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Evaluation of the Tumor Registration Error in Biopsy Procedures Performed Under Real Time PET/CT Guidance

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l fanchon

L Fanchon1,2 *, A Apte1, O Dzyubak1, G Mageras1, E Yorke1, D Visvikis2, M Hatt2, S Solomon1, A Kirov1, (1) Memorial Sloan-Kettering Cancer Center, New York, NY (2) INSERM U1101, Brest, France


WE-AB-BRA-4 (Wednesday, July 15, 2015) 7:30 AM - 9:30 AM Room: Ballroom A

Purpose:PET/CT guidance is used for biopsies of metabolically active lesions, which are not well seen on CT alone or to target the metabolically active tissue in tumor ablations. It has also been shown that PET/CT guided biopsies provide an opportunity to verify the location of the lesion border at the place of needle insertion. However the error in needle placement with respect to the metabolically active region may be affected by motion between the PET/CT scan performed at the start of the procedure and the CT scan performed with the needle in place and this error has not been previously quantified.

Methods:Specimens from 31 PET/CT guided biopsies were investigated and correlated to the intraoperative PET scan under an IRB approved HIPAA compliant protocol. For 4 of the cases in which larger motion was suspected a second PET scan was obtained with the needle in place. The CT and the PET images obtained before and after the needle insertion were used to calculate the displacement of the voxels along the needle path. CTpost was registered to CTpre using a free form deformable registration and then fused with PETpre. The shifts between the PET image contours (42% of SUVmax) for PETpre and PETpost were obtained at the needle position.

Results:For these extreme cases the displacement of the CT voxels along the needle path ranged from 2.9 to 8 mm with a mean of 5 mm. The shift of the PET image segmentation contours (42% of SUVmax) at the needle position ranged from 2.3 to 7 mm between the two scans.

Conclusion:Evaluation of the mis-registration between the CT with the needle in place and the pre-biopsy PET can be obtained using deformable registration of the respective CT scans and can be used to indicate the need of a second PET in real-time.

Funding Support, Disclosures, and Conflict of Interest: This work is supported in part by a grant from Biospace Lab, S.A.

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