title: Phase-based vascular input function: Improved quantitative DCE-MRI of atherosclerotic plaques.
abstract: OBJECTIVE
  Quantitative pharmacokinetic modeling of dynamic contrast-enhanced (DCE)-MRI can be used to assess atherosclerotic plaque microvasculature, which is an important marker of plaque vulnerability. Purpose of the present study was (1) to compare magnitude- versus phase-based vascular input functions (m-VIF vs ph-VIF) used in pharmacokinetic modeling and (2) to perform model calculations and flow phantom experiments to gain more insight into the differences between m-VIF and ph-VIF.
  
  
  METHODS
  Population averaged m-VIF and ph-VIFs were acquired from 11 patients with carotid plaques and used for pharmacokinetic analysis in another 17 patients. Simulations, using the Bloch equations and the MRI scan geometry, and flow phantom experiments were performed to determine the effect of local blood velocity on the magnitude and phase signal enhancement.
  
  
  RESULTS
  Simulations and flow phantom experiments revealed that flow within the lumen can lead to severe underestimation of m-VIF, while this is not the case for the ph-VIF. In line, the peak concentration of the m-VIF is significantly lower than ph-VIF (p < 0.001), in vivo. Quantitative model parameters for m- and ph-VIF differed in absolute values but were moderate to strongly correlated with each other [K(trans) Spearman's ρ > 0.93 (p < 0.001) and vp Spearman's ρ > 0.58 (p < 0.05)].
  
  
  CONCLUSIONS
  m-VIF is strongly influenced by local blood velocity, which leads to underestimation of the contrast medium concentration. Therefore, it is advised to use ph-VIF for DCE-MRI analysis of carotid plaques for accurate quantification.
authors.affiliation: Department of Radiology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands and CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht 6200 MD, The Netherlands.
authors.forename: R H M
authors.initials: RH
authors.lastname: van Hoof
authors.affiliation: Department of Radiology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands and CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht 6200 MD, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Hermeling
authors.affiliation: Department of Radiology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands; CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht 6200 MD, The Netherlands; and Department of Clinical Neurophysiology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands.
authors.forename: M T B
authors.initials: MT
authors.lastname: Truijman
authors.affiliation: Department of Neurology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands and CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht 6200 MD, The Netherlands.
authors.forename: R J
authors.initials: RJ
authors.lastname: van Oostenbrugge
authors.affiliation: Department of Surgery, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands.
authors.forename: J W H
authors.initials: JW
authors.lastname: Daemen
authors.affiliation: Department of Radiology, Leiden University Medical Center, Leiden 2333 ZA, The Netherlands.
authors.forename: R J
authors.initials: RJ
authors.lastname: van der Geest
authors.affiliation: Department of Neurology, Orbis Medical Center, Sittard 6130 MB, The Netherlands.
authors.forename: N P
authors.initials: NP
authors.lastname: van Orshoven
authors.affiliation: Department of Neurology, Atrium Medical Center, Heerlen 6401 CX, The Netherlands.
authors.forename: A H
authors.initials: AH
authors.lastname: Schreuder
authors.affiliation: Department of Radiology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands.
authors.forename: W H
authors.initials: WH
authors.lastname: Backes
authors.affiliation: Department of Pathology, Academic Medical Center, Amsterdam 1100 DD, The Netherlands.
authors.forename: M J A P
authors.initials: MJ
authors.lastname: Daemen
authors.affiliation: Department of Radiology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands and CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht 6200 MD, The Netherlands.
authors.forename: J E
authors.initials: JE
authors.lastname: Wildberger
authors.affiliation: Department of Radiology, Maastricht University Medical Center, Maastricht 6202 AZ, The Netherlands and CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht 6200 MD, The Netherlands.
authors.forename: M E
authors.initials: ME
authors.lastname: Kooi
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D002340:Carotid Artery Diseases / Q000378:metabolism* / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D058226:Plaque, Atherosclerotic / Q000378:metabolism* / Q000473:pathology*
chemical_list: D003287:Contrast Media; D005682:Gadolinium