in patients with cancer and clarify the indications for tomography.

Unenhanced multidetector computed tomography findings in acute central pulmonary embolism

Background

Computed tomography pulmonary angiography (CTPA) is the gold standard for the diagnosis of pulmonary embolism (PE). However, contrast is contraindicated in some patients. The purpose of this study was to determine the diagnostic accuracy of unenhanced multidetector CT (MDCT) for diagnosis of central PE using CTPA as the gold standard.

Methods

The records of patients with suspected PE seen between 2010 and 2013 were retrospectively reviewed. Inclusion criteria were an acute, central PE confirmed by CTPA and non-enhanced MDCT before contrast injection. Patients with a PE ruled out by CTPA served as a control group. MDCT findings studied were high-attenuation emboli in pulmonary artery (PA), main PA dilatation > 33.2 mm, and peripheral wedge-shaped consolidation. Receiver operating characteristic (ROC) analysis was used to determine the sensitivity and specificity of unenhanced MDCT to detect PE. Wells score of all patients were calculated using data extracted from medical records prior to imaging analysis.

Results

Thirty-two patients with a PE confirmed by CTPA and 32 with a PE ruled out by CTPA were included. Among the three main MDCT findings, high-attenuation emboli in the PA showed best diagnostic performance (Sensitivity 72.9%; Specificity 100%), followed by main PA dilatation > 33.2 mm (sensitivity 46.9%; specificity 90.6%), and peripheral wedge-shaped consolidation (sensitivity 43.8%; specificity 78.1%). Given any one or more positive findings on unenhanced MDCT, the sensitivity was 96.9% and specificity was 71.9% for a diagnosis of PE in patients. The area under the curve (AUC) of a composite measure of unenhanced MDCT findings (0.909) was significantly higher than that of the Wells score (0.688), indicating unenhanced MDCT was reliable for detecting PE than Wells score.

Conclusions

Unenhanced MDCT is an alternative for the diagnosis of acute central PE when CTPA is not available.

A new perspective for pulmonary thromboembolism radiology: 'Pulmonary vein sign'

INTRODUCTION

Pulmonary thromboembolism (PTE) is a clinical condition that can result in sudden death. Computed tomography pulmonary angiography (CTPA) is the most sensitive imaging technique for the diagnosis of PTE. Filling defects in the pulmonary veins, which can be identified in areas adjacent to PTE, have been named the 'pulmonary vein sign' (PVS).

OBJECTIVES

The aim of our study is to determine the frequency, sensitivity and specificity of PVS due to the decreased venous drainage in the affected area in PTE patients.

METHODS

Patients who were admitted to the emergency department due to the suspicion of PTE and who underwent CTPA were evaluated retrospectively. The study group consisted of the patients who had an arterial filling defect on CTPA and were diagnosed with PTE. The control group consisted of the patients who had no arterial filling defect on CTPA.

RESULTS

This study included 286 patients with a mean age of 62(20-94) years. The PVS was detected in 51(32.7%) of the patients in the study group and in 15(11.5%) of the patients in the control group. The PVS had a sensitivity of 32.69%, a specificity of 88.46%, a positive predictive value of 77.27% and a negative predictive value of 52.27% for PTE. The PVS was significantly more common in the patients having PTE in the bilateral pulmonary arteries or the main pulmonary arteries.

CONCLUSION

Despite low sensitivity, the presence of PVS on CTPA is a radiographic marker with high specificity for PTE. To use in practice, there is need for studies with large numbers of patients.

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 Vein Sign" for Pulmonary Embolism Diagnosis in Computed Tomography Angiography

PURPOSES

Considering that pulmonary arterial obstruction decreases venous flow, we hypothesized that filling defects in pulmonary veins can be identified in areas adjacent to pulmonary embolism (PE). This sign was named the "pulmonary vein sign" (PVS), and we evaluated its prevalence and performance for PE diagnosis in computed tomography pulmonary angiography (CTPA).

METHODS

This retrospective study enrolled consecutive patients with clinical suspicion of PE who underwent CTPA scan. The PVS was defined by the following criteria: (a) presence of a homogeneous filling defect of at least 2 cm in a pulmonary vein; (b) attenuation of the left atrium > 160 Hounsfield units. Using the cases that presented PE on CTPA as reference, sensitivity, specificity, and positive and negative predictive values were calculated for PVS.

RESULTS

In total, 119 patients (73 female; mean age, 62 years) were included in this study. PE was diagnosed in 44 (35.8%) patients. The PVS was present in 16 out of 44 patients with PE. Sensitivity was 36.36% (95% confidence interval (CI) 22.83-52.26%); specificity, 98.67% (95% CI 91.79-99.93%); positive predictive value, 94.12% (95% CI 69.24-99.69%); negative predictive value, 72.55% (95% CI 62.67-80.70%). The Kappa index for the PVS was good (0.801; 95% CI 0.645-0.957). PVS was correlated with lobar and segmental pulmonary embolism (p < 0.01).

CONCLUSION

Despite a low sensitivity, presence of the pulmonary vein sign was highly specific for PE, with a good agreement between readers. This sign could contribute for PE diagnosis on CTPA studies.

Historical Evolution of Imaging Techniques for the Evaluation of Pulmonary Embolism

As we celebrate the 100th anniversary of the founding of the Radiological Society of North America (RSNA), it seems fitting to look back at the major accomplishments of the radiology community in the diagnosis of pulmonary embolism. Few diseases have so consistently captured the attention of the medical community. Since the first description of pulmonary embolism by Virchow in the 1850s, clinicians have struggled to reach a timely diagnosis of this common condition because of its nonspecific and often confusing clinical picture. As imaging tests started to gain importance in the 1900s, the approach to diagnosing pulmonary embolism also began to change. Rapid improvements in angiography, ventilation-perfusion imaging, and cross-sectional imaging modalities such as computed tomography (CT) and magnetic resonance imaging have constantly forced health care professionals to rethink how they diagnose pulmonary embolism. Needless to say, the way pulmonary embolism is diagnosed today is distinctly different from how it was diagnosed in Virchow's era; and imaging, particularly CT, now forms the cornerstone of diagnostic evaluation. Currently, radiology offers a variety of tests that are fast and accurate and can provide anatomic and functional information, thus allowing early diagnosis and triage of cases. This review provides a historical journey into the evolution of these imaging tests and highlights some of the major breakthroughs achieved by the radiology community and RSNA in this process. Also highlighted are areas of ongoing research and development in this field of imaging as radiologists seek to combat some of the newer challenges faced by modern medicine, such as rising health care costs and radiation dose hazards.

Incidence of pleural effusion in patients with pulmonary embolism

Background:

No data on the incidence of pleural effusion (PE) in Chinese patients with pulmonary embolism are available to date. The aim of the current study was to investigate the frequency of PE in a Chinese population of patients with pulmonary embolism.

Methods:

This was a retrospective observational single-center study. All data of computed tomography pulmonary angiography (CTPA) performed over 6-year period on adult patients with clinically suspected pulmonary embolism were analyzed.

Results:

From January 2008 until December 2013, PE was identified in 423 of 3141 patients (13.5%) with clinically suspected pulmonary embolism who underwent CTPA. The incidence of PE in patients with pulmonary embolism (19.9%) was significantly higher than in those without embolism (9.4%) (P < 0.001). Majority of PEs in pulmonary embolism patients were small to moderate and were unilateral. The locations of emboli and the numbers of arteries involved, CT pulmonary obstruction index, and parenchymal abnormalities at CT were not associated with the development of PE.

Conclusions:

PEs are present in about one fifth of a Chinese population of patients with pulmonary embolism, which are usually small, unilateral, and unsuitable for diagnostic thoracentesis.

Frequency of nonthromboembolic imaging abnormalities in pregnant women referred for computed tomography pulmonary arteriography

PURPOSE

The study sought to determine the frequency of nonthromboembolic imaging abnormalities in pregnant women referred for computed tomography pulmonary arteriography (CTPA).

MATERIALS AND METHODS

CTPA studies on 100 consecutive pregnant women performed over a 5-year period were reviewed independently by 2 radiologists, with conflicts resolved by consensus. Age range was 18-43 years (mean 28 years). The presence or absence of pulmonary embolism and of nonthromboembolic imaging abnormalities was recorded. These were graded as A if the abnormalities were thought to provide potential alternative explanations for acute symptoms, B if findings were incidental that required clinical or radiologic follow-up, and C if the findings did not require further action.

RESULTS

Pulmonary embolism was seen in 5 women. In 2 of these additional findings of consolidation and infarction were seen. Ninety-five women did not have pulmonary embolism. Eleven women (12%) had grade A abnormalities; 6 cases of consolidation, 2 cases of lobar collapse, and 3 cases of heart failure with pleural effusions. One woman had a grade B abnormality due to the presence of pulmonary nodules. Ten women had incidental grade C abnormalities.

