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Free keywords:
Animals; Body Size; Calibration; Central Nervous System Diseases; Disease Models, Animal; Head; Humans; Magnetic Resonance Imaging; Male; Mice; Mice, Nude; Neoplasm Transplantation; Rats; Rats, Wistar; Rodentia; Transplantation, Heterologous; Tumor Cells, Cultured
Abstract:
Background: Small animal models of human diseases are an indispensable aspect of pre-clinical research. Being dynamic,
most pathologies demand extensive longitudinal monitoring to understand disease mechanisms, drug efficacy and side
effects. These considerations often demand the concomitant development of monitoring systems with sufficient temporal
and spatial resolution.
Methodology and Results: This study attempts to configure and optimize a clinical 3 Tesla magnetic resonance scanner to
facilitate imaging of small animal central nervous system pathologies. The hardware of the scanner was complemented by a
custom-built, 4-channel phased array coil system. Extensive modification of standard sequence protocols was carried out
based on tissue relaxometric calculations. Proton density differences between the gray and white matter of the rodent
spinal cord along with transverse relaxation due to magnetic susceptibility differences at the cortex and striatum of both
rats and mice demonstrated statistically significant differences. The employed parallel imaging reconstruction algorithms
had distinct properties dependent on the sequence type and in the presence of the contrast agent. The attempt to
morphologically phenotype a normal healthy rat brain in multiple planes delineated a number of anatomical regions, and all
the clinically relevant sequels following acute cerebral ischemia could be adequately characterized. Changes in blood-brainbarrier
permeability following ischemia-reperfusion were also apparent at a later time. Typical characteristics of intracerebral
haemorrhage at acute and chronic stages were also visualized up to one month. Two models of rodent spinal cord
injury were adequately characterized and closely mimicked the results of histological studies. In the employed rodent
animal handling system a mouse model of glioblastoma was also studied with unequivocal results.
Conclusions: The implemented customizations including extensive sequence protocol modifications resulted in images of
high diagnostic quality. These results prove that lack of dedicated animal scanners shouldn’t discourage conventional small
animal imaging studies.
