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Session: Advances in CT II [Return to Session]

Correction Factors for Partial Volume Averaging in the Quantification of Radiopaque Nanomaterial-Embedded Resorbable Polymers

Adam D. Melancon1, Jossana Damasco2, Megan Jacobsen3, Joy Perez2, Marvin Bernardino2, Erin San Valentin2, Karem A. Court4, Biana Godin4, Rick Layman3, and Marites P. Melancon2 Departments of 1Radiation Physics, 2Interventional Radiology, and 3Imaging Physics, The University of MD Anderson Cancer Center, Houston, TX 77030 4Department of Nanomedicine, Houston Methodist Research Hospital, Houston, TX 77030


TU-D930-IePD-F8-1 (Tuesday, 7/12/2022) 9:30 AM - 10:00 AM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 8

Purpose: Resorbable inferior vena cava filters require embedded contrast for image-guided placement and integrity monitoring. In this study, we calculated correction factors to account for partial volume averaging of thin nanoparticle (NP)-embedded materials, accounting for object and slice thicknesses, background signal, and kVp.

Methods: Three set of phantoms containing disks of polycaprolactone embedded with bismuth (Bi) and ytterbium (Yb) were fabricated: 0.4-1.2mm disks of 20% NP (thickness phantom), 0.4mm disks of 0-20% NP in 2mg/ml iodine (concentration phantom), and 20% NP in 0.4mm disks in 0-10 mg/ml iodine (thickness phantom). Phantoms were scanned on a dual-source CT from 80-150 kVp and reconstructed at 1.5mm slice thickness with a 0.1mm interval. Following scanning, disks were processed for inductively coupled plasma optical emission spectrometry (ICP-OES) to determine NP concentration. Mean and max CT number (HU) of all disks and background were measured over a 0.5cm2 area for each kVp. HU was converted to concentration using previously measured calibrations. Concentration measurements were corrected for partial volume averaging by subtracting residual slice background and extrapolating disk thickness to both the nominal and measured slice thicknesses (SSP). Slice thickness to agreement (STTA) was calculated by replacing the measured concentration with the ICPMS and solving for thickness.

Results: Slice thickness correction factors improved agreement with ICP-OES for all measured data. Yb slightly outperformed Bi on the concentration phantom (1.18 vs 1.37 STTA/SSP, where 1.0 is perfect agreement) and Bi outperformed Yb in phantoms with varying background (1.39 vs 1.56 STTA/SSP) and in phantoms with varying thickness (1.05 vs 1.40 STTA/SSP). All measured concentrations correlated strongly with ICP-OES when NP concentration changed.

Conclusion: : Correction for partial volume averaging increased agreement with ICPMS concentration, demonstrating potential for monitoring integrity of thin IVC resorbable filters with CT.


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