Symmetrical central tegmental tract（CTT）lesion on MR imaging in children −preliminary study

Shoko Yoshida1）, Katsumi Hayakawa1）, Akira Yamamoto1）, Souzo Okano2）, Hiroko Matsushita2）, Toyoko Kanda3）, Yuriko Yamori3）, Naoko Yoshida3）, Haruyo Hirota3）
Department of Radiology1）, Pediatrics2）, Kyoto City Hospital
Department of Pediatric Neurology3）, St.Joseph Hospital for Handicapped Children

Abstract
　　The central tegmental tract (CTT) is mainly the extrapyramidal tract connecting the red nucleus and inferior olivary nucleus. There are only a few case reports describing CTT abnormalities on magnetic resonance imaging (MRI) in congenital metabolic disorders. Our purpose was to evaluate the frequency of CTT lesions and characteristics on MRI, and to correlate MR imaging with the clinical aspect.
We reviewed the MR imaging of 347 children (172 boys and 175 girls) retrospectively at ages ranging from 38 post conceptional weeks to 15 years. To evaluate symmetrical CTT hyperintensity lesions, we defined the CTT lesion as bilateral symmetrical hyperintensity in the tegmentum pontis on both T2-weighted images and diffusion-weighted images in more than two slices. We measured the ADC (apparent diffusion coefficiency) values of symmetrical CTT hyperintensity, and compared this with normal CTT.
Among 347 children, CTT lesions were detected in 11 cases (3.2％). The mean ADC value of the 11 children with CTT lesions was significantly lower than that of normal CTT (p<0.005). On MR imaging, associated parenchymal lesions other than CTT lesions included : none (n=3), periventricular leukomalacia (n=3), thin corpus callosum (n=3), mild ventricular dilatation (n=1), and polymicrogyria (n=1). Clinically, cerebral palsy was the most frequent clinical diagnosis (n=6) among the 11 children. Metabolic disorder was not detected among the 11 children with CTT lesions.
In conclusion, CTT lesions were detected in 3.2％ of all cases. The mean ADC value of CTT lesions was significantly lower than that of normal CTT. Cerebral palsy was the most frequent clinical diagnosis.

Keywords： Central tegmental tract, MRI, Cerebral palsy