Article

This was a prospective cohort observational study. OBJECTIVE: To
determine the effect of dehydration and rehydration on spinal cord
cross-sectional area (CSA) measurement on magnetic resonance imaging (MRI).
SETTING: MRI Research Centre, University of British Columbia, Canada. METHODS:
Ten healthy subjects (aged 21-32 years) were scanned on a 3T MRI scanner at four
time points: (1) baseline, (2) rescan after 1 h, (3) the next day after fasting
for a minimum of 14 h and (4) after rehydration with 1.5 l of water over the
course of 1 h. Two independent, established semi-automatic CSA measurement
techniques (one based on two-dimensional (2D) edge detection, the other on
three-dimensional (3D) surface fitting) were applied to a 3D T1-weighted scan of
each subject at each time point, with the operator blinded to scan order. The
percentage change in CSA from baseline to each subsequent time point was
calculated. One-tailed paired t-tests were used to assess the significance of the
changes from baseline. RESULTS: A decrease in CSA following dehydration was
detected by both measurement methods, with a mean change of -0.654% (s.d.=0.778,
P<0.05) and -0.650% (s.d.=1.071, P<0.05) for the first and second methods,
respectively. CONCLUSION: Dehydration can confound CSA measurements on MRI. The
magnitude of the effect is significant relative to short-term pathological
changes that have been observed in diseases such as multiple sclerosis.

Langue : ANGLAIS