The racing car sign refers to widely spaced lateral ventricles due to agenesis of the corpus callosum with intervening Probst bundles. Appearances on axial MRI or CT are reminiscent of a formula one car seen from above, with the tires represented.
There is asymmetry of the navicular bones with a small and sclerotic navicular on the left. Features here are of Kohler disease which is the epnonymous name given to avascular necrosis of the navicular.
Freiberg disease (also known as Freiberg infraction) is osteochondrosis of metatarsal heads. It typically affects the 2nd metatarsal head (the third and fourth may also be affected). It can be bilateral in up to 10% of cases. http://radiopaedia.org/articles/freiberg-disease
Butterfly gliomas are a high grade astrocytoma, usually a glioblastoma (WHO grade IV), which crosses the midline via the corpus callosum. Other white matter commissures are also occasionally involved. The term butterfly refers to the symmetric wi.