Pulmonary embolism in patients with chronic coronary syndrome masquerading as acute coronary syndrome: a case report and literature review.

BACKGROUND: Pulmonary embolisms (PEs) exhibit clinical features similar to those of acute coronary syndrome (ACS), including electrocardiographic abnormalities and elevated troponin levels, which frequently lead to misdiagnoses in emergency situations. CASE PRESENTATION: Here, we report a case of PE coinciding with chronic coronary syndrome in which the patient's condition was obscured by symptoms mimicking ACS. A 68-year-old female with syncope presented to the hospital. Upon admission, she was found to have elevated troponin levels and an electrocardiogram showing ST-segment changes across multiple leads, which initially led to a diagnosis of ACS. Emergency coronary arteriography revealed occlusion of the posterior branches of the left ventricle of the right coronary artery, but based on the complexity of the intervention, the occlusion was considered chronic rather than acute. On the 3rd day after admission, the patient experienced recurrent chest tightness and shortness of breath, which was confirmed as acute PE by emergency computed tomography pulmonary angiography. Following standardized anticoagulation treatment, the patient improved and was subsequently discharged. CONCLUSIONS: This case report highlights the importance of recognizing the nonspecific features of PE. Clinicians should be vigilant when identifying other clinical features that are difficult to explain accompanying the expected disease, and it is necessary to carefully identify the causes to prevent missed diagnoses or misdiagnoses.

Lemierre Syndrome: Clinical Challenges And The Anticoagulation Dilemma In Adolescent Care.

Lemierre syndrome is a rare, life-threatening condition characterized by an acute otorhinolaryngologic infection with septic thrombophlebitis of the internal jugular vein and septic embolism, particularly to the lungs. We describe a case of a previously healthy 15-year-old female patient who initially presents fever and odynophagia but quickly develops neck and pleuritic chest pain. Computed tomography was performed and the radiological findings confirmed the diagnosis of a Lemierre syndrome. She was managed with antibiotics, anticoagulant for three days and symptomatic treatment, with a gradually improving condition. After 17 days of hospitalisation, due to reappearance of pleuritic pain, a new imaging assessment was performed and showed additional septic emboli in the lungs, which prompted the reintroduction of anticoagulant therapy. Awareness of the existence of this syndrome is essential to ensure a radiological evaluation with computed tomography and thus timely diagnosis and treatment.

Fault in Our Genes: A Case of Pulmonary Thromboembolism in Young.

Methylenetetrahydrofolate reductase (MTHFR) enzyme is one of the key enzymes involved in the metabolism of folate. Mutations in this enzyme can lead to a procoagulant state. We present a case of a 20-year-old male with no known comorbidities, who presented with fever and hemoptysis and was diagnosed as a case of pulmonary embolism. He was found to have a homozygous mutation in the MTHFR gene that was responsible for his disease state. He was started on unfractionated heparin infusion and underwent catheter-directed thrombolysis. He showed marked improvement in his condition and was discharged on oral anticoagulants with an advice to follow-up.

RésuméL'enzyme méthylènetétrahydrofolate réductase (MTHFR) est l'une des enzymes clés impliquées dans le métabolisme du folate. Les mutations de cette enzyme peuvent conduire à un état procoagulant. Nous présentons le cas d'un homme de 20 ans sans comorbidités connues, qui s'est présenté avec de la fièvre et une hémoptysie et a été diagnostiqué comme un cas d'embolie pulmonaire. Il s'est avéré qu'il présentait une mutation homozygote du gène MTHFR responsable de son état pathologique. Il a commencé une perfusion d'héparine non fractionnée et a subi une thrombolyse dirigée par cathéter. Il a montré une nette amélioration de son état et a été libéré sous anticoagulants oraux avec un conseil de suivi.

Low Stroke Volume Predicts Deterioration in Intermediate-Risk Pulmonary Embolism: Prospective Study.

