Manganese-enhanced magnetic resonance imaging (MEMRI) of rat brain after systemic administration of MnCl2: changes in T1 relaxation times during postnatal development.
OBJECTIVE
To measure regional T(1) changes in the postnatal rat brain following systemic administration of the contrast agent manganese chloride (MnCl(2)).


METHODS
MnCl(2) (120 mM) was administered intravenously (i.v.) at 1.25 mL/hour to a dose of 175 mg/kg body weight. MRI experiments were performed on anaesthetized animals (32 male Wistar rats, postnatal days (PDs) 11, 16, 21, and 31) at 2.0 T. Regions of interest (ROIs) were drawn in sagittal slices and placed over five brain regions: olfactory bulb, cerebellum, cortex, thalamus, and hypothalamus. The signal intensities of each ROI were measured and fitted to a three-parameter function to estimate T(1) values.


RESULTS
In the brains of animals who did not receive the contrast agent (control group), we observed a consistent age-dependent decrease in T(1) values. In the brains of manganese-infused animals (manganese group), however, T(1) values were significantly lower than in the control group, indicating the uptake of manganese, but no dependence of T(1) on age was found.


CONCLUSIONS
Our T(1) measurements indicate that the relative Mn(2+) concentrations are higher in neonates and decrease with brain development. An estimate of the relative cortical concentration of manganese shows a two-fold drop from PD 11 to PD 31.
de Sousa
Paulo L
PL
Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique, Orléans, France. loureiro@cnrs-orleans.fr
de Souza
Sandra L
SL
Silva
Afonso C
AC
de Souza
Ricardo E
RE
de Castro
Raul Manhães
RM
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000254:growth & development*; D001931:Brain Mapping / Q000379:methods*; D002712:Chlorides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007089:Image Enhancement; D007262:Infusions, Intravenous; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D017895:Manganese Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar
D002712:Chlorides; D003287:Contrast Media; D017895:Manganese Compounds; C025340:manganese chloride