New Developments in Image-Guided Percutaneous Irreversible Electroporation of Solid Tumors

PURPOSE OF REVIEW

This review will describe the various applications, benefits, risks, and approaches of conventional irreversible electroporation (IRE), as well as highlight the new technological developments of this procedure along with their clinical applications.

RECENT FINDINGS

Minimally invasive image-guided percutaneous IRE ablation has emerged as a newer, non-thermal ablation technique for tumors in the solid organs, particularly within the liver, pancreas, kidney, and prostate. IRE allows for ablation near heat-sensitive structures, including major blood vessels and nerves, and is not susceptible to the heat sink effect. However, it is limited by certain requirements, such as the need for precise parallel placement of at least two probes with a maximum inter-probe distance of 2.5 cm to reduce the risk of arching phenomenon, the requirement for general anesthesia with muscle relaxant, and the need for cardiac synchronization. However, new technological advancements in the ablation system and image guidance tools have been introduced to improve the efficiency and efficacy of IRE. IRE is a safe and effective treatment option for solid tumor ablation within the liver, pancreas, kidney, and prostate. Compared with other ablation techniques, IRE has several advantages, such as the absence of heat sink effect and minimal injury to blood vessels and bile ducts while activating the immune system. Novel techniques such as H-FIRE, needle placement systems, and robotics have enhanced the accuracy and performance in placement of IRE probes. IRE can be especially beneficial when combined with chemotherapy, immunomodulation, and immunotherapy.

Primary and Metastatic Lung Cancer: Rationale, Indications, and Outcomes of Thermal Ablation

The widespread use of imaging as well as the efforts conducted through screening campaigns has dramatically increased the early detection rate of lung cancer. Historically, the management of lung cancer has heavily relied on surgery. However, the increased proportion of patients with comorbidities has given significance to less invasive therapeutic options like minimally invasive surgery and image-guided thermal ablation, which could precisely target the tumor without requiring general anesthesia or a thoracotomy. Thermal ablation is considered low-risk for lung tumors smaller than 3 cm that are located in peripheral lung and do not involve major blood vessels or airways. The rationale for ablative therapies relies on the fact that focused delivery of energy induces cell death and pathologic necrosis. Image-guided percutaneous thermal ablation therapies are established techniques in the local treatment of hepatic, renal, bone, thyroid and uterine lesions. In the lung, and specifically in the setting of metastatic disease, the 3 main indications for lung ablation are to serve as (1) curative intent, (2) as a strategy to achieve a chemo-holiday in oligometastatic disease, and (3) in oligoprogressive disease. Following these premises, the current paper aims to review the rationale, indications, and outcomes of thermal ablation as a form of local therapy in the treatment of primary and metastatic lung disease.

Image-Guided Percutaneous and Transarterial Therapies for Primary and Metastatic Lung Cancer

Lung cancer is the leading cause of cancer mortality in the world. A significant proportion of patients with lung cancer are not candidates for surgery and must resort to other treatment alternatives. Rapid technological advancements in fields like interventional radiology have paved the way for valid treatment modalities like image-guided percutaneous and transarterial therapies for treatment of both primary and metastatic lung cancer. The rationale of ablative therapies relies on the fact that focused delivery of energy induces tumor destruction and pathological necrosis. Image-guided percutaneous thermal ablation therapies are established techniques in the local treatment of hepatic, renal, bone, thyroid, or uterine lesions. In the lung, the 3 main indications for lung ablation include local curative intent, a strategy to achieve a chemoholiday in oligometastatic disease, and recently, oligoprogressive disease. Transarterial therapies include a set of catheter-based treatments that involve delivering embolic and/or chemotherapeutic agents directed into the target tumor via the supplying arteries. This article provides a comprehensive review of the various techniques available and discusses their applications and associated complications in primary and metastatic lung cancer.

MINIMALLY INVASIVE TREATMENT OF ABDOMINAL LYMPHOCELE: A REVIEW OF CONTEMPORARY OPTIONS AND HOW TO APPROACH THEM

Lymphoceles are lymphatic fluid collections resulting from lymphatic vessel disruption after surgery or trauma. They are most often described following retroperitoneal surgeries such as cystectomies, prostatectomies, renal transplants, and gynecologic surgeries. Most lymphoceles are asymptomatic and resolve spontaneously without treatment. If persistent, they can become infected or exert mass effect on adjacent structures causing pain, urinary, or lower limb edema particularly for lymphoceles in the pelvis Symptomatic lymphoceles should be treated to relieve symptoms and prevent functional compromise of vital adjacent structures. Although surgery has been traditionally accepted as the gold standard treatment, advances in imaging and interventional technology allow for less invasive, percutaneous treatment. Available minimally invasive treatment options include percutaneous aspiration, catheter drainage, sclerotherapy, and lymphangiography with lymphatic embolization. A review of these treatment options and a suggested algorithm for managing lymphoceles is presented.

