Multimodal indirect imaging signs of pulmonary embolism

Abstract

The clinical diagnosis of pulmonary embolism is often difficult, as symptoms range from syncope and chest pain to shock and sudden death. Adding complexity to this picture, some patients with non-diagnosed pulmonary embolism may undergo unenhanced imaging examinations for a number of reasons, including the prevention of contrast medium-related nephrotoxicity, anaphylactic/anaphylactoid reactions and nephrogenic systemic fibrosis, as well as due to patients’ refusal or lack of venous access. In this context, radiologists’ awareness and recognition of indirect signs are cornerstones in the diagnosis of pulmonary embolism. This article describes the indirect signs of pulmonary embolism on chest X-ray, unenhanced CT, and MRI.

Radiological findings of COVID-19-related thromboembolic complications

“…Therefore, the radiological findings of lung infarction from pulmonary embolism should be differentiated from GGO as well as consolidations of the COVID-19 pneumonia that may also show reverse a halo sign in about 4% of patients as this will positively impact the patient management. In non-enhanced CT, the presence of peripheral lung opacities with a reverse halo sign, dilatation of pulmonary trunk, and/or increased cardiac volume (particularly, enlargement of the right cardiac chamber) indicate risk of PE and may aid in the decision to perform CT pulmonary angiography to confirm or exclude pulmonary embolism [ 20 ]. Clinical parameters including highly elevated d -dimer levels, haemoptysis, and/or sudden worsening of respiratory function or chest pain should also be considered [ 21 ].…”

A Case of Pulmonary Infarction Resembling Pneumonia during Immunosuppressive Treatment for Rheumatoid Arthritis

“…“Hampton's hump” is a characteristic sign of PE in chest radiographs that is only seen in cases of pulmonary infarction and presents as a wedge-shaped, pleural-based consolidation [ 6 ]. In contrast, GGO-like features in the lung parenchyma, as in this case, are suggestive of two possible diagnoses.…”

“…In contrast, GGO-like features in the lung parenchyma, as in this case, are suggestive of two possible diagnoses. The first is mosaic perfusion, which is seen in cases of chronic pulmonary thromboembolism and is characterized by areas of GGO with hyperperfused vascular segments contrasted by areas with low attenuation due to hypoperfusion caused by vascular occlusion [ 6 ]. The second possibility is pulmonary infarction, as a fan-shaped GGO is an early sign of the condition [ 7 ].…”

“…The second possibility is pulmonary infarction, as a fan-shaped GGO is an early sign of the condition [ 7 ]. In such cases, lung tissue ischemia leads to marked dilatation of the blood vessels in the pulmonary microcirculation, accompanied by increased vascular permeability that causes leakage of fluid and erythrocytes before tissue necrosis [ 6 , 7 ]. These pathological changes likely contribute to the presence of the GGO.…”

Pulmonary embolism and COVID-19 pneumonia: the role of non-enhanced chest computed tomography

“…Firstly, careful attention to the intraluminal density of a pulmonary vessel may reveal a slight increase in the focal attenuation of the vessel, marked by a hyperattenuating finding, compared with other parts. This is observed in the setting of acute PE on noncontrast CT scan, and can be explained by the higher concentration of hemoglobin in a retracting clot, commonly seen within the first seven days of PE (Morita et al, 2010;Torres et al, 2020).…”