Image Alignment and Normalisation for MR-DUAL SPECT Imaging in Epilepsy

SPECT imaging provides a direct method of examining brain state during epileptic seizure: The key advantage of SPECT imaging in epilepsy is that tracer uptake patterns in the brain following injection are essentially 'frozen' for a time after injection. This permits imaging of seizure activity in the brain after the patient recovers from the seizure.

In subtraction imaging studies two SPECT studies of a patient are acquired, one during a normal brain state (interictal) and one during seizure (ictal). Changes between these combined with a knowledge of how soon after seizure onset the tracer injection was made can provide valuable information in localising the seizure focus. In order to examine changes the scans are coregistered with high resolution MRI anatomy. My work on this project has been to integrate fully automated multi-modality registration and normalisation techniques into the data processing. This (hopefully!) reduces user interaction and increases the reproducibility of the results. The steps involved in the processing are illustrated in the following pages.

Firstly, having read the MRI and SPECT image data from their respective scanners, the alignment between the reference SPECT study and the MRI is estimated:

MR Dual Spect data
Top row shows orthogonal slices through the patients MRI scan, middle row shows SPECT scan 'A' (aligned with MRI) ,
lower row shows SPECT scan 'B'  (here 'A' and 'B' are displayed with different colour scales to help distinguish between the two).

 
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