title: A new technique with high reproducibility to estimate renal oxygenation using BOLD-MRI in chronic kidney disease.
abstract: OBJECTIVE
  To assess inter-observer variability of renal blood oxygenation level-dependent MRI (BOLD-MRI) using a new method of analysis, called the concentric objects (CO) technique, in comparison with the classical ROI (region of interest)-based technique.
  
  
  METHODS
  MR imaging (3T) was performed before and after furosemide in 10 chronic kidney disease (CKD) patients (mean eGFR 43±24ml/min/1.73m(2)) and 10 healthy volunteers (eGFR 101±28ml/min1.73m(2)), and R2* maps were determined on four coronal slices. In the CO-technique, R2* values were based on a semi-automatic procedure that divided each kidney in six equal layers, whereas in the ROI-technique, all circles (ROIs) were placed manually in the cortex and medulla. The mean R2*values as assessed by two independent investigators were compared.
  
  
  RESULTS
  With the CO-technique, inter-observer variability was 0.7%-1.9% across all layers in non-CKD, versus 1.6%-3.8% in CKD. With the ROI-technique, median variability for cortical and medullary R2* values was 3.6 and 6.8% in non-CKD, versus 4.7 and 12.5% in CKD; similar results were observed after furosemide.
  
  
  CONCLUSIONS
  The CO-technique offers a new, investigator-independent, highly reproducible alternative to the ROI-based technique to estimate renal tissue oxygenation in CKD.
authors.affiliation: Department of Nephrology and Hypertension, CHUV, Lausanne, Switzerland; Department of Radiology, Medical University of Gdansk, Gdansk, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Piskunowicz
authors.affiliation: Department of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland.
authors.forename: Lucie
authors.initials: L
authors.lastname: Hofmann
authors.affiliation: Department of Nephrology and Hypertension, CHUV, Lausanne, Switzerland.
authors.forename: Emilie
authors.initials: E
authors.lastname: Zuercher
authors.affiliation: Department of Nephrology and Hypertension, CHUV, Lausanne, Switzerland.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Bassi
authors.affiliation: Department of Nephrology and Hypertension, CHUV, Lausanne, Switzerland.
authors.forename: Bastien
authors.initials: B
authors.lastname: Milani
authors.affiliation: Department of Radiology, CHUV, Lausanne, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Stuber
authors.affiliation: Department of Hypertension and Diabetology, Medical University of Gdansk, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Narkiewicz
authors.affiliation: Department of Nephrology and Hypertension, CHUV, Lausanne, Switzerland; Department of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Vogt
authors.affiliation: Department of Nephrology and Hypertension, CHUV, Lausanne, Switzerland.
authors.forename: Michel
authors.initials: M
authors.lastname: Burnier
authors.affiliation: Department of Nephrology and Hypertension, CHUV, Lausanne, Switzerland. Electronic address: mennopruijm@hotmail.com.
authors.forename: Menno
authors.initials: M
authors.lastname: Pruijm
mesh_terms: D000368:Aged; D001331:Automation; D001330:Electronic Data Processing; D005260:Female; D005665:Furosemide / Q000737:chemistry; D005919:Glomerular Filtration Rate; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007668:Kidney / Q000378:metabolism* / Q000503:physiopathology; D007672:Kidney Cortex; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010101:Oxygen Consumption; D011379:Prognosis; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results; D012984:Software
chemical_list: D005665:Furosemide
keywords: BOLD-MRI; Chronic kidney disease; Concentric objects; Furosemide; Imaging analysis; Onion peel technique; Region of interest; Reproducibility