Functional Imaging of Memory Networks in patients undergoing temporal lobe surgery
- Advanced Imaging Research Center (AIRC)
- Parkland Health & Hospital System
Bradley Lega, M.D.
There are two main patient groups who we will target in this study. The first is patients who will undergo surgery to localize or remove an epileptic focus. These patients will be identified at the weekly epilepsy surgery conference and referred by the epileptology group at uT Southwestern/Parkland Hospital for evaluation. Patients referred for resection of temporal lobe gliomas will also be included. These patients are identified at the weekly glioma surgery conference. Those patients who agree to participate will undergo an fMRi evaluation prior to surgical resection and then a second study after recovering from the surgical procedure. These patients will be identified and contacted initially by Dr. Lega.
The second group consists of patients that have been identified via review of the epilepsy surgery database of the epileptology group, managed by the Department of neurology and neurosurgery at uT Southwestern. These patients will be identified by Dr. Lega or Dr. King. These patients will be those who underwent temporal lobe resections. They will be contacted by Dr. Lega and those that agree to participate will undergo functional imaging to examine memory networks.
in addition to the two patient groups, healthy controls will be also recruited for a comparison to the patient groups. These patients will be recruited through advertisements in local newspapers and posted around the uTSW and uTD campuses. individuals interested in participating in the study can they contact the research staff at uTD for initial screening. Screening will include questions that will ensure their safety during the MR scanning as well as questions used to match patients in terms of age and years of education. Both patient groups will be matched. We will match subjects within 5 years of age and 2 years of education.
Behavioral data collected during the memory task will be analyzed in terms of overall memory accuracy as well as encoding and retrieval response time. Memory accuracy will be used to correlate functional and structural MRi measures with individual differences in performance.
Data will be collected at the uTSW advanced imaging Research Center. MRi data will always be collected by members of the research personnel with the assistance of an experienced and accredited MRi technologist. all members of the research personnel will contribute to the analysis of both structural and functional MRi data. The analysis of the fMRi data will involve an analysis of both the structural and functional scans. anatomical scans will include both a high resolution, T1-weighted magnetization-prepared rapid acquisition structural image and a diffusion tensor image (DTi). Structural MRi images will be analyzed to characterize different features of tissue integrity, including grey matter volume and cortical thickness. DTi images will be will be analyzed to characterize different aspects of white matter integrity, using measures such as fractional anisotropy (Fa), mean diffusivity (MD), radial diffusivity (Dr) and axial diffusivity (Da). Functional scans will be analyzed to characterize both event-related changes in BoLD activity and connectivity. Regional changes in BoLD activity will be estimated with a general linear model (GLM). Psychophysiological interactions (PPi) analyses will be conducted to assess event-related changes in functional connectivity. Parameter estimates derived from these analyses will be used to construct whole-brain connectivity matrices which can then be assessed using Graph Theory to characterize the network properties associated with successful episodic retrieval.
For pre- and post-operative patients, standard repeated-measures analyses will be used to compare each of these measures pre- and post- operatively. For both pre- and post- operative patients as well as post-operative patients only, each of these measures will be compared to those derived from the analysis of control patients.
Inclusion Criteria for all Participants:
* Individuals who are 18 years of age or older
* Must pass fMRI screening process
Additional Inclusion Criteria for Patients:
* Patients who have previously undergone temporal lobectomy in the UT/Parkland system.
* Patients who have been referred for temporal lobe surgery, either for glioma or for epilepsy alone