Quantitative 3-Dimensional Chest CT Vascular Reconstruction Before and After Anticoagulation for Pulmonary Embolism

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The pulmonary vascular response to ultrasound-facilitated, catheter-directed fibrinolysis for treatment of pulmonary embolism (PE) results in rapid improvement in patient symptoms and right ventricular (RV) recovery, while minimizing the risk of intracranial hemorrhage. The investigators recently co...

The pulmonary vascular response to ultrasound-facilitated, catheter-directed fibrinolysis for treatment of pulmonary embolism (PE) results in rapid improvement in patient symptoms and right ventricular (RV) recovery, while minimizing the risk of intracranial hemorrhage. The investigators recently completed an analysis of the chest computed tomographic (CT) data from the SEATTLE II Trial of ultrasound-facilitated, catheter-directed fibrinolysis for treatment of PE using a previously-validated 3-dimensional (3D) reconstruction technique pioneered at Brigham and Women's Hospital (BWH). This software-based 3D technique enables anatomic and structural resolution of the distal pulmonary arteries (microvasculature) far beyond the imaging capabilities of clinically utilized methods. This technique also provides a precise quantitation of RV volume and quantification of the perfusion of the proximal and distal pulmonary arteries. In our 3D reconstruction analysis of the multicenter, U.S.-based SEATTLE II Trial chest CT data, the investigators found that loss of intraparenchymal blood vessel volume was associated with RV enlargement and change in distal small vessel pulmonary artery perfusion predicted RV recovery with ultrasound-facilitated, catheter-directed fibrinolysis in subjects with acute PE. These data were presented at the American Heart Association (AHA) Annual Scientific Sessions in 2017 and have been submitted for publication. While ultrasound-facilitated, catheter-directed fibrinolysis has been studied using this 3D reconstruction technique, the pulmonary vascular response in PE patients treated clinically with anticoagulation alone has not been. The investigators propose a study to evaluate inpatients diagnosed with acute PE, in whom clinical providers have already prescribed standard anticoagulation alone for treatment based on clinical grounds at Brigham and Women's Hospital, applying this 3-dimensional reconstruction technique to compare data from a standard clinical contrast-enhanced chest CT scan performed 48 hours after initiation of therapy and those data from the standard clinically-indicated baseline contrast-enhanced chest CT scan. The specific aims for this proposed study are as follows: Aim #1: To quantify the CT-determined percent change in perfusion of the pulmonary vasculature from baseline to 48 hours in inpatients diagnosed with acute PE, in whom clinical providers have prescribed standard anticoagulation alone for treatment based on clinical grounds at Brigham and Women's Hospital. Hypothesis #1: The greatest change in pulmonary vascular perfusion following anticoagulation alone for acute PE will take place in the distal small (<5 mm2 cross-sectional area) pulmonary arteries compared with larger (>5 mm2 cross-sectional area) vessels. However, the magnitude of change will be less than that observed in our previously reported analysis focused on patients with acute PE undergoing ultrasound-facilitated, catheter-based fibrinolysis. Aim #2: To quantify the CT-determined percent change in RV volume from baseline to 48 hours in inpatients diagnosed with acute PE, in whom clinical providers have prescribed standard anticoagulation alone for treatment based on clinical grounds at Brigham and Women's Hospital. Hypothesis #2: RV volume will decrease over 48 hours of anticoagulation alone but the percent change will be less than that observed in our previously reported analysis focused on patients with acute PE undergoing ultrasound-facilitated, catheter-based fibrinolysis

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