Introduction: Prognosis and management of patients with intermediate-risk pulmonary embolism (PE) is challenging. We investigated whether stroke volume may be used to identify the subset of this population at increased risk of clinical deterioration or PE-related death. Our secondary objective was to compare echocardiographic measurements of patients who received escalated interventions vs anticoagulation monotherapy. Methods: We selected patients with intermediate-risk PE, who had comprehensive echocardiography within 18 hours of PE diagnosis and before any escalated interventions, from a PE registry populated by 11 emergency departments. Echocardiographers measured right ventricle (RV) size, tricuspid annular plane systolic excursion (TAPSE), and stroke volume (SV) using velocity time integral (VTI) by left ventricular (LV) outflow tract Doppler or two-dimensional method of discs (MOD). The primary outcome was a composite of PE-related death, cardiac arrest, catecholamine administration for sustained hypotension, or emergency respiratory intervention during the index hospitalization. Secondary outcome was escalated intervention with reperfusion or extracorporeal membrane oxygenation therapy. Results: Of 370 intermediate-risk PE patients (mean age 64.0 ± 15.5 years, 38.1% male), 39 (10.5%) had the primary outcome. These 39 patients had lower mean SV regardless of measurement method than those without the primary outcome: SV MOD 36.2 vs 49.9 milliliters (mL), P < 0.001; SV Doppler 41.7 vs 57.2 mL, P = 0.003; VTI 13.6 vs 17.9 centimeters [cm], P = 0.003. Patients with primary outcome also had lower mean TAPSE than those without (1.54 vs 1.81 cm, P = 0.003). Multivariable models, selecting SV as predictor, had area under the receiver operating curve of 0.8 and Brier score 0.08. The best echocardiographic predictor of our primary outcome was SV MOD (odds ratio 0.72 [0.53, 0.94], P = 0.02). Patients who received escalated interventions had significantly lower SV or surrogate measurements, greater RV dilatation, and lower RV systolic function than patients who received anticoagulation monotherapy. Conclusion: Low stroke volume was a predictor of clinical deterioration and PE-related death. Low SV may be used to identify a subset of intermediate-risk PE patients, who are higher risk (intermediate-high risk), and for whom escalated interventions should be considered.

Computed tomography imaging-based radiologic evaluation of pulmonary artery thrombosis in a series of patients with Behcet's disease.

AIM: Pulmonary artery involvement is a severe complication of Behcet's disease (BD). Although venous thrombosis is common in BD, pulmonary embolism is considered to be rare because the inflammatory nature makes the thrombi strongly adherent to the venous walls. This study aimed to define the radiological characteristics of pulmonary artery thrombosis (PAT) on computed tomography (CT) imaging in BD patients. METHODS: We retrospectively evaluated 165 BD patients with vascular involvement. Among the patients with venous involvement (n = 146), we identified 65 patients who had undergone thorax CT imaging previously. Fourteen patients who were diagnosed with PAT were included in the study. Expert radiologists re-evaluated the patients' initial and control thorax CT scans, classified the PAT as acute or chronic based on their radiological features. RESULTS: The patients' median age was 35 (min-max: 15-60) years at the time of the initial CT scan, and nine were male. Twelve (85.7%) patients were symptomatic at the time of CT evaluation. Upon re-evaluating the thorax CTs, acute PAT was diagnosed in six (42.8%); chronic PAT was detected in eight (57.1%) patients. Two patients with chronic PAT also had acute PAT. Pulmonary artery aneurysms were present in three (21.4%) patients, and intracardiac thrombus was found in three (21.4%) patients. CONCLUSION: A significant number of BD patients with venous involvement had radiological findings consistent with acute PAT potentially due to pulmonary emboli in this study. The clinical importance of these lesions has to be defined with future studies.

nnU-Net-based deep-learning for pulmonary embolism: detection, clot volume quantification, and severity correlation in the RSPECT dataset.

OBJECTIVES: CT pulmonary angiography is the gold standard for diagnosing pulmonary embolism, and DL algorithms are being developed to manage the increase in demand. The nnU-Net is a new auto-adaptive DL framework that minimizes manual tuning, making it easier to develop effective algorithms for medical imaging even without specific expertise. This study assesses the performance of a locally developed nnU-Net algorithm on the RSPECT dataset for PE detection, clot volume measurement, and correlation with right ventricle overload. MATERIALS & METHODS: User input was limited to segmentation using 3DSlicer. We worked with the RSPECT dataset and trained an algorithm from 205 PE and 340 negatives. The test dataset comprised 6573 exams. Performance was tested against PE characteristics, such as central, non-central, and RV overload. Blood clot volume (BCV) was extracted from each exam. We employed ROC curves and logistic regression for statistical validation. RESULTS: Negative studies had a median BCV of 1 µL, which increased to 345 µL in PE-positive cases and 7,378 µL in central PEs. Statistical analysis confirmed a significant BCV correlation with PE presence, central PE, and increased RV/LV ratio (p < 0.0001). The model's AUC for PE detection was 0.865, with an 83 % accuracy at a 55 µL threshold. Central PE detection AUC was 0.937 with 91 % accuracy at 850 µL. The RV overload AUC stood at 0.848 with 79 % accuracy. CONCLUSION: The nnU-Net algorithm demonstrated accurate PE detection, particularly for central PE. BCV is an accurate metric for automated severity stratification and case prioritization. CLINICAL RELEVANCE STATEMENT: The nnU-Net framework can be utilized to create a dependable DL for detecting PE. It offers a user-friendly approach to those lacking expertise in AI and rapidly extracts the Blood Clot Volume, a metric that can evaluate the PE's severity.