CONCLUSION

Pulmonary embolism occurs in 5% of pregnant women referred for CTPA. In pregnant women without embolism on CTPA, potential alternative causes for patient symptoms are seen on CT in 12% of cases.

Reduced z-axis coverage in multidetector-row CT pulmonary angiography decreases radiation dose and diagnostic accuracy of alternative diseases

OBJECTIVE

To investigate the effect of a two-third reduction of the scanned length (i.e. 10 cm) on diagnosis of both pulmonary embolism (PE) and alternative diseases.

METHODS

247 consecutive patients suspected of acute PE had a CT pulmonary angiography (CTPA) of the thorax (standard length, L). Based on this acquisition, a second set of images was created to obtain a scan length of 10 cm caudally to the aortic arch (l). Images were anonymized, randomized and interpreted by two independent readers. The quality of enhancement, the presence of PE and the possible alternative and/or complementary diagnoses were recorded. A McNemar exact test investigated differences in discrepancies between readers and between scan lengths.

RESULTS

57 (23%) patients had an acute PE. Among l sets, PE was missed by both readers in one (1.8%) patient, because the unique clot was localized in a subsegmental artery out of the 10-cm range. There were discrepancies between L and l sets in 9 (3.6%) and 11 (4.5%) patients, by Readers 1 and 2 (p=0.820), respectively. Discrepancies between the readers of L sets and those between both sets were not different regardless of the reader (p>0.99). There were discrepancies between both sets for alternative and/or complementary diagnoses in 43 (17.2%) patients.

CONCLUSION

Although its performance in diagnosing PE is maintained, CTPA should not be restricted to a range of 10 cm centred over the pulmonary hilum, because alternative and/or complementary diagnoses could be missed.

ADVANCES IN KNOWLEDGE

(1) A 10-cm CTPA acquisition reduces the radiation dose by two-thirds as compared with a standard one, but does not impair the accuracy for the diagnosis of PE. (2) Significant alternative diagnoses are missed in 17.2% of patients when reducing the acquisition height to 10 cm.

Iterative reconstructed ultra high pitch CT pulmonary angiography with cardiac bowtie-shaped filter in the acute setting: effect on dose and image quality

PURPOSE

To evaluate the effect of a cardiac bowtie-shaped filter in an ultra high pitch CTPA protocol at 100 kV on image quality and radiation dose.

MATERIALS AND METHODS

Retrospective study of 100 patients referred for CTPA. 50 patients scanned with a standard 100 kV protocol at pitch 2.8 (Protocol A) and 50 patients scanned with a 100 kV protocol at pitch 3.2 with a cardiac bowtie-shaped filter (Protocol B). All other scanning parameters kept constant. Images from both groups reconstructed with filtered back projection and iterative reconstruction. Central pulmonary vessel attenuation and background noise were quantitatively measured and signal-to-noise (SNR) and contrast-to-noise (CNR) were calculated. Two radiologists performed qualitative assessment grading visualization of the pulmonary vasculature and noise level. CTDIvol and DLP were recorded and effective dose was calculated.

RESULTS

CTDIvol, DLP and effective dose were significantly (p<0.0001) lower in Protocol B (2.3 ± 0.5 mGy, 78.4 ± 16.5 mGycm, 1.4 ± 0.3 mSy, respectively) compared to Protocol A (4.3 ± 0.5 mGy, 152.0 ± 19.6 mGycm, 2.7 ± 0.3 mSy, respectively). Protocol B had significantly (p<0.0001) higher noise than Protocol A (23.8 ± 6.9 HU vs 36.8 ± 7.3 HU) and lower SNR (11.8 ± 3.7 HU vs 19.2 ± 8.1 HU) and CNR (10.3 ± 3.7 HU vs 24.9 ± 13.4 HU) but there was no significant difference in the subjective visualization of the pulmonary vasculature (p=0.63). Furthermore, iterative reconstruction significantly (p<0.0001) improves image noise (29.4 ± 5.5 HU from 36.8 ± 7.3 HU).

CONCLUSION

The addition of a cardiac bowtie-shaped filter with an ultra high pitch CTPA protocol at 100 kV resulted in a 48% dose reduction without significantly affecting diagnostic image quality. In addition, the use of iterative reconstruction significantly improves image quality by reducing noise permitting the possibility for further dose reduction strategies.

