Incidence and morphological characteristics of the reversed halo sign in patients with acute pulmonary embolism and pulmonary infarction undergoing computed tomography angiography of the pulmonary arteries

Figures

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  Figure 1. Patient selection process. CTA: CT angiography; PE: pulmonary embolism; and RHS: reversed halo sign.

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  Figure 2. In A, computed tomography angiography image, with lung window settings, showing a lesion characteristic of pulmonary infarction with the reversed halo sign (black arrow) in the subpleural region of the right lower lobe, comprising heterogeneous areas of low attenuation. A small pleural effusion is also seen on this side. In B, computed tomography angiography image, with mediastinal window settings, showing a small filling defect (white arrow) at the emergence of the segmental branch that connects the right pulmonary artery to the lateral basal segment of the lower lobe.

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  Figure 3. In A, computed tomography angiography image, with lung window settings, showing lesions characteristic of pulmonary infarction with the reversed halo sign (black arrows) in the subpleural region of the lower lobes, containing reticulation; the lesion in the right lower lobe is oval, and the one in the left lower lobe is round. In B, computed tomography angiography image, with mediastinal window settings, showing filling defects (white arrows) at the emergence of the pulmonary arteries.

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  Figure 4. In A, computed tomography angiography image, with lung window settings, showing a round lesion characteristic of subpleural pulmonary infarction with the reversed halo sign (white arrow) in the right lower lobe, comprising heterogeneous areas of low attenuation and no evident reticulation. In B, computed tomography angiography image, with mediastinal window settings, showing a small filling defect (white arrow) in the segmental branch that connects the right pulmonary artery to the lower lobe.

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  Figure 5. In A, computed tomography angiography image, with lung window settings, showing oval lesions characteristic of pulmonary infarction with the reversed halo sign (black arrows) in the subpleural region of the left lower lobe, comprising heterogeneous areas of low attenuation. In B, sagittal reconstruction, with mediastinal window settings, showing an extensive filling defect (white arrow) in the segmental branch that connects the left pulmonary artery to the posterior basal segment of the lower lobe.