Abstract Rationale Intratumoral drug delivery into lung tumors through bronchoscopy is a safe and feasible procedure that aims to maximize anti-cancer agent retention within the tumor while minimizing off-target exposure. Our group has previously demonstrated the benefit of dose apportioning through multiple injections. In an attempt to implement a multiple injection strategy and reduce the operational challenges involved in needle reinsertion, repositioning the needle within the same needle tract has been proposed. We therefore investigated the distribution of a radiopaque agent injected into a freshly resected canine tumor following this strategy. Methods A freshly resected pulmonary carcinoma from a domestic dog (68.2g, 37.6mm x 31.7mm x 29.6mm) that underwent segmental resection was injected with the contrast agent Visipaque (320 mg/mL, GE Healthcare) at 2.6 mL/min through an 18G needle using a syringe pump (PHD ULTRA , Harvard Apparatus). A fluoroscope (Smart-C, Turner) captured a two-dimensional projection of the injectate at 10 frames/second. Two injections were performed (10.35ml and10.35 ml) with the needle moved backwards by 10mm through the same needle tract for the second injection. Results Figure 1A and 1C present the final frames of the fluoroscopy recordings for the first and second injection, respectively, and show accumulation of the contrast agent within the tumor as well as leakage from the bottom left region of the tumor. The background subtraction images from the first (1B) and second (1D) injections depict the final frame minus the first frame and can be thought of as a pixel-wise change in intensity from the beginning to the end of the injection. Conclusion We observed little qualitative difference in the retention and distribution profiles of the injected agent within the tumor after the two injections, indicating that the additional injection yielded little benefit. This was further confirmed by subtracting the initial frame from the final frame in the second injection. Qualitative assessment of the videos indicated that leakage in the second injection occurred through spatially identical paths as observed in the first injection. This abstract is funded by: Johnson & Johnson Interventional Oncology
Kennedy et al. (Fri,) studied this question.