title: Use of cardiac output to improve measurement of input function in quantitative dynamic contrast-enhanced MRI.
abstract: OBJECTIVE
  To validate a new method for converting MR arterial signal intensity versus time curves to arterial input functions (AIFs).
  
  
  METHODS
  The method constrains AIF with patient's cardiac output (Q). Monte Carlo simulations of MR renography and tumor perfusion protocols were carried out for comparison with two alternative methods: direct measurement and population-averaged input function. MR renography was performed to assess the method's inter- and intraday reproducibility for renal parameters.
  
  
  RESULTS
  In simulations of tumor perfusion, the precision of the parameters (K(trans) and v(e)) computed using the proposed method was improved by at least a factor of three compared to direct measurement. Similar improvements were obtained in simulations of MR renography. Volunteer study for testing interday reproducibility confirmed the improvement of precision in renal parameters when using the proposed method compared to conventional methods. In another patient study (two injections within one session), the proposed method significantly increased the correlation coefficient (R) between GFR of the two exams (0.92 vs. 0.83) compared to direct measurement.
  
  
  CONCLUSIONS
  A new method significantly improves the precision of dynamic contrast-enhanced (DCE) parameters. The method may be especially useful for analyzing repeated DCE examinations, such as monitoring tumor therapy or angiotensin converting enzyme-inhibitor renography.
authors.affiliation: Department of Radiology, New York University School of Medicine, New York, NY, USA. Lei.Zhang@nyumc.org
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Zhang
authors.forename: Henry
authors.initials: H
authors.lastname: Rusinek
authors.forename: Louisa
authors.initials: L
authors.lastname: Bokacheva
authors.forename: Qun
authors.initials: Q
authors.lastname: Chen
authors.forename: Pippa
authors.initials: P
authors.lastname: Storey
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002302:Cardiac Output; D003198:Computer Simulation; D003287:Contrast Media; D004562:Electrocardiography; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D007668:Kidney / Q000473:pathology; D007680:Kidney Neoplasms / Q000098:blood supply / Q000473:pathology*; D007700:Kinetics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA