title: Performance of an efficient image-registration algorithm in processing MR renography data.
abstract: OBJECTIVE
  To evaluate the performance of an edge-based registration technique in correcting for respiratory motion artifacts in magnetic resonance renographic (MRR) data and to examine the efficiency of a semiautomatic software package in processing renographic data from a cohort of clinical patients.
  
  
  METHODS
  The developed software incorporates an image-registration algorithm based on the generalized Hough transform of edge maps. It was used to estimate glomerular filtration rate (GFR), renal plasma flow (RPF), and mean transit time (MTT) from 36 patients who underwent free-breathing MRR at 3T using saturation-recovery turbo-FLASH. The processing time required for each patient was recorded. Renal parameter estimates and model-fitting residues from the software were compared to those from a previously reported technique. Interreader variability in the software was quantified by the standard deviation of parameter estimates among three readers. GFR estimates from our software were also compared to a reference standard from nuclear medicine.
  
  
  RESULTS
  The time taken to process one patient's data with the software averaged 12 ± 4 minutes. The applied image registration effectively reduced motion artifacts in dynamic images by providing renal tracer-retention curves with significantly smaller fitting residues (P < 0.01) than unregistered data or data registered by the previously reported technique. Interreader variability was less than 10% for all parameters. GFR estimates from the proposed method showed greater concordance with reference values (P < 0.05).
  
  
  CONCLUSIONS
  These results suggest that the proposed software can process MRR data efficiently and accurately. Its incorporated registration technique based on the generalized Hough transform effectively reduces respiratory motion artifacts in free-breathing renographic acquisitions.
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.|Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Conlin
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.|Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Zhang
authors.affiliation: Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah, USA.|CPE Lyon, Lyon, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Rousset
authors.affiliation: Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Clement
authors.initials: C
authors.lastname: Vachet
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Morton
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Kristi
authors.initials: K
authors.lastname: Carlston
authors.affiliation: Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Guido
authors.initials: G
authors.lastname: Gerig
authors.affiliation: Department of Radiology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007668:Kidney / Q000473:pathology*; D007674:Kidney Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results
keywords: Hough transform; glomerular filtration rate; image registration; magnetic resonance renography