Stereotactic Thermal Ablation of Liver Tumors: 3D Planning, Multiple Needle Approach, and Intraprocedural Image Fusion Are the Key to Success—A Narrative Review

Thermal ablation is an emerging, potentially curative approach in treating primary and metastatic liver cancer. Different technologies are available, with radiofrequency ablation (RFA) and microwave ablation (MWA) being the most widely used. Regardless of the technique, destruction of the entire tumor, including an adequate safety margin, is key. In conventional single-probe US- or CT-guided thermal ablation, the creation of such large necrosis zones is often hampered by technical limitations, especially for large tumors (i.e., >2–3 cm). These limitations have been overcome by stereotactic RFA (SRFA): a multiple needle approach with 3D treatment planning and precise stereotactic needle placement combined with intraprocedural image fusion of pre- and post-interventional CT scans for verification of treatment success. With these sophisticated tools and advanced techniques, the spectrum of locally curable liver malignancies can be dramatically increased. Thus, we strongly believe that stereotactic thermal ablation can become a cornerstone in the treatment of liver malignancies, as it offers all the benefits of a minimally invasive method while providing oncological outcomes comparable to surgery. This article provides an overview of current stereotactic techniques for thermal ablation, summarizes the available clinical evidence for this approach, and discusses its advantages.

3D printed rodent skin-skull-brain model: A novel animal-free approach for neurosurgical training

In neuroscience, stereotactic brain surgery is a standard yet challenging technique for which laboratory and veterinary personnel must be sufficiently and properly trained. There is currently no animal-free training option for neurosurgeries; stereotactic techniques are learned and practiced on dead animals. Here we have used three-dimensional (3D) printing technologies to create rat and mouse skin-skull-brain models, specifically conceived for rodent stereotaxic surgery training. We used 3D models obtained from microCT pictures and printed them using materials that would provide the most accurate haptic feedback for each model—PC-ABS material for the rat and Durable resin for the mouse. We filled the skulls with Polyurethane expanding foam to mimic the brain. In order to simulate rodent skin, we added a rectangular 1mm thick clear silicone sheet on the skull. Ten qualified rodent neurosurgeons then performed a variety of stereotaxic surgeries on these rat and mouse 3D printed models. Participants evaluated models fidelity compared to cadaveric skulls and their appropriateness for educational use. The 3D printed rat and mouse skin-skull-brain models received an overwhelmingly positive response. They were perceived as very realistic, and considered an excellent alternative to cadaveric skulls for training purposes. They can be made rapidly and at low cost. Our real-size 3D printed replicas could enable cost- and time-efficient, animal-free neurosurgery training. They can be absolute replacements for stereotaxic surgery techniques practice including but not limited to craniotomies, screw placement, brain injections, implantations and cement applications. This project is a significant step forward in implementing the replacement, reduction, and refinement (3Rs) principles to animal experimentation. These 3D printed models could lead the way to the complete replacement of live animals for stereotaxic surgery training in laboratories and veterinary studies.

Symptomatic intracranial hemorrhages and frame-based stereotactic brain biopsy

Background: Stereotactic biopsy is a well-established procedure in neurosurgery. Our objective is to define the clinical, radiological, and technical factors that can condition the emergence of postbiopsy symptomatic intracranial hemorrhage. Based on our findings, we suggest recommendations to improve its usual clinical practice. Methods: We made a retrospective study of 429 cases with stereotactic biopsies performed in the past 37 years. The surgical procedure-was adapted in terms of the stereotactic frames (Todd-Wells, CRW, Leksell), neuroimaging tests, and planning programs available in the hospital. Fifty-three variables were analyzed for each patient (SPSS.23). Results: The diagnostic yield was 90.7%. Forty-one patients (9.5%) suffered a symptomatic postbiopsy hemorrhage; only 17 (3.9%) had permanent morbidity. The mortality was 0.93% (n = 4). A postsurgical CT scan was requested only in 99 patients (23%) of our series. Lesion mass effect, cystic component, contrast enhancement, histological nature, or number of targets were not associated with a greater risk of symptomatic postbiopsy hemorrhage (P > 0.05). On the other hand, the biopsies made by nonexpert neurosurgeons (P = 0.01) or under general anesthesia (P = 0.02) resulted in a greater risk of symptomatic postbiopsy hemorrhage. Anesthetic type was the clearest predictive factor of bleeding with this technique (OR: 0.24). Conclusion: Stereotactic biopsy is a very valuable tool. To optimize its safety and minimize the risk of intracranial bleeding, it requires both a knowledge of stereotactic techniques and very careful surgical planning. While the patient’s stay in intensive vigilance units after the procedure is a useful strategy, the request for control CT scans should be conditioned by the clinical evolution of each patient.

Ablation in Primary Liver Tumors

Minimal invasive thermal ablation techniques have a key role in the treatment regimen of primary liver tumors. These relatively low-risk procedures are established in nonresectable liver tumors and even challenge the surgical approach, which is regarded as first-line treatment in eligible patients.The location and size of the liver tumor, the applied ablation, and guidance technique are crucial for treatment outcome. The confirmation of an adequate ablation zone including sufficient tumor overlap and a safety margin (A0 ablation analogous to R0 resection) is crucial to minimize local recurrence rates and improve survival. A variety of different ablation devices is available. The outcome of conventional computed tomography- or ultrasound-guided thermal ablation in small lesions is well comparable to surgery. However, in liver lesions with large diameter overlapping ablation zones are required to ensure an adequate ablation margin. Therefore, stereotactic techniques in combination with a multiple needle approach, three-dimensional trajectory planning, and image fusion for intraoperative treatment evaluation have been successfully introduced.

Challenges Facing Radiation Oncologists in The Management of Older Cancer Patients: Consensus of The International Geriatric Radiotherapy Group

The management of older cancer patients remains difficult because of data paucity. Radiation oncologists need to identify potential issues which could affect treatment of those patients. A workshop was organized in Barcelona among international radiation oncologists with special interest in the management of older cancer patients on April 22, 2018. The following consensus was reached: 1. Older cancer patients often faced unconscious discriminating bias from cancer specialists and institutions because of their chronological age. 2. Advances in radiotherapy techniques have allowed patients with multiple co-morbidities precluding surgery or systemic therapy to achieve potential cure in early disease stages. 3. The lack of biomarkers for frailty remains an impediment to future research. 4. Access to healthcare insurance and daily transportation remains an issue in many countries; 5. Hypofractionation, brachytherapy, or stereotactic techniques may be ideally suited for older cancer patients to minimize transportation issues and to improve tolerance to radiotherapy. 6. Patients with locally advanced disease who are mentally and physically fit should receive combined therapy for potential cure. 7. The role of systemic therapy alone or combined with radiotherapy for frail patients needs to be defined in future clinical trials because of targeted agents or immunotherapy may be less toxic compared to conventional chemotherapy.

An Overview of Robotics in Functional Neurosurgery

Stereotactic techniques are used in a wide range of neurosurgical procedures. The procedures demand a high degree of spatial accuracy and minimal error. There are diverse functional surgeries that require stereotactic procedures, including deep brain stimulation, brain biopsies, and epilepsy procedures. Though the disease processes are diverse, all these procedures require accurate targeting of deep structures without visual guidance. The use of robots for stereotactic procedures is a natural progression in the surgeon's quest for higher accuracy and lower complications. This paper reviews the role of robots in stereotactic procedures and outlines current status of robots in stereotactic procedures. The shortcomings of current systems and an outline of an ideal stereotactic device are presented.

Frame-based Stereotactic Biopsy: Description and Association of Anatomical, Radiologic, and Surgical Variables with Diagnostic Yield in a Series of 407 Cases

Background and Study Aims Stereotactic biopsy is a versatile, minimally invasive technique to obtain tissue safely from intracranial lesions for their histologic diagnosis and therapeutic management. Our objective was to determine the anatomical, radiologic, and technical factors that can affect the diagnostic yield of this technique. We suggest recommendations to improve its use in clinical practice. Methods This retrospective study evaluated 407 patients who underwent stereotactic biopsies in the past 34 years. The surgical methodology changed through time, distinguished by three distinct periods. Different stereotactic frames (Todd-Wells, CRW, Leksell), neuroimaging tests, and planning programs were used. Using SPSS software v.23, we analyzed a total of 50 variables for each case. Results The series included 265 men (65.1%) and 142 women (34.9%) (average age 53.8 years). The diagnostic yield was 90.4%, morbidity was 5.65% (n = 17), and mortality was 0.98% (n = 4). Intraoperative biopsy improved accuracy (p = 0.024). Biopsies of deep lesions (p = 0.043), without contrast enhancement (p = 0.004), edema (p = 0.036), extensive necrosis (p = 0.028), or a large cystic component (p = 0.023) resulted in a worse diagnostic yield. Neurosurgeons inexperienced in stereotactic techniques obtained more nondiagnostic biopsies (p = 0.043). Experience was the clearest predictive factor of diagnostic yield (odds ratio: 4.049). Conclusions Increased experience in stereotactic techniques, use of the most suitable magnetic resonance imaging sequences during biopsy planning, and intraoperative evaluation of the sample before finalizing the collection are recommended features and ways to improve the diagnostic yield of this technique.

History of Invasive EEG

‘History of Invasive EEG’ traces the development of electroencephalography (EEG) from the pioneering animal studies of Richard Caton (1875) up to the more recent development of stereoencephalography (SEEG) and large subdural electrodes. The following historical highlights are discussed: the first recording of EEG seizures in animals (PY Kaufman); the first recording of EEG in humans (Hans Berger); the first recording of interictal and ictal epileptiform discharges in humans (Hans Berger); the important role played by Reginald Bickford, Carl Sem-Jacobsen, and Jose Delgado in the development of chronically implanted invasive recordings; the development of stereotactic techniques for precise insertion of depth electrodes (Jean Talairach and Jean Bancaud); the use of large subdural plates for recording of EEG and cortical stimulation of extensive cortical regions.

Fractionated stereotactic radiotherapy for the treatment of optic nerve sheath meningiomas

Radiosurgery has become an important treatment alternative to surgery for a variety of intracranial lesions. As currently practiced, it has in fact replaced surgery as a standard of care in some instances, compliments surgery as a post-operative adjunct in others, and most commonly represents an alternative to surgery or the only treatment option. Radiosurgery techniques have evolved quickly with the development of new technologies enabling more complex yet more efficient treatment plans. As a consequence, these technologies have broadened radiosurgery applications and improved radiosurgery outcomes. Among these newer techniques, treatments involving fractionated stereotactic radiation referred to as fractionated stereotactic radiotherapy, or FSR, have emerged as a consequence of linear accelerators designed for and dedicated to stereotactic techniques. Without the logistical constraints of retrofitted general purpose linear accelerators used in radiation oncology, often available only once or twice a week, dedicated units have enabled the design of treatment paradigms that strive for an ideal treatment based on the radiobiology of the target and dose-limiting contiguous tissues.This chapter will summarize our fifteen year experience with the Varian 600SR, initially with the Radionics software more recently modified to a Novalis shaped beam radiosurgery unit, and our practice of FSR for a variety of intracranial lesions. Special attention will be devoted to tumors involving or near the special sensory cranial nerves. Given the versatility of the Novalis treatment planning platform, one has the option of comparing different treatment planning solutions at once, including stereotactic intensity-modulated radiation therapy (IMRT). For selected skull base lesions, we have found that stereotactic IMRT yields greater conformality than FSR and we will therefore include its application among fractionation strategies.