Feasibility of a Modified Biopsy Needle for Irreversible Electroporation Ablation and Periprocedural Tissue Sampling

Abstract

Objectives: To test the feasibility of modified biopsy needles as probes for irreversible electroporation ablation and periprocedural biopsy.

Methods: Core biopsy needles of 16-G/9-cm were customized to serve as experimental ablation probes. Computed tomography-guided percutaneous irreversible electroporation was performed in in vivo porcine kidneys with pairs of experimental (n = 10) or standard probes (n = 10) using a single parameter set (1667 V/cm, ninety 100 µs pulses). Two biopsy samples were taken immediately following ablation using the experimental probes (n = 20). Ablation outcomes were compared using computed tomography, simulation, and histology. Biopsy and necropsy histology were compared.

Results: Simulation-suggested ablations with experimental probes were smaller than that with standard electrodes (455.23 vs 543.16 mm²), although both exhibited similar shape. Computed tomography (standard: 556 ± 61 mm², experimental: 515 ± 67 mm²; P = .25) and histology (standard: 313 ± 77 mm², experimental: 275 ± 75 mm²; P = .29) indicated ablations with experimental probes were not significantly different from the standard. Histopathology indicated similar morphological changes in both groups. Biopsies from the ablation zone yielded at least 1 core with sufficient tissue for analysis (11 of the 20).

Conclusions: A combined probe for irreversible electroporation ablation and periprocedural tissue sampling from the ablation zone is feasible. Ablation outcomes are comparable to those of standard electrodes.

Keywords: ablation technique; computed tomography; core needle biopsy; irreversible electroporation; kidney.

Figure 1

(A) Modified core biopsy needle design for ablation and biopsy with exposed inner stylet tip and specimen notch (a) and insulated cannula (6 cm length) (b). (B) Schematic display of two parallel biopsy-ablation devices with the inner stylet and specimen notch exposed and expected ablation zone (a, enlarged). The biopsy core is taken from the same location. The cutting cannulas (b) are partially insulated to avoid inadvertent ablation of the tracts. The proximal exposed parts are used to connect the pulse generator cables (+, −). The vertical line indicates the skin surface.

Figure 2

CAD model rendering for the experimental core biopsy needle design.

Figure 3

(A) Biopsy core taken from the ablation zone containing sufficient tissue for histology evaluation (a), and specimen notch containing blood and debris insufficient for histology assessment (b). Ablation zone created with the combined device (B) and standard needle electrodes (C). Arrows indicate the needle trajectories.

Figure 4

CT-guided needle placement using the combined biopsy device (A) and standard IRE needle electrodes (C). Contrast enhanced CT showing an ablation zone created with the experimental electrodes (B) and standard IRE needle electrodes (D).

Figure 5

Mean (±standard deviation [SD]) cross-sectional area of ablation zones as measured on computed tomography (CT) for the experimental electrodes and control needle electrodes at sample locations in the middle and lower pole in the kidney.

Figure 6

Computed tomography (CT)-guided needle placement using the combined biopsy device (A) and the standard irreversible electroporation (IRE) needle electrodes (C). Contrast-enhanced CT showing an ablation zone created with the experimental electrodes (B) and the standard IRE needle electrodes (D).