Interrater agreement for final infarct MRI lesion delineation.
OBJECTIVE
Lesion volume measured on follow-up magnetic resonance imaging (MRI) is commonly used as an outcome parameter in clinical stroke trials. However, few studies have evaluated the optimal sequence choice and the interrater reliability of this outcome measure. The objective of this study was to quantify the geometric interrater agreement for lesion delineation of chronic infarcts on T2-weighted and fluid-attenuated inverse recovery (FLAIR) MRI.


METHODS
In a retrospective study of 14 patients, lesions on 90-day follow-up FLAIR and T2 fast spin echo MRI were outlined by 9 independent, blinded, experienced neuroradiologists. Voxel-wise interrater agreement was measured as (1) the volume of the intersection of individual rater's lesion outlines relative to the mean lesion volume (overlap ratio) and (2) the Hausdorff distance between the lesion markings.


RESULTS
Mean patient age was 64.4 years (range, 45 to 79). Lesion volumes on FLAIR were, on average, 2.5 mL greater than were T2 volumes (median; P<0.001). We found considerable differences between raters' lesion markings, but interrater agreement was consistently better on FLAIR than on T2 images, as measured by a greater overlap ratio (P<0.0001) and a smaller Hausdorff distance (P<0.0001) on FLAIR than on T2.


CONCLUSIONS
FLAIR should be used to quantify follow-up infarct size to minimize interrater variability. Our study suggests that imaging analysis performed by 1 or a few trained readers may be preferred. Future studies should address objective and preferably automated criteria for final lesion delineation.
Center of Functionally Integrative Neuroscience, Aarhus University Hospitals, Aarhus, Denmark. neumann@pet.auh.dk
Anders B
AB
Neumann
Kristjana Y
KY
Jonsdottir
Kim
K
Mouridsen
Niels
N
Hjort
Carsten
C
Gyldensted
Alberto
A
Bizzi
Jens
J
Fiehler
Roberto
R
Gasparotti
Jonathan H
JH
Gillard
Marc
M
Hermier
Thomas
T
Kucinski
Elna-Marie
EM
Larsson
Leif
L
Sørensen
Leif
L
Ostergaard
D000368:Aged; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D020520:Brain Infarction / Q000473:pathology* / Q000503:physiopathology; D003951:Diagnostic Errors; D018450:Disease Progression; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012189:Retrospective Studies; D012680:Sensitivity and Specificity