Magnetic resonance imaging of intraspinal cystic lesions: a pictorial review.

Magnetic resonance imaging is the imaging modality of choice for the evaluation of diseases of the spinal cord and its coverings primarily because of improved lesion detection and characterization. The differentiation of intramedullary pathologic conditions (arising within the spinal cord) from extramedullary lesions (lying either within the thecal sac (intradural) or outside it (extradural) is usually straightforward. Although many lesions may occur in more than one compartment or may extend to involve more than one compartment simultaneously, accurate positioning of a detected lesion within the spinal canal and the assessment of its signal characteristics may help differentiate many of the more commonly encountered lesions and aid preoperative diagnosis. This pictorial review discusses the imaging findings and distinguishing features of a variety of intramedullary and extramedullary intraspinal cystic lesions with the use of magnetic resonance imaging. The imaging appearances are correlated with histologic findings where available.