Computational study of a novel catheter for liver radioembolization

Abstract

Radioembolization (RE) is a medical treatment for primary and secondary liver cancer that involves the transcatheter intraarterial delivery of micron-sized and radiation-emitting microspheres, with the goal of improving microsphere deposition in the tumoral bed while sparing healthy tissue. An increasing number of in vitro and in silico studies on RE in the literature suggest that the particle injection velocity, spatial location of the catheter tip and catheter type are important parameters in particle distribution. The present in silico study assesses the performance of a novel catheter design that promotes particle dispersion near the injection point, with the goal of generating a particle distribution that mimics the flow split to facilitate tumour targeting. The design is based on two factors: the direction and the velocity at which particles are released from the catheter. A series of simulations was performed with the catheter inserted at an idealised hepatic artery tree with physiologically realistic boundary conditions. Two longitudinal microcatheter positions in the first generation of the tree were studied by analysing the performance of the catheter in terms of the outlet-to-outlet particle distribution and split flow matching. The results show that the catheter with the best performance is one with side holes on the catheter wall and a closed frontal tip. This catheter promotes a flow-split-matching particle distribution, which improves as the injection crossflow increases.

Keywords: hemodynamics; liver cancer; microcatheter; particle-fluid dynamics; radioembolization; side-holes catheter.

FIGURE 1

Idealised hepatic artery geometry views. (A) Isometric view, (B) top view with the cross‐sectional position of the catheter at the inlet and injection section, (C) top view with the two longitudinal positions of the catheter, and (D) front view with outlet nomenclature and gravity vector F_G direction

FIGURE 2

Computational mesh around the artery wall at the PHA and details of the mesh in two cross‐sections of the computational domain, before and after the bifurcation

FIGURE 3

Inflow velocity waveform (blood flow) and particle injection velocity (V_cath)

FIGURE 4

Factor settings for side‐hole catheters

FIGURE 5

Particle distribution and blood flow distribution in the outlets and matching deviation index (MDI) values per case with an injection point at 30 mm from the bifurcation. (A) Outlet‐to‐outlet particle distribution for simulations I to VIII, including case 0. (B) MDI and standard deviation for simulations I to VIII. (C) Outlet‐to‐outlet particle distribution for simulations IX to XVI, including case 0. (D) MDI and standard deviation for simulations IX to XVI

FIGURE 6

Particle distribution and blood flow distribution in the outlets and matching deviation index (MDI) values per case with an injection point at 10 mm from the bifurcation. (A) Outlet‐to‐outlet particle distribution for simulations I to VIII, including case 0. (B) MDI and standard deviation for simulations I to VIII. (C) Outlet‐to‐outlet particle distribution for simulations IX to XVI, including case 0. (D) MDI and standard deviation for simulations IX to XVI

FIGURE 7

CoV along level I for the simulations with (A) the injection point 30 mm from the bifurcation and (B) the injection point 10 mm from the bifurcation

FIGURE 8

Matching deviation index (MDI) at several area ratio parameters for the simulations (A) with an injection point at 30 mm from the bifurcation and (B) with an injection point at 10 mm from the bifurcation

FIGURE 9

(A) Ratio of the velocity to the injection velocity in one cardiac cycle for cases 0, II, and III (when injecting 30 mm from the bifurcation). (B) Contour plots of the radial velocity for side‐hole design cases (II and III) at the injection surface