42 - Comparative Analysis of Nanoparticle Delivery and Distribution Efficiency: End-Hole vs. Side-Hole Needles in Agarose Phantoms and Tissue

Intratumoral injection of therapeutic agents has been shown to be feasible and safe in clinical trials and is currently used in practice. Previous studies showed that injection technique, including needle design, affects delivery and distribution within targeted tumors {1}. In this study, we compare the delivery and distribution efficiency of prussian blue nanoparticles (PBNPs) injected through end-hole needles with side-hole needles of the same size in agarose and tissue phantoms.

Materials and Methods:

1% (n=5) and 2% (n=5) agarose gel phantoms and six chicken breasts were used to compare the distribution profiles of end-hole and side-hole needles (25G). Each model was injected with a side-hole and an end-hole needle, delivering a mixture of 20% PBNPs and 80% water via a syringe pump at a rate of 0.25 ml/minute. Real-time injection and spread of PBNPs were recorded and analyzed. Area of dispersion (cm2) and maximal diametral spread (cm) were calculated in a vertical and transverse view using ImageJ, an image analysis software, for the agarose phantoms {2}. Volume of dispersion (cm3) and maximal diametral spread (DS) were calculated similarly for the chicken breast tissues. CT scanning was used to further evaluate the volume of distribution. Average values of area of dispersion, maximal diametral spread, volume of dispersion, and percent change were calculated to compare distribution efficiency between end hole versus side hole needles. Single T-test was performed to assess the significance.

Results: In 1% agarose phantoms, the side-hole needle had a 76.45% increase in transverse dispersion (p = 0.0097), a 73.65% increase in transverse DS (p = 0.0192), a 77.67% increase in vertical dispersion (p = 0.0032), and a 72.93% increase in vertical DS (p = 0.0017) compared to the end-hole needle. In 2% agarose phantoms, the side-hole needle showed a 90.41% increase in transverse dispersion (p = 0.029), an 85.85% increase in transverse DS (p = 0.024), a 94.81% increase in vertical dispersion (p = 0.000002), and a 90.68% increase in vertical DS (p = 0.000008). For the chicken breast model, the side-hole needle increased the volume of distribution by 26.53% (p = 0.0897) and the DS by 31.48% (p = 0.084) compared to the end-hole needle.

Conclusion: Side-hole needles provide significantly better distribution of PBNPs than end-hole catheters, particularly in denser media. This highlights the influence of needle design on intratumoral delivery and its importance in enhancing therapy, as improved delivery with broader and more uniform distribution can potentially improve clinical outcomes.