There, the authors have used a direct method to determine edema by measuring brain total water content by the dry weight method.
We used MRI to measure brain tumor growth, water content (edema) [ 15, 16], relative cerebral blood volume (rCBV) [ 17– 19], and vascular permeability as determined by the vascular transfer coefficient (Ktrans) [ 20, 21] in a rat model of human lung cancer brain metastasis.
To ensure that there was no oedema in the brain, we measured the brain water content (Additional file 1: Figure S1).
To measure brain edema, we evaluated the brain water content at 48 h after i.p. treatment.
Using computed tomography scans to measure brain density, Ronco and colleagues [ 122] showed an increase of brain water content after IHD whereas no such changes were observed after CRRT.
Some researchers prefer to measure brain signals on the scalp.
Using a more quantitative approach, using measures of brain water content, Neeb et al. [ 2006] estimated mean brain age in healthy adults, 23 74 years of age, with a median absolute deviation of 6.3 years between real and predicted ages.
Unfortunately there are no comparative human studies in AKI; although Chen and colleagues showed significantly increased brain water measured by diffusion-weighted magnetic resonance imaging compared with normal controls [ 49], this study was performed in CKD patients, and as such the changes reported during chronic dialysis [ 50] may not be representative of those in AKI.
For example, Silver did not find any difference in organic osmolytes, myoinositol, taurine, glutamate, glutamine, aspartate, alanine and glycine between uraemic nondialysed mice and nonuraemic controls using a mouse model, although significant decreases in brain water, measured by weight, were also observed in uraemic nondialysed mice when compared with normal control animals at 42 hours [ 47].
Neurological deficit scores, infarct volume and brain water content were measured at 24 h after stroke.
