title: A preliminary study of blood-oxygen-level-dependent MRI in patients with chronic kidney disease.
abstract: BACKGROUND
  Blood-oxygen-level-dependent (BOLD) magnetic resonance imaging (MRI) can provide regional measurements of oxygen content using deoxyhemoglobin paramagnetic characteristics. The apparent relaxation rate or R2*(=1/T2*) can be determined from the slope of log (intensity) versus echo time and is directly proportional to the tissue content of deoxyhemoglobin. Thus, as the level of deoxyhemoglobin increases, T2* will decrease, leading to an increase in R2*. Chronic kidney disease (CKD) can affect oxygenation levels in renal parenchyma, which influences the clinical course of the disease. The goal of this study was to detect and assess renal oxygenation levels in CKD using BOLD MRI.
  
  
  METHODS
  Fifteen healthy subjects and 11 patients with CKD underwent a renal scan using multigradient-recalled-echo sequence with eight echoes. R2* (1/s) of the renal cortex and medulla was measured on BOLD images. Of the 11 patients, nine had biopsy-proven chronic glomerulonephritis, and two had a similar diagnosis based on clinical symptoms and investigations.
  
  
  RESULTS
  Mean medullary R2* (MR2*) and cortex R2* (CR2*) levels were significantly higher in patients (22 kidneys, MR2*=24.79±4.84 s(-1), CR2*=18.97±2.72 s(-1)) than in controls (30 kidneys, MR2*=19.98±1.19 s(-1), CR2*=16.03±1.23 s(-1)) (P<.01), and MR2* was increased more than CR2*. Medullary to cortical R2* ratios (MCR2*) of patients were significantly increased when compared with those of controls (P<.01). In the patient group, estimated glomerular filtration rate levels were greater than or equal to 60 ml/min/1.73 m(2) in six patients (12 kidneys), whose MR2* and CR2* were also significantly higher than those of controls (P<.01). Serum creatinine levels were normal in seven patients (14 kidneys), whose MR2*, CR2* and MCR2* were also higher than those of controls (P<.01).
  
  
  CONCLUSIONS
  BOLD MRI can be used to evaluate changes in renal oxygenation in CKD, suggesting that it has the potential to be an excellent noninvasive tool for the evaluation of renal function.
authors.affiliation: Department of Radiology, Peking University Third Hospital, Beijing, 100191, PR China.
authors.forename: Pei
authors.initials: P
authors.lastname: Xin-Long
authors.forename: Xie
authors.initials: X
authors.lastname: Jing-Xia
authors.forename: Liu
authors.initials: L
authors.lastname: Jian-Yu
authors.forename: Wang
authors.initials: W
authors.lastname: Song
authors.forename: Tian
authors.initials: T
authors.lastname: Xin-Kui
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D001806:Blood Urea Nitrogen; D016022:Case-Control Studies; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D005921:Glomerulonephritis / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011507:Proteinuria / Q000175:diagnosis
chemical_list: D003404:Creatinine; D010100:Oxygen