Electrochemical prevention of needle-tract seeding

Nanoporous platinum needle for cancer tumor destruction by EChT and impedance-based intra-therapeutic monitoring

Herein, we present a new design on the Single Needle Electrochemical Therapy (SNEChT) method by introducing some major improvements, including a nanoporous platinum electrode, tunable in situ anode size that depends on the width and location of the tumor, and the capability of measuring the efficacy of therapy based in intra-therapeutic impedance recording by the same EChT needle. It could have significant implications in optimizing EChT operative conditions. The nanoporous Pt electrode increased the interactive surface with a tumor, and produced a higher amount of current with lower stimulating DC voltage. The tunable anode size prevents the over-acidification of treated or non-desired lesions. Hence, this feature reduced the over distribution of tissue. Monitoring the impedance during the therapy clearly informs us about the local destruction of the tumor in each location. Thus, we can be informed about the threshold of tissue acidosis with the lowest electrical stimulation. The insertion of one needle with a tunable anode length for both precise therapy and impedance-based intra-therapeutic monitoring will shed new light on the applications of EChT.

A numerical investigation of the electric and thermal cell kill distributions in electroporation-based therapies in tissue

Electroporation-based therapies are powerful biotechnological tools for enhancing the delivery of exogeneous agents or killing tissue with pulsed electric fields (PEFs). Electrochemotherapy (ECT) and gene therapy based on gene electrotransfer (EGT) both use reversible electroporation to deliver chemotherapeutics or plasmid DNA into cells, respectively. In both ECT and EGT, the goal is to permeabilize the cell membrane while maintaining high cell viability in order to facilitate drug or gene transport into the cell cytoplasm and induce a therapeutic response. Irreversible electroporation (IRE) results in cell kill due to exposure to PEFs without drugs and is under clinical evaluation for treating otherwise unresectable tumors. These PEF therapies rely mainly on the electric field distributions and do not require changes in tissue temperature for their effectiveness. However, in immediate vicinity of the electrodes the treatment may results in cell kill due to thermal damage because of the inhomogeneous electric field distribution and high current density during the electroporation-based therapies. Therefore, the main objective of this numerical study is to evaluate the influence of pulse number and electrical conductivity in the predicted cell kill zone due to irreversible electroporation and thermal damage. Specifically, we simulated a typical IRE protocol that employs ninety 100-µs PEFs. Our results confirm that it is possible to achieve predominant cell kill due to electroporation if the PEF parameters are chosen carefully. However, if either the pulse number and/or the tissue conductivity are too high, there is also potential to achieve cell kill due to thermal damage in the immediate vicinity of the electrodes. Therefore, it is critical for physicians to be mindful of placement of electrodes with respect to critical tissue structures and treatment parameters in order to maintain the non-thermal benefits of electroporation and prevent unnecessary damage to surrounding healthy tissue, critical vascular structures, and/or adjacent organs.

Needle-tract seeding after percutaneous vertebroplasty: a case report

STUDY DESIGN

A case report.

OBJECTIVE

We report a case of needle-tract seeding (NTS) of adenocarcinoma of the lung in the thoracic spine that manifested after vertebroplasty (VP).

SUMMARY OF BACKGROUND DATA

NTS after a biopsy is sometimes observed. However, NTS after an injection, as in VP, is a very rare complication.

METHODS

A 61-year-old female presented with a painful back mass and weakness in both lower extremities. She had been diagnosed with adenocarcinoma of the lung 2 years previously. The patient had complained of severe back pain 5 months before and was diagnosed with a metastatic pathological fracture of T4-T6. She underwent uneventful percutaneous VP at T4-T6 followed by radiation therapy at that time.

RESULTS

Magnetic resonance imaging revealed that the subcutaneous mass extended to the right T5 pedicle with an extension to the adjacent epidural space of T4-T7. Paramedian skin incision was made like a spindle and the back mass was totally removed with the covering skin and surrounding soft tissue. The tumor was connected with lamina, but ribs and pleura were clear. We performed T4-T7 laminectomy, right T5 pediculectomy, epidural tumor curettage, pedicle screw placement at T2-T3, T6-T9. Histological analysis confirmed the diagnosis of metastatic adenocarcinoma of the lung. The patient recovered after the operation, and her back pain and weakness had improved.

CONCLUSION

NTS can be caused by even VP in patients with a pathological fracture. NTS needs to be considered in cases where it is difficult to inject polymethyl methacrylate.

Prevention of needle-tract seeding by two-step freezing after lung cancer biopsy

Fine-needle aspiration biopsy is a method to detect malignancy for undetermined pulmonary nodules, but has the potential to spread malignant cells from the tumor to the pleural cavity or chest wall. We developed a two-step freezing method to avoid needle-tract seeding, by use of percutaneous cryoablation after biopsy but before the biopsy needle was removed. A man aged 72 years was admitted because of a large mass in right upper lobe. After biopsy, the patient underwent surgery. Pathological assessment of the resected tumor showed that tissue around the biopsy probe and cryoprobe had been killed before needle withdrawal.