The Harms of Unnecessary CT Pulmonary Angiography: A Case Report and Literature Review.

Pulmonary embolism (PE) poses a significant health risk in the United States, with high mortality rates. Clinicians maintain a low threshold for suspecting PE, potentially leading to deviation from guideline-recommended algorithms and unnecessary computed tomography pulmonary angiography (CTPA). This case discusses a 46-year-old woman who presented with symptoms suggestive of PE following a prolonged road trip. Despite a low Wells score and negative D-dimer results, she underwent CTPA, resulting in an unnecessary and harmful interventional radiology-guided thrombectomy. This highlights the importance of adhering to guidelines in PE diagnosis to mitigate potential harms associated with the overuse of available medical tools.

The Diagnostic Accuracy of SPECT Imaging in Patients With Suspected Pulmonary Embolism: Systematic Review and Network Meta-analysis.

BACKGROUND: This meta-analysis and systematic review assessed the diagnostic accuracy of lung SPECT compared with lung planar imaging in patients with suspected acute pulmonary embolism (PE) or chronic thromboembolic pulmonary hypertension. PATIENTS AND METHODS: A search of Medline, Embase, and Cochrane databases identified suitable articles published before October 2023. Meta-analyses were performed to determine the diagnostic accuracy of SPECT imaging modalities, including perfusion (Q) SPECT, ventilation (V)/Q SPECT, Q SPECT/CT, and V/Q SPECT/CT. Network meta-analyses were performed to compare the diagnostic accuracy of SPECT and planar imaging in paired-design studies. RESULTS: Twenty-four articles (total n = 6576) were included in the analysis. For suspected acute PE, the respective sensitivity and specificity of SPECT imaging modalities were as follows: Q SPECT, 0.93 (95% confidence interval [CI], 0.87-0.99; I2 = 49%) and 0.72 (95% CI, 0.54-0.95; I2 = 94%); V/Q SPECT, 0.96 (95% CI, 0.94-0.98; I2 = 51%) and 0.95 (95% CI, 0.92-0.98; I2 = 80%); Q SPECT/CT, 0.93 (95% CI, 0.87-0.98; I2 = 66%) and 0.82 (95% CI, 0.70-0.96; I2 = 87%); and V/Q SPECT/CT, 0.97 (95% CI, 0.93-1.00; I2 = 7%) and 0.98 (95% CI, 0.97-1.00; I2 = 31%). The relative sensitivity and specificity of SPECT compared with planar imaging were 1.17 (95% CI, 1.06-1.30; P < 0.001) and 1.14 (95% CI, 1.00-1.29; P = 0.05), respectively. For suspected chronic thromboembolic pulmonary hypertension, the pooled sensitivity and specificity of SPECT imaging were 0.97 (95% CI, 0.95-1.00; I2 = 0%) and 0.91 (95% CI, 0.87-0.94; I2 = 0%), respectively. CONCLUSIONS: SPECT exhibited superior diagnostic performance for PE. V/Q SPECT/CT was the most accurate modality.

Ultrasound Rounds: Intraoperative Point-of-Care Ultrasound Identifies Intracardiac Thrombus and Pulmonary Embolism Allowing for Alteration in Surgical Management.

Most of the cases demonstrating describing acute findings using point-of-care ultrasound (POCUS) have been described in emergency medicine and critical care medicine. While the use of POCUS has become more prevalent in anesthesia practice, documentation of acute findings resulting in alteration in management based on real-time ultrasound findings during pediatric anesthesia remains limited. This case highlights the use of POCUS during cardiopulmonary collapse occurring during correction of neuromuscular scoliosis. POCUS excluded the presumed diagnosis of venous air embolism and identified an intracardiac thrombus leading to the diagnosis and treatment of pulmonary embolism.

Radiological findings and their relationship with mortality in acute pulmonary embolism.

