title: Reliability of MRI-derived measurements of human cerebral cortical thickness: the effects of field strength, scanner upgrade and manufacturer.
abstract: In vivo MRI-derived measurements of human cerebral cortex thickness are providing novel insights into normal and abnormal neuroanatomy, but little is known about their reliability. We investigated how the reliability of cortical thickness measurements is affected by MRI instrument-related factors, including scanner field strength, manufacturer, upgrade and pulse sequence. Several data processing factors were also studied. Two test-retest data sets were analyzed: 1) 15 healthy older subjects scanned four times at 2-week intervals on three scanners; 2) 5 subjects scanned before and after a major scanner upgrade. Within-scanner variability of global cortical thickness measurements was <0.03 mm, and the point-wise standard deviation of measurement error was approximately 0.12 mm. Variability was 0.15 mm and 0.17 mm in average, respectively, for cross-scanner (Siemens/GE) and cross-field strength (1.5 T/3 T) comparisons. Scanner upgrade did not increase variability nor introduce bias. Measurements across field strength, however, were slightly biased (thicker at 3 T). The number of (single vs. multiple averaged) acquisitions had a negligible effect on reliability, but the use of a different pulse sequence had a larger impact, as did different parameters employed in data processing. Sample size estimates indicate that regional cortical thickness difference of 0.2 mm between two different groups could be identified with as few as 7 subjects per group, and a difference of 0.1 mm could be detected with 26 subjects per group. These results demonstrate that MRI-derived cortical thickness measures are highly reliable when MRI instrument and data processing factors are controlled but that it is important to consider these factors in the design of multi-site or longitudinal studies, such as clinical drug trials.
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Han
authors.forename: Jorge
authors.initials: J
authors.lastname: Jovicich
authors.forename: David
authors.initials: D
authors.lastname: Salat
authors.forename: Andre
authors.initials: A
authors.lastname: van der Kouwe
authors.forename: Brian
authors.initials: B
authors.lastname: Quinn
authors.forename: Silvester
authors.initials: S
authors.lastname: Czanner
authors.forename: Evelina
authors.initials: E
authors.lastname: Busa
authors.forename: Jenni
authors.initials: J
authors.lastname: Pacheco
authors.forename: Marilyn
authors.initials: M
authors.lastname: Albert
authors.forename: Ronald
authors.initials: R
authors.lastname: Killiany
authors.forename: Paul
authors.initials: P
authors.lastname: Maguire
authors.forename: Diana
authors.initials: D
authors.lastname: Rosas
authors.forename: Nikos
authors.initials: N
authors.lastname: Makris
authors.forename: Anders
authors.initials: A
authors.lastname: Dale
authors.forename: Bradford
authors.initials: B
authors.lastname: Dickerson
authors.forename: Bruce
authors.initials: B
authors.lastname: Fischl
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology*; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012016:Reference Values; D015203:Reproducibility of Results