title: Contrast-enhanced sonography of the lung for differential diagnosis of atelectasis.
abstract: OBJECTIVE
  Because of the absence of air in atelectatic tissue, sonography allows visualization of lung atelectasis and may characterize pulmonary and bronchial arterial vascularity by contrast-enhanced sonography (CES).
  
  
  METHODS
  Thirty consecutive patients with obstructive atelectasis (OA) (n = 17) and compression atelectasis (n = 13) were retrospectively studied by CES using a second-generation sulfur hexafluoride contrast agent (SonoVue [BR1]; Bracco SpA, Milan, Italy). The following CES parameters were evaluated: (1) time to enhancement (TE) of the contrast agent after intravenous application was determined and classified as short TE and delayed TE (short TE, < or =6 seconds; versus delayed TE, >7 seconds); and (2) extent of enhancement (EE) was evaluated during the arterial phase (2-30 seconds) and the parenchymal phase (1-5 minutes): the EE of pleural lesions was determined in comparison with splenic enhancement and classified in reduced EE versus marked EE.
  
  
  RESULTS
  All 13 patients with compression atelectasis had a short TE and a marked EE during arterial and parenchymal phases. In the remaining 17 patients with OA, 10 patients had a short TE and 7 patients had a delayed TE. The EE during both phases was reduced in 5 patients and marked in 3. Nine of 17 patients with OA had different EE during arterial and parenchymal phases.
  
  
  CONCLUSIONS
  Compression atelectasis is characterized by CES with a short TE and a marked EE, indicating patent pulmonary arterial vascularization. In patients with OA, a variable CES pattern is found. With regard to only the TE, a delayed TE implies OA. This indicates a shifting of pulmonary vascularization to bronchial arterial vascularization in these patients.
authors.affiliation: Klinik für Hämatologie/Onkologie, Marburg, Germany. goergc@staff.uni-marburg.de
authors.forename: Christian
authors.initials: C
authors.lastname: Görg
authors.forename: Tillmann
authors.initials: T
authors.lastname: Bert
authors.forename: Rudolf
authors.initials: R
authors.lastname: Kring
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010743:Phospholipids; D001261:Pulmonary Atelectasis / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D013459:Sulfur Hexafluoride; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride