title: Perfusion magnetic resonance imaging: comparison of semiologic characteristics in first-pass perfusion of brain tumors at 1.5 and 3 Tesla.
abstract: OBJECTIVE
  To investigate whether using 3 Tesla (T) instead of 1.5T modifies the data obtained from first-pass perfusion in relation to the quantitative values of cerebral blood volume (CBV) and estimation of micro-vascular leakage (MVL). To describe the differences in data in the setting of neuro-oncology cases and propose explanations based on the discrepancies.
  
  
  METHODS
  In total, 21 patients presenting an intracranial intra-axial space-occupying lesion underwent two MRI explorations, one at 1.5T and another at 3T, including a first-pass perfusion sequence using sequence parameters, defined by the manufacturer Philips. Using a gamma variate analysis, the ratio of cerebral blood volume (rCBV) in tumor, peritumoral, and normal appearing areas was first assessed. After a global analysis, a subgroup analysis was conducted according to the rCBV value measured at 1.5T. Lastly, MVL was assessed based on the signal intensity recorded above baseline after the passage of the contrast medium.
  
  
  RESULTS
  At 3T, compared to 1.5T data that are currently the reference, rCBV was constantly and significantly over-evaluated (P=0.0041 for all tumors), while MVL was constantly and significantly under-evaluated (P<0.0001 for all tumors).
  
  
  CONCLUSIONS
  The increase in magnetic field strength along with the associated modifications in sequence parameters led to variations in rCBV and MVL when measured using first-pass perfusion. In some cases, such as lymphomas, there was a loss of diagnostic information. It therefore appears necessary to optimize the acquisition parameters to allow for radiologic semiology to become relevant again.
authors.affiliation: Clinique Universitaire de Neuroradiologie et IRM, CHU de Grenoble, BP 217, 38043 Grenoble cedex 9, France. natachamauz@hotmail.fr
authors.forename: Natacha
authors.initials: N
authors.lastname: Mauz
authors.forename: Alexandre
authors.initials: A
authors.lastname: Krainik
authors.forename: Irène
authors.initials: I
authors.lastname: Tropres
authors.forename: Laurent
authors.initials: L
authors.lastname: Lamalle
authors.forename: Elodie
authors.initials: E
authors.lastname: Sellier
authors.forename: Omer
authors.initials: O
authors.lastname: Eker
authors.forename: Florence
authors.initials: F
authors.lastname: Tahon
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Le Bas
authors.forename: Sylvie
authors.initials: S
authors.lastname: Grand
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001932:Brain Neoplasms / Q000150:complications* / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000150:complications* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity