Interventional magnetic-resonance-guided cryotherapy combined with microsurgery for recurrent glioblastoma: An innovative treatment?

BACKGROUND: Glioblastoma invariably recurs after primary Stupp tumor therapy and portends a poor prognosis. Cryoablation is a well-established treatment strategy for extra-cranial tumors. The safety and efficacy of interventional MR-guided cryoablation (iMRgC) has not been explored in recurrent glioblastoma. METHODS: A retrospective analysis of data collected over a period of 24 months was performed. The inclusion criteria were: (I) recurrent glioblastoma despite Stupp protocol; (II) MRI followed by histological confirmation of recurrent glioblastoma; (III) location allowing iMRgC followed by microsurgical resection; and (IV) patient's consent. The primary objective was to assess feasibility in terms of complications. The secondary objective was to analyze progression-free survival (PFS), post-iMRgC survival and overall survival (OS). RESULTS: The study included 6 patients, with a mean age of 67±7.6 years [range, 54-70 years]. No major complications were observed. Median PFS was 7.5 months [IQR 3.75-9.75] and 6-month PFS was 50%. Median post-iMRgC survival was 9 months [IQR 7.5-15.25] and 6-month post-iMRgC survival was 80%. Median OS was 22.5 months [IQR 21.75-30]. CONCLUSION: iMRgC for recurrent glioblastoma demonstrated a good safety profile, with no major complications. Our data suggest improved PFS and OS. TRIAL REGISTRATION NUMBER: No. IRB00011687 retrospectively registred on July 7th 2021.

The Cryo-immunologic effect: A therapeutic advance in the treatment of glioblastomas?

The immunotherapy of cerebral glioblastoma has become a hot topic. Immune checkpoint blockade antibodies have progressively acquired a role in the management of malignant tumors. A multimodal approach using surgery, radiotherapy, chemotherapy in combination with immunotherapy represent a potent weapon against glioblastomas. In parallel, clinical applications of cryotherapy-freezing tumors based on repetition of rapid freeze-slow thaw cycle-for various cancers such as skin, lung, breast, esophagus, hepatic, kidney, prostate and bone tumors were developed. The future immunomodulatory approaches might be combined with brain tumors cryoablation to increase the cryoimmune response. The objective of this study was to analyze from the literature the relationship between cerebral cryosurgery and immunomodulation using PRISMA method. The animals' studies demonstrate the dendritic cells maturation and activation with the enhancement of antigen-presenting function after cryotherapy suggesting the potential usefulness of the association of cryotherapy and immunomodulator in the management of gliomas.

Evaluation of percutaneous biopsies of renal masses under MRI-guidance: a retrospective study about 26 cases.

OBJECTIVE: To determine whether MRI allows safe and accurate guidance for biopsies of renal masses. MATERIALS AND METHODS: Between May 2010 and September 2013, 26 patients (15 men and 11 women) with 26 renal masses underwent MRI-guided percutaneous biopsy. For each patient, we retrospectively collected the epidemiological, procedural and histopathological data. RESULTS: Mean size of tumour was 3.6 cm (range 0.6 - 9 cm). Mean procedure time was 48 minutes (range 37 - 70 min). Malignancy was found in the percutaneous samples in 81 % (21/26) of the masses. All these cases were considered as true positive biopsies. Benignity was found in the percutaneous samples in 5/26 (19 %) of the masses but was confirmed only in 3 cases. The other 2 cases included one false negative case and one undetermined biopsy, as patient was lost to follow-up. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of this study were 95.4 %, 100 %, 100 %, 75 % and 96 %, respectively CONCLUSION: MRI-guidance is safe and accurate to target renal masses.

Towards a Hall effect magnetic tracking device for MRI.

This paper presents the first prototype of a magnetic tracking device for Magnetic Resonance Imaging. The unique relationship between the space coordinates of a MRI scanner bore and the magnetic field gradients used in MRI allows building a localization system based on an accurate measurement of these gradients. These gradients are measured thanks to a 3D Hall device with a footprint of only 50µm(2), integrated with its specific conditioning circuit in a low cost, low voltage 0.35µm CMOS process. The first experimental results show that a sub-millimeter localization is possible. It opens the way to the development of MRI compatible magnetic tracking systems integrable in a surgical tool.

A custom robot for Transcranial Magnetic Stimulation: first assessment on healthy subjects.

In this paper, a custom robotic system for Transcranial Magnetic Stimulation is assessed in clinical conditions on healthy subjects. A motor cortex mapping is performed using the robotic system with comparison to a manual approach using a neuronavigation system. Stimulation accuracy, repeatability are evaluated as well as the feeling of the system operator and the subject in terms of comfort, tiredness, stress level, ease-of-use. Very encouraging results are obtained on all these aspects, which strengthens the idea of developing robotic assistance for TMS.

Evaluation of an image-based tracking workflow using a passive marker and resonant micro-coil fiducials for automatic image plane alignment in interventional MRI.

In this paper, an original workflow is presented for MR image plane alignment based on tracking in real-time MR images. A test device consisting of two resonant micro-coils and a passive marker is proposed for detection using image-based algorithms. Micro-coils allow for automated initialization of the object detection in dedicated low flip angle projection images; then the passive marker is tracked in clinical real-time MR images, with alternation between two oblique orthogonal image planes along the test device axis; in case the passive marker is lost in real-time images, the workflow is reinitialized. The proposed workflow was designed to minimize dedicated acquisition time to a single dedicated acquisition in the ideal case (no reinitialization required). First experiments have shown promising results for test-device tracking precision, with a mean position error of 0.79 mm and a mean orientation error of 0.24°.

Can injection CT scan assess the residual femoral head vascularity after acute neck fracture?

INTRODUCTION: Femoral neck fracture jeopardizes the vital prognosis of the elderly subject and the functional prognosis of the young subject. The vascular consequence is important, with the risk of osteonecrosis of the femoral head. In young patients, predicting the risk of necrosis at the acute stage seems warranted so as to optimize the choice of therapy. CT with injection could be useful to study the residual bone vascularity after an acute fracture of the femoral neck. HYPOTHESIS: The CT scan with injection can diagnose ischemia of the femoral head after neck fracture by demonstrating hypoperfusion and thus estimating the risk for osteonecrosis. PATIENTS AND METHOD: A CT scan with injection was performed prospectively in 20 adult patients who had given informed consent after verification of the inclusion and exclusion criteria. Ten presented femoral neck fracture and 10 a pertrochanteric fracture, the latter making up the control group. The second control group was the healthy side of patients presenting a femoral neck fracture. The images were analyzed after delineating a region of interest as a volume at the center of the femoral head. The results were analyzed after modeling based on the physical principle of diffusion. RESULTS: No differences were found between the "healthy hip," "fractured hip," "femoral neck fracture," and "trochanteric region fracture" groups. The only statistically significant correlation was found between the "fractured hip" and "healthy hip" of the same patient independently of the type of fracture. DISCUSSION: The results do not confirm the working hypothesis. This study was mainly limited by the small number of patients included, but this did not substantially effect the study's conclusions. According to the results, it seems that this study provided a CT evaluation of bone mineral density. At the end of the study, it seems that CT with injection is not well adapted in assessing residual femoral head vascularity or estimating the risk of progression towards avascular necrosis. According to the literature, only dynamic MRI with injection seems to be effective in this assessment and estimation. LEVEL OF EVIDENCE: Level III prospective comparative diagnostic.

Design considerations for a novel MRI compatible manipulator for prostate cryoablation.

PURPOSE: Prostate carcinoma is a commonly diagnosed cancer in men. Nonsurgical treatment of early stage prostate cancer is an important alternative. The use of MRI for tumor cryoablation is of particular interest: it offers lower morbidity compared with other localized techniques. However, the current manual procedure is very time-consuming and has limited accuracy. A novel robotic assistant is therefore designed for prostate cancer cryotherapy treatment under MRI guidance to improve efficiency and accuracy. METHODS: Gesture definition was achieved based on actions of interventional radiologists at University Hospital of Strasbourg. A transperineal approach with a semiautonomous prostatic cryoprobe localization procedure was developed where the needle axis is automatically positioned before manual insertion. The workflow was developed simultaneously with the robotic assistant used for needle positioning. RESULTS: The design and the associated workflow of an original wire-driven manipulator were developed. The device is compact and has a low weight: its overall dimensions in the scanner are 100 × 100 × 40 mm with a weight of 120 g. Very good MRI compatibility was demonstrated. CONCLUSIONS: A novel cryoablation procedure based on the use of a robotic assistant is proposed. The device design was presented with demonstration of MRI compatibility. Further developments include automatic registration and in vivo experimental testing.

Early prediction of femoral head avascular necrosis following neck fracture.

Femoral neck fracture puts at risk functional prognosis in young patients and can be life-threatening in the elderly. The present study reviews methods of femoral head vascularity assessment following neck fracture, to address the following issues: what is the risk of osteonecrosis? And what, in the light of this risk, is the best-adapted treatment to avoid iterative surgery? Femoral head vascularity depends on retinacular vessels and especially the lateral epiphyseal artery, which contributes from 70 to 80% of the femoral head vascular supply. Fracture causes vascular lesions, which are in turn the prime cause of necrosis. Other factors combine with this: hematoma tamponade effect, reduced joint space and increased pressure due to lower extremity positioning in extension/internal rotation/abduction during surgery. Head deformity is not due to direct cell death but to the repair process originating from the surrounding living bone. In post-traumatic necrosis, proliferation rapidly invades the head, with significant osteogenesis. Pathologic fractures occur at the boundary between the new and dead bone. Many techniques have been reported to help assess residual hemodynamics and risk of necrosis. Some are invasive: superselective angiography, intra-osseous oxygen pressure measurement, or Doppler-laser hemodynamic measurement; others involve imaging: scintigraphy, conventionnal or dynamic MRI. The future seems to lie with dynamic MRI, which allows a new classification of femoral neck fractures, based on a non-invasive assessment of femoral head vascularity.

Comparison of visual tracking algorithms on in vivo sequences for robot-assisted flexible endoscopic surgery.

Flexible endoscopes are used in many diagnostic and interventional procedures. Physiological motions may render the physician's task very difficult to perform. Assistance could be achieved by using motorized endoscopes and real-time visual tracking algorithm to automatically follow a selected target. In order to control the motors, one needs to have an accurate estimation of the motion of the target in the endoscopic view, which requires an efficient tracking algorithm. In this paper, we compare tracking algorithms on various in vivo targets in order to assess their behavior under different conditions. The study shows that among the difficulties which arise when tracking an in vivo target, the change of illumination is paramount. Nevertheless, some algorithms, with minor modifications and without a priori knowledge about the target, achieve very good results.