title: Renal perfusion imaging with two-dimensional navigator gated arterial spin labeling.
abstract: OBJECTIVE
  To develop a navigator technique enabling free-breathing acquisition to afford sufficient signal averaging for quantitative renal perfusion measurement using arterial spin labeling MRI.
  
  
  METHODS
  A novel two-dimensional (2D) navigator technique was implemented in concert with flow-sensitive alternating inversion recovery (FAIR) preparation and true fast imaging with steady precession (True-FISP) readout. The navigator images were obtained with a low-resolution fast low angle shot readout at end of each arterial spin labeling acquisition. A retrospective algorithm was developed to automatically detect respiratory motion for selective signal averaging. The 2D navigator-gated FAIR True-FISP sequence was performed in ten healthy volunteers and five patients with chronic kidney disease.
  
  
  RESULTS
  Excellent image quality and comparable cortical perfusion rates (healthy: 276 ± 28 mL/100 g/min, patients: 155 ± 25 mL/100 g/min) to literature values were obtained. An average of 3-fold signal-to-noise ratio improvement was obtained in the 2D navigator-gated approach compared with the breath-hold acquisition in healthy volunteers. Good image quality was achieved in patients while the results from breath-hold acquisition were unusable. The quantitative perfusion rates were significantly lower in chronic kidney disease patients compared with the healthy volunteers.
  
  
  CONCLUSIONS
  2D navigator-gated free breathing arterial spin labeling is feasible and is a noninvasive method to evaluate renal perfusion both in healthy subjects and those with chronic kidney disease.
authors: Department of Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA.
authors: Huan
authors: H
authors: Tan
authors: Ioannis
authors: I
authors: Koktzoglou
authors: Pottumarthi V
authors: PV
authors: Prasad
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D007668:Kidney / Q000098:blood supply*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D051436:Renal Insufficiency, Chronic / Q000503:physiopathology; D059629:Signal-To-Noise Ratio; D013113:Spin Labels
chemical_list: D013113:Spin Labels