OBJECTIVE: The aim of the study was to investigate whether sarcopenia had the potential to predict mortality by analyzing epicardial and visceral fat thickness measurements, which are among the radiological findings and scores known to be crucial in determining the prognosis and risk classification of patients diagnosed with acute pulmonary embolism (PE) in the emergency department. PATIENTS AND METHODS: The study included patients diagnosed with acute PE in the emergency department from January 2019 to December 2022 and involved the retrospective examination of their demographic characteristics, clinical parameters, and radiological data obtained from computed tomography pulmonary angiography (CTPA) [main pulmonary artery (MPA) diameter, pulmonary artery obstruction, right and left ventricular diameters, epicardial and visceral tissue thicknesses, and pectoralis muscle thickness (PMT)]. The primary endpoint was mortality during the hospitalized treatment and follow-up processes, and the secondary endpoint was mortality within 90 days after diagnosis. RESULTS: Of the 389 patients included in the study, 11.6% had a fatal outcome in the early period following hospitalization for treatment, and 22.6% had a fatal outcome within the 90-day (late) period after diagnosis. In patients with late-period mortality, pleural fluid (30.8%), pericardial fluid (16.7%), and atelectasis (32.6%) were found to be statistically significantly higher. Among the markers obtained from imaging examinations, only PMT - right: 9.4 [interquartile range (IQR): 6.0-14.0]; left: 9.1 (IQR: 5.4-13.8) - was associated with mortality. According to logistic regression analysis, the MPA diameter was associated with early-period mortality, and it was determined that the right ventricular diameter and the right and left PMT values had a predictive effect on late-period mortality. CONCLUSIONS: To predict mortality, CTPA-based scoring systems that include markers such as PMT, pericardial and pleural fluid, and atelectasis would be more effective; however, large-scale studies are needed to enrich these findings.

Automatic detection of pulmonary embolism on computed tomography pulmonary angiogram scan using a three-dimensional convolutional neural network.

OBJECTIVE: To propose a convolutional neural network (EmbNet) for automatic pulmonary embolism detection on computed tomography pulmonary angiogram (CTPA) scans and to assess its diagnostic performance. METHODS: 305 consecutive CTPA scans between January 2019 and December 2021 were enrolled in this study (142 for training, 163 for internal validation), and 250 CTPA scans from a public dataset were used for external validation. The framework comprised a preprocessing step to segment the pulmonary vessels and the EmbNet to detect emboli. Emboli were divided into three location-based subgroups for detailed evaluation: central arteries, lobar branches, and peripheral regions. Ground truth was established by three radiologists. RESULTS: The EmbNet's per-scan level sensitivity, specificity, positive predictive value (PPV), and negative predictive value were 90.9%, 75.4%, 48.4%, and 97.0% (internal validation) and 88.0%, 70.5%, 42.7%, and 95.9% (external validation). At the per-embolus level, the overall sensitivity and PPV of the EmbNet were 86.0% and 61.3% (internal validation), and 83.5% and 57.5% (external validation). The sensitivity and PPV of central emboli were 89.7% and 52.0% (internal validation), and 94.4% and 43.0% (external validation); of lobar emboli were 95.2% and 76.9% (internal validation), and 93.5% and 72.5% (external validation); and of peripheral emboli were 82.6% and 61.7% (internal validation), and 80.2% and 59.4% (external validation). The average false positive rate was 0.45 false emboli per scan (internal validation) and 0.69 false emboli per scan (external validation). CONCLUSION: The EmbNet provides high sensitivity across embolus locations, suggesting its potential utility for initial screening in clinical practice.

A woman in her thirties with dyspnoea two weeks after abdominoplasty. / En kvinne i 30-årene med dyspné to uker etter bukplastikkoperasjon.

Background: While most cases of venous thromboembolism follow a benign course, occasionally the condition may manifest a complex clinical presentation and need a comprehensive diagnostic workup to identify the underlying cause and provide the patient with appropriate treatment. Case presentation: A woman in her late thirties presented to the emergency department with a five-day history of dyspnoea. She had recently undergone liposuction surgery after pregnancy. Upon admission, initial investigations revealed a pulmonary embolism with right heart strain, and she was treated with anticoagulants. The following day, she complained of acute-onset right flank pain without fever or other accompanying symptoms. A CT scan of the abdomen confirmed a right-side renal infarction. Further investigations revealed patent foramen ovale between the right and left atria of the heart, believed to be the source of a right-to-left shunt of arterial emboli. Although the patient had not suffered a clinical stroke, it was decided to close this defect using percutaneous technique. Interpretation: Patent foramen ovale is a common condition in adults, but in most cases it remains asymptomatic. However, patients with patent foramen ovale have an elevated risk of arterial emboli affecting multiple organs. The diagnosis depends on thorough assessment to prevent potentially fatal outcomes.

