Joint Ictal-Interictal SPECT Reconstruction for Accurate Epileptic Focus Localization

Massachusetts General Hospital, Boston MA

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Abstract

? DESCRIPTION (provided by applicant): Epilepsy, one of the most common neurological disorders in children and young adults, is a devastating disease with a major psychosocial and economic impact. In current clinical practice, interictal image is subtracted from ictal image to obtain a seizure image. The seizure image is overlapped to the subject's structural MRI for localizing epileptic focus. One major challenge of ictal SPECT is to obtain rapid tracer injection after the seizure. It is not uncommon that tracer injection is delayed by minutes in clinical practice. The statistical counts associated with the seizure become much less as the delay of the tracer injection increases. Also, the overall noise level in the seizure image is increased because of the subtraction. The resulting high variance in the seizure image caused by these two effects degrades the performance of epileptic focus localization. We propose a novel approach to reconstruct ictal and inter-ictal SPECT projections jointly to obtain the seizure image directly. Because Poisson noise on both the ictal and inter- ictal SPECT projections are preserved in this single reconstruction framework, image quality of the seizure image is greatly improved. We also propose to incorporate point spread function modeling and MR-based SPECT attenuation correction into the joint SPECT reconstruction. We expect that our method will greatly improve the accuracy of epileptic focus localization and have high clinical impact.