title: Quantitative high-resolution renal perfusion imaging using 3-dimensional through-time radial generalized autocalibrating partially parallel acquisition.
abstract: OBJECTIVE
  Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) examinations of the kidneys provide quantitative information on renal perfusion and filtration. However, these examinations are often difficult to implement because of respiratory motion and their need for a high spatiotemporal resolution and 3-dimensional coverage. Here, we present a free-breathing quantitative renal DCE-MRI examination acquired with a highly accelerated stack-of-stars trajectory and reconstructed with 3-dimensional (3D) through-time radial generalized autocalibrating partially parallel acquisition (GRAPPA), using half and quarter doses of gadolinium contrast.
  
  
  METHODS
  Data were acquired in 10 asymptomatic volunteers using a stack-of-stars trajectory that was undersampled in-plane by a factor of 12.6 with respect to Nyquist sampling criterion and using partial Fourier of 6/8 in the partition direction. Data had a high temporal (2.1-2.9 seconds per frame) and spatial (approximately 2.2 mm) resolution with full 3D coverage of both kidneys (350-370 mm × 79-92 mm). Images were successfully reconstructed with 3D through-time radial GRAPPA, and interframe respiratory motion was compensated by using an algorithm developed to automatically use images from multiple points of enhancement as references for registration. Quantitative pharmacokinetic analysis was performed using a separable dual-compartment model.
  
  
  RESULTS
  Region-of-interest (ROI) pharmacokinetic analysis provided estimates (mean (SD)) of quantitative renal parameters after a half dose: 218.1 (57.1) mL/min per 100 mL; plasma mean transit time, 4.8 (2.2) seconds; renal filtration, 28.7 (10.0) mL/min per 100 mL; and tubular mean transit time, 131.1 (60.2) seconds in 10 kidneys. The ROI pharmacokinetic analysis provided estimates (mean (SD)) of quantitative renal parameters after a quarter dose: 218.1 (57.1) mL/min per 100 mL; plasma mean transit time, 4.8 (2.2) seconds; renal filtration, 28.7 (10.0) mL/min per 100 mL; and tubular mean transit time, 131.1 (60.2) seconds in the 10 kidneys. Three-dimensional pixelwise parameter maps were also evaluated.
  
  
  CONCLUSIONS
  Highly undersampled data were successfully reconstructed with 3D through-time radial GRAPPA to achieve a high-resolution 3-dimensional renal DCE-MRI examination. The acquisition was completely free breathing, and the images were registered to compensate for respiratory motion. This allowed for an accurate high-resolution 3D quantitative renal functional mapping of perfusion and filtration parameters.
authors.affiliation: From the Departments of *Biomedical Engineering, †Radiology, Case Western Reserve University, Cleveland, OH; and ‡Siemens Healthcare USA, Inc, Chicago, IL.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Wright
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Haris
authors.initials: H
authors.lastname: Saybasili
authors.forename: Mark A
authors.initials: MA
authors.lastname: Griswold
authors.forename: Nicole
authors.initials: N
authors.lastname: Seiberlich
authors.forename: Vikas
authors.initials: V
authors.lastname: Gulani
mesh_terms: D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007668:Kidney / Q000033:anatomy & histology* / Q000098:blood supply*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA