Oliver M Afchani MD, Presenter: Nothing to Disclose

Phillip Epstein MD, Abstract Co-Author: Nothing to Disclose

Keith Raymond Thulborn MD, Abstract Co-Author: Nothing to Disclose

Can fMRI using an oculomotor control paradigm produce patterns of activation that distinguish cognitively impaired patients from normal subjects?

Patients with cognitive dysfunction without significant anatomic or physiological abnormality (n=10) and with cognitive decline from cerebrovascular disease (n=5) were referred for MRI for their clinical management. Normal subjects (n=10) were recruited from the local community. Functional MRI using blood oxygenation level dependent (BOLD) contrast was performed using a 8.5 cycle block-designed oculomotor control paradigm. This paradigm alternates visually-guided saccades to a bright spot moving at 2Hz between 5 locations on a horizontal meridian (30s) with central fixation (30s). The subject was instructed to: "follow the spot with your eyes without moving your head". A 3T whole body MRI scanner (GEMS, Milwaukee, WI) was used to acquire gradient-echo, echo-planar images while the subject performed the paradigm. Eye movement was monitored. Radiology customized software (NIVANA, www.mrixtechnologies.com) was used to derive activation patterns and perform rapid region-of-interest analysis. The laterality ratios ([left -right activation]/total activation) and the volumes of activation (percentages of total brain activation) in frontal, parietal, occipital and temporal lobes were calculated. These parameters were compared between normals and patients using group statistics.

Significantly decreased activation was found for total activation in both patient groups compared to normal subjects. The laterality ratios and percentage of activation in frontal, parietal, occipital or temporal lobes showed greater variability reflecting the heterogeneity of patient groups.

Considerable variability in activation maps for these patient groups limits generalizations about characteristic changes in activation patterns for the visually guided saccade paradigm although the total amount of activation is significantly decreased in these patients. Alternative paradigms will be required to produce pathonemonic patterns useful in neuroradiological reporting of cognitively impaired patients.

K.R.T.: Keith Thulborn has a research agreement with General Electric Medical Systems and owns Thulborn Associates, Inc.

Afchani, O, Epstein, P, Thulborn, K, Evaluation of Oculomotor Activation Patterns from fMRI for Clinical Reporting of Cognitive Impairment.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4412382.html