MR evaluation of spinal dermal sinus tracts in children.

The MR studies of seven pediatric patients with surgically proved spinal dorsal dermal sinuses were reviewed retrospectively. Five of the seven had associated congenital tumors (three epidermoids, two dermoids). The subcutaneous portions of the spinal tracts and intramedullary portions of tumor were easily identified with the use of standard spin-echo techniques. However, except for limited areas where they were lined by fat, the intraspinal portions of the dermal sinuses were poorly seen. Moreover, diffuse subarachnoid tumor was missed in two patients. Three-dimensional Fourier transform gradient-echo acquisition using a volumetric radiofrequency pulse as a "spoiler" proved to be helpful in evaluating these abnormalities. Optimal radiologic workup of patients with dorsal dermal sinuses awaits the development of new MR imaging sequences. For now, heavily T1-weighted MR sequences should be obtained and supplemented with sonography in infants and with CT myelography in older children.