Each analysis begins with two SPECT scans (one interictal SPECT scan and one ictal SPECT scan) and optionally a 3D MRI for the same patient, and ends with ISAS results as summarized below. Detailed step-by-step instructions for performing the ISAS BioImage Suite Analysis are found in the Details section.

Sample Analysis

We recommend that before processing your own images, you should run a complete analysis on the sample patient (see Downloads page) using the instructions below, and confirm that the results obtained agree with those shown on the Sample Analysis results page.

File Format

BioImage Suite can work with several image file formats, but the recommended file formats are either Analyze or NIFTI formats. See the Software Setup page for information on converting the DICOM standard into the Analyze format. Note that the sample analysis scans are already in Analyze format, and are ready for pre-processing (next step).

Pre-processing Scans

  1. Reorient the scan a similar orientation as the template images.
  2. Rigidly algin the ictal scan to the interictal scan.
  3. Nonlinearly co-register the patients scans to the template image.
  4. Mask the spatially normalized images with an a priori brain mask to remove the skull
  5. Smooth your realigned, normalized, and masked images with a kernel of 16x16x16 mm.
  6. Proportionally scale the patient scans to have an image mean of 50 and mask out any voxels with an intensity value below 40.

The Statistical Model

  1. ISAS BioImage Suite uses a two sample t-test with unequal sample size and equal variance between the scan differences to calculate voxel by voxel significance

Display and Interpret Results

  1. Display results using cross sections, and the stastical print outs. Repeat analysis and check with Subtraction Processing.
  2. For SPECT scans injected during seizures (true ictal SPECT), localize the lobe of seizure onset based on the “Reading Rules.”
  3. For SPECT scans injected post-ictally, lateralize the hemisphere of seizure onset based on the hypoperfusion asymmetry index.
  4. If you are performing the sample analysis, compare your results to those on the Sample Analysis page to ensure they match.

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