title: MR angiography with an ultrasmall superparamagnetic iron oxide blood pool agent.
abstract: The purpose of the study was to investigate the use of a dextran-coated ultrasmall superparamagnetic iron oxide (USPIO) as a blood pool contrast agent for thoracic and abdominal MR angiography. Abdominal and thoracic MR angiography was performed in six healthy volunteers using two-dimensional and three-dimensional spoiled gradient echo (SPGR) sequences before and after intravenous administration of USPIO. Doses ranged from 1.1 to 2.6 mg Fe/kg. Flip angle was varied from 20 to 60 degrees. Subjective image quality, analysis of signal-to-noise ratio (SNR), and blood T1 relaxation times were measured. USPIO significantly lowered the T1 of blood (from 1,210 ms precontrast to 159 ms postcontrast at a dose of 2.6 mg Fe/kg) (P < .01). Image quality on coronal fast three-dimensional breath-hold SPGR images of the abdomen increased with increasing dose and was maximum at the highest dose, producing an aortic SNR of 9.6 compared to 1.8 precontrast. Axial two-dimensional time-of-flight (TOF) aortic SNR was reduced significantly from 13 on precontrast to 6 on the postcontrast images at the highest dose (P < .05) due to T2* shortening effects. There was little flip angle dependence on image quality. Due to the T1 shortening effect and long intravascular half-life, USPIO improved visualization of vascular anatomy using three-dimensional fast SPGR imaging. The echo time must be minimized to minimize signal loss from T2* shortening effects. The blood pool distribution of USPIO is useful for equilibrium-phase MR angiography.
authors.affiliation: Department of Radiology, University of Michigan School of Medicine, Ann Arbor 48109-0030, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Anzai
authors.forename: M R
authors.initials: MR
authors.lastname: Prince
authors.forename: T L
authors.initials: TL
authors.lastname: Chenevert
authors.forename: J H
authors.initials: JH
authors.lastname: Maki
authors.forename: F
authors.initials: F
authors.lastname: Londy
authors.forename: M
authors.initials: M
authors.lastname: London
authors.forename: S J
authors.initials: SJ
authors.lastname: McLachlan
mesh_terms: D000005:Abdomen / Q000098:blood supply*; D000328:Adult; D000792:Angiography; D003287:Contrast Media; D004305:Dose-Response Relationship, Drug; D005240:Feasibility Studies; D005260:Female; D005290:Ferric Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics; D006207:Half-Life; D006801:Humans; D007275:Injections, Intravenous; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010690:Phlebography; D012016:Reference Values; D012680:Sensitivity and Specificity; D013909:Thorax / Q000098:blood supply*
chemical_list: D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide