title: Overtime reliability of medial temporal lobe atrophy rating in a clinical setting.
abstract: BACKGROUND
  Medial temporal lobe atrophy (MTA) is one of the first magnetic resonance imaging (MRI) signs in patients with Alzheimer's disease (AD) and used as a measure of disease progression. Visual assessment of MTA is easy to perform but the reliability of MTA rating over time has not been studied.
  
  
  OBJECTIVE
  To investigate what happens to the MTA rating scores if two radiologists rate the same MRI scans six times over a period of 1 year.
  
  
  METHODS
  One hundred outpatients were included in this study. All patients underwent MRI with a protocol and sequences used for geriatric patients, according to local clinical standards. One neuroradiologist and one general radiologist independently of each other performed retrospective visual assessments of MTA six times, using the same scans, over a period of 1 year.
  
  
  RESULTS
  Intra-rater kappa varied between κ 0.65 and 0.84 for the neuroradiologist and κ 0.38 and 0.74 for the general radiologist. Intra-rater weighted kappa (wκ) values showed almost perfect agreement for both investigators (wκ 0.83-0.94). Inter-rater reliability showed fair to moderate agreement, with the kappa value varying from κ 0.29 to 0.48 and weighted kappa values ranging from wκ 0.72 to 0.84. There was a statistically significant difference in rating between the two investigators.
  
  
  CONCLUSIONS
  Visual assessment of MTA repeated over time has a high grade of reproducibility when performed by an experienced investigator. The reproducibility drops when assessment is rarely performed. Inter-rater reliability is low when two investigators not working together are compared.
authors.affiliation: CLINTEC Division of Medical Imaging and Technology, Karolinska Institute, Department of Radiology, Karolinska University Hospital, Huddinge, Stockholm, Sweden. lena.cavallin@karolinska.se
authors.forename: Lena
authors.initials: L
authors.lastname: Cavallin
authors.forename: Kirsti
authors.initials: K
authors.lastname: Løken
authors.forename: Knut
authors.initials: K
authors.lastname: Engedal
authors.forename: Anne-Rita
authors.initials: AR
authors.lastname: Oksengård
authors.forename: Lars-Olof
authors.initials: LO
authors.lastname: Wahlund
authors.forename: Lena
authors.initials: L
authors.lastname: Bronge
authors.forename: Rimma
authors.initials: R
authors.lastname: Axelsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000473:pathology*; D001284:Atrophy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013702:Temporal Lobe / Q000473:pathology*