Magnetic resonance perfusion imaging in malformations of cortical development

Background: Malformations of cortical development vary in neuronal maturity and level of functioning. Purpose: To characterize regional relative cerebral blood volume ( rCBV) and difference in first moment transit time ( TTfm) in polymicrogyria and cortical tubers using magnetic resonance ( MR) perfusion imaging. Material and Methods: MR imaging and dynamic T2*-weighted MR perfusion imaging were performed in 13 patients with tuberous sclerosis complex, 10 with polymicrogyria, and 18 controls with developmental delay but no macroscopic brain abnormality. Regions of interest were placed in cortical tubers or polymicrogyric cortex and in the contralateral normal-appearing side in patients with malformations. In "control'' subjects, regions of interest were placed in the frontal and parietal lobes in both hemispheres. The rCBV and TTfm of the tuber/contralateral side ( rCBV(R)TSC and Delta TTFMTSC) as well as those of the polymicrogyria/contralateral side ( rCBV(R)PMG and Delta TT(FM)PMG) were assessed. The right-to-left asymmetry of rCBV and TTfm in the control group was also assessed ( rCBV(R)Controls and Delta TT(FM)Controls). Results: There was no significant asymmetry between right and left rCBV or TTfm ( P>0.05) in controls. There was significant reduction in rCBVRTSC compared to rCBVRControls ( P>0.05), but no significant difference in DTTFMTSC compared to DTTFMControls ( P>0.05). There were no significant differences between rCBVRPMG and rCBVRControls ( P>0.05) or DTTFMPMG and DTTFMControls ( P>0.05). Conclusion: Our findings imply that cerebral blood volume of polymicrogyria is similar to normal cortex, but there is reduced cerebral blood volume in cortical tubers. The lower rCBV ratio of cortical tubers may be related to known differences in pathogenetic timing of the underlying abnormalities during brain development or the presence of gliosis.