Power estimation for non-standardized multisite studies
A concern for researchers planning multisite studies is that scanner and T1-weighted sequence-related biases on regional volumes could overshadow true effects, especially for studies with a heterogeneous set of scanners and sequences. Current approaches attempt to harmonize data by standardizing hardware, pulse sequences, and protocols, or by calibrating across sites using phantom-based corrections to ensure the same raw image intensities. We propose to avoid harmonization and phantom-based correction entirely. We hypothesized that the bias of estimated regional volumes is scaled between sites due to the contrast and gradient distortion differences between scanners and sequences. Given this…
Tract-specific white matter structural disruption in patients with bipolar disorder
Benedetti F, Absinta M, Rocca MA, Radaelli D, Poletti S, Bernasconi A, Dallaspezia S, Pagani E, Falini A, Copetti M, Colombo C, Comi G, Smeraldi E, Filippi M. Tract-specific white matter structural disruption in patients with bipolar disorder. Bipolar Disord 2011: 13: 414–424. © 2011 The Authors. Journal compilation © 2011 John Wiley & Sons A/S. Objectives: A growing body of evidence suggests that, independent of localized brain lesions, mood disorders can be associated with dysfunction of brain networks involved in the modulation of emotional and cognitive behavior. We used diffusion tensor (DT) tractography to quantify the presence and extent of structural injury to the connections betwe…
Diagnosis of multiple sclerosis: a multicentre study to compare revised McDonald-2010 and Filippi-2010 criteria
MRI has been formally included in the diagnostic work-up of patients with a suspicion of multiple sclerosis (MS) in 2001, to demonstrate disease dissemination in space (DIS) and time (DIT) and to exclude alternative diagnoses.1 Over time, these criteria have been modified to simplify their use and to clarify specific aspects (eg, spinal cord findings).2 One aspect marginally analysed in the diagnostic work-up of patients with clinically isolated syndrome (CIS) is the role of intracortical lesions (ICLs), which are a prominent feature of MS and contribute to disability and cognitive impairment.2 A single-centre study3 showed that inclusion of ICL for the evaluation of DIS in CIS increased th…