Pleural effusion in pulmonary embolism

PURPOSE OF REVIEW

Pulmonary embolism is a common and potentially lethal disease that recurs frequently and is associated with long-term impairment and suffering. Patients with pulmonary embolism are at risk of death, recurrence of embolism, or chronic morbidity. Appropriate therapy can reduce the incidence of all. Pulmonary embolism is the most commonly overlooked disorder in patients with pleural effusion. Recent findings of pleural effusions due to pulmonary embolism are discussed in this review.

RECENT FINDINGS

The presence of pleuritic chest pain in a patient with a pleural effusion is highly suggestive of pulmonary embolism. Nearly all pleural effusions due to pulmonary embolism are exudates, frequently hemorrhagic, and with a marked mesothelial hyperplasia. Patients with a pleural effusion are likely to have an embolus in the central, lobar, segmental, or subsegmental pulmonary arteries and these are the regions in which spiral computed tomography pulmonary angiography (CTPA) can detect an embolus. No specific treatment is required for pleural effusion. The presence of bloody pleural fluid is not a contraindication for the administration of anticoagulant therapy.

SUMMARY

Pulmonary embolism is probably responsible for a significant percentage of undiagnosed exudative pleural effusions. Spiral CTPA is the best way to evaluate the possibility of pulmonary embolism in a patient with a pleural effusion. The treatment protocol of the patient with pleural effusion secondary to pulmonary embolism is the same as that for any patient with pulmonary embolism.

Risk-benefit analysis of pulmonary CT angiography in patients with suspected pulmonary embolus

OBJECTIVE

The objective of our study was to estimate the mortality benefit-to-risk ratio of pulmonary CT angiography (CTA) by setting (ambulatory [emergency department or outpatient] or inpatient), age, and sex.

MATERIALS AND METHODS

A retrospective evaluation of 1424 consecutive pulmonary CTA examinations was performed and the following information was recorded: examination setting, patient age, patient sex, pulmonary CTA interpretation for pulmonary embolus (PE), and CT radiation exposure (dose-length product). We estimated mortality benefit of pulmonary CTA by multiplying the rate of positive pulmonary CTA examinations by published estimates of mortality of untreated PE in ambulatory and inpatient settings. We estimated the lifetime attributable risk of cancer mortality due to radiation from pulmonary CTA by calculating the estimated effective dose and using sex-specific polynomial equations derived from the Biological Effects of Ionizing Radiation VII report. We calculated benefit-to-risk ratios by dividing the mortality benefit of preventing a fatal PE by the mortality risk of a radiation-induced cancer.

RESULTS

Pulmonary CTA diagnosed PE in 188 of 1424 patients (13.2%). Both inpatients (101/723, 14.0%) and emergency department patients (74/509, 14.5%) had significantly higher rates of PE than outpatients (13/192 [6.8%]). Males received significantly (p = 0.02451) higher radiation dose (9.7 mSv) than females (8.4 mSv), but males had a significantly (p < 0.0001) lower lifetime attributable risk of cancer mortality than females. Assuming an untreated PE mortality rate of 5% for ambulatory patients and 30% for inpatients, the benefit-to-risk ratio ranged from 25 for ambulatory patients to 187 for inpatients. Ambulatory women had the lowest benefit-to-risk ratio.

CONCLUSION

The benefit-to-risk ratio of pulmonary CTA in patients with suspected PE ranges from 25 to 187 and can be increased by optimizing the radiation dose.

Imaging of congenital and acquired disorders of the pulmonary artery

The pulmonary artery is affected by a multitude of conditions that can be congenital or acquired. These disorders may be detected incidentally, or the clinical features of the different conditions may overlap. This pictorial review illustrates the imaging findings of some of the main conditions that affect the pulmonary artery by considering them in 3 main categories: congenital disorders; enlargement of the pulmonary arteries, most commonly seen in pulmonary hypertension; obstruction or occlusion of the pulmonary arteries, as seen in thromboembolic disease or large vessel vasculitis. It is important for the radiologist to understand the radiological manifestations of these disorders, as early recognition would be of significant benefit in their diagnosis and treatment.

Clinical relevance of pulmonary infarction in patients with pulmonary embolism

INTRODUCTION

Data regarding the clinical relevance of pulmonary infarction (PI) in patients with pulmonary embolism (PE) are lacking. The aim of this study was to investigate the clinical features of PE patients with PI and the prognostic role of PI for PE patients.

MATERIALS AND METHODS

Based on computed tomography scan, 509 patients with PE were divided into two groups, the infarction group (n=45) and the non-infarction group (n=464). A variety of clinical parameters were compared between the two groups.

RESULTS

In the infarction group, the largest pulmonary arteries involved by emboli were central rather than peripheral and more proximal as compared to the non-infarction group (p=0.01 and p<0.03, respectively). Thrombolytic agents tended to be more frequently administered in the infarction group (13.3% [n=6] versus 6.3% [n=29], p=0.07). In-hospital mortality, PE-related deaths, and the recurrence rate of PE did not differ between the two groups.

CONCLUSIONS

The present study did not demonstrate that PI is a prognostic indicator of recurrence and mortality in PE patients. We suggest the possibility that blood clot burden is greater in PE patients with PI, although PI by itself occurs in small pulmonary arteries.

Ancillary findings on CT pulmonary angiograms and abnormalities on chest radiographs in patients in whom pulmonary embolism was excluded

To determine whether chest radiographs identify some abnormalities not shown as ancillary findings on computed tomography(CT) pulmonary angiograms of patients in whom pulmonary embolism (PE) was excluded. This was a retrospective study of reports of negative 64-detector CT pulmonary angiograms and chest radiographs. Among 332 patients with no PE, pulmonary parenchymal disease was shown in 60 (18%) only on standard chest radiographs, and pleural or pericardial disease was shown in 17 (5%) only on chest radiographs. Skeletal abnormalities were reported more frequently on standard chest radiographs, lymph nodes more frequently on CT angiograms. Some abnormalities on chest radiographs of patients in whom PE is excluded may not be described as ancillary findings on CT pulmonary angiograms. This suggests a need for ancillary findings on CT pulmonary angiograms to be described systematically. At present, however, plain chest radiographs in some patients show ancillary findings not reported on CT angiograms. [corrected].

Chest multidetector computed tomography (MDCT) in patients with suspected acute pulmonary embolism: diagnostic yield and proportion of other clinically relevant findings

PURPOSE

The authors evaluated the diagnostic yield of chest multidetector computed tomography (MDCT) in acute pulmonary embolism (PE) and the proportion of other clinically relevant findings in a large cohort of consecutive inpatients and patients referred from the emergency department (outpatients).

MATERIALS AND METHODS

A total of 327 radiological reports of chest MDCT scans performed for suspected acute PE in 327 patients (158 men, 169 women; mean age 69 years, standard deviation 17.33 years; 233 inpatients, 94 outpatients) were retrospectively evaluated and classified into four categories: 1, positive for PE; 2, negative for PE but positive for other findings requiring specific and immediate intervention; 3, completely negative or positive for findings with a potential for significant morbidity requiring specific action on follow-up; 4, indeterminate. The distribution of findings by categories among the entire population and inpatients and outpatients separately was calculated (chi-square test, α=0.05).

RESULTS

In the entire population, the diagnostic yield (i.e. proportion of cases classified as category 1) was 20.2% (66/327). Proportions of cases classified as categories 2, 3 and 4 were 27.5% (90/327), 44.3% (145/327) and 7.9% (26/327), respectively. No statistically significant difference was found between inpatients and outpatients (p=0.193).

CONCLUSIONS

In patients with suspected acute PE, chest MDCT provides evidence of conditions requiring immediate and specific intervention (i.e. categories 1 and 2) in nearly 50% of cases, without differences between inpatients and outpatients.

The validity of hyperdense lumen sign in non-contrast chest CT scans in the detection of pulmonary thromboembolism

It is possible to identify high-attenuation clots in pulmonary thromboembolism using non-contrast computed tomography (CT) of the chest. Such detection may be crucial for timely initiation of appropriate therapy. This study was undertaken to determine the validity of the hyperdense lumen (high-attenuation clot) sign in unenhanced chest CT in detecting pulmonary thromboembolism. Non-contrast and contrast-enhanced CT images of the chest of 121 patients who had undergone standard CT pulmonary angiography (pulmonary CTA) were reviewed separately. The absence or presence of luminal hyperdensities within the pulmonary arteries in the non-contrast images was determined. The average CT attenuation differences between the high attenuation clots and pulmonary arteries were computed. Findings in the non-contrast images were correlated with the contrast-enhanced images. Twenty-five patients were positive for pulmonary thromboembolism in the pulmonary CTAs. Of these 25 patients, nine were positive for the hyperdense lumen sign in the non-contrast CT images. The hyperdense lumen sign has an over-all sensitivity of 36.0%, specificity of 99.0%, PPV of 90.0%, and NPV of 85.6% (κ=0.449; P-value<0.001). In detecting central thromboembolism, the sensitivity, specificity, PPV, and NPV of this sign were 66.7, 99.1, 88.9, and 96.4%, respectively (κ=0.740; P-value<0.001). The sign was less sensitive in peripheral thromboembolism (κ=0.358; P-value<0.001). The mean (±SD) attenuation difference between the clot and pulmonary blood pool was 22.76 (±4.20) HU (P-value<0.001). The hyperdense lumen sign is a useful indicator of acute pulmonary thromboembolism in non-contrast chest CT scans particularly in cases involving the central pulmonary arteries.

