Dual-energy CT evidence of pulmonary microvascular occlusion in patients with sickle cell disease experiencing acute chest syndrome.

Abstract

PURPOSE\nAcute chest syndrome (ACS), defined by the presence of a chest radiographic opacity in sickle cell disease patients experiencing respiratory symptoms is a leading cause of death in these patients. The etiology is ACS is not well understood however pulmonary microvascular occlusion has been postulated to be a major pathophysiologic driver. Our study aims to assess the value of dual-energy CT (DECT) as a marker of pulmonary microvascular occlusion.\n\n\nMATERIALS/METHODS\nA search tool was used to identify CT angiography studies from 1/1/2017 to 9/15/2019 with any variation of the phrases Acute chest syndrome and Sickle cell . These studies were manually reviewed for the use of DECT technique. An age-matched control group was created. DECT pulmonary blood volume (PBV) maps were reviewed semi-quantitatively for the presence of iodine defects and the number of involved bronchopulmonary segments were scored. Other recorded values included type of parenchymal opacities, diameter of main pulmonary artery (MPA) and presence of right ventricular dilatation. Mean values between cases and controls were compared using a two-sample t-test.\n\n\nRESULTS\nNine sickle cell DECT cases with PBV maps and nine age-matched controls were evaluated. Bronchopulmonary segments with iodine defects were significantly higher in cases vs controls (mean: 4.7 vs 0.3, p\xa0<\xa00.003). PBV defects were more extensive than parenchymal findings. MPA diameter was higher in cases (2.9\xa0cm) vs control (2.4\xa0cm), P\xa0<\xa00.03.\n\n\nCONCLUSIONS\nDECT demonstrates abnormal PBV in sickle cell patients, often the predominant abnormality identified early, and likely reflects the presence of pulmonary microvascular occlusion.