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McDaniels – Feb 29, 2008. Outline. Patient 6 question Patient 11 ADC results Abstract for AAPM conference. Patient 6. DW 00015i. Contour 5. Patient 6. DW 00015i. Contour 6. Patient 11. 6 contours 3 of one type scan 3 of another type but same slices 3 exams. Patient 11.
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Outline • Patient 6 question • Patient 11 ADC results • Abstract for AAPM conference
Patient 6 • DW 00015i • Contour 5
Patient 6 • DW 00015i • Contour 6
Patient 11 • 6 contours • 3 of one type scan • 3 of another type but same slices • 3 exams
AAPM Abstract • Purpose: This work investigates the use of Diffusion Weighted Magnetic Resonance Imaging (DWMRI) in evaluating GlioBlastoma Multiforme (GBM) patients. The goal is to assess the ability to discriminate among recurrent tumor, normal tissue and Radiation Induced Necrosis (RIN) based on Apparent Diffusion Constant (ADC) values.
AAPM Abstract • Method and Materials: DWMRI Images were taken for several GBM patients at specific intervals following radiation therapy. Location of lesions were defined by treatment plan contours and transferred to DWMRI images using a simplified geometric algorithm. ADC values were calculated by a least squares fit to DW intensities at varied magnetic field gradients. ADC values for whole lesion volumes were calculated by a weighted sum of individual DWMRI slice values. Initially, the weighting on the individual slice volumes compared to the total volume as gauged by the number of lesion voxels in each slice.
AAPM Abstract • Results: Greater uncertainty in ADC values were obtained for baseline field gradients (b=0) where the average intensity was lower than 1000. Because of this, ADC values for whole volumes were also wieghted by the b=0 average intensity within the lesion, with lower intensities given a lesser relative weighting.
AAPM Abstract • Conclusion: Using DWMRI imaging to evaluate GBM patients presents several challenges. They include transferring lesion geometry from treatment or diagnostic images to DW images and evaluating image data, accounting for image quality.