Optimization of the differentiation and quantification of high‐Z nanoparticles incorporated in medical devices for CT‐guided interventions

Abstract

Purpose Material differentiation has been made possible using dual‐energy computed tomography (DECT), in which the unique, energy‐dependent attenuating characteristics of materials can provide new diagnostic information. One promising application is the clinical integration of biodegradable polymers as temporary implantable medical devices impregnated with high‐atomic number (high‐Z) materials. The purpose of this study was to explore the incorporation of high atomic number (high‐Z) contrast materials in a bioresorbable inferior vena cava filter for advanced CT‐based monitoring of its location and differentiating from surrounding materials. Materials and methods Imaging optimization and calibration studies were performed using a body phantom. The dual‐energy CT (DECT) ratios for iron, zirconium, barium, gadolinium, ytterbium, tantalum, tungsten, gold, and bismuth were generated for peak kilovoltage combinations of 80/150Sn, 90/150Sn, and 100/150Sn kVp in dual‐source CT via linear regression of the CT numbers at low and high energies. A secondary calibration of the material map to the nominal material concentration was generated to correct for use of materials other than iodine. CT number was calibrated to the material concentration based on single‐energy CT (SECT) with additional filtration (150Sn kVp). These quantification methods were applied to monitoring of biodegradable inferior vena cava filters (IVCFs) made of braided poly(p‐dioxanone) sutures infused with ultrasmall bismuth nanoparticles (BiNPs) implanted in an adult domestic pig. Results Qualitative material differentiation was optimal for high‐Z (>73) contrast agents in DECT. However, quantification became nonlinear and inaccurate as the K‐edge of the material increased. Using the high‐energy (150Sn kVp) data component as a SECT scan, the linearity of quantification curves was maintained with lower limits of detection than with DECT. Among the materials tested, bismuth had optimal differentiation from iodine in DECT while maintaining increased contrast in high‐energy SECT for quantification (11.5% error). Coating the IVCF with BiNPs resulted in markedly greater radiopacity (maximum CT number, 2028 HU) than that of an uncoated IVCF (maximum CT number, 127 HU). Using DECT imaging and processing, the BiNP‐IVCF could be clearly differentiated from iodine contrast injected into the inferior vena cava of the pig. Conclusions These findings may improve widespread integration of medical devices incorporated with high‐Z materials into the clinic, where technical success, possible complications, and device integrity can be assessed intraoperatively and postoperatively via DECT imaging.

Localized Perivascular Therapeutic Approaches to Inhibit Venous Neointimal Hyperplasia in Arteriovenous Fistula Access for Hemodialysis Use

“…Using external reinforcement and self-sealing polymers, which have been used in the development of modified AVGs, perivascular scaffolds can also be enhanced to optimize their capacity to provide mechanical support. Despite the fact that bioresorbable polymers are naturally radiolucent, they can also be combined with nanoparticles to give them radiopacity, enabling the tracking of their deployment and breakdown over time [ 94 ]. An all-in-one electrospun perivascular wrap that delivers drugs and/or cells locally while also providing mechanical support for ideal hemodynamics should be possible with the integration of emerging technologies.…”

Bismuth Nanoparticle and Polyhydroxybutyrate Coatings Enhance the Radiopacity of Absorbable Inferior Vena Cava Filters for Fluoroscopy-Guided Placement and Longitudinal Computed Tomography Monitoring in Pigs

“…As in our previous studies, 10,20−22 BiNPs were infused into PPDO monofilament sutures via a wet dipping technique to provide radiopacity to the inherently radiolucent PPDO. One previous study evaluating different high-Z contrast agents showed that Bi has optimal differentiation from iodine in dual-energy CT and has significantly increased contrast for quantification in high-energy singleenergy CT. 11 Moreover, dual-energy CT revealed that BiNP− PPDO IVCFs could be clearly differentiated from injected iodine contrast in a pig model. These promising results could lead to breakthroughs in the noninvasive intraoperative and postoperative CT assessment of bioresorbable medical devices.…”

“…BiNPs were synthesized via the thermal decomposition of BiAc 3 in the presence of high-boiling point organic solvents. ,, In detail, 3 mmol BiAc 3 , 50 mL of oleylamine, 20 mL of oleic acid, and 30 mL of 1-octadecene were mixed in a 500 mL three-necked, round-bottom flask and heated at 100 °C with stirring for 1 h. The solution was then heated at 240 °C for 10 min under argon gas protection. A needle was used to vent the argon gas during the synthesis.…”

“…In one systematic study of different high-Z elements (iron, zirconium, barium, gadolinium, ytterbium, tantalum, tungsten, gold, and bismuth [Bi]), the single-energy CT attenuation of Bi was the highest in high-energy scans and remained relatively steady across all energies. 11 Similar to gold, the more cost-effective Bi can be differentiated from iodinated agents using dual-energy CT, which is a potentially valuable trait in the iodine-enhanced monitoring of blood clots trapped by IVCFs. Furthermore, Bi nanoparticles (BiNPs) are biocompatible and have been utilized as theranostic agents for photoacoustic imaging, CT, and near-infrared photothermal therapy.…”

“…Therefore, a biocompatible radiopacifier that can provide higher contrast than AuNPs is needed. In one systematic study of different high-Z elements (iron, zirconium, barium, gadolinium, ytterbium, tantalum, tungsten, gold, and bismuth [Bi]), the single-energy CT attenuation of Bi was the highest in high-energy scans and remained relatively steady across all energies . Similar to gold, the more cost-effective Bi can be differentiated from iodinated agents using dual-energy CT, which is a potentially valuable trait in the iodine-enhanced monitoring of blood clots trapped by IVCFs.…”