Parenchymal and pleural abnormalities in children with and without pulmonary embolism at MDCT pulmonary angiography

BACKGROUND

Prior studies in adults suggest that a wedge-shaped peripheral consolidation may be predictive of pulmonary embolism (PE). In contrast, a previous study in children provided no evidence of an association between this finding and PE, but it was limited by a small sample size and was not specifically designed to answer this question.

OBJECTIVE

To compare the frequencies of parenchymal and pleural abnormalities in children with and without PE at multidetector computed tomographic pulmonary angiography (CTPA).

MATERIALS AND METHODS

The study population included 22 consecutive pediatric patients (11 males, 11 females; mean age 13.2 +/- 5.8 years; range 4 months to 18 years) with PE diagnosed by CTPA from July 2004 to January 2009 and identified using our hospital database. The comparison group included 22 randomly selected pediatric patients (10 males, 12 females; mean age 15.2 +/- 3.3 years; range 5.6 to 18 years) who underwent CTPA studies without evidence of PE during the same study period. All CTPA studies were reviewed by consensus by two pediatric radiologists for the presence of parenchymal and pleural abnormalities including: wedge-shaped peripheral consolidation, other forms of consolidation, atelectasis, linear opacity, ground-glass opacity, mosaic attenuation pattern, nodule, mass, focal patchy increased attenuation, and pleural effusion. Differences in frequencies of parenchymal and pleural abnormalities between the two groups were analyzed by logistic regression to determine odds ratios for association with PE. The two groups were also compared with respect to risk factors for PE.

RESULTS

Wedge-shaped peripheral consolidation was seen in eight children (36%) with PE and in two children (9%) without PE [odds ratio = 5.7, 95% confidence interval (CI): 1.2 to 30, p = 0.03]. There were no significant differences in the frequency of other findings between the groups (all p-values > 0.10). Prior history of neoplasm was the only independent risk factor significantly associated with the presence of PE (p = 0.006).

CONCLUSION

Wedge-shaped peripheral consolidation is significantly associated with PE on CTPA studies of children. The identification of a wedge-shaped peripheral consolidation in children should alert radiologists to carefully evaluate for concurrent PE.

Clinically suspected acute pulmonary embolism: a comparison of presentation, radiological features and outcome in patients with and without PE

BACKGROUND

Relatively little is known about prognosis in patients for whom suspected pulmonary embolism (PE) is refuted by imaging.

AIM

This prospective study of suspected PE therefore compared clinico-radiological features and outcome in patients with and without PE.

DESIGN AND METHODS

Computed tomographic pulmonary angiography (CTPA) confirmed or refuted PE in consecutive patients. Clinical, laboratory and radiological features were recorded at baseline, and mortality at 1 year determined. Univariate and multivariate analyses identified variables associated with PE.

RESULTS

PE was diagnosed in 45 patients and refuted in 141. The PE and 'non-PE' groups were similar with regard to extravascular radiology (though consolidation was significantly more common in the PE group [present in 24 (53%) of the PE group and 42 (30%) of the non-PE group, P < 0.01)], comorbidities (no significant differences), and baseline characteristics (only serum D-dimer concentrations were independently associated with PE by multivariate analysis, P = 0.001). Right ventricular dimensions were significantly higher in the PE group, [right ventricular to left ventricular ratio was 0.98 (range 0.64-2.48) in the PE group and 0.92 (range 0.66-1.95) in the non-PE group, P < 0.05]. In the PE group, right ventricular dimensions rose sharply when 10 or more segmental pulmonary arteries were occluded. One year all-cause mortality was 6.7% in the PE group and 13.5% in the non-PE group (no significant difference, P = 0.218).

CONCLUSION

Among a cohort of patients presenting with clinically suspected PE, clinical characteristics, co-morbidities and radiological features were similar when comparing groups with CTPA-proven or CTPA-refuted PE. However RV dimensions, radiological consolidation on imaging and D-dimer levels were significantly higher in the PE group. Patients with suspected PE have a poor prognosis irrespective of whether PE is confirmed. This appears accentuated in patients without PE, a finding possibly under-recognized in clinical practice.

