title: Effect of gadolinium on phase-contrast MR angiography of the renal arteries.
abstract: OBJECTIVE
  Our aim was to evaluate the effect of gadolinium chelates on image quality in phase-contrast MR angiography of renal arteries in patients suspected of having renal artery stenosis.
  
  
  METHODS
  In 24 patients, axial three-dimensional phase-contrast MR angiography of the renal arteries was obtained on a 1.5-T MR imaging system before and after administration of gadolinium contrast agent. The improvement in distal renal artery signal-to-noise ratio after enhancement was measured and correlated with patient age, serum creatinine level, clinical estimation of renal artery flow, and the imaging parameter flip angle.
  
  
  RESULTS
  On average, the distal renal artery signal-to-noise ratio increased 2.2-fold after gadolinium administration (p < .001). The increase was greatest in patients more than 60 years old (3.1-fold; p < .001) and in patients with serum creatinine levels greater than 3.0 mg/dl (4.3-fold; p < .01). After enhancement, we found an apparent increase in renal artery diameter (3.5 +/- 1.1 mm before enhancement versus 4.8 +/- 1.4 mm after enhancement [mean +/- SD; p < .001]). We believe this increase reflects improved visualization of slow blood flow along the artery wall. Although the visualization of renal arteries was better in most patients after enhancement, two patients had poorer image quality after enhancement because of increased venous signal obscuring the arteries.
  
  
  CONCLUSIONS
  Gadolinium administration significantly increases distal renal artery signal-to-noise ratio on three-dimensional phase-contrast MR angiography in most patients. The signal-to-noise ratio improvement is greatest in older patients and in patients with impaired renal function. However, in some cases, increased venous signal may obscure arteries.
authors.affiliation: Department of Radiology, University of Michigan, University Hospital, Ann Arbor 48109-0030, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Bass
authors.forename: M R
authors.initials: MR
authors.lastname: Prince
authors.forename: F J
authors.initials: FJ
authors.lastname: Londy
authors.forename: T L
authors.initials: TL
authors.lastname: Chenevert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000175:diagnosis; D003287:Contrast Media; D005260:Female; D005682:Gadolinium; D006801:Humans; D007091:Image Processing, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012077:Renal Artery / Q000473:pathology*; D012078:Renal Artery Obstruction / Q000175:diagnosis*
chemical_list: D003287:Contrast Media; D005682:Gadolinium