Patricia J. Zondervan

The safety and efficacy of irreversible electroporation for the ablation of prostate cancer: a multicentre prospective human in vivo pilot study protocol

Introduction Current surgical and ablative treatment options for prostate cancer have a relatively high incidence of side effects, which may diminish the quality of life. The side effects are a consequence of procedure-related damage of the blood vessels, bowel, urethra or neurovascular bundle. Ablation with irreversible electroporation (IRE) has shown to be effective in destroying tumour cells and harbours the advantage of sparing surrounding tissue and vital structures. The aim of the study is to evaluate the safety and efficacy and to acquire data on patient experience of minimally invasive, transperineally image-guided IRE for the focal ablation of prostate cancer. Methods and analysis In this multicentre pilot study, 16 patients with prostate cancer who are scheduled for a radical prostatectomy will undergo an IRE procedure, approximately 30 days prior to the radical prostatectomy. Data as adverse events, side effects, functional outcomes, pain and quality of life will be collected and patients will be controlled at 1 and 2 weeks post-IRE, 1 day preprostatectomy and postprostatectomy. Prior to the IRE procedure and the radical prostatectomy, all patients will undergo a multiparametric MRI and contrast-enhanced ultrasound of the prostate. The efficacy of ablation will be determined by whole mount histopathological examination, which will be correlated with the imaging of the ablation zone. Ethics and dissemination The protocol is approved by the ethics committee at the coordinating centre (Academic Medical Center (AMC) Amsterdam) and by the local Institutional Review Board at the participating centres. Data will be presented at international conferences and published in peer-reviewed journals. Conclusions This pilot study will determine the safety and efficacy of IRE in the prostate. It will show the radiological and histopathological effects of IRE ablations and it will provide data to construct an accurate treatment planning tool for IRE in prostate tissue. Trial registration number Clinicaltrials.gov database: NCT01790451.

Irreversible electroporation: state of the art

The field of focal ablative therapy for the treatment of cancer is characterized by abundance of thermal ablative techniques that provide a minimally invasive treatment option in selected tumors. However, the unselective destruction inflicted by thermal ablation modalities can result in damage to vital structures in the vicinity of the tumor. Furthermore, the efficacy of thermal ablation intensity can be impaired due to thermal sink caused by large blood vessels in the proximity of the tumor. Irreversible electroporation (IRE) is a novel ablation modality based on the principle of electroporation or electropermeabilization, in which electric pulses are used to create nanoscale defects in the cell membrane. In theory, IRE has the potential of overcoming the aforementioned limitations of thermal ablation techniques. This review provides a description of the principle of IRE, combined with an overview of in vivo research performed to date in the liver, pancreas, kidney, and prostate.

Thermal ablation in renal cell carcinoma management: a comprehensive review.

Purpose of review This article provides an overview of recent developments in the field of thermal ablation for renal cell carcinoma and focuses on current standard techniques, new technologies, imaging for ablation guidance and evaluation, and future perspectives. Recent findings Emerging long-term data on cryoablation and radiofrequency ablation (RFA) show marginally lower oncologic outcomes compared to surgical treatment, balanced by better functional and perioperative outcomes. Reports on residual disease vary widely, influenced by different definitions and strategies in determining ablation failure. Stratifying disease-free survival after RFA according to tumor size suggests 3 cm to be a reasonable cut off for RFA tumor selection. Microwave ablation and high-intensity focal ultrasound are modalities with the potential of creating localized high temperatures. However, difficulties in renal implementation are impairing sufficient ablation results. Irreversible electroporation, although not strictly thermal, is a new technology showing promising results in animal and early human research. Summary Although high-level randomized controlled trials comparing thermal ablation techniques are lacking, evidence shows that thermal ablation for small renal masses is a safe procedure for both long-term oncologic and functional outcomes. Thermal ablation continues to be associated with a low risk of residual disease, for which candidates should be properly informed. RFA and cryoablation remain the standard techniques whereas alternative techniques require further studies.

Irreversible electroporation of the porcine kidney: Temperature development and distribution.

OBJECTIVE Although tissue ablation by irreversible electroporation (IRE) has been characterized as nonthermal, the application of frequent repetitive high-intensity electric pulses has the potential of substantially heating the targeted tissue and causing thermal damage. This study evaluates the risk of possible thermal damage by measuring temperature development and distribution during IRE of porcine kidney tissue. METHODS The animal procedures were conducted following an approved Institutional Animal Ethics Committee protocol. IRE ablation was performed in 8 porcine kidneys. Of them, 4 kidneys were treated with a 3-needle configuration and the remaining 4 with a 4-needle configuration. All IRE ablations consisted of 70 pulses with a length 90 µs. The pulse frequency was set at 90 pulses/min, and the pulse intensity at 1,500 V/cm with a spacing of 15 mm between the needles. The temperature was measured internally using 4 fiber-optic temperature probes and at the surface using a thermal camera. RESULTS For the 3-needle configuration, a peak temperature of 57°C (mean = 49 ± 10°C, n = 3) was measured in the core of the ablation zone and 40°C (mean = 36 ± 3°C, n = 3) at 1cm outside of the ablation zone, from a baseline temperature of 33 ± 1°C. For the 4-needle configuration, a peak temperature of 79°C (mean = 62 ± 16°C, n = 3) was measured in the core of the ablation zone and 42°C (mean = 39 ± 3°C, n = 3) at 1cm outside of the ablation zone, from a baseline of 35 ± 1°C. The thermal camera recorded the peak surface temperatures in the center of the ablation zone, reaching 31°C and 35°C for the 3- and 4-needle configuration IRE (baseline 22°C). CONCLUSIONS The application of repetitive high-intensity electric pulses during IRE ablation in porcine kidney causes a lethal rise in temperature within the ablation zone. Temperature monitoring should be considered when performing IRE ablation near vital structures.

Prostate cancer diagnosis: the feasibility of needle-based optical coherence tomography

Abstract. The objective of this study is to demonstrate the feasibility of needle-based optical coherence tomography (OCT) and functional analysis of OCT data along the full pullback trajectory of the OCT measurement in the prostate, correlated with pathology. OCT images were recorded using a commercially available C7-XR™ OCT Intravascular Imaging System interfaced to a C7 Dragonfly™ intravascular 0.9-mm-diameter imaging probe. A computer program was constructed for automated image attenuation analysis. First, calibration of the OCT system for both the point spread function and the system roll-off was achieved by measurement of the OCT signal attenuation from an extremely weakly scattering medium (Intralipid® 0.0005 volume%). Second, the data were arranged in 31 radial wedges (pie slices) per circular segments consisting of 16 A-scans per wedge and 5 axial B-scans, resulting in an average A-scan per wedge. Third, the decay of the OCT signal is analyzed over 50 pixels (500  μm) in depth, starting from the first found maximum data point. Fourth, for visualization, the data were grouped with a corresponding color representing a specific μoct range according to their attenuation coefficient. Finally, the analyses were compared to histopathology. To ensure that each single use sterile imaging probe is comparable to the measurements of the other imaging probes, the probe-to-probe variations were analyzed by measuring attenuation coefficients of 0.03, 6.5, 11.4, 17, and 22.7 volume% Intralipid®. Experiments were repeated five times per probe for four probes. Inter- and intraprobe variation in the measured attenuation of Intralipid samples with scattering properties similar to that of the prostate was <8% of the mean values. Mean attenuation coefficients in the prostate were 3.8  mm−1 for parts of the tissue that were classified as benign (SD: 0.8  mm−1, minimum: 2.2  mm−1, maximum: 8.9  mm−1) and 4.1  mm−1 for parts of tissue that were classified as malignant (SD: 1.2  mm−1, minimum: 2.5  mm−1, maximum: 9.0  mm−1). In benign areas, the tissue looked homogeneous, whereas in malignant areas, small glandular structures were seen. However, not all areas in which a high attenuation coefficient became apparent corresponded to areas of prostate cancer. This paper describes the first in-tissue needle-based OCT imaging and three-dimensional optical attenuation analysis of prostate tissue that indicates a correlation with pathology. Fully automated attenuation coefficient analysis was performed at 1300 nm over the full pullback. Correlation with pathology was achieved by coregistration of three-dimensional (3-D) OCT attenuation maps with 3-D pathology of the prostate. This may contribute to the current challenge of prostate imaging and the rising interest in focal therapy for reduction of side effects occurring with current therapies.

Histopathological Outcomes after Irreversible Electroporation for Prostate Cancer: Results of an Ablate and Resect Study

PURPOSE Irreversible electroporation is a tissue ablation modality that uses high voltage electric energy to induce an increase in cell membrane permeability. This causes destabilization of the existing cellular transmembrane potential leading to cell death, due to the inability to maintain cellular homeostasis. This phase I-II study was designed to evaluate the histopathological outcomes of irreversible electroporation to prostate and surrounding tissue in radical prostatectomy specimens. MATERIALS AND METHODS Sixteen patients with prostate cancer underwent an irreversible electroporation ablation without curative intent, followed by radical prostatectomy scheduled 4 weeks later. For histopathological examination of the prostate, whole mounted tissue slices were examined by dedicated genitourinary pathologists. The borders of the ablation zone and residual tumor were outlined on the slides. RESULTS The irreversible electroporation ablation zones were characterized as areas of fibrosis, necrosis and loss of epithelial tissue in terms of denudation in the glandular structures. The ablation zone was well demarcated, showing trenchant delineations between viable and nonviable tissue. The ablated tissue showed mild to moderate inflammation, with atrophic cells in 1 case. The area was surrounded by hemorrhage at the location of the electrodes. No skip lesions or viable tissue was seen in the ablation zone. Fibrinoid necrosis of the neurovascular bundle was observed in 13 patients and denudation of the urothelium of the prostatic urethra was seen in 9. CONCLUSIONS Histopathological assessment of the prostate 4 weeks after irreversible electroporation ablation showed sharply demarcated fibrotic and necrotic tissue in the ablation zone. No viable tissue was observed in the irreversible electroporation ablation zone.

Diagnostic dilemmas in patients with upper tract urothelial carcinoma

Upper tract urothelial carcinoma (UTUC) is a rare condition and recommendations based on a high level of evidence for diagnosis, treatment and follow-up monitoring are lacking. Current decision-making is often based on evidence from trials investigating urothelial carcinoma of the lower tract. Radical nephroureterectomy has been the standard of care for UTUC but kidney-sparing treatment using endoscopic approaches has been established for a select patient group with low-grade and low-stage disease. Optimal treatment choice requires correct tumour characterization. According to available recommendations, diagnostic work-up of UTUC includes evaluation by CT urography or MRI urography, cystoscopy and urine cytology. Ureterorenoscopy and lesion biopsy are grade C recommendations in patients with suspected UTUC. When kidney-sparing treatment is planned, ureterorenoscopy and biopsy should be considered and are the procedures of choice in most cases. These diagnostics have limitations and their accuracy varies in defining tumour characteristics and predicting grade and stage. Urinary tests have higher sensitivity than cytology for detection of lower tract urothelial carcinoma but evidence of their benefit in UTUCs is lacking. New optical and image enhancement techniques are being developed to facilitate real-time diagnostics with increased accuracy. A new diagnostic algorithm for patients with suspected UTUC that integrates the diagnosis, treatment and clinical risk stratification is required.

Focal therapy in the management of small renal masses.

Purpose of reviewFocal therapy has gained attention in the treatment of small renal masses. However its use is encased by scarce data on long-term outcomes and low evidence regarding perioperative complications. Our purpose is to review the emerging data in the past 18 months. Recent findingsPopulation US-based studies show steady increase in the use of thermal ablation. Clinical series and comprehensive reviews support safety and mid/long-term efficacy. Comparative studies and meta-analysis outlined oncological inferiority against partial nephrectomy in local tumor control. There are profound demographic and tumor differences between patients treated by one or another. Complication rate is lower after ablation but the lack of standard reporting weakens conclusions on this point. Generalizable cost-benefit studies are yet missed. Clinical and basic research aims to diminish radiological associated burden, improving lesion targeting and developing new energy-based technologies. SummaryData confirm acceptable outcomes of focal therapy in the small renal masses treatment.Although these are inferior in terms of local control compared with partial nephrectomy, patients and tumor characteristics differ between treatments.Current data remain of low evidence but for some meta-analysis. Preliminary reports suggest the possibility to decrease radiation burden and bipolar radiofrequency and photodynamic therapy as focus of future interest.

In vivo, percutaneous, needle based, optical coherence tomography of renal masses

Optical coherence tomography (OCT) is the optical equivalent of ultrasound imaging, based on the backscattering of near infrared light. OCT provides real time images with a 15 µm axial resolution at an effective tissue penetration of 2-3 mm. Within the OCT images the loss of signal intensity per millimeter of tissue penetration, the attenuation coefficient, is calculated. The attenuation coefficient is a tissue specific property, providing a quantitative parameter for tissue differentiation. Until now, renal mass treatment decisions have been made primarily on the basis of MRI and CT imaging characteristics, age and comorbidity. However these parameters and diagnostic methods lack the finesse to truly detect the malignant potential of a renal mass. A successful core biopsy or fine needle aspiration provides objective tumor differentiation with both sensitivity and specificity in the range of 95-100%. However, a non-diagnostic rate of 10-20% overall, and even up to 30% in SRMs, is to be expected, delaying the diagnostic process due to the frequent necessity for additional biopsy procedures. We aim to develop OCT into an optical biopsy, providing real-time imaging combined with on-the-spot tumor differentiation. This publication provides a detailed step-by-step approach for percutaneous, needle based, OCT of renal masses.

Duplicated Ureters and Renal Transplantation: A Case-Control Study and Review of the Literature

INTRODUCTION Complications of the transplant ureter are the most important cause of surgical morbidity after renal transplantation. The presence of ureteral duplication in the renal graft might result in an increased complication rate. We analyzed our data of double-ureter renal transplantations using a case-control study design. Additionally, we performed a review of the literature. METHODS From January 1995 to April 2012, 12 patients received a donor kidney with a double ureter (0.8%). We created a control group of 24 patients matched in age, sex, donor type, and ureteral stenting. Patient charts and surgical reports were reviewed retrospectively. RESULTS In 7 patients both ureters were separately anastomosed to the bladder. In 4 patients a common ostium was created. In 1 patient 1 of the 2 ureters was ligated. No postoperative urologic complications occured. In the single-ureter group, the urologic complication rate was 17% (P = .71). Mean creatinine levels after transplantation were comparable between both groups. DISCUSSION A double-ureter donor kidney is not associated with an increased complication rate after renal transplantation and yields equal outcomes as compared to single-ureter donor kidneys. We conclude that transplantation of a kidney with a duplicated ureter is safe.