Presentation
Known previous pulmonary thromboembolism, presenting for a follow-up CTPA to assess treatment response.
Patient Data
Extensive acute pulmonary thromboembolism with thromboemboli present within the distal right and left main pulmonary arteries, bilateral ascending lobar and descending interlobar arteries with extension to involve the segmental branches. There is a combination of occlusive and non-occlusive thromboemboli. There is pulmonary arterial hypertension with right ventricular strain, however, no IVC or intrahepatic reflux. The main pulmonary arterial trunk is unaffected with normal opacification of the right heart.
The lung fields are clear with no groundglass opacities, no pulmonary infarcts and no effusions.
CTPA is otherwise unremarkable.
There is near total resolution of the extensive pulmonary thromboembolism previously documented 6 months prior. Pulmonary arterial hypertension and right ventricular strain have resolved on treatment.
There are residual bands (synechiae) within the descending right interlobar artery.
The CTPA is otherwise normal with no other chronic sequela of the previous pulmonary thromboembolism.
Axial and coronal images with the bands (synechiae) as arrowed within the descending right interlobar pulmonary artery.
Case Discussion
This is an example of the residual bands (synechiae) that persist in chronic pulmonary thromboemboli as demonstrated in this case of extensive acute pulmonary arterial thromboembolism 6 months prior.
The patient had a previous history of deep venous thrombosis and COVID-19 exposure. She presented with acute dyspnea, chest pain, elevated D-dimer and tachycardia. Positive CTPA as demonstrated above. She was managed conservatively on oral anticoagulation (Xarelto) for 6 months and presented for a follow-up clinical and CT assessment.
Synechiae represent fibrous bands that form after recanalization and remodeling of thromboemboli. They are occasionally identified on follow-up duplex Doppler studies for deep vein thrombosis. This is a case of synechiae on follow-up CTPA.
Fibrous bands (synechiae) are linear, attached to the vessel walls at both ends, with a free midportion1. They have an approximate length of 3-20 mm and a width of 1-3mm1. They follow the vessel and blood flow orientation1. When multiple bands form a network they are referred to as a web1. On CTPA, they appear as thin lines surrounded by contrast1. They are mostly seen in the lobar or segmental arteries (as in this case) and rarely identified within the main pulmonary artery1.
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