Computer tomography for venous thromboembolic disease

Venous thromboembolic disease is composed of two disease entities: pulmonary thromboembolism/pulmonary embolism and deep venous thrombosis. Clinical signs and symptoms of venous thromboembolic disease often are nonspecific and, as a result, the diagnosis may be difficult. If left untreated, pulmonary embolism can lead to a potentially fatal outcome. This article focuses on CT angiography as the diagnostic modality for thromboembolic pulmonary embolism and briefly discusses nonthromboembolic pulmonary embolism.

Relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism: Assessment with breath-hold SPECT–CT pulmonary angiography fusion images

PURPOSE

The relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism (PTE) was comprehensively assessed on deep-inspiratory breath-hold (DIBrH) perfusion SPECT-computed tomographic pulmonary angiography (CTPA) fusion images.

MATERIALS AND METHODS

Subjects were 34 acute PTE patients, who had successfully performed DIBrH perfusion SPECT using a dual-headed SPECT and a respiratory tracking system. Automated DIBrH SPECT-CTPA fusion images were used to assess the relation between lung perfusion defects and intravascular clots detected by CTPA.

RESULTS

DIBrH SPECT visualized 175 lobar/segmental or subsegmental defects in 34 patients, and CTPA visualized 61 intravascular clots at variable locations in 30 (88%) patients, but no clots in four (12%) patients. In 30 patients with clots, the fusion images confirmed that 69 (41%) perfusion defects (20 segmental, 45 subsegmental and 4 lobar defects) of total 166 defects were located in lung territories without clots, although the remaining 97 (58%) defects were located in lung territories with clots. Perfusion defect was absent in lung territories with clots (one lobar branch and three segmental branches) in four (12%) of these patients. In four patients without clots, nine perfusion defects including four segmental ones were present.

CONCLUSION

Because of unexpected dissociation between intravascular clots and lung perfusion defects, the present fusion images will be a useful adjunct to CTPA in the diagnosis of acute PTE.

CT and MRI of acute thoracic cardiovascular emergencies

A wide spectrum of acute cardiovascular disorders is seen in patients who are hospitalized in a critical care setting. Imaging plays a central role in the diagnosis and management of these conditions. The most frequently used imaging remains chest radiography; however, more advanced modalities, including coronary angiography, echocardiography, and radioisotope scintigraphy, have well established roles in the assessment of patients in the critical care setting. More recently, multidetector row CT (MDCT) and MRI are being used increasingly for evaluation of coronary artery disease, cardiac structure and function, coronary artery anomalies, cardiac masses, pericardial disease, valvular disease, postoperative cardiovascular abnormalities, venous thromboembolism and acute aortic syndromes, often with other ancillary findings that can provide important clinical information. The three most common life-threatening cardiovascular processes in which advanced imaging plays a role, particularly CT, are discussed, including pulmonary embolism, aortic dissection, and coronary artery disease.

Is It possible to recognize pulmonary infarction on multisection CT images?

PURPOSE

To retrospectively determine sensitivity and specificity of four findings for distinguishing pulmonary infarction from other causes of peripheral pulmonary consolidations on multidetector computed tomographic (CT) images, with other CT and clinical findings as reference.

MATERIALS AND METHODS

Institutional review board approved the study and waived informed consent. Three independent radiologists blindly analyzed selected multisection CT images of 50 pulmonary infarctions-not showing direct arterial signs of pulmonary embolism-and 100 peripheral consolidations of other origins. Readers analyzed four findings: triangular shape, vessel sign (defined as presence of an enlarged vessel at the apex of consolidation), central lucencies, and air bronchograms. Interobserver agreement; frequency on CT images with and without infarct; and sensitivity, specificity, and positive likelihood ratio (LR) for diagnosis of pulmonary infarction were assessed for each finding.

