To determine the effect changing threshold values has on SISCOM image data sets.

1. Comparing the Spatial Resolution of a Novel 72-Detector SPECT Technology and a Standard 2-Detector SPECT ScannerMelissa Zagorski, RET Fellow 2011Lake View High School, ChicagoRET Mentor: Dr. Marvin Rossi, MD, PhDNSF- RET Program Abstract Background Epilepsy is a serious neurological condition; it is the general diagnosis given for unprovoked recurrent seizures. It occurs when a hyper-synchronous electrical charge flows through the brain’s normal non-synchronous electric circuits. Epilepsy can be caused by brain injury or disease, although in approximately 80% of individuals with epilepsy, the cause is unknown.1 Three million people in the United States have epilepsy, of those approximately 500,000 of those are medically resistant to medication1. Other treatments are available these include other medication, surgery and implantable devices. In order to determine the location for surgery or implantation a series of SPECT scans are made and through the process of SISCOM areas of increased blood perfusion are determined. Together with clinical observations and EEG the primary seizure-onset site is determined, and appropriate treatment can be implemented Single-Photon Emission Computed Tomography (SPECT) scanners use gamma ray cameras. The Siemens Scanner has two gamma ray cameras and a novel NeuroLogica scanner has 72 gamma ray photomultipliers. Differences of intensity, shape and exact location of areas of large blood perfusion are seen. Smaller areas of transient alterations in blood perfusion often do not correlate between scanners. These differences could significantly impact surgical treatment decisions. The significance of these differences are not well understood. The goal of my work was to compare these spatial differences using the Subtraction Ictal SPECT CO-registered to MRI (SISCOM) process. The results of this study demonstrate that the 72 detector system visualizes a greater extent of the epileptic circuit compared to the 2 detector SPECT scanner. The imaging data are independent of the thresholding process. Materials and Methods Co-Registration between MRI and SPECT Subtraction MRI Brain Extraction for Co-Registration to SPECT Subtraction SPECT Image Subtraction Ictal and Interictal SPECT Co-Registration Goal Binary Thresholding To determine the effect changing threshold values has on SISCOM image data sets. Results Fig2 72 Detector Standard Threshold Fig1 2 Detector Standard Threshold Fig3 2 Detector Minus 1 Threshold Fig5 2 Detector Plus 1 Threshold Fig4 2 Detector Minus 1 Threshold Fig6 2 Detector Plus 2 Threshold In Figures 3-6 there are fewer regions of small transient blood flow and the locations do not correlate when compared to image data sets that use standard threshold values (Fig1-2). Figures 1,3-6 do not show the area of large blood perfusion on the basal frontal as shown in Figure 2. Areas of large blood perfusion are similar but differences in exact brightness, size, shape and location are significant. Conclusion Teaching Module Plan Acknowledgements • Threshold changes used did not increase the similarity of the 2-detector SPECT scanner to the 72-detector scanner image data sets. • Fewer regions of small transient blood perfusion in the data sets where the thresholds were changed compared to the standard data sets, could indicate artifacts. • Continue to use both the 2-detector and 72-detector SPECT scanners image to locate seizure activity. • Use image data sets with different threshold values. • Future Studies: • Compare the Analyze 9.0 SISCOM process to a different computer aided SISCOM process. • Change the threshold values of 72-detector image data sets and compare with the standard threshold values. • NSF Grant # EEC-0743068 • Dr. Andreas Linninger, RET Program Director • Dr. Marvin Rossi, Research Advisor • Vlodomyr Pylypyuk, CNMT • Rush Research Assistants – Forrest Jacoby, Brian Quinn, Natasha Khan and Ryan Hanson • Rush Epilepsy Center, Rush University Medical Center • University of Illinois- Chicago • Who: Lake View High School students • What: Modeling the SISCOM process. • When: Summer 2011 • Why: Exposure of cutting edge research inspires students to study science in the future References 1. www.epilepsyfoundation.org/