title: Improved visualization of delayed perfusion in lung MRI.
abstract: BACKGROUND
  The investigation of pulmonary perfusion by three-dimensional (3D) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was proposed recently. Subtraction images are generated for clinical evaluation, but temporal information is lost and perfusion defects might therefore be masked in this process. The aim of this study is to demonstrate a simple analysis strategy and classification for 3D-DCE-MRI perfusion datasets in the lung without omitting the temporal information.
  
  
  METHODS
  Pulmonary perfusion measurements were performed in patients with different lung diseases using a 1.5 T MR-scanner with a time-resolved 3D-GRE pulse sequence. 25 3D-volumes were acquired after iv-injection of 0.1 mmol/kg KG Gadolinium-DTPA. Three parameters were determined for each pixel: (1) peak enhancement S(n,max) normalized to the arterial input function to detect regions of reduced perfusion; (2) time between arterial peak enhancement in the large pulmonary artery and tissue peak enhancement τ to visualize regions with delayed bolus onset; and (3) ratio R=S(n,max)/τ was calculated to visualize impaired perfusion, irrespectively of whether related to reduced or delayed perfusion.
  
  
  RESULTS
  A manual selection of peak perfusion images is not required. Five different types of perfusion can be found: (1) normal perfusion; (2) delayed non-reduced perfusion; (3) reduced non-delayed perfusion; (4) reduced and delayed perfusion; and (5) no perfusion. Types II and IV could not be seen in subtraction images since the temporal information is necessary for this purpose.
  
  
  CONCLUSIONS
  The analysis strategy in this study allows for a simple and observer-independent visualization and classification of impaired perfusion in dynamic contrast-enhanced pulmonary perfusion MRI by using the temporal information of the datasets.
authors.affiliation: Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Risse
authors.forename: Monika
authors.initials: M
authors.lastname: Eichinger
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Wolfhard
authors.initials: W
authors.lastname: Semmler
authors.forename: Michael
authors.initials: M
authors.lastname: Puderbach
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008168:Lung / Q000098:blood supply / Q000473:pathology*; D008171:Lung Diseases / Q000175:diagnosis*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D011651:Pulmonary Artery / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media