title: On the Use of DSC-MRI for Measuring Vascular Permeability.
abstract: OBJECTIVE
  Contrast agent extravasation has been shown to confound brain tumor perfusion measurements with DSC-MR imaging, necessitating the use of correction techniques (eg, Weisskoff, Bjornerud). Leakage parameters (K2 and K(a)) postulated to reflect vessel permeability can be extracted from these correction methods; however, the biophysical interpretation of these parameters and their relationship to commonly used MR imaging measures of vascular permeability (eg, contrast agent volume transfer constant, [K(trans)]) remain unclear. Given that vascular density, as assessed by blood volume, and vascular permeability, as reflected by K(trans) (and potentially K2 or K(a)), report on unique and clinically informative vascular characteristics, there is a compelling interest to simultaneously assess these features.
  
  
  METHODS
  We acquired multiecho DSC-MR imaging data, allowing the simultaneous computation and voxelwise comparison of single- and dual-echo derived measures of K2, K(a) and K(trans) in patients with glioma. This acquisition enabled the investigation of competing T1 and T2* leakage effects and TE dependency on these parameters.
  
  
  RESULTS
  K2 and K(a) displayed nonsignificant (P = .150 and P = .060, respectively) voxelwise linear correlations with K(trans), while a significant (P < .001) inverse relationship was observed between K2 and Ka (coefficient of determination [r(2)] = 0.466-0.984). Significantly different (P < .005) mean estimates were found between voxels exhibiting predominately T1 and T2* effects for K2 and K(a). K(trans), however, was observed to be similar between these voxels (0.109 versus 0.092 minutes(-1)). Significant differences (P < .001) in extracellular-extravascular volume fraction (v(e)) (0.285 versus 0.167) were also observed between cohorts. Additionally, K2 and K(a) were found to have a significant quadratic relationship (P = .031 and P = .005, respectively) with v(e).
  
  
  CONCLUSIONS
  Estimates of vascular permeability in brain tumors may be simultaneously acquired from multiple-echo DSC-MR imaging via K(trans); however, caution should be used in assuming a similar relationship for K2 and K(a).
authors.affiliation: From the Vanderbilt University Institute of Imaging Science (J.T.S., C.C.Q.) Departments of Radiology and Radiological Sciences (J.T.S., C.C.Q.).
authors.forename: J T
authors.initials: JT
authors.lastname: Skinner
authors.affiliation: Neurology (P.L.M.).
authors.forename: P L
authors.initials: PL
authors.lastname: Moots
authors.affiliation: Biostatistics (G.D.A.), Vanderbilt University School of Medicine, Nashville, Tennessee.
authors.forename: G D
authors.initials: GD
authors.lastname: Ayers
authors.affiliation: From the Vanderbilt University Institute of Imaging Science (J.T.S., C.C.Q.) Departments of Cancer Biology (C.C.Q.) Biomedical Engineering (C.C.Q.), Vanderbilt University, Nashville, Tennessee Departments of Radiology and Radiological Sciences (J.T.S., C.C.Q.) christopher.quarles@dignityhealth.org.
authors.forename: C C
authors.initials: CC
authors.lastname: Quarles
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D055592:Biophysical Phenomena / Q000502:physiology; D001932:Brain Neoplasms / Q000098:blood supply* / Q000473:pathology; D002199:Capillary Permeability / Q000502:physiology*; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000503:physiopathology*; D005260:Female; D019786:Gadolinium DTPA; D005910:Glioma / Q000098:blood supply* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA