Magnetic susceptibility matched fluid for neuroimaging assessed in histology and stereology: A pilot study

Ex vivo MRI allows for ultra-high resolution image acquisition and valuable validation when combined with histology. Postmortem brain samples may undergo long scan times without motion artifacts. Perfluoropolyethers such as Fomblin have become a popular choice of immersion liquid for their "proton free" appearance and their ability to eliminate susceptibility artifacts from the tissue-air interface but the effect of Fomblin on downstream histology experiments has not been previously studied. We exposed rat brain samples to Fomblin (n = 4) versus a control group (n = 4). Samples underwent histochemical (Nissl) and immunohistochemical staining for NeuN to assess neurons and background staining. The optical fractionator method was applied to assess total neuron counts and tissue thickness. Samples from the Fomblin group showed consistent NeuN and Nissl staining when compared to the control group. The staining color, evenness, and neuron visualization appeared unaffected with no background staining. The total neuron counts, and tissue thickness showed only slight differences in absolute numbers between groups with insufficient evidence to conclude the distribution of total neuron number or tissue thickness differed by group. These data suggest that Fomblin may not negatively impact histochemical staining, immunohistochemistry, or total neuron counts in the short term.