FIG 2.

Patients 1 (A and B) and 9 (C and D). Comparison of 3T axial 3D FSPGR (A) and 7T axial 3D SWAN (B) images. Contiguous 7T axial 3D SWAN acquisitions show anatomic details of the polymicrogyric cortex (C and D). A, Delicate appearance of the polymicrogyric cortex in the left pre- and postcentral sulci, characterized by multiple small and delicate gyri of thin cortex (arrow). B, Thin and undulated polymicrogyric cortex, in which the spaces between microgyri are filled by thin white matter digitations, which have a low periodicity and are loosely packed. The gray-white matter junction is bordered by a thin hypointense line. 7T can, therefore, resolve the individual microgyri, revealing how grossly different morphologic characters (coarse or delicate) at 3T result, in fact, from variations of a common underlying morphologic pattern. B, Examples of cortical thickness measurements of normal (2.23 mm)and polymicrogyric cortex (1.13–5.22 mm) by using the straight-line distance measure between the surface and depth of the cortex. C and D, SWAN images show details of cortical structures and allow disentanglement of the structural units underlying the radiologic appearance of polymicrogyria. The typical undulated aspect is clearly detectable following the hypointense lines of the cortical border (arrowheads), which we assume represent arcuate white matter fibers, the white matter digitations within the gyri (arrows), the small vessels joining the pial veins (asterisks), and the fused molecular layer (crosses).