title: Distinguishing high-flow from low-flow vascular malformations using maximum intensity projection images in dynamic magnetic resonance angiography - comparison to other MR-based techniques.
abstract: BACKGROUND
  In addition to ultrasound, magnetic resonance imaging (MRI) is considered a suitable, non-invasive technique to assess the type and extent of vascular malformations. The distinction between low- and high-flow lesions is crucial because it determines appropriate patient treatment.
  
  
  OBJECTIVE
  To distinguish high-flow from low-flow lesions on the basis of the enhancement pattern on MIP images acquired from dynamic time-resolved MR angiography (MRA) and compare it with previously described MR-based methods.
  
  
  METHODS
  We examined 25 consecutive patients with previously diagnosed vascular malformations. Next, each malformation was classified as "high-flow" or "low-flow" using the following criteria: (i) findings on T1-weighted (T1W) and T2-weighted (T2W) imaging (signal voids, signal intensity); (ii) the time interval between the start of arterial enhancement and the onset of lesion enhancement (artery-lesion time); (iii) the time of maximum lesion enhancement; and (iv) analysis of the slope of the enhancement curve.
  
  
  RESULTS
  Of the 25 patients, seven had high-flow and 18 had low-flow malformations. Signal voids on spin-echo T1W images were observed only in four of seven high-flow malformations and in two of 18 low-flow malformations. Analysis of signal intensity on T2W images showed increased signal intensity in 17 of 18 low-flow malformations, and in two of seven high-flow lesions. Calculation of the artery-lesion time, maximum enhancement time, and slope revealed significant differences between the high- and low-flow groups.
  
  
  CONCLUSIONS
  In conclusion, the slope of the enhancement curve appears to be useful in distinguishing between high- and low-flow vascular malformations. Standardization of MR image evaluation criteria is essential.
authors.affiliation: First Clinic of Cardiology, Department of Cardiology, University of Medical Sciences, Poznan, Poland kociemba.anna@gmail.com.
authors.forename: Anna
authors.initials: A
authors.lastname: Kociemba
authors.affiliation: Department of General Radiology, University of Medical Sciences, Poznan, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Karmelita-Katulska
authors.affiliation: Department of General Radiology, University of Medical Sciences, Poznan, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Stajgis
authors.affiliation: Department of Vascular Surgery, University of Medical Sciences, Poznan, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Oszkinis
authors.affiliation: First Clinic of Cardiology, Department of Cardiology, University of Medical Sciences, Poznan, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Pyda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D054079:Vascular Malformations / Q000145:classification* / Q000503:physiopathology*
keywords: Magnetic resonance imaging (MRI); classification; imaging; magnetic resonance angiography (MRA); maximum intensity projection; vascular malformations