Magnetic resonance imaging of congenital hydrocephalus in the rat.
Magnetic resonance imaging (MRI) is an increasingly available technique in clinical medicine for the noninvasive imaging of soft tissues. The purpose of the present study was to demonstrate the potential utility of MRI in experimental toxicology and teratology studies. The progression of severity of prenatally induced hydrocephalus was observed in rat pups from 1 to 4 weeks of age. Pregnant Sprague-Dawley rats were given 0, 15, 30, or 45 mg/kg ethylenethiourea (ETU), po, on Gestation Day 15. The two higher doses have been reported to induce a high incidence of hydrocephalus, which is mild at birth but becomes extensive by 4 weeks of age. The low dose was a no effect level for hydrocephalus. None of the doses of ETU altered birth weight or litter size. Pups from each dose group were imaged serially, on Postnatal Days (PD) 6, 13, 17, and 27, in order to determine the progression in the severity of hydrocephalus. Littermates were also imaged on each of these days, then killed immediately in order to compare the anatomy of the brain with its MR image. Hydrocephalus was detectable in the images from all animals of the 30 and 45 mg/kg dose groups on PD 6, the earliest observation day. At this time, the lateral ventricles were dilated less than 1 mm. Hydrocephalus became increasingly severe, and by 4 weeks of age all of the 45 mg/kg group and approximately half of the 30 mg/kg group had died. The brains of the surviving 30 mg/kg rats were severely hydrocephalic, with little cortex remaining. In all cases, the MR image corresponded precisely with the brain anatomy observed after termination. We have demonstrated that MRI is a useful technique for noninvasively imaging lesions in experimental animals. A number of other potential uses for MRI in toxicology are presented.
Miami Valley Laboratories, Procter & Gamble Company, Cincinnati, Ohio 45247.
G P
GP
Daston
T A
TA
Neubecker
J E
JE
Yonker
L J
LJ
Busse
R G
RG
Pratt
R C
RC
Samaratunga
S R
SR
Thomas
D000818:Animals; D005031:Ethylenethiourea; D005260:Female; D006849:Hydrocephalus / Q000139:chemically induced / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
D005031:Ethylenethiourea