Effects of metformin on autoimmune immunoglobins and interferon-γ in patients with early diagnosed pemphigus vulgaris: a prospective clinical trial

The management of pemphigus vulgaris (PV) is challenging. This study aimed to evaluate the immunomodulating effects of metformin on PV. The study was conducted in two phases: in the first phase, patients received routine first-line treatment (prednisolone plus azathioprine) for 2 months, then in the second phase, metformin was added to this regimen for another 2 months. After addition of metformin to the first-line medications, significant reductions were seen in serum IgG1 (reduced from 534.92 ± 134.83 mg/dL to 481.58 ± 130.46 mg/dL, P < 0.001), IgG4 (51.83 ± 27.26 mg/dL to 44.50 ± 26.05 mg/dL, P < 0.001) and interferon-γ (277.99 ± 108.71 pg/mL to 45.05 ± 17.080 pg/mL, P = 0.03) concentrations. The suppressant effect of metformin was greatest on IgG4 (coefficient of variation 1.28), the dominant subclass of IgG involved in PV. Metformin could have immunomodulating effects on PV with controlling effects on steroid complications.

Minimally invasive treatment of abdominal lymphocele: A review of contemporary options and how to approach them

Lymphoceles are lymphatic fluid collections resulting from lymphatic vessel disruption after surgery or trauma. They are most often described following retroperitoneal surgeries such as cystectomies, prostatectomies, renal transplants, and gynecologic surgeries. Most lymphoceles are asymptomatic and resolve spontaneously without treatment. If persistent, they can become infected or exert mass effect on adjacent structures causing pain, urinary, or lower limb edema particularly for lymphoceles in the pelvis Symptomatic lymphoceles should be treated to relieve symptoms and prevent functional compromise of vital adjacent structures. Although surgery has been traditionally accepted as the gold standard treatment, advances in imaging and interventional technology allow for less invasive, percutaneous treatment. Available minimally invasive treatment options include percutaneous aspiration, catheter drainage, sclerotherapy, and lymphangiography with lymphatic embolization. A review of these treatment options and a suggested algorithm for managing lymphoceles is presented.

Skin Dosimetry in Radiotherapy of Breast Cancer: a Comparison between EBT and EBT3 Radiochromic Films

OBJECTIVE

Radiochromic EBT3 film is a later generation of radiochromic films. The aim of this study is to compare EBT and EBT3 radiochromic films in radiotherapy fields of breast cancer.

METHODS

A RANDO phantom was irradiated by a 6 MV Siemens Primus linac with medial and lateral fields of radiotherapy of breast cancer. Dosimetry was performed in various points in the fields using EBT and EBT3 films. Films were scanned by a Microtek color scanner. Dose values from two films in corresponding points were compared.

RESULTS

In the investigation of calibration, net optical density (NOD) of EBT radiochromic is more than the EBT3 radiochromic film. The highest percentage difference between NODs of two films is related to 0.75 Gy and equals to 14.19%. The lowest value is related to 0.2 Gy dose and is equal to 3.31%. The highest percentage difference between two films on the RANDO phantom in breast cancer fields is 13.51% and the minimum value is equal to 0.33%.

CONCLUSION

From the comparison between the two films, most of the points show differences in dose in the measurements in fields of breast cancer radiotherapy. These differences are attributed to the thickness of the active layers, the overall thickness of the films, and the difference in the calibration fitted functions. The advantage of EBT film over EBT3 is a higher sensitivity; on the other hand EBT3 film allows to use its both sides in the scanning process and it is a new version of this film type.

Comparison of EBT and EBT3 RadioChromic Film Usage in Parotid Cancer Radiotherapy

BACKGROUND

EBT and EBT3 radioChromic films have been used in radiotherapy dosimetry for years.

OBJECTIVE

The aim of the current study is to compare EBT and EBT3 radioChromic films in dosimetry of radiotherapy fields for treatment of parotid cancer.

METHODS

Calibrations of EBT and EBT3 films were performed with identical setups using a 6 MV photon beam of a Siemens Primus linac. Skin dose was measured at different points in the right anterior oblique (RAO) and right posterior oblique (RPO) fields by EBT and EBT3 films on a RANDO phantom.

RESULTS

While dosimetry was performed with the same conditions for the two film types for calibration and in phantom in parotid cancer radiotherapy, the measured net optical density (NOD) in EBT film was found to be higher than that from EBT3 film. The minimum difference between these two films under calibration conditions was about 2.9% (for 0.2 Gy) with a maximum difference of 35.5% (for 0.5 Gy). In the therapeutic fields of parotid cancer radiotherapy at different points, the measured dose from EBT film was higher than the EBT3 film. In these fields the minimum and maximum measured dose differences were 16.0% and 25.5%, respectively.

CONCLUSION

EBT film demonstrates higher NOD than EBT3 film. This effect may be related to the higher sensitivity of EBT film over EBT3 film. However, the obtained dose differences between these two films in low dose range can be due to the differences in fitting functions applied following the calibration process.