title: Quantitative determination of Gd-DTPA concentration in T1-weighted MR renography studies.
abstract: A method for calculating contrast agent concentration from MR signal intensity (SI) was developed and validated for T(1)-weighted MR renography (MRR) studies. This method is based on reference measurements of SI and relaxation time T(1) in a Gd-DTPA-doped water phantom. The same form of SI vs. T(1) dependence was observed in human tissues. Contrast concentrations calculated by the proposed method showed no bias between 0 and 1 mM, and agreed better with the reference values derived from direct T(1) measurements than the concentrations calculated using the relative signal method. Phantom-based conversion was used to determine the contrast concentrations in kidney tissues of nine patients who underwent dynamic Gd-DTPA-enhanced 3D MRR at 1.5T and (99m)Tc-DTPA radionuclide renography (RR). The concentrations of both contrast agents were found to be close in magnitude and showed similar uptake and washout behavior. As shown by Monte Carlo simulations, errors in concentration due to SI noise were below 10% for SNR = 20, while a 10% error in precontrast T(1) values resulted in a 12-17% error for concentrations between 0.1 and 1 mM. The proposed method is expected to be particularly useful for assessing regions with highly concentrated contrast.
authors.affiliation: Department of Radiology, New York University School of Medicine, New York, NY 10016, USA. louisa.bokacheva@med.nyu.edu
authors.forename: Louisa
authors.initials: L
authors.lastname: Bokacheva
authors.forename: Henry
authors.initials: H
authors.lastname: Rusinek
authors.forename: Qun
authors.initials: Q
authors.lastname: Chen
authors.forename: Niels
authors.initials: N
authors.lastname: Oesingmann
authors.forename: Chekema
authors.initials: C
authors.lastname: Prince
authors.forename: Manmeen
authors.initials: M
authors.lastname: Kaur
authors.forename: Elissa
authors.initials: E
authors.lastname: Kramer
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D002138:Calibration; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000493:pharmacokinetics; D012079:Renal Circulation; D016284:Technetium Tc 99m Pentetate / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D019786:Gadolinium DTPA; D016284:Technetium Tc 99m Pentetate