title: Hippocampal magnetization transfer ratio at 3T: validation of automated postprocessing and comparison of quantification metrics.
abstract: BACKGROUND
  To investigate the reliability of a novel magnetization transfer ratio (MTR) postprocessing technique for the hippocampus using histogram analysis, and compare results to more established volumetric measurements. This study is conducted in healthy volunteers as a precursor to future applications regarding progressive neurologic diseases, such as Alzheimer's disease.
  
  
  METHODS
  Eight healthy subjects were scanned twice with interval of 1 week using quantitative magnetic resonance imaging (MRI). Automated pixel-wise analysis was performed for the hippocampal regions of each patient. Reliability was assessed using intraclass correlation coefficients (ICCs), coefficients of variation (COVs), and instrumental standard deviation (ISD).
  
  
  RESULTS
  Reliable metrics were 25th percentile, median, 75th percentile, peak location, and mean approach (ranges: ICC = .93-.96, COV = 2.71-3.88%, ISD .78-1.01). Histogram peak height had ICC below .7, and a COV above 10%. Volumetric measurements had (ICC = .95-.97, COV = 1.43-3.39%).
  
  
  CONCLUSIONS
  Excellent scan-rescan reproducibility (ICC > .9, COV < 10%) was observed for specific MTR histogram metrics and the mean MTR approach. These results are comparable to the volumetric approach. Future studies can examine the possibility that MTR changes precede morphological changes as this study suggests that both MTR and volumetric measurements of the hippocampus can be used as reliable imaging tools.
authors: Radiology Department, NorthShore University Health Systems, Evanston, IL, USA.
authors: Shawn
authors: S
authors: Sidharthan
authors: Ryan
authors: R
authors: Hutten
authors: Christopher
authors: C
authors: Glielmi
authors: Hongyan
authors: H
authors: Du
authors: Fiona
authors: F
authors: Malone
authors: Ann B
authors: AB
authors: Ragin
authors: Robert R
authors: RR
authors: Edelman
authors: Ying
authors: Y
authors: Wu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult