MRI and CT in the follow-up after irreversible electroporation of small renal masses

PURPOSE

Ablation plays a growing role in the treatment of small renal masses (SRMs) due to its nephron sparing properties and low invasiveness. Irreversible electroporation (IRE) has the potential, although still experimental, to overcome current limitations of thermal ablation. No prospective imaging studies exist of the ablation zone in the follow up after renal IRE in humans. Objectives are to assess computed tomography (CT) and magnetic resonance imaging (MRI) on the ablation zone volume (AZV), enhancement and imaging characteristics after renal IRE.

METHODS

Prospective phase 2 study of IRE in nine patients with ten SRMs. MRI imaging was performed pre-IRE, 1 week, 3 months, 6 months and 12 months after IRE. CT was performed pre-IRE, perioperatively (direct after ablation), 3 months, 6 months and 12 months after IRE. AZVs were assessed by two independent observers. Observer variation was analyzed. Evolution of AZVs, and relation between the needle configuration volume (NCV; planned AZV) and CT- and MRI volumes were evaluated.

RESULTS

Eight SRMs were clear cell renal cell carcinomas, one SRM was a papillary renal cell carcinoma and one patient had a non-diagnostic biopsy. On CT, median AZV increased perioperatively until 3 months post-IRE (respectively, 16.8 cm3 and 6.2 cm3) compared to the NCV (4.8 cm3). On MRI, median AZV increased 1-week post-IRE until 3 months post-IRE (respectively, 14.5 cm3 and 4.6 cm3) compared to the NCV (4.8 cm3). At 6 months the AZV starts decreasing (CT 4.8 cm3; MRI 3.0 cm3), continuing at 12 months (CT 4.2 cm3, MRI 1.1 cm3). Strong correlation was demonstrated between the planning and the post-treatment volumes. Inter-observer agreement between observers was excellent (CT 95% CI 0.82-0.95, MRI 95% CI 0.86-0.96). All SRMs appeared non-enhanced immediately after ablation, except for one residual tumour. Subtraction images confirmed non-enhancement on MRI in unclear enhancement cases (3/9). Directly after IRE, gas bubbles, perinephric stranding and edema were observed in all cases.

CONCLUSION

The AZV increases immediately on CT until 3 months after IRE. On MRI, the AZV increases at 1 week until 3 months post-IRE. At 6 months the AZV starts decreasing until 12 months post-IRE on both CT and MRI. Enhancement was absent post-IRE, except for one residual tumour. Gas bubbles, perinephric stranding and edema are normal findings directly post-IRE.

Gray matter atrophy but not vascular brain injury is related to cognitive impairment in patients with heart failure

Background

Cognitive impairment in heart failure (HF) interferes with the capacity to self-care and is associated with adverse health outcomes. This underlines the importance of detecting the extent and nature of cognitive impairment in HF. We report on the presence and mutual association of neuroimaging markers and cognitive impairment in patients with HF.

Method

We included 147 patients with HF (69±10yrs; 32%F; MMSE 29±1) and 121 reference participants (66±8yrs; 46%F; MMSE 29±1) from the Dutch multicenter Heart-Brain study. Brain MRI scans were rated for (lacunar) infarcts and microbleeds. Total grey and white matter volume, hippocampal volume and white matter hyperintensity (WMH) volume were calculated. We used a standardized neuropsychological test battery to measure cognition and calculated compound z-scores for each cognitive domain. Associations between neuroimaging markers and cognitive functioning were investigated using linear regression analyses, with separate models for each cognitive domain. We adjusted for participant group, age, sex and education. To investigate whether associations differed according to participant group, interaction terms were included in our analyses.

Result

Patients with HF had lower total grey matter volume and more vascular brain injury compared to the reference group, including WMH (median (interquartile range) 1.7 (40) versus 0.6 (1.8), p<0.001), (sub-)cortical infarcts (13% versus 3%, p<0.01) and lacunar infarcts (28% versus 10%, p<0.001). Cognitive impairment was found in 18% of HF, most often in the domains of memory and attention/psychomotor speed. Overall, we found associations between smaller total grey matter volume and worse global cognition, more cortical and lacunar infarcts (standardized beta [stβ] = −0.14–0.56, p<0.05). Stratification for participant group showed associations between worse global cognition and smaller total (stβ=0.43, p<0.01) and hippocampal (stβ=0.22, p<0.05) grey matter volumes in HF. We found no association between cognition and vascular brain injury.

Conclusion

Patients with HF exhibit cognitive deficits more pronounced in the domains of memory and attention/psychomotor speed. Grey matter atrophy, but not vascular brain injury seems to be related to cognitive impairment in HF.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Cardiovasculair Onderzoek Nederland (CVON)

Available ablation energies to treat cT1 renal cell cancer: emerging technologies

Purpose

An increasing interest in percutaneous ablation of renal tumors has been caused by the increasing incidence of SRMs, the trend toward minimally invasive nephron-sparing treatments and the rapid development of local ablative technologies. In the era of shared decision making, patient preference for non-invasive treatments also leads to an increasing demand for image-guided ablation. Although some guidelines still reserve ablation for poor surgical candidates, indications may soon expand as evidence for the use of the two most validated local ablative techniques, cryoablation (CA) and radiofrequency ablation (RFA), is accumulating. Due to the collaboration between experts in the field in biomedical engineering, urologists, interventional radiologists and radiation oncologists, the improvements in ablation technologies have been evolving rapidly in the last decades, resulting in some new emerging types of ablations.

Methods

A literature search was conducted to identify original research articles investigating the clinical outcomes of new emerging technologies, percutaneous MWA, percutaneous IRE and SABR, in patients with primary cT1 localized renal cell cancer.

Results

Due to the collaboration between experts in the field in biomedical engineering, urologists, interventional radiologists and radiation oncologists, the improvements in ablation technologies have been evolving rapidly in the last decades. New emerging technologies such as microwave ablation (MWA), irreversible electroporation (IRE) and stereotactic ablative radiotherapy (SABR) seem to be getting ready for prime time.

Conclusion

This topical paper describes the new emerging technologies for cT1 localized renal cell cancer and investigates how they compare to CA and RFA.

Irreversible electroporation for the treatment of localized prostate cancer: a summary of imaging findings and treatment feedback

PURPOSE

Imaging plays a crucial role in ablative therapies for prostate cancer (PCa). Irreversible electroporation (IRE) is a new treatment modality used for focal treatment of PCa. We aimed to demonstrate what imaging modalities can be used by descriptively reporting contrast-enhanced ultrasonography (CEUS), multiparametric magnetic resonance imaging (mpMRI), and grey-scale transrectal ultrasound (TRUS) results. Furthermore, we aimed to correlate quantitatively the ablation zone seen on mpMRI and CEUS with treatment planning to provide therapy feedback.

METHODS

Imaging data was obtained from two prospective multicenter trials on IRE for localized low- to intermediate-risk PCa. The ablation zone volume (AZV) seen on mpMRI and CEUS was 3D reconstructed to correlate with the planned AZV.

RESULTS

Descriptive examples are provided using mpMRI, TRUS, and CEUS for treatment planning and follow-up after IRE. The mean AZV on T2-weighted imaging 4 weeks following IRE was 12.9 cm3 (standard deviation [SD]=7.0), 5.3 times larger than the planned AZV. Linear regression showed a positive correlation (r=0.76, P = 0.002). For CEUS the mean AZV was 20.7 cm3 (SD=8.7), 8.5 times larger than the planned AZV with a strong positive correlation (r=0.93, P = 0.001). Prostate volume is reduced over time (mean= -27.5%, SD=11.9%) due to ablation zone fibrosis and deformation, illustrated by 3D reconstruction.

CONCLUSION

The role of imaging in conjunction with IRE is of crucial importance to guide clinicians throughout the treatment protocol. CEUS and mpMRI may provide essential treatment feedback by visualizing the ablation zone dimensions and volume.

Irreversible Electroporation for the Ablation of Renal Cell Carcinoma: A Prospective, Human, In Vivo Study Protocol (IDEAL Phase 2b)

Background

Irreversible electroporation (IRE) is an emerging technique delivering electrical pulses to ablate tissue, with the theoretical advantage to overcome the main shortcomings of conventional thermal ablation. Recent short-term research showed that IRE for the ablation of renal masses is a safe and feasible treatment option. In an ablate and resect design, histopathological analysis 4 weeks after radical nephrectomy demonstrated that IRE-targeted renal tumors were completely covered by ablation zone. In order to develop a validated long-term IRE follow-up study, it is essential to obtain clinical confirmation of the efficacy of this novel technology. Additionally, follow-up after IRE ablation obliges verification of a suitable imaging modality.

Objective

The objectives of this study are the clinical efficacy and safety of IRE ablation of renal masses and to evaluate the use of cross-sectional imaging modalities in the follow-up after IRE in renal tumors. This study conforms to the recommendations of the IDEAL Collaboration and can be categorized as a phase 2B exploration trial.

Methods

In this prospective clinical trial, IRE will be performed in 20 patients aged 18 years and older presenting with a solid enhancing small renal mass (SRM) (≤4 cm) who are candidates for ablation. Magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) will be performed at 1 day pre-IRE, and 1 week post-IRE. Computed tomography (CT), CEUS, and MRI will be performed at 3 months, 6 months, and 12 months post-IRE.

Results

Presently, recruitment of patients has started and the first inclusions are completed. Preliminary results and outcomes are expected in 2018.

Conclusions

To establish the position of IRE ablation for treating renal tumors, a structured stepwise assessment in clinical practice is required. This study will offer fundamental knowledge on the clinical efficacy of IRE ablation for SRMs, potentially positioning IRE as ablative modality for renal tumors and accrediting future research with long-term follow-up.

Trial Registration

Clinicaltrials.gov registration number NCT02828709; https://clinicaltrials.gov/ct2/show/NCT02828709 (archived by WebCite at http://www.webcitation.org/6nmWK7Uu9). Dutch Central Committee on Research Involving Human Subjects NL56935.018.16

Detection superiority of 7 T MRI protocol in patients with epilepsy and suspected focal cortical dysplasia

In 11 adult patients with suspicion of Focal cortical dysplasia (FCD) on 1.5 T (n = 1) or 3 T (n = 10) magnetic resonance imaging (MRI), 7 T MRI was performed. Visibility, extent, morphological features and delineation were independently rated and subsequently discussed by three observers. Additionally, head-to-head comparisons with corresponding 3 T images were made in the eight patients with a previous 3 T MRI and sustained suspicion of FCD. Comparison with histopathology was done in the five patients that underwent surgery. All lesions, seen at 1.5 and 3 T, were also recognized on 7 T. At 7 T FLAIR highlighted the FCD-like lesions best, whereas T2 and T2* were deemed better suited to review structure and extent of the lesion. Image quality with the used 7 T MRI setup was higher than the quality with the used 3 T MRI setup. In 2 out of 11 patients diagnosis changed, in one after re-evaluation of the images, and in the other based on histopathology. With the used 7 T MRI setup, FCD-like lesions can be detected with more confidence and detail as compared to lower field strength. However, concordance between radiologic diagnosis and final diagnosis seems to be lower than expected.

Cryoablation of small kidney tumors

INTRODUCTION

Cryoablation (CA) has been broadly used mostly in the treatment of small renal masses (SRMs). The present review aims to define the current role of CA in the treatment of SRMs by assessing clinical indications and outcomes.

METHOD

A comprehensive review on patient selection, procedural details, perioperative complications, and short/long-term oncological and functional outcomes was conducted. For each section, a take-home message was formulated with level of evidence (LoE) according to Cochrane collaboration.

RESULTS

Age and comorbidity drive the choice of ablation in SRMs, although hospital setting also influences the decision. Technically in adequate CA or first post-CA control occurs in 3-5% of laparoscopic cryoablation (LCA) or percutaneous cryoablation (PCA) series. Meta-analysis does not evidence differences in the rate of residual tumor per person-year between the approaches (0.033 LCA vs. 0.046 PCA, p = 0.25). Perioperative complications (8-25%) are erratically reported. LCA has significantly lower likelihood of complications than minimally invasive partial nephrectomy (MIPN). Systematic reviews indicate 30-month local tumor progression rate of 8.5% for LCA in renal cell carcinoma but low metastatic progression (1-4.4%). Few LCA long-term follow-up series (mean/media 48-98 months) report recurrence-free survival (RFS) and cancer-specific survival (CSS) ranges of 80-100%. For PCA, Kaplan-Meier local disease-free survival (DFS) of 95.6% at 3-5 years [32] and 5-year overall survival and local RFS of 86.3% were reported. The decrease in renal function after CA is minimal, and the only risk factor associated is the basal estimated glomerular filtration rate (eGFR).

CONCLUSION

LoE 3a/b confirms lower CA perioperative complication rate and higher local progression rate than those for MIPN. CA preserves postoperative renal functional, without any evidence of differences in mid-/long-term follow-up compared to nephron sparing surgery.

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.

3-bromopyruvate: a new targeted antiglycolytic agent and a promise for cancer therapy

The pyruvate analog, 3-bromopyruvate, is an alkylating agent and a potent inhibitor of glycolysis. This antiglycolytic property of 3-bromopyruvate has recently been exploited to target cancer cells, as most tumors depend on glycolysis for their energy requirements. The anticancer effect of 3-bromopyruvate is achieved by depleting intracellular energy (ATP) resulting in tumor cell death. In this review, we will discuss the principal mechanism of action and primary targets of 3-bromopyruvate, and report the impressive antitumor effects of 3-bromopyruvate in multiple animal tumor models. We describe that the primary mechanism of 3-bromopyruvate is via preferential alkylation of GAPDH and that 3-bromopyruvate mediated cell death is linked to generation of free radicals. Research in our laboratory also revealed that 3-bromopyruvate induces endoplasmic reticulum stress, inhibits global protein synthesis further contributing to cancer cell death. Therefore, these and other studies reveal the tremendous potential of 3-bromopyruvate as an anticancer agent.

A 3-D model for chromatin organisation of G1 and G2 populations from quantitative confocal image analysis

A study on the chromatin organisation of synchronised G1 and G2 populations of maize root cell nuclei is reported using 3-D images acquired with a confocal fluorescence microscope. The analysis is based on the concept of accessibility. Accessibility of a position x is the effort to arrive at x, when choosing the minimum effort path to arrive at x from the nuclear border. The effort is then taken to be proportional to the amount of all mass encountered on the path, and computed by a technique called the grey valued distance transform. The approach relies heavily on quantitative analysis of the intensity information. Hence, considerable attention was paid to the quantitative modification of the confocal intensity values by diffraction, absorption and scatter corrections. Three texture features are extracted from the accessibility maps: the global object inaccessibility, the relative object accessibility, and the object homogeneity. On the basis of individual texture features, no distinction between the G1 and G2 populations could be established. However, the three features combined did show a clear difference with a high significance.