RESULTS

One hundred fifty peripheral consolidations were analyzed in 134 (75 men, 59 women) patients (mean age, 55.9 years+/-17.4 [standard deviation] vs 54.7+/-19.9; P=.71). Interobserver agreement was good for central lucencies and air bronchograms and poor to moderate for the other two findings (kappa<0.61). Compared with CT images without infarct, CT images with infarct had a higher frequency of vessel sign (32% [16 of 50] vs 11% [11 of 100], P=.029) and central lucencies (46% [23 of 50] vs 2% [two of 100], P<.001) and a lower frequency of air bronchograms (8% [four of 50] vs 40% [40 of 100], P=.003). Frequency of triangular shape was similar in both groups (52% [26 of 50] vs 40% [40 of 100], P=.17). Positive LR was 23.0 for central lucencies, 2.9 for vessel sign, 1.3 for triangular shape, and 0.2 for air bronchograms. Presence of central lucencies had 98% specificity and 46% sensitivity for pulmonary infarction. When the vessel sign and negative air bronchogram were combined with central lucencies, specificity increased to 99% but sensitivity decreased to 14%.

CONCLUSION

Central lucencies in peripheral consolidations are highly suggestive of pulmonary infarction.

Analysis of pleural effusions in acute pulmonary embolism: Radiological and pleural fluid data from 230 patients

BACKGROUND AND OBJECTIVE

The aims of this study were to describe the frequency and radiographical characteristics of pleural effusions in a large population of patients with acute pulmonary embolism (PE) and characterize the pleural fluid biochemistry in those patients who underwent diagnostic thoracentesis.

METHODS

This was a retrospective observational single-centre study. A total of 230 consecutive patients with a diagnosis of PE over a 9-year period were enrolled. Spiral CT pulmonary angiography (52%) and high-probability ventilation and perfusion scans (42%) were used as the main reference methods.

RESULTS

Pleural effusions were observed in 32% and 47% of patients by CXR and CT, respectively. Typically, pleural effusions were small (90% occupied less than one third of the hemithorax) and unilateral (85%), but occasionally they reached more than a half of the hemithorax. On CT, 21% of pleural effusions showed loculation. In patients with loculated pleural fluid the diagnosis of PE had been delayed for a mean of 12.2 days after symptoms developed. The presence of pleural fluid was not related to infarction. Twenty-six of 93 (28%) patients with effusions on imaging underwent thoracentesis. All the fluids met Light's criteria for exudate, 58% contained erythrocyte counts >10,000/microL and 46% showed neutrophilic predominance.

CONCLUSIONS

Small pleural effusions, mostly unsuitable for diagnostic thoracentesis, were present in about one third of patients with PE. All the pleural effusions due to PE were exudates. If PE diagnosis was delayed the pleural effusion tended to become loculated.

Congenital and acquired pulmonary artery anomalies in the adult: radiologic overview

Various congenital and acquired anomalies may affect the pulmonary arteries in adult patients. Congenital anomalies (proximal interruption, anomalous origin of the left pulmonary artery [pulmonary artery sling], and idiopathic dilatation of the pulmonary trunk) are usually found incidentally at chest radiography or computed tomography (CT). Acquired anomalies include diffuse or focal enlargement of the arteries because of pulmonary hypertension, aneurysm, and intravascular pulmonary metastasis; decreased arterial diameter because of bronchial carcinoma, mediastinal fibrosis, and Takayasu arteritis; and intraluminal filling defects due to pulmonary thromboembolism and pulmonary artery sarcoma. An awareness of the radiologic manifestations of the disease entities and potential pulmonary artery complications secondary to infection or vasculitis may enable an early diagnosis. CT angiography is becoming the standard method for evaluating patients in whom the presence of pulmonary embolism is suspected. CT assessment of the extent of heart effects in patients with pulmonary hypertension and pulmonary embolism is particularly important because such effects largely determine the prognosis.

Computed tomography pulmonary angiogram diagnosis of pulmonary embolism

Over the last decade, contrast-enhanced spiral CT has been established as a non-invasive alternative to catheter angiography and is now regarded as the first-line imaging investigation for the diagnosis of pulmonary embolism (PE). The reported sensitivities for the diagnosis of PE of spiral CT vary from 45 to 100% and the specificities vary from 78 to 100%. Prospective outcome studies have shown a high negative predictive value for a single-detector spiral CT for PE. Patients' outcomes were not adversely affected in these studies when anticoagulation was withheld after a negative CT pulmonary angiogram. The main limitation of single-detector spiral CT has been its limited ability to detect isolated subsegmental PE. However, multidetector spiral CT allows evaluation of pulmonary vessels down to sixth-order branches and significantly increases the rate of detection of PE in segmental and subsegmental levels. The interobserver correlations for diagnosis of subsegmental PE with multidetector spiral CT exceed the reproducibility of selective pulmonary angiography. If appropriate equipment is available (multidetector CT), then CT pulmonary angiogram is safe to be used as the first-line imaging investigation for the diagnosis of PE.