Spiral CT of acute pulmonary thromboembolism: evaluation of pleuroparenchymal abnormalities

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.

A Frequently Missed Pulmonary Infarction: Clinical and 18F-FDG PET/CT Manifestation of Hilar Tumor-Induced Pulmonary Infarction

PURPOSE

This study aimed to summarize the clinical and 18F-FDG PET/CT manifestations of hilar tumor-induced pulmonary infarction.

METHODS

A retrospective analysis was performed on patients with hilar masses who underwent FDG PET/CT scans between July 2015 and January 2021 and had complete clinical data. Pulmonary infarction was confirmed by concurrent chest CT and imaging follow-up or pathology.

RESULTS

A total of 58 patients (mean age, 56 [SD, 13] years; 44 males) with 122 infarcts were included in the study. Hilar masses were mostly associated with small cell lung cancer (64%). The most common clinical manifestations were cough (64%) and hemoptysis (36%). Most patients (62%) had multiple pulmonary infarcts. The CT findings of pulmonary infarcts included the "Hampton hump" (48%) and patchy consolidation (52%). The density of infarcts included "bubbly consolidation" (61%) and "homogenous consolidation" (39%). The metabolic activity of 95 infarcts (78%) was higher than lung parenchyma, with the SUVmax of 3.3 (SD, 1.1). The metabolic patterns on PET/CT were "rim sign," "mismatch between PET and CT," and "no metabolism." Pulmonary vein involvement was found in 25 patients (43%), pleural effusion in 22 patients (38%), and the pleural curvilinear sign in 8 patients (14%).

CONCLUSIONS

The clinical manifestations of hilar tumor-induced pulmonary infarction are not specific, and 18F-FDG PET/CT could be an effective diagnostic tool.

Clues to vascular disorders at non-contrast CT of the chest, abdomen, and pelvis

Non-contrast chest CT scans are commonly performed while CT scans of the abdomen and pelvis are performed in a select subset of patients; those with limited renal function, an allergy to iodinated contrast, in the setting of suspected renal calculus, retroperitoneal hematoma, common duct calculus, abdominal aortic aneurysm with or without rupture, and in patients undergoing a PET-CT scan. In the absence of intravenous contrast, vascular structures may prove challenging to evaluate, yet their assessment is an important component of every non-contrast CT examination. We describe the key imaging features of both arterial and venous pathology, and review clues and common associated non-vascular findings, which can help the radiologist identify vascular disorders at non-contrast CT. Briefly, alternative imaging options are discussed.

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.

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.

The surgical pathology of pulmonary infarcts: diagnostic confusion with granulomatous disease, vasculitis, and neoplasia

Twenty-three cases of surgically resected pulmonary infarcts sent in consultation were reviewed to evaluate their morphology and to assess reasons for consultation. The morphology of these infarcts demonstrated that only a minority had the classical triangular shape at low magnification (26%) whereas the majority were either spherical (17%) or had a geographic pattern of necrosis (35%). The margin of the infarcted tissue often had a pseudogranulomatous appearance due to palisaded histiocytes, foam cells, or perpendicularly oriented proliferations of fibroblasts and myofibroblasts (74%) and occasional cholesterol- and hemosiderin-laden giant cells. Basophilic granular karyorrhectic necrosis was seen focally (52%) as was vascular inflammation (56%) raising the differential diagnosis of Wegener's granulomatosis or infectious granulomas. These nonclassical features combined with a low incidence of clinical hemoptysis, chest pain and pleurisy, and a primary radiographic diagnosis of 'nodule r/o malignancy' highlight the need to consider thromboembolic pulmonary infarcts in the differential diagnosis of necrotic lung nodules with a histiocytic and fibroproliferative rim.

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.

Pulmonary infarction: spectrum of findings on multidetector helical CT

OBJECTIVE

Despite the dual blood supply to the lung, acute pulmonary embolism (PE) can lead to a spectrum of ischemic injury to the lung resulting in infarction and hemorrhage. In this series we systematically describe the spectrum of CT findings and clinical correlates of pulmonary infarction in patients with PE.

METHODS

We retrospectively identified 24 consecutive adults with pulmonary infarction on multidetector CT between July 2002 and March 2004. There were 13 women and 11 men, with a mean age of 59 years. The cases were identified by review of 74 consecutive CTs demonstrating PE. Each CT was evaluated by 2 of 3 reviewers in consensus for presence and characteristics of peripheral parenchymal opacities and extent of PE. Peripheral opacities were evaluated for degree of enhancement, internal air lucencies, and contour. The presence of adjacent vessels and linear strands were noted. At the end of interpreting each case, the reviewers determined whether or not an infarct was present based on the constellation of previously described imaging features. The extent of pulmonary vascular obstruction was graded using the CT clot burden scoring system. Each chart was reviewed for predisposing factors for PE and infarction, presenting clinical symptoms/signs, and co-existing pulmonary or cardiac conditions.

RESULTS

Thirty-two percent (24/74) of patients with PE had pulmonary infarction. Thirty-three percent (8/24) of patients had more than 1 infarct. Seventy-three percent (27/37) of infarcts were in the lower lobes. The CT findings of pulmonary infarction included: focal decrease in parenchymal enhancement in 95% (35/37), broad pleural base in 65% (24/37), truncated apex in 57% (21/37), convex border in 46% (17/37), internal air lucencies in 32% (12/37), linear stranding from the apex toward the hilum in 24% (9/37), and a thickened vessel leading to the apex of the infarct in 14% (5/37). There was a trend toward a higher mean clot burden (12.3 vs. 10.5) between the patients with PE with and without infarction. Ninety-six percent (23/24) of patients with pulmonary infarction had predisposing factors for infarction, including PE involving more than 1 lobe (n = 21), malignancy (n = 5), and heart failure (n = 3). Pleuritic chest pain was significantly more frequent in patients with infarction (P = 0.0064).

CONCLUSION

Pulmonary infarction occurred in nearly 1/3 of patients with PE in this series. The infarcts were peripheral parenchymal opacities characterized by a distinctive complex of findings on CT reflecting ischemic injury in the setting of a dual blood supply to the lung. Pleuritic chest pain was significantly associated with infarction.

Quantification of Thin-Section CT Lung Attenuation in Acute Pulmonary Embolism: Correlations with Arterial Blood Gas Levels and CT Angiography

OBJECTIVE

The purposes of this study were to investigate the frequency histogram of lung attenuation on CT angiography (CTA) in patients with and without acute pulmonary embolism (PE) and to evaluate the relation of the frequency histogram of lung attenuation and hypoxemia.

MATERIALS AND METHODS

Twenty-six patients with PE and 11 patients without PE who underwent CTA were evaluated with frequency histograms. We obtained quantitative parameters such as mean lung attenuation, median lung attenuation, SD, skewness, kurtosis, and the proportion of lung attenuation except for the median +/- 50 H (P +/- 50 H). Lung attenuation was also assessed visually and scored. The relationship between those histogram parameters, or visual score, and Pa(O2) was evaluated. CTA scores for evaluation of the degree of pulmonary artery obstruction were obtained, and the relation with Pa(O2) was assessed.

RESULTS

No significant differences were found in mean lung attenuation and median lung attenuation between patients with and without PE. Meanwhile, SD, skewness, kurtosis, and P +/- 50 H were significantly different between patients with and without PE (p = 0.0003, 0.0071, 0.0047, and 0.0028, respectively) and significantly correlated with Pa(O2) (r = -0.770, 0.797, 0.786, -0.871, respectively). Significant differences were found in visual scores between patients with and without PE (p < 0.0001). There were significant but relatively low correlations between CTA score and arterial blood gas levels (r = -0.442, p = 0.03).

CONCLUSION

In patients with acute PE, heterogeneity in lung attenuation is more prominent than in patients without PE.

Comprehensive assessment of lung CT attenuation alteration at perfusion defects of acute pulmonary thromboembolism with breath-hold SPECT-CT fusion images

Regional computed tomography attenuation (CTA) alteration at perfusion defects in acute pulmonary thromboembolism (PTE) was comprehensively assessed using deep-inspiratory breath-hold SPECT-CT fusion images. Subjects were 14 acute and 9 chronic PTE patients and 13 control subjects. Regional perfusion, CTA, and intravascular clots were correlated on deep-inspiratory breath-hold SPECT-unenhanced/angiographic CT fusion images. Fusion images visualized hypo-CTA in 57% of the acute PTE patients, which preferentially occurred at extensively and severely decreased perfusion areas caused by central clots. CTA at 35 defects of acute PTE was significantly decreased compared with that of normal lungs (P<0.001), but the degree was less compared with chronic PTE (P<0.0001). Fusion images also revealed variable relationships of clots and regional perfusion/CTA in the distal lungs of each central clot. Fusion images provide important information about the actual effects of intravascular clots on peripheral perfusion/CTA and indicate that lung CTA can be decreased at perfusion defects in acute PTE.

Vascular Diseases of the Thorax: Evaluation with Multidetector CT

The list of vascular diseases in the thorax has been narrowed to three, which are considered essential information for radiologists interpreting CT scans of the thorax: (1) aortic dissection and its variants, intramural hematoma and penetrating atherosclerotic ulcer; (2) acute pulmonary embolism; and (3) coronary artery disease. The spatial resolution of multidetector CT is such that CT has become the imaging modality of choice for aortic dissection and pulmonary embolism. This move away from angiography has transpired over the last decade; perhaps the next decade will see the same occur for evaluation of coronary artery disease.

Clinicoradiological features of pulmonary infarctions mimicking lung cancer

OBJECTIVE

To describe presenting features of pulmonary infarction that may simulate those of lung cancer.

PATIENTS AND METHODS

We reviewed the medical records of 43 patients with pulmonary infarction diagnosed by surgical lung biopsy at the Mayo Clinic in Rochester, Minn, from January 1, 1996, to December 31, 2002. Of 16 patients presenting with an undiagnosed solitary pulmonary nodule or mass, 6 had features suggestive of lung cancer on additional imaging, including abnormalities on contrast-enhancement computed tomography (CT), positron emission tomography (PET), or nonsurgical lung biopsy before surgical resection. We examined the presenting symptoms, epidemiological, clinical, and radiological features, and clinical course of these 6 patients.

RESULTS

All 6 patients, ranging in age from 41 to 85 years, had a history of smoking and underlying cardiopulmonary disease. In 5 of the 6 patients, CT showed a nodule in the subpleural region of the lung. Three patients had abnormalities on contrast-enhancement CT, 2 had abnormalities on PET, and 1 had abnormal cytologic findings on a transthoracic needle biopsy of the lung; all these studies showed abnormalities suggestive of lung cancer. Surgical resection of the nodule or mass revealed pulmonary infarction associated with organizing thrombi in all 6 patients.

CONCLUSIONS

Pulmonary infarctions can closely mimic the clinicoradiological characteristics of lung cancer, an association not reported previously. Furthermore, cytologic changes that occur in pulmonary infarctions may produce malignant-appearing cells on needle biopsy of the lung. The possibility of pulmonary infarction should be considered in the differential diagnosis of a solitary lung nodule or mass located in the subpleural region, even in the absence of clinically recognized venous thromboembolism.