title: Dynamic and simultaneous MR measurement of R1 and R2* changes during respiratory challenges for the assessment of blood and tissue oxygenation.
abstract: This work presents a novel method for the rapid and simultaneous measurement of R1 and R2* relaxation rates. It is based on a dynamic short repetition time steady-state spoiled multigradient-echo sequence and baseline R1 and B1 measurements. The accuracy of the approach was evaluated in simulations and a phantom experiment. The sensitivity and specificity of the method were demonstrated in one volunteer and in four patients with intracranial tumors during carbogen inhalation. We utilized (ΔR2*, ΔR1) scatter plots to analyze the multiparametric response amplitude of each voxel within an area of interest. In normal tissue R2* decreased and R1 increased moderately in response to the elevated blood and tissue oxygenation. A strong negative ΔR2* and ΔR1 response was observed in veins and some tumor areas. Moderate positive ΔR2* and ΔR1 response amplitudes were found in fluid-rich tissue as in cerebrospinal fluid, peritumoral edema, and necrotic areas. The multiparametric approach was shown to increase the specificity and sensitivity of oxygen-enhanced MRI compared to measuring ΔR2* or ΔR1 alone. It is thus expected to provide an optimal tool for the identification of tissue areas with low oxygenation, e.g., in tumors with compromised oxygen supply.
authors.affiliation: Philips Research, Hamburg, Germany. Stefanie.Remmele@philips.com
authors.forename: Stefanie
authors.initials: S
authors.lastname: Remmele
authors.forename: Alois M
authors.initials: AM
authors.lastname: Sprinkart
authors.forename: Andreas
authors.initials: A
authors.lastname: Müller
authors.forename: Frank
authors.initials: F
authors.lastname: Träber
authors.forename: Marec
authors.initials: M
authors.lastname: von Lehe
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
authors.forename: Sebastian
authors.initials: S
authors.lastname: Flacke
authors.forename: Winfried A
authors.initials: WA
authors.lastname: Willinek
authors.forename: Hans H
authors.initials: HH
authors.lastname: Schild
authors.forename: Julien
authors.initials: J
authors.lastname: Sénégas
authors.forename: Jochen
authors.initials: J
authors.lastname: Keupp
authors.forename: Petra
authors.initials: P
authors.lastname: Mürtz
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods*; D009369:Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000008:administration & dosage / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen