N. Gutta

Comparison of simulation-based treatment planning with imaging and pathology outcomes for percutaneous CT-guided irreversible electroporation of the porcine pancreas: a pilot study.

PURPOSE To investigate the reliability of simulations for planning pancreatic irreversible electroporation (IRE) ablations compared with computed tomography (CT) and pathology outcomes in an animal model. MATERIALS AND METHODS Simulations were performed varying treatment parameters, including field strength (1.5-2.5 kV/cm), pulse number (70-90 pulses), and pulse length (70-100 µs). Pancreatic IRE was performed in six pigs under CT guidance. Two animals each were sacrificed for histology after 1 day, 14 days, and 28 days. Follow-up CT scans were performed on day 0, day 1, day 14, and day 28. Biochemical markers were collected before the procedure, 1 day after the procedure, and 14 days after the procedure. RESULTS All ablation zones could be visualized on CT scan immediately after the procedure and on day 1 follow-up CT scan, and all animals survived until the designated endpoints. Histopathology revealed necrosis and edema on day 1 and fibrosis and glandular atrophy after 28 days. Blood vessels close to the ablation zone appeared normal. Laboratory analysis indicated mild to moderate amylasemia and lipasemia with normalization after 14 days. The ablation size on CT scan measured a mean (± SD) 146% ± 18 (day 0, P < .126) and 168% ± 18 (day 1, P < .026) of the simulation and on pathology measured 119% ± 10 (day 1, not significant) of the simulation. CONCLUSIONS Results from simulations for planning IRE ablations, CT, and pathology may differ from each other. Ablation zones on CT and pathology appear larger than simulated, suggesting that clinically used treatment planning may underestimate the ablation size in the pancreas.

Novel use of noninvasive high-intensity focused ultrasonography for intercostal nerve neurolysis in a swine model.

Background High-intensity focused ultrasound (HIFU) is a noninvasive thermal ablation technique. High-intensity focused ultrasound has been used in small-animal models to lesion neural tissue selectively. This study aimed to evaluate the efficacy of HIFU in a large-animal model for ablation of nerves similar in size to human nerves. Methods Twelve acute magnetic resonance–guided HIFU ablation lesions were created in intercostal nerves in a swine model. In a second pig, as a control, 4 radiofrequency ablation and 4 alcohol lesions were performed on intercostal nerves under ultrasound guidance. Preprocedural and postprocedural magnetic resonance imaging was then performed to evaluate radiologically the lesion size created by HIFU. Animals were euthanized 1 hour postprocedure, and necropsy was performed to collect tissue samples for histopathologic analysis. Results On gross and histological examination of the intercostal nerve, acute HIFU nerve lesions showed evidence of well-demarcated, acute, focally extensive thermal necrosis. Four intercostal nerves ablated with HIFU were sent for histopathologic analysis, with 2 of 4 lesions showing pathologic damage to the intercostal nerve. Similar results were shown with radiofrequency ablation technique, whereas the intercostal nerves appeared histologically intact with alcohol ablation. Conclusions High-intensity focused ultrasound may be used as a noninvasive neurolytic technique in swine. High-intensity focused ultrasound may have potential as a neuroablation technique for patients with chronic and cancer pain.

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

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.