Cerebral MRI on fetuses submitted to repeated cocaine administration during the gestation: an ovine model

The aim of this study was to determine the role of Magnetic Resonance imagi ng (MRI) in investigating fetal cerebral lesions induced by long term expos ure to cocaine during sheep pregnancy. Cerebral Magnetic Resonance Imaging was performed on two groups of fetuses at 125 days of gestation (normal ges tation: 145 days). The control group consisted of eight fetuses of four pre gnant ewes. The study group consisted of eight fetuses of four pregnant ewe s receiving daily 140 mg/kg injection of cocaine from day 60 until delivery . The following MR sequences were applied: T1-weighted FLASH, and T2-weight ed Fast-Spin-Echo. Cerebral images were evaluated semi quantitatively using the following criteria: Heterogenicity, contrast between grey and white ma tter, contours irregularity, hyposignal, lateral ventricle sizes. The brigh tness distribution and homogenicity of the images were analysed by means of edge pair distributions using a new computerized method originally designe d for ultrasound images analysis developed by Ultrasight inc (USA). (1) Fla sh T1: Heterogenic areas and irregular contours were more frequent in cocai ne exposed fetuses. The contrast between grey and white matter was more imp ortant in the cocaine group. Hyposignal was found only in the cocaine group . Enlarged lateral ventricle occurred more frequently in the cocaine group. (2) Spin echo T2: The contrast between grey and white matter was higher an d the contours of the brain more irregular in the cocaine group. Heterogeni city and hyposignal were also more frequent in this group but the differenc e with the control group was not significant. The computerized analysis of the contrast density on the cerebral images showed that 88% of the areas ex ceeding the reference level concerned the cocaine group, while only 14% of the areas exceeding the reference level concerned the control group. Long t erm exposure to cocaine induces cerebral tissue modifications, in favor of an advanced maturation and the development of hypoxic lesions. The histolog y of the brains confirmed in the cocaine group, the existence of hypoxic le sions with,gliosis, perivascular edema and hemorrhages, and neuronal death. (C) 1999 Elsevier Science Ireland Ltd. AU rights reserved.