title: A simplified spin and gradient echo approach for brain tumor perfusion imaging.
abstract: OBJECTIVE
  In this study, we propose a simplified acquisition and analysis approach for spin and gradient echo (SAGE)-based dynamic susceptibility-contrast MRI (DSC-MRI) data that is free of contrast agent T1 leakage effects.
  
  
  METHODS
  A five-echo SAGE sequence was used to acquire DSC-MRI data in rat C6 tumors (n = 7). Nonlinear fitting of all echoes was performed to obtain T1-insensitive ΔR2* and ΔR2 time series. The simplified approach, which includes two gradient echoes and one spin echo, was also used to analytically compute T1-insensitive ΔR2* using the two gradient echoes and ΔR2 using all three echoes. The blood flow, blood volume, and vessel size values derived from each method were compared.
  
  
  RESULTS
  In all cases, the five-echo and simplified SAGE ΔR2* and ΔR2 were in excellent agreement and demonstrated significant T1 leakage correction compared with the uncorrected single-echo data. The derived hemodynamic parameters for blood volume, blood flow, and vessel size were not significantly different between the two methods.
  
  
  CONCLUSIONS
  The proposed simplified SAGE technique enables the acquisition of gradient and spin echo DSC-MRI data corrected for T1 leakage effects yields parameters that are in agreement with the five-echo SAGE approach and does not require nonlinear fitting to extract ΔR2* and ΔR2 time series.
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.|Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Stokes
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.|Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: C Chad
authors.initials: CC
authors.lastname: Quarles
mesh_terms: D000465:Algorithms; D000818:Animals; D001783:Blood Flow Velocity; D001932:Brain Neoplasms / Q000150:complications / Q000473:pathology* / Q000503:physiopathology*; D045744:Cell Line, Tumor; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D009389:Neovascularization, Pathologic / Q000150:complications / Q000473:pathology* / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D013113:Spin Labels
keywords: SAGE; contrast agent leakage; dynamic susceptibility-contrast MRI; multi-echo sequence; perfusion imaging; spin echo EPI