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Magnetic resonance imaging‐based hippocampus volume for prediction of dementia in mild cognitive impairment: Why does the measurement method matter so little?
Author(s) -
Buchert Ralph,
Lange Catharina,
Suppa Per,
Apostolova Ivayla,
Spies Lothar,
Teipel Stefan,
Dubois Bruno,
Hampel Harald,
Grothe Michel J.
Publication year - 2018
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2018.03.006
Subject(s) - memory clinic , dementia , cognitive impairment , magnetic resonance imaging , medicine , montreal cognitive assessment , university hospital , gerontology , nuclear medicine , cognition , disease , psychiatry , radiology
Magnetic resonance imaging (MRI)-based hippocampus volume (HV) is the best established imaging marker to support the prediction of AD dementia (ADD) in mild cognitive impairment (MCI), although its utility in clinical patient care has not yet been fully demonstrated [1,2]. HV can be scored on an ordinal scale based on visual inspection of MRI [3], or it can be estimated quantitatively by manual or automatic delineation of the hippocampus in MRI. While visual scoring tends to perform worse in MCI-to-ADD prediction, manual delineation and automatic methods show very similar performance [4]. Furthermore, there is hardly any difference among the numerous automatic methods with respect to predictive power in MCI. In the head-to-head comparison of four HV measurement methods in MCI subjects of the Alzheimer’s Disease Neuroimaging Initiative by the EuropeanMedicines Agency, the area (AUC) under the receiver operating characteristic (ROC) curve for 2-year prediction of ADD ranged between 0.7290 and 0.7565, and among three of the four methods, the AUC ranged between 0.7516 and 0.7565 [5]. This appears surprising at first sight given that the quantitative methods differ strongly in accuracy and precision with respect to the anatomical delineation of the hippocampus. Time spent by the rater and computer processing time also differ strongly [4]. Here, we aim to provide a simple mathematical explanation of the stability of the performance of MRI-based HV in MCI with respect to the HV measurement method. Let us assume that the true, error-free HV follows a Gaussian distribution in both MCI stable subjects and in MCI-to-ADD progressors: