In vivo measurements of T1 relaxation times in mouse brain associated with different modes of systemic administration of manganese chloride.
OBJECTIVE
To measure regional T1 and T2 values for normal C57Bl/6 mouse brain and changes in T1 after systemic administration of manganese chloride (MnCl2) at 9.4 T.


METHODS
C57Bl/6 mice were anesthetized and baseline T1 and T2 measurements obtained prior to measurement of T1 after administration of MnCl2 at 9.4 T. MnCl2 was administered systemically either by the intravenous (IV), intraperitoneal (IP), or subcutaneous (SC) routes. T1 and T2 maps for each MRI transverse slice were generated using commercial software, and T1 and T2 values of white matter (WM), gray matter (GM), pituitary gland, and lateral ventricle were obtained.


RESULTS
When compared with baseline values at low-field, significant lengthening of the T1 values was shown at 9.4 T, while no significant change was seen for T2 values. Significant T1 shortening of the normal mouse brain was observed following IV, IP, and SC administration of MnCl2, with IV and IP showing similar acute effects. Significant decreases in T1 values were seen for the pituitary gland and the ventricles 15 minutes after either IV or IP injection. GM showed greater uptake of the contrast agent than WM at 15 and 45 minutes after either IV or IP injections. Although both structures are within the blood-brain barrier (BBB), GM and WM revealed a steady decrease in T1 values at 24 and 72 hours after MnCl2 injection regardless of the route of administration.


CONCLUSIONS
Systemic administration of MnCl2 by IV and IP routes induced similar time-course of T1 changes in different regions of the mouse brain. Acute effects of MnCl2 administration were mainly influenced by either the presence or absence of BBB. SC injection also provided significant T1 change at subacute stage after MnCl2 administration.
Kuo
Yu-Ting
YT
Molecular Imaging Group, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College, London, UK.
Herlihy
Amy H
AH
So
Po-Wah
PW
Bhakoo
Kishore K
KK
Bell
Jimmy D
JD
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000502:physiology; D002712:Chlorides / Q000008:administration & dosage; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D020547:Lateral Ventricles / Q000187:drug effects / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008345:Manganese / Q000008:administration & dosage*; D051379:Mice; D008810:Mice, Inbred C57BL; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology
D002712:Chlorides; D003287:Contrast Media; D008345:Manganese