CT-guided irreversible electroporation in an acute porcine liver model: effect of previous transarterial iodized oil tissue marking on technical parameters, 3D computed tomographic rendering of the electroporation zone, and histopathology

Standardizing lymphangiography and lymphatic interventions: a preclinical in vivo approach with detailed procedural steps

PURPOSE

To present a preclinical in vivo approach for standardization and training of lymphangiography and lymphatic interventions using a pictorial review.

MATERIALS AND METHODS

Different lipiodol- and gadolinium-based lymphangiography and lymphatic interventions were performed in twelve (12) landrace pigs with a mean bodyweight of 34 ± 2 kg using various imaging and guiding modalities, similar to the procedures used in humans. The techniques used were explicitly introduced and illustrated. The potential applications of each technique in preclinical training were also discussed.

RESULTS

By applying visual, ultrasonography, fluoroscopy, CT, cone-beam CT, and/or MRI examination or guidance, a total of eleven techniques were successfully implemented in twelve pigs. The presented techniques include inguinal postoperative lymphatic leakage (PLL) establishment, interstitial dye test, five types of lymphangiography [incl. lipiodol-based translymphatic lymphangiography (TL), lipiodol-based percutaneous intranodal lymphangiography (INL), lipiodol-based laparotomic INL, lipiodol-based interstitial lymphangiography, and interstitial magnetic resonance lymphangiography (MRL)], and four types of percutaneous interventions in the treatment of PLL [incl. thoracic duct embolization (TDE), intranodal embolization (INE), afferent lymphatic vessel sclerotherapy (ALVS), and afferent lymphatic vessel embolization (ALVE)].

CONCLUSION

This study provides a valuable resource for inexperienced interventional radiologists to undergo the preclinical training in lymphangiography and lymphatic interventions using healthy pig models.

Percutaneous Irreversible Electroporation for Treatment of Small Hepatocellular Carcinoma Invisible on Unenhanced CT: A Novel Combined Strategy with Prior Transarterial Tumor Marking

INTRODUCTION

To explore the feasibility, safety, and efficiency of ethiodized oil tumor marking combined with irreversible electroporation (IRE) for small hepatocellular carcinomas (HCCs) that were invisible on unenhanced computed tomography (CT).

METHODS

A retrospective analysis of the institutional database was performed from January 2018 to September 2018. Patients undergoing ethiodized oil tumor marking to improve target-HCC visualization in subsequent CT-guided IRE were retrieved. Target-HCC visualization after marking was assessed, and the signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNR) were compared between pre-marking and post-marking CT images using the paired t-test. Standard IRE reports, adverse events, therapeutic endpoints, and survival were summarized and assessed.

RESULTS

Nine patients with 11 target-HCCs (11.1-18.8 mm) were included. After marking, all target-HCCs demonstrated complete visualization in post-marking CT, which were invisible in pre-marking CT. Quantitatively, the SNR of the target-HCCs significantly increased after marking (11.07 ± 4.23 vs. 3.36 ± 1.79, p = 0.006), as did the CNR (4.32 ± 3.31 vs. 0.43 ± 0.28, p = 0.023). In sequential IRE procedures, the average current was 30.1 ± 5.3 A, and both the delta ampere and percentage were positive with the mean values of 5.8 ± 2.1 A and 23.8 ± 6.3%, respectively. All procedures were technically successful without any adverse events. In the follow-up, no residual unablated tumor (endpoint-1) was observed. The half-year, one-year, and two-year local tumor progression (endpoint-2) rate was 0%, 9.1%, and 27.3%. The two-year overall survival rate was 100%.

CONCLUSIONS

Ethiodized oil tumor marking enables to demarcate small HCCs that were invisible on unenhanced CT. It potentially allows a safe and complete ablation in subsequent CT-guided IRE.

Intra-arterial Injection of Lidocaine as a Cell Sensitizer during Irreversible Electroporation

PURPOSE

To investigate whether intra-arterial injection of lidocaine enhances irreversible electroporation (IRE) in a liver model.

MATERIALS AND METHODS

Conventional IRE (C-IRE) and lidocaine-enhanced IRE (L-IRE) were performed in 8 pig livers. Protocol 1 (tip exposure and electrode distance of 2.0 cm each) and protocol 2 (increased tip exposure and electrode distance 2.5 cm each) were used. Animals were sacrificed 3 hours after IRE. Study goals included electrical tissue properties (eg, current, conductivity) during IRE, geometry of IRE zones analyzed using computed tomography and magnetic resonance imaging (eg, volume and sphericity index), degree of acute liver damage, and irreversible cell death analyzed using microscopy (hematoxylin and eosin staining and terminal deoxynucleotidyl transferase deoxyuridine 5-triphosphate nick end labeling). Statistical comparisons were performed using the paired t test and Wilcoxon test.

RESULTS

All treatments were performed without adverse events. Electrical tissue properties were not significantly different between C-IRE and L-IRE. For protocol 1, the diameter of the largest sphere within the IRE zone was significantly larger for L-IRE than for C-IRE (25.0 ± 4.7 mm vs 18.4 ± 3.1 mm [P = .013]). For protocol 2, the volume of IRE zone was significantly larger for L-IRE compared with C-IRE (46.0 ± 5.4 cm³ vs 22.6 ± 6.4 cm³ [P = .018]), as well as the diameter of the largest sphere within the IRE zone (27.1 ± 2.2 mm vs 19.8 ± 2.3 mm [P = .020]). For protocol 1, a significantly higher degree of irreversible cell death was noted for L-IRE than for C-IRE (1.8 ± 1.0 vs 0.8 ± 1.0 [P = .046]).

CONCLUSIONS

Intra-arterial injection of lidocaine can enhance IRE in terms of larger IRE zones and an increase of irreversible cell death.

Time-Dependent Impact of Irreversible Electroporation on Pancreas, Liver, Blood Vessels and Nerves: A Systematic Review of Experimental Studies

Introduction

Irreversible electroporation (IRE) is a novel ablation technique in the treatment of unresectable cancer. The non-thermal mechanism is thought to cause mostly apoptosis compared to necrosis in thermal techniques. Both in experimental and clinical studies, a waiting time between ablation and tissue or imaging analysis to allow for cell death through apoptosis, is often reported. However, the dynamics of the IRE effect over time remain unknown. Therefore, this study aims to summarize these effects in relation to the time between treatment and evaluation.

Methods

A systematic search was performed in Pubmed, Embase and the Cochrane Library for original articles using IRE on pancreas, liver or surrounding structures in animal or human studies. Data on pathology and time between IRE and evaluation were extracted.

Results

Of 2602 screened studies, 36 could be included, regarding IRE in liver (n = 24), pancreas (n = 4), blood vessels (n = 4) and nerves (n = 4) in over 440 animals (pig, rat, goat and rabbit). No eligible human studies were found. In liver and pancreas, the first signs of apoptosis and haemorrhage were observed 1–2 hours after treatment, and remained visible until 24 hours in liver and 7 days in pancreas after which the damaged tissue was replaced by fibrosis. In solitary blood vessels, the tunica media, intima and lumen remained unchanged for 24 hours. After 7 days, inflammation, fibrosis and loss of smooth muscle cells were demonstrated, which persisted until 35 days. In nerves, the median time until demonstrable histological changes was 7 days.

Conclusions

Tissue damage after IRE is a dynamic process with remarkable time differences between tissues in animals. Whereas pancreas and liver showed the first damages after 1–2 hours, this took 24 hours in blood vessels and 7 days in nerves.

Electrochemical Effects after Transarterial Chemoembolization in Combination with Percutaneous Irreversible Electroporation: Observations in an Acute Porcine Liver Model

PURPOSE

To evaluate the effects of combined use of transarterial chemoembolization and irreversible electroporation (IRE) for focal tissue ablation in an acute porcine liver model.

MATERIALS AND METHODS

Two established interventional techniques were combined: IRE with zones of irreversible and reversible electroporation and chemoembolization with microspheres, iodized oil, and doxorubicin. IRE was performed before chemoembolization in two pigs (pigs 1 and 2; IRE/chemoembolization group), chemoembolization was performed before IRE in two pigs (pigs 3 and 4; chemoembolization/IRE group), and only IRE was performed in two pigs (pigs 5 and 6). Five study groups were defined: IRE/chemoembolization (pigs 1 and 2), chemoembolization/IRE (pigs 3 and 4), IRE only (pigs 5 and 6), chemoembolization only (tissue outside the IRE zones in pigs 1-4), and control (untreated liver tissue outside the IRE zones in pigs 5 and 6). Animals were euthanized 2 hours after intervention. Size and shape of IRE zones on contrast-enhanced computed tomography, cell death on light microscopy, and doxorubicin tissue concentrations on chromatography and fluorescence microscopy were analyzed.

RESULTS

Size and shape of IRE zones were not significantly different (eg, P = .067 for volume). A histologic marker for irreversible cell death was positive in IRE/chemoembolization, chemoembolization/IRE, and IRE groups only in the macroscopically visible IRE zones. Doxorubicin tissue concentrations were not significantly different (P = .873). However, in the reversible electroporation (RE) zones, broad areas with intense intranuclear doxorubicin accumulation were observed in IRE/chemoembolization but not in chemoembolization/IRE and chemoembolization groups.

CONCLUSIONS

IRE before chemoembolization enhances the intranuclear accumulation of doxorubicin in the RE zone.