Andrea Chincarini1, Francesco Sensi2, Luca Rei3, Gianluca Gemme2, Sandro Squarcia3, Renata Longo4, Francesco Brun5, Sabina Tangaro6, Roberto Bellotti7, Nicola Amoroso7, Martina Bocchetta8, Alberto Redolfi9, Paolo Bosco9, Marina Boccardi9, Giovanni B Frisoni10, Flavio Nobili11. 1. Istituto Nazionale di Fisica Nucleare, Sezione di Genova, I-16146 Genova, Italy. Electronic address: andrea.chincarini@ge.infn.it. 2. Istituto Nazionale di Fisica Nucleare, Sezione di Genova, I-16146 Genova, Italy. 3. Istituto Nazionale di Fisica Nucleare, Sezione di Genova, I-16146 Genova, Italy; Dipartimento di Fisica, Università degli Studi di Genova, I-16146 Genova, Italy. 4. Dipartimento di Fisica, Università degli Studi di Trieste, Italy; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Italy. 5. Dipartimento di Ingegneria e Architettura, Università degli Studi di Trieste, Italy; Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Italy. 6. Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Italy. 7. Dipartimento Interateneo di Fisica, Università degli Studi di Bari, Italy; Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Italy. 8. IRCCS Centro San Giovanni di Dio Fatebenefratelli, I-25125 Brescia, Italy; Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy. 9. IRCCS Centro San Giovanni di Dio Fatebenefratelli, I-25125 Brescia, Italy. 10. University Hospitals and University of Geneva, Geneva, Switzerland; IRCCS Centro San Giovanni di Dio Fatebenefratelli, I-25125 Brescia, Italy. 11. Neurofisiologia Clinica, Dipartimento di Neuroscienze, Oftalmologia e Genetica, Azienda Ospedale-Università S. Martino, Genova I-16132, Italy.
Abstract
BACKGROUND: Structural MRI measures for monitoring Alzheimer's Disease (AD) progression are becoming instrumental in the clinical practice, and more so in the context of longitudinal studies. This investigation addresses the impact of four image analysis approaches on the longitudinal performance of the hippocampal volume. METHODS: We present a hippocampal segmentation algorithm and validate it on a gold-standard manual tracing database. We segmented 460 subjects from ADNI, each subject having been scanned twice at baseline, 12-month and 24month follow-up scan (1.5T, T1 MRI). We used the bilateral hippocampal volume v and its variation, measured as the annualized volume change Λ=δv/year(mm(3)/y). Four processing approaches with different complexity are compared to maximize the longitudinal information, and they are tested for cohort discrimination ability. Reference cohorts are Controls vs. Alzheimer's Disease (CTRL/AD) and CTRL vs. Mild Cognitive Impairment who subsequently progressed to AD dementia (CTRL/MCI-co). We discuss the conditions on v and the added value of Λ in discriminating subjects. RESULTS: The age-corrected bilateral annualized atrophy rate (%/year) were: -1.6 (0.6) for CTRL, -2.2 (1.0) for MCI-nc, -3.2 (1.2) for MCI-co and -4.0 (1.5) for AD. Combined (v, Λ) discrimination ability gave an Area under the ROC curve (auc)=0.93 for CTRL vs AD and auc=0.88 for CTRL vs MCI-co. CONCLUSIONS: Longitudinal volume measurements can provide meaningful clinical insight and added value with respect to the baseline provided the analysis procedure embeds the longitudinal information.
BACKGROUND: Structural MRI measures for monitoring Alzheimer's Disease (AD) progression are becoming instrumental in the clinical practice, and more so in the context of longitudinal studies. This investigation addresses the impact of four image analysis approaches on the longitudinal performance of the hippocampal volume. METHODS: We present a hippocampal segmentation algorithm and validate it on a gold-standard manual tracing database. We segmented 460 subjects from ADNI, each subject having been scanned twice at baseline, 12-month and 24month follow-up scan (1.5T, T1 MRI). We used the bilateral hippocampal volume v and its variation, measured as the annualized volume change Λ=δv/year(mm(3)/y). Four processing approaches with different complexity are compared to maximize the longitudinal information, and they are tested for cohort discrimination ability. Reference cohorts are Controls vs. Alzheimer's Disease (CTRL/AD) and CTRL vs. Mild Cognitive Impairment who subsequently progressed to AD dementia (CTRL/MCI-co). We discuss the conditions on v and the added value of Λ in discriminating subjects. RESULTS: The age-corrected bilateral annualized atrophy rate (%/year) were: -1.6 (0.6) for CTRL, -2.2 (1.0) for MCI-nc, -3.2 (1.2) for MCI-co and -4.0 (1.5) for AD. Combined (v, Λ) discrimination ability gave an Area under the ROC curve (auc)=0.93 for CTRL vs AD and auc=0.88 for CTRL vs MCI-co. CONCLUSIONS: Longitudinal volume measurements can provide meaningful clinical insight and added value with respect to the baseline provided the analysis procedure embeds the longitudinal information.
Authors: Michael W Weiner; Dallas P Veitch; Paul S Aisen; Laurel A Beckett; Nigel J Cairns; Robert C Green; Danielle Harvey; Clifford R Jack; William Jagust; John C Morris; Ronald C Petersen; Andrew J Saykin; Leslie M Shaw; Arthur W Toga; John Q Trojanowski Journal: Alzheimers Dement Date: 2017-03-22 Impact factor: 21.566