Abstract
Commercial mouse chow is designed to provide a complete, nutrient-rich diet, and it can contain upwards of 100 mg/kg manganese, an essential mineral. Manganese acts as a relaxation time-shortening contrast agent for both T1 and T2, and where standard chow is hydrated in the gastrointestinal tract, bright signals are produced when using T1-weighted imaging (T1WI). As a result of peristalsis, gastrointestinal hyperintensities result in temporally unstable signals, leading to image ghosting and decreased resolution from that prescribed. To avoid the problem, various methods of gastrointestinal tract modulation, including the use of intestinal cleansing with laxatives and dietary modulation, have been reported. Here, dietary modulation has been extended to the use of a biologically innocuous, long-term change of diet. In this study, we report on the use of a commercially available manganese-free chow to improve the image quality of the gastrointestinal tract. This manganese-free chow, apart from the omitted manganese which is available in tap water, is a complete diet and readily available. We investigated the time-dependent, diet-related gastrointestinal intensities on short-TR T1WI magnetic resonance imaging; monitored body mass, food and water consumption and standard blood biochemistry analysis following diet change; and determined manganese concentration in blood plasma following a five-day change to manganese-free chow. We show that the manganese-free chow presents a refinement to other gastrointestinal tract modulation, as it avoids the need for invasive procedures for gut voiding and can be provided ad libitum so that animals can be maintained with no need for prescribed diet change before imaging.
Highlights
In preclinical magnetic resonance imaging (MRI), the gastrointestinal tract often appears bright when using short-TR, T1-weighted imaging (T1WI).[1,2] some applications such as bowel-disease diagnosis and small-bowel motility studies benefit from high signal intensities in the gut,[3,4] this can pose a problem in Laboratory Animals 54(4)target identification in other parts of the abdomen.[1]
We report on the use of a commercially available manganese-free chow to improve image quality of the gastrointestinal tract
Analysis of blood plasma manganese levels showed no significant difference between the standard chow group and the manganese-free diet group five days post food change
Summary
In preclinical magnetic resonance imaging (MRI), the gastrointestinal tract often appears bright when using short-TR, T1-weighted imaging (T1WI).[1,2] some applications such as bowel-disease diagnosis and small-bowel motility studies benefit from high signal intensities in the gut,[3,4] this can pose a problem in Laboratory Animals 54(4)target identification in other parts of the abdomen.[1]. In preclinical magnetic resonance imaging (MRI), the gastrointestinal tract often appears bright when using short-TR, T1-weighted imaging (T1WI).[1,2] some applications such as bowel-disease diagnosis and small-bowel motility studies benefit from high signal intensities in the gut,[3,4] this can pose a problem in Laboratory Animals 54(4). Commercial rodent chow is designed to provide a complete and nutrient-rich diet that, in the European Union, can contain upwards of 100 mg/kg manganese in the form of crystallised manganous oxide powder.[5] Mn2þ is paramagnetic, acts as a relaxation time-shortening contrast agent for both T1 and T2 and is one of the few ions that can generate similar MRI contrast to gadolinium.[6] As such, bright signals are produced where this food is hydrated in the gastrointestinal tract. Nutritional deficiency of manganese may be more readily diagnosed from its concentration in plasma than in whole blood
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