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IS IT NECESSARY LOOK AT IMAGES WITHOUT ATTENUATION CORRECTION ? Ryan Ryan D. Niederkohr, M.D. D Niederkohr M D Associate Physician, Nuclear Medicine Kaiser Permanente (Santa Clara, CA) OVERVIEW • Potential Potential reasons to look at images without reasons to look at images without attenuation correction: – Misregistration artifact • Patient motion – “High High Attenuation Attenuation” Artifact Artifact – Small pulmonary nodules – Skin Lesions Skin Lesions – Diaphragmatic motion artifact Slides not to be reproduced without permission of author MISREGISTRATION ARTIFACT MISREGISTRATION ARTIFACT Slides not to be reproduced without permission of author MISREGISTRATION ARTIFACT AC NAC Slides not to be reproduced without permission of author MISREGISTRATION ARTIFACT Slides not to be reproduced without permission of author MISREGISTRATION ARTIFACT NAC AC Slides not to be reproduced without permission of author HIGH ATTENUATION ARTIFACT HIGH ATTENUATION ARTIFACT NAC AC Slides not to be reproduced without permission of author HIGH ATTENUATION ARTIFACT HIGH ATTENUATION ARTIFACT AC NAC Slides not to be reproduced without permission of author HIGH ATTENUATION ARTIFACT Images courtesy of Dr. L. Ramanna, USC Slides not to be reproduced without permission of author SMALL PULMONARY NODULES REFERENCE: Reinhardt et al., Eur J Nucl Med Mol Imag 2006; 33: 134‐139. Slides not to be reproduced without permission of author SKIN LESIONS AC NAC Slides not to be reproduced without permission of author DIAPHRAGMATIC MOTION Slides not to be reproduced without permission of author DIAPHRAGMATIC MOTION REFERENCE: Goerres et al., Radiology 2003; 226: 906‐910. Slides not to be reproduced without permission of author QUESTION • In In oncologic PET/CT imaging, correction of oncologic PET/CT imaging correction of images for signal attenuation allows for: – A: Reduction of motion‐induced artifact A: Reduction of motion induced artifact – B: Semi‐quantitative image analysis (e.g., SUV) – C: Increased diagnostic specificity C: Increased diagnostic specificity – D: Improved spatial resolution of reconstructed images. images Slides not to be reproduced without permission of author ANSWER • In In oncologic PET/CT imaging, correction of oncologic PET/CT imaging correction of images for signal attenuation allows for: – A: Reduction of motion‐induced artifact A: Reduction of motion induced artifact – B: Semi‐quantitative image analysis (e.g., SUV) – C: Increased diagnostic specificity C: Increased diagnostic specificity – D: Improved spatial resolution of reconstructed images. images Slides not to be reproduced without permission of author INCORRECT ANSWERS INCORRECT ANSWERS • In oncologic PET/CT imaging, correction of images g / g g, g for signal attenuation allows for: – A: Reduction of motion‐induced artifact • Incorrect: Incorrect: AC does not correct for patient motion during AC does not correct for patient motion during the PET acquisition, and patient movement between CT and PET acquisitions induces considerable artifact on AC images. – C: Increased diagnostic specificity C: Increased diagnostic specificity • Incorrect: AC may make “deep” lesions easier to identify, but this would improve sensitivity. In general, specificity is not directly improved solely due to attenuation correction. y p y – D: Improved spatial resolution of reconstructed images. • Incorrect: Incorrect: AC does not change intrinsic spatial resolution of AC does not change intrinsic spatial resolution of the scanner. Slides not to be reproduced without permission of author
