title: The concordance of MRI and quantitative autoradiography estimates of the transvascular transfer rate constant of albumin in a rat brain tumor model.
abstract: The apparent forward transfer constant, K transa, for albumin was measured in 9L cerebral tumors in 15 rats. An MRI study using gadolinium-labeled bovine serum albumin was followed by terminal quantitative autoradiography (QAR) using radioiodinated serum albumin. Look-Locker MRI estimates of T(1) followed gadolinium-labeled bovine serum albumin blood and tissue concentration. QAR and MRI maps of K transa were coregistered, a region of interest (ROI) that included the tumor and its surround was selected, and the two estimates of K transa from the ROI on QAR and MRI maps were compared by either mean per animal ROI or on pixel-by-pixel data using a generalized estimating equation. An ROI analysis showed a moderate correlation between the two measures (r = 0.57, P = 0.026); pixel-by-pixel generalized estimating equation analysis concurred (r = 0.54, P < 0.0001). The estimates of QAR with MRI of last time points (e.g., 25 min) showed a moderate correlation (ROI r = 0.55, P < 0.035; generalized estimating equation r = 0.58, P < 0.0001). Differences between the QAR and MRI estimates of K transa did not differ from zero, but the MRI 25-min estimate was significantly lower than the QAR estimate. Thus, noninvasive MRI estimates of vascular permeability can serve as a surrogate for QAR measures.
authors.affiliation: Department of Neurology, Henry Ford Hospital, Detroit, Michigan, USA.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Paudyal
authors.forename: James R
authors.initials: JR
authors.lastname: Ewing
authors.forename: Tavarekere N
authors.initials: TN
authors.lastname: Nagaraja
authors.forename: Hassan
authors.initials: H
authors.lastname: Bagher-Ebadian
authors.forename: Robert A
authors.initials: RA
authors.lastname: Knight
authors.forename: Swayamprava
authors.initials: S
authors.lastname: Panda
authors.forename: Mei
authors.initials: M
authors.lastname: Lu
authors.forename: Karyn
authors.initials: K
authors.lastname: Ledbetter
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Fenstermacher
mesh_terms: D000418:Albumins / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography / Q000379:methods*; D001932:Brain Neoplasms / Q000378:metabolism*; D002199:Capillary Permeability / Q000502:physiology; D005909:Glioblastoma / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008962:Models, Theoretical; D009374:Neoplasms, Experimental / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D012711:Serum Albumin, Radio-Iodinated / Q000378:metabolism
chemical_list: D000418:Albumins; D012711:Serum Albumin, Radio-Iodinated