Background Hypodense filling defects within the pulmonary veins on computed tomography described as pulmonary vein sign (PVS) have been noted in acute pulmonary embolism and shown to be associated with poor prognosis. We evaluated venous flow abnormalities in chronic thromboembolic pulmonary hypertension (CTEPH) to determine its usefulness in the computed tomography assessment of CTEPH. Methods and Results Blinded retrospective computed tomography analysis of 50 proximal CTEPH cases and 3 control groups—50 acute pulmonary embolism, 50 nonthromboembolic cohort, and 50 pulmonary arterial hypertension. Venous flow reduction was assessed by the following: (1) presence of a filling defect of at least 2 cm in a pulmonary vein draining into the left atrium, and (2) left atrium attenuation (>160 Hounsfield units). PVS was most prevalent in CTEPH. Compared with all controls, sensitivity and specificity of PVS for CTEPH is 78.0% and 85.3% (95% CI, 64.0–88.5 and 78.6–90.6, respectively) versus 34.0% and 70.7% (95% CI, 21.2−48.8 and 62.7–77.8) in acute pulmonary embolism, 8.0% and 62% (95% CI, 2.2–19.2 and 53.7–69.8) in nonthromboembolic and 2.0% and 60% (95% CI, 0.1−10.7 and 51.7−67.9) in pulmonary arterial hypertension. In CTEPH, lobar and segmental arterial occlusive disease was most commonly associated with corresponding absent venous flow. PVS detection was highly reproducible (Kappa=0.96, 95% CI, 0.90–1.01, P <0.001). Conclusions PVS is easy to detect with higher sensitivity and specificity in CTEPH compared with acute pulmonary embolism and is not a feature of pulmonary arterial hypertension. Asymmetric enhancement of pulmonary veins may serve as an additional parameter in the computed tomography assessment of CTEPH and can be used to differentiate CTEPH from pulmonary arterial hypertension.

PurposeTo follow up the clinical outcome of patients with suspected pulmonary embolism (PE), in those only imaged using unenhanced, free-breathing magnetic resonance imaging (MRI).Methods and materialsFifty-seven patients aged 29–99 years (mean 70, SD 18) that could not undergo Computed Tomography Pulmonary Angiography (CTPA) were offered alternative imaging diagnostics in parallel with ongoing methodological studies validating MRI vs CTPA. Contraindications included renal failure (n = 44), severe iodine contrast allergy (n = 10), pregnancy (n = 2) and radioactive iodine therapy (n = 1). The unenhanced MRI protocol was based on free-breathing, steady-state free precession with no cardiac or respiratory gating. Retrospective review of the electronic medical record (EMR) was made of 0–12 months post-imaging and was collected during 2012–2018.ResultsAll 57 MRIs were of diagnostic quality and 12 pulmonary embolisms were diagnosed. Of the 57 patients, 44 were already on, or had started anticoagulation therapy due to clinical suspicion of PE. Four of the patients were put on anticoagulation after the positive MRI and 13 were taken off anticoagulation after a negative MRI report. Other diagnoses reported (considering dyspnea) were pleural effusion (n = 24), consolidation (n = 12) and pericardial effusion (n = 2). One patient had a deep vein thrombosis (DVT) within three months of our negative MRI result and then had a stroke within one year. Another patient suffered a stroke within three months of being diagnosed (by MRI) with PE and given anticoagulation as treatment.ConclusionsOur method supported or altered clinical decision-making and treatment in this cohort. A diagnostic tool for PE without intravenous contrast agent or radiation is of great benefit for certain patients.