Effect of focal and nonfocal cerebral lesions on functional connectivity studied with MR imaging.
OBJECTIVE
Functional connectivity MR (fcMR) imaging is used to map regions of brain with synchronous, regional, slow fluctuations in cerebral blood flow. We tested the hypothesis that focal cerebral lesions do not eradicate expected functional connectivity.


METHODS
Functional MR (fMR) and fcMR maps were acquired for 12 patients with focal cerebral tumors, cysts, arteriovenous malformations, or in one case, agenesis of the corpus callosum. Task activation secondary to text listening, finger tapping, and word generation was mapped by use of fMR imaging. Functional connectivity was measured by selecting "seed" voxels in brain regions showing activation (based on the fMR data) and cross correlating with every other voxel (based on data acquired while the subject performed no task). Concurrence of the fMR and fcMR maps was measured by comparing the location and number of voxels selected by both methods.


RESULTS
Technically adequate fMR and fcMR maps were obtained for all patients. In patients with focal lesions, the fMR and fcMR maps correlated closely. The fcMR map generated for the patient with agenesis of the corpus callosum failed to reveal functional connectivity between blood flow in the left and right sensorimotor cortices and in the frontal lobe language regions. Nonetheless, synchrony between blood flow in the auditory cortices was preserved. On average, there was 40% concurrence between all fMR and fcMR maps.


CONCLUSIONS
Patterns of functional connectivity remain intact in patients with focal cerebral lesions. Disruption of major neuronal networks, such as agenesis of the corpus callosum, may diminish the normal functional connectivity patterns. Therefore, functional connectivity in such patients cannot be fully demonstrated with fcMR imaging.
Quigley
M
M
Department of Medical Physics, University of Wisconsin, Clinical Sciences Center, Madison 53792-3252, USA.
Cordes
D
D
Wendt
G
G
Turski
P
P
Moritz
C
C
Haughton
V
V
Meyerand
M E
ME
D061085:Agenesis of Corpus Callosum; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D001927:Brain Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000175:diagnosis / Q000503:physiopathology; D000013:Congenital Abnormalities / Q000175:diagnosis; D003337:Corpus Callosum / Q000473:pathology / Q000503:physiopathology; D003560:Cysts / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology