Imaging of Pulmonary Embolus: Thrombotic, Nonthrombotic, and Mimickers

Nontrombotic Pulmonary Embolism: Different Etiology, Same Significant Consequences

Nontrombotic pulmonary embolism represents the embolization of different types of materials (cells, organisms, gas, foreign material) into pulmonary circulation. The disease is uncommon, and clinical presentation together with laboratory findings are nonspecific. Its pathology is usually misdiagnosed based on imaging findings as pulmonary thromboembolism, but the correct diagnosis is essential because different therapeutic approaches are required. In this context, knowledge of the risk factors associated with nontrombotic pulmonary embolism and specific clinical symptoms is fundamental. Our objective was to discuss the specific features of the most common etiologies of nontrombotic pulmonary embolism, gas, fat, amniotic fluid, sepsis and tumors, to provide assistance for a rapid and correct diagnosis. Because the most common etiologies are iatrogenic, knowledge of the risk factors could be an important tool for prevention or rapid treatment if the disease develops during different procedures. The diagnosis of nontrombotic pulmonary embolisms represent a laborious challenge, and endeavors should be made to prevent development and increase awareness of this disease.

Radiologic mimics of pulmonary embolism

The diagnosis of pulmonary embolism (PE) is often made more challenging by the presence of diseases that can mimic thromboembolic disease. There is no specific or sensitive constellation of clinical signs or symptoms that can be used to diagnose PE. Ventilation/perfusion scans can have false-positive findings related to mediastinal conditions that can compress the pulmonary arteries, and pulmonary hemorrhage can resemble PE on V/Q scanning with potentially devastating consequences if anticoagulation is started. CT-scan related issues l eading to potential false-positive diagnoses range from inadequate imaging technique, to systemic-pulmonary shunting, to non-thrombotic occlusion of pulmonary arteries by tumor, septic emboli, and emboli of fat, air, and foreign material, as well as vasculitic processes. Careful assessment of the patient and consideration of these potential mimickers is imperative to correct diagnosis of this potentially life-threatening condition.

Computed Tomography Angiography Assessment of Acute Aortic Syndromes: Classification, Differentiating Imaging Features, and Imaging Interpretation Pitfalls

An acute aortic syndrome (AAS) is an important life-threatening condition that requires early detection and management. Acute intramural hematoma (IMH), aortic dissection (AD) and penetrating atherosclerotic ulcer (PAU) are included in AAS. ADs can be classified using the well-known Stanford or DeBakey classification systems. However, these classification systems omit description of arch dissections, anatomic variants, and morphologic features that impact outcome. The Society for Vascular Surgery and Society of Thoracic Surgeons (SVS-STS) have recently introduced a classification system that classifies ADs according to the location of the entry tear (primary intimomedial tear, PIT) and the proximal and distal extent of involvement, but does not include description of all morphologic features that may have diagnostic and prognostic significance. This review describes these classification systems for ADs and other AAS entities as well as their limitations. Typical computed tomography angiography (CTA) imaging appearance and differentiating features of ADs, limited intimal tears (LITs), IMHs, intramural blood pools (IBPs), ulcer-like projections (ULPs), and PAUs will be discussed. Furthermore, this review highlights common imaging interpretation pitfalls, what should be included in a comprehensive CTA report, and provides a brief overview of current management options.

Surgical Management of a Bullet Embolism to the Pulmonary Artery

Bullet embolism is a rare but potentially serious complication of a gunshot wound. This case report describes a 26-year-old male who presented with a gunshot to the lower back. Diagnostics revealed a migrating bullet that became lodged in the left pulmonary artery. After two unsuccessful attempts at endoscopic removal, the decision was made by the multidisciplinary team to retrieve the bullet surgically. The patient recovered well postoperatively. Four- and eight-month follow-up in the emergency department revealed no significant postoperative complications. Bullet embolism should be suspected when radiographs reveal a migrating projectile. Treatment options include conservative management, endoscopic bullet retrieval, and surgical removal. No guidelines for the management of a bullet embolism exist. Management should be based on the patient's clinical status and comorbidities, facility resources, and perceived risk of undergoing surgical retrieval of the bullet.

Non-thrombotic pulmonary embolism in emergency CT

Non-thrombotic pulmonary embolism (NTPE) results from the embolization of non-thrombotic materials. It can often be a challenging diagnosis due to non-specific (similar to thrombotic pulmonary embolism) or uncommon clinical and imaging findings. Patients with NTPE often present to the emergency department with acute respiratory distress, and contrast-enhanced computed tomography (CT) of the chest and CT pulmonary angiography are the imaging modalities of choice for respiratory distress. Since the treatment of NTPE is entirely different from thromboembolism, its distinction is essential. Moreover, early diagnosis of NTPE is necessary. Radiologists must be familiar with the diagnostic findings of NTPE, and this article aims to review the imaging features of various causes of NTPE.