Modern imaging of acute pulmonary embolism.

The first-choice imaging test for visualization of thromboemboli in the pulmonary vasculature in patients with suspected acute pulmonary embolism (PE) is multidetector computed tomography pulmonary angiography (CTPA) - a readily available and widely used imaging technique. Through technological advancements over the past years, alternative imaging techniques for the diagnosis of PE have become available, whilst others are still under investigation. In particular, the evolution of artificial intelligence (AI) is expected to enable further innovation in diagnostic management of PE. In this narrative review, current CTPA techniques and the emerging technology photon-counting CT (PCCT), as well as other modern imaging techniques of acute PE are discussed, including CTPA with iodine maps based on subtraction or dual-energy acquisition, single-photon emission CT (SPECT), magnetic resonance angiography (MRA), and magnetic resonance direct thrombus imaging (MRDTI). Furthermore, potential applications of AI are discussed.

Diagnostic performance of fluoroscopic video analysis for pulmonary embolism: a prospective observational study.

PURPOSE: Dynamic chest radiography using X-ray fluoroscopic video analysis has shown potential for the diagnosis of pulmonary embolism (PE), but its diagnostic performance remains uncertain. We aimed to evaluate the diagnostic performance of fluoroscopic video analysis for diagnosing PE. METHODS: A prospective single-center observational study was conducted between October 2020 and January 2022. Fifty consecutive adult patients, comprising definitive PE, pulmonary hypertension (PH), or suspected PH, were enrolled. The study population was classified into 23 PE and 27 non-PE cases by contrast-enhanced computed tomography, lung scintigraphy, right heart catheterization, and pulmonary angiography. Cineradiographic images of 10-second breath-holds were obtained and analyzed using a fluoroscopic video analysis workstation to generate pulmonary circulation images. Two blinded cardiologists qualitatively assessed the presence or absence of perfusion defects on the pulmonary circulation images. The diagnosis obtained from the fluoroscopic analysis was compared with the definitive diagnosis. The primary outcomes included sensitivity, specificity, positive and negative predictive values, and overall accuracy for diagnosing PE. RESULTS: Perfusion defects were observed in 21 of 23 PE patients and 13 of 27 non-PE patients. The diagnostic performance of fluoroscopic video analysis for diagnosing PE showed a sensitivity of 91%, specificity of 52%, positive predictive value of 62%, negative predictive value of 88%, and overall accuracy of 70%. CONCLUSIONS: The high sensitivity of the fluoroscopic video analysis suggests its potential usefulness in ruling out PE without the need for contrast media or radionuclide; however, its specificity and overall accuracy remain limited.

Laterality of CT-measured hepatic extracellular volume fraction in patients with chronic thromboembolic pulmonary hypertension.

PURPOSE: This study examines the hepatic extracellular volume fraction (ECV) disparity between the left and right lobes (ECV_left and ECV_right) in patients with chronic thromboembolic pulmonary hypertension (CTEPH), its association with right heart catheterization (RHC) metrics, and with intolerance to increased pulmonary hypertension (PH)-targeted medication dosages. METHODS: We retrospectively analyzed 72 CTEPH-diagnosed patients who underwent equilibrium-phase abdominal dual-energy CT (DECT) and RHC. Hepatic ECVs, derived from DECT's iodine maps using circular regions of interest in the liver and aorta, were correlated with RHC parameters via Spearman's rank correlation and lobe differences through the Wilcoxon signed-rank test. Logistic regression assessed cases with ECV_left exceeding ECV_right by > 0.05, while receiver operating characteristic curve analysis gauged ECVs' predictive power for medication intolerance. RESULTS: Of the 72 patients (57 females; median age 69), ECV_total (0.24, IQR 0.20-0.27) moderately correlated with RHC parameters (rs = 0.28, -0.24, 0.3 for mean pulmonary arterial pressure, cardiac index [CI], and pulmonary vascular resistance index, respectively). ECV_left significantly surpassed ECV_right (0.25 vs. 0.22, p < 0.001), with a greater ECV_left by > 0.05 indicating notably lower CI (p < 0.001). In 27 patients on PH medication, ECV_left effectively predicted medication intolerance (AUC = 0.84). CONCLUSION: In CTEPH patients, hepatic ECV correlated with RHC metrics, where elevated left lobe ECV suggested reduced CI and potential medication intolerance.

Delayed Diagnosis of Pulmonary Artery Thrombosis in a Patient Undergoing Mitral Valve Replacement.

ABSTRACT: The occurrence of pulmonary artery thrombus in association with rheumatic mitral stenosis is a rare complication. Pulmonary artery thrombus formation may worsen pulmonary artery pressures, and this may precipitate acute right heart failure. The possible mechanisms behind pulmonary artery thrombus formation during mitral valve replacement surgery could be acute coagulopathy following surgery, the presence of chronic pulmonary thromboembolism, or chronic atrial fibrillation. We report an unusual case of pulmonary artery thrombus in a patient with rheumatic MS which was diagnosed with transoesophageal echocardiography after MVR.

Risk factors for suspected pulmonary embolism in children: Complication of Mycoplasma pneumoniae pneumonia.

PURPOSE: Pulmonary embolism (PE) is not a rare complication of Mycoplasma pneumoniae pneumonia (MPP) in children. We sought to determine the incidence of PE in children with MPP who underwent clinically indicated CT pulmonary angiography (CTPA) and to evaluate the risk factors for PE. METHODS: All 106 children with MPP who were clinically suspected of having PE and who underwent CTPA were retrospectively enrolled from June 2018 to December 2021. The clinical features, laboratory data, and radiological parameters were recorded (e.g., lung consolidation involved and the Qanadli score). A Cox proportional hazards model and area under the receiver operating characteristic (ROC) curve were used to evaluate the risk factors and prognostic discriminatory capacity for PE. RESULTS: PE was detected in 26 of 106 (24.5 %) children (mean age, 6.2 years ± 3.3 years; 53 boys). Sixteen of the 26 (61.5 %) children with PE were boys. The mean age of the children with PE was 8.1 ± 2.9 years, and the mean Qanadli score was 15.3 ± 10.2. Children with PE had higher D-dimer levels (9.3 ± 7.1 mg/Lvs. 3.6 ± 3.8 mg/L) and a greater frequency of lung lobe consolidation (25 (96.2 %) vs. 64 (80.0 %)) (all P < 0.05). For children with MPP, age (hazard ratio (HR) = 1.96 (95 % CI1.04, 3.71; P = 0.037), D-dimer level (HR = 1.52, 95 % CI: 1.03, 2.24; P = 0.029), and bilateral lung consolidation (HR = 2.41, 95 % CI: 1.03, 5.58; P = 0.043) were found to be independent predictors of PE. CONCLUSION: Clinical and CT radiological predictors could be used to predict PE in children with MPP. The use of risk factor assessment as a tool has the potential to guide more appropriate use of CTPA in children.

Pulmonary embolism versus pulmonary vasculitis in Hughes-Stovin syndrome: Characteristic computed tomography pulmonary angiographic findings and diagnostic and therapeutic implications. HSS International Study Group.

BACKGROUND AND AIM: Hughes-Stovin syndrome (HSS) is a rare systemic vasculitis with widespread venous/arterial thrombosis and pulmonary vasculitis. Distinguishing between pulmonary embolism (PE) and in-situ thrombosis in the early stages of HSS is challenging. The aim of the study is to compare clinical, laboratory, and computed tomography pulmonary angiography (CTPA) characteristics in patients diagnosed with PE versus those with HSS. METHODS: This retrospective study included 40 HSS patients with complete CTPA studies available, previously published by the HSS study group, and 50 patients diagnosed with PE from a single center. Demographics, clinical and laboratory findings, vascular thrombotic events, were compared between both groups. The CTPA findings were reviewed, with emphasis on the distribution, adherence to the mural wall, pulmonary infarction, ground glass opacification, and intra-alveolar hemorrhage. Pulmonary artery aneurysms (PAAs) in HSS were assessed and classified. RESULTS: The mean age of HSS patients was 35 ± 12.3 years, in PE 58.4 ± 17 (p < 0.0001). Among PE 39(78 %) had co-morbidities, among HSS none. In contrast to PE, in HSS both major venous and arterial thrombotic events are seen.. Various patterns of PAAs were observed in the HSS group, which were entirely absent in PE. Parenchymal hemorrhage was also more frequent in HSS compared to PE (P < 0.001). CONCLUSION: Major vascular thrombosis with arterial aneurysms formation are characteristic of HSS. PE typically appear loosely-adherent and mobile whereas "in-situ thrombosis" seen in HSS is tightly-adherent to the mural wall. Mural wall enhancement and PAAs are distinctive pulmonary findings in HSS. The latter findings have significant therapeutic ramifications.