Lisette van Dam

CTPP and 3-months clinical outcomes after acute PE 11 171 The aim of this analysis was to investigate the predictive value of CTPP-assessed perfusion defects at initial PE diagnosis for persistent symptoms and adverse outcomes at 3-month follow-up. Persistent symptoms included self-reported: 1) dyspnea; 2) chest pain; or 3) post-PE functional impairment. Adverse outcomes included: 1) recurrent venous thromboembolism (VTE); 2) PE-related readmission or; 3) all-cause mortality. Post-PE functional impairment was defined as new/progressive dyspnea, exercise intolerance and/or diminished functional status following PE adequately treated with anticoagulation for at least 3 months, without an apparent non-PE alternative explanation. 10 PE-related readmission was defined as readmission to hospital due to PE-related complications, such as dyspnea, chest pain, major bleeding or (suspected) recurrent VTE. CT examinations were performed on a 320-multislice detector row CT scanner (Canon). Perfusion images were obtained with subtraction CT technique in which pre-contrast images are subtracted fromcontrast-enhanced images. Subsequently, a colour-coded parametric map is produced representing iodine distribution within the lungs, that is fused with the CTPA image. Display settings can be set for normal perfusion: yellow to orange, moderately decreased perfusion: red to purple, severely decreased or absent perfusion: purple to dark blue/black ( Figure 1 ). The evaluation of CTPP images was performed by a researcher (L.D.) trained by an expert thoracic radiologist (L.K.) with over 20 years of experience in pulmonary CT reading, and was blinded for symptoms and adverse outcomes. Perfusion defect score (PDS) on CTPP was assessed by using the score proposed by Chae et al. and was expressed as mean PDS in percentages. 2 Additionally, the CTPP images of 24 consecutive patients were independently evaluated by a second reviewer (L.K.) to assess the interobserver agreement for perfusion defect measurement. Baseline characteristics are described as mean with standard deviation (SD). To assess the correlation between PDS on CTPP and both persistent symptoms and adverse outcomes, differences between mean PDS with corresponding 95% confidence interval (95%CI) in patients with and without persistent symptoms and adverse outcomes were calculated. All statistical analyses were performed in SPSS version 25 (IBM, Armonk, NY, USA).