title: Quantification of pulmonary blood flow (PBF): validation of perfusion MRI and nonlinear contrast agent (CA) dose correction with H(2)15O positron emission tomography (PET).
abstract: Validation of quantification of pulmonary blood flow (PBF) with dynamic, contrast-enhanced MRI is still missing. A possible reason certainly lies in difficulties based on the nonlinear dependence of signal intensity (SI) from contrast agent (CA) concentration. Both aspects were addressed in this study. Nine healthy pigs were examined by first-pass perfusion MRI using gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and H(2)(15)O positron emission tomography (PET) imaging. Calculations of hemodynamic parameters were based on a one-compartment model (MR) and a two-compartment model (PET). Simulations showed a significant error when assuming a linear relation between MR SI and CA dose in the arterial input function (AIF), even at low doses of 0.025 mmol/kg body weight (BW). To correct for nonlinearity, a calibration curve was calculated on the basis of the signal equation. The required accuracy of equation parameters (like longitudinal relaxation time) was evaluated. Error analysis estimates <5% over-/underestimation of the corrected SI. Comparison of PET and MR flow values yielded a significant correlation (P < 0.001) in dorsal regions where signal-to-noise ratio (SNR) was sufficient. Changes in PBF due to the correction method were significant (P < 0.001) and resulted in a better agreement: mean values (standard deviation) in units of ml/min/100 ml lung tissue were 59 (15) for PET, 112 (28) for uncorrected MRI, and 80 (21) for corrected MRI.
authors.affiliation: Department of Radiology, Johannes Gutenberg-University Medical School, Mainz, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Neeb
authors.forename: Rainer Peter
authors.initials: RP
authors.lastname: Kunz
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ley
authors.forename: Gábor
authors.initials: G
authors.lastname: Szábo
authors.forename: Ludwig G
authors.initials: LG
authors.lastname: Strauss
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Karl-Friedrich
authors.initials: KF
authors.lastname: Kreitner
authors.forename: Laura Maria
authors.initials: LM
authors.lastname: Schreiber
mesh_terms: D000818:Animals; D016477:Artifacts; D003287:Contrast Media; D019786:Gadolinium DTPA; D007089:Image Enhancement / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D010104:Oxygen Radioisotopes; D055420:Perfusion Imaging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D011652:Pulmonary Circulation / Q000502:physiology*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D014867:Water
chemical_list: D003287:Contrast Media; D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D014867:Water; D019786:Gadolinium DTPA