Errors and other considerations in brain imaging

A couple of recent posts, in
Increase in prefrontal cortical volume following cognitive behavioural therapy in patients with CFS, 2008, de Lange et al
(that one made a big deal of a 0.7% change in grey matter volume in people with ME/CFS, supposedly achieved by CBT)
Hypothalamus volumes in adolescent [ME/CFS]: Impact of self-reported fatigue and illness duration, 2023, Byrne et al.
(that didn't really find much at all)
made me wonder what the accuracy of brain size measurements might be, and if they can change quickly.

I found this paper, that seemed to suggest that grey matter volumes can change quickly:
Estimated gray matter volume rapidly changes after a short motor task 2022

They concluded
"Larger GMV while resting (as compared with Finger Tapping Task) indicates that engaging in a task prior to anatomical imaging may induce morphological changes."

I'm not sure that these changes would add up to much at the whole grey matter volume level, but for sure they could change things for particular bits of the brain. So, rushing to get to the MRI, or having to do a cognitive task just before imaging might also possibly affect volume estimates.

 

Variability in the analysis of a single neuroimaging dataset by many teams, 2019, Botvinik-Nezer et al
This paper highlights the issues with analytic flexibility in fMRI.

And a couple more about fMRI.

A Machine Learning Approach to the Differentiation of Functional Magnetic Resonance Imaging Data of Chronic Fatigue Syndrome (CFS) From a Sedentary Control
A study of people with CFS and healthy controls found 29 regions of interest on Day 1 and 28 regions on Day 2 after a physical and cognitive challenge. However, only 10 of the regions of interest were common to both days, demonstrating how important it is to manage activity prior to fMRI.

Time of day is associated with paradoxical reductions in global signal fluctuation and functional connectivity
fMRI also varies during the day; it has been suggested that variation in time of day could potentially account for between-study variation in results and failed replications.

 

Interpreting BOLD: towards a dialogue between cognitive and cellular neuroscience

some background on BOLD signals in fMRI - although a 2016 paper