Temperature Simulation of an Ablation Needle for the Prediction of Tissue Necrosis during Liver Ablation.

Microwave ablation (MWA) is the leading therapy method for treating patients with liver cancer. MWA simulation is used to further improve the therapy and to help develop new devices. A water-cooled ablation needle was reconstructed.

MRI-compatible and sensorless haptic feedback for cable-driven medical robotics to perform teleoperated needle-based interventions.

Purpose: Surgical robotics have demonstrated their significance in assisting physicians during minimally invasive surgery. Especially, the integration of haptic and tactile feedback technologies can enhance the surgeon's performance and overall patient outcomes. However, the current state-of-the-art lacks such interaction feedback opportunities, especially in robotic-assisted interventional magnetic resonance imaging (iMRI), which is gaining importance in clinical practice, specifically for percutaneous needle punctures.

Reducing electromagnetic interference in MR thermometry: A comparison of setup configurations for MR-guided microwave ablations.

Magnetic Resonance (MR) thermometry is used for the monitoring of MR-guided microwave ablations (MWA), and for the intraoperative evaluation of ablation regions. Nevertheless, the accuracy of temperature mapping may be compromised by electromagnetic interference emanating from the microwave (MW) generator. This study evaluated different setups for improving magnetic resonance imaging (MRI) during MWA with a modified MW generator.

MRI-compatible abdomen phantom to mimic respiratory-triggered organ movement while performing needle-based interventions.

Purpose: In vivo studies are often required to prove the functionality and safety of medical devices. Clinical trials are costly and complex, adding to ethical scrutiny of animal testing. Anthropomorphic phantoms with versatile functionalities can overcome these issues with regard to medical education or an effective development of assistance systems during image-guided interventions (e.

Compartment-specific Xe HyperCEST z spectroscopy and chemical shift imaging of cucurbit[6]uril in spontaneously breathing rats.

Xe hyperpolarized gas chemical exchange saturation transfer (HyperCEST) MRI has been suggested as molecular imaging modality but translation to in vivo imaging has been slow, likely due to difficulties of synthesizing suitable molecules. Cucurbit[6]uril-either in readily available non-functionalized or potentially in functionalized form-may, combined with Xe HyperCEST MRI, prove useful as a switchable Xe MR contrast agent but the likely differential properties of contrast generation in individual chemical compartments as well as the influence of Xe signal drifts encountered in vivo on HyperCEST MRI are unknown. Here, HyperCEST z spectroscopy and chemical shift imaging with compartment-specific analysis are performed in a total of 10 rats using cucurbit[6]uril injected i.

A probabilistic thermal dose model for the estimation of necrosis in MR-guided tumor ablations.

Background: Monitoring minimally invasive thermo ablation procedures using magnetic resonance (MR) thermometry allows therapy of tumors even close to critical anatomical structures. Unfortunately, intraoperative monitoring remains challenging due to the necessary accuracy and real-time capability. One reason for this is the statistical error introduced by MR measurement, which causes the prediction of ablation zones to become inaccurate.

Liver segmentation using Turbolift learning for CT and cone-beam C-arm perfusion imaging.

Model-based reconstruction employing the time separation technique (TST) was found to improve dynamic perfusion imaging of the liver using C-arm cone-beam computed tomography (CBCT). To apply TST using prior knowledge extracted from CT perfusion data, the liver should be accurately segmented from the CT scans. Reconstructions of primary and model-based CBCT data need to be segmented for proper visualisation and interpretation of perfusion maps.

Free-breathing 3D Stack-of-Stars Gradient Echo Sequence in MR-guided Percutaneous Liver Interventions: Evaluation of Workflow and Diagnostic Quality.

Purpose: To evaluate workflow efficiency and diagnostic quality of a free-breathing 3D stack-of-stars gradient echo (Radial GRE) sequence compared to a breath-hold 3D Cartesian gradient echo (Cartesian GRE) sequence for needle position control in MR-guided liver interventions.

Materials And Methods: 12 MR-guided liver interventions were performed on a 1.5 T Siemens Aera and analyzed retrospectively.

Adaptive simulation of 3D thermometry maps for interventional MR-guided tumor ablation using Pennes' bioheat equation and isotherms.

Minimally-invasive thermal ablation procedures have become clinically accepted treatment options for tumors and metastases. Continuous and reliable monitoring of volumetric heat distribution promises to be an important condition for successful outcomes. In this work, an adaptive bioheat transfer simulation of 3D thermometry maps is presented.

Identification of Relevant Attributes for Liver Cancer Therapies (IRALCT): a maximum-difference-scaling analysis.

The Identification of Relevant Attributes for Liver Cancer Therapies (IRALCT) project is intended to provide new insights into the relevant utility attributes regarding therapy choices for malignant primary and secondary liver tumors from the perspective of those who are involved in the decision-making process. It addresses the potential value of taking patients' expectations and preferences into account during the decision-making and, when possible, adapting therapies according to these preferences. Specifically, it is intended to identify the relevant clinical attributes that influence the patients', medical laymen's, and medical professionals' decisions and compare the three groups' preferences.

Correction of heat-induced susceptibility changes in respiratory-triggered 2D-PRF-based thermometry for monitoring of magnetic resonance-guided hepatic microwave ablation in a human-like porcine model.

Purpose: To develop and evaluate susceptibility corrected 2D proton resonance frequency (PRF)-based magnetic resonance (MR)-thermometry for the accurate assessment of the ablation zone of hepatic microwave ablation (MWA).

Methods And Materials: Twelve hepatic MWA were performed in five LEWE minipigs with human-like fissure-free liver. Temperature maps during ablation of PRF-based MR-thermometry were corrected by modeling heat induced susceptibility changes.

Absolute thermometry using hyperpolarized Xe free-induction decay and spin-echo chemical-shift imaging in rats.

Purpose: To implement and test variants of chemical shift imaging (CSI) acquiring both free induction decays (FIDs) showing all dissolved-phase compartments and spin echoes for specifically assessing Xe in lipids in order to perform precise lipid-dissolved Xe MR thermometry in a rat model of general hypothermia.

Methods: Imaging was performed at 2.89 T.

A Real-Time Energy Monitoring System for an MRI Hybrid Ablation System.

The MRI hybrid ablation system is an approach to use the MR (magnetic resonance) scanner's radiofrequency amplifier itself as power source for ablation. Hereby, an electrode is connected to the MR internal radiofrequency amplifier. An average RF power is provided through a train of short RF pulses, which is sufficient to thermally destroy tissue.

Comparison study of reconstruction algorithms for volumetric necrosis maps from 2D multi-slice GRE thermometry images.

Cancer is a disease which requires a significant amount of careful medical attention. For minimally-invasive thermal ablation procedures, the monitoring of heat distribution is one of the biggest challenges. In this work, three approaches for volumetric heat map reconstruction (Delauney triangulation, minimum volume enclosing ellipsoids (MVEE) and splines) are presented based on uniformly distributed 2D MRI phase images rotated around the applicator's main axis.

Detection of Ablation Boundaries Using Different MR Sequences in a Swine Liver Model.

Purpose: To determine the magnetic resonance (MR) sequences best suited for the assessment of ablation zones after radiofrequency ablation (RFA).

Methods: Three percutaneous MR-guided RFA of the liver were performed on three swine. Four pre-contrast and two hepatobiliary post-contrast sequences were obtained after ablation.

First experiences and results after cryoablation of prostate cancer with histopathological evaluation and imaging-based follow-up.

To share our experience after 28 cryoablation treatments for prostate cancer (PCa) with histopathology, clinical data and MRI as the follow-up methods. Clinical follow-up comprised prostate-specific antigen (PSA)-measurements, PSA-density and quality of life-parameters. multi-parametric (mp)MRI pre- and post-cryoablation were retrospectively re-analyzed in 23 cases using Likert scores.

Design of a System for Magnetic-Resonance-Guided Irreversible Electroporation.

Irreversible electroporation (IRE) is a non-thermal tumor ablation method where strong electrical fields between at least two electrodes are used and can be seen as an alternative to thermal ablation techniques. The therapy outcome directly dependents on the position of the electrodes. Real-time monitoring of the IRE by magnetic resonance imaging (MRI) would allow to detect unwanted electrode displacement and to apply visualization methods for the ablation area.

Design and Implementation of a Test Procedure for the Evaluation of Interference Coupling in Magnetic Resonance Imaging.

External therapy devices in the shielded room of a magnetic resonance tomograph (MRT) can cause radio frequency (RF) imaging artifacts, which renders the image useless for diagnosis or guiding the procedure. At present, there is no standard procedure to evaluate their conformity with MR imaging.The aim of this paper is to adapt an already existing procedure from the electromagnetic compatibility (EMC), the reverberation chamber (RVC), to evaluate interferences in the magnetic resonance (MR) environment.

3D-Printed Floating Cable Traps for MRI guided Microwave Ablation.

Magnetic Resonance Imaging (MRI) guided Microwave Ablation (MWA) allows for real-time therapy monitoring with MRI-thermometry. The MWA generator emits Radio Frequency (RF) interference, which can limit the accuracy of therapy monitoring. The image quality is enhanced by Floating Cable Traps (FCTs) that are used to attenuate common mode currents on supply lines between a MWA generator, and its ablation applicator.

Diffusion Weighted Imaging and T2 Mapping Detect Inflammatory Response in the Renal Tissue during Ischemia Induced Acute Kidney Injury in Different Mouse Strains and Predict Renal Outcome.

To characterize ischemia reperfusion injury (IRI)-induced acute kidney injury (AKI) in C57BL/6 (B6) and CD1-mice by longitudinal functional MRI-measurement of edema formation (T2-mapping) and inflammation (diffusion weighted imaging (DWI)). IRI was induced with unilateral right renal pedicle clamping for 35min. 7T-MRI was performed 1 and 14 days after surgery.

Impact of sarcopenia in advanced and metastatic soft tissue sarcoma.

Introduction: Advanced or metastatic soft tissue sarcoma (a/mSTS) is associated with a dismal prognosis. Patient counseling on treatment aggressiveness is pivotal to avoid over- or undertreatment. Recently, evaluation of body composition markers like the skeletal muscle index (SMI) became focus of interest in a variety of cancers.

Early antihypertensive treatment and ischemia-induced acute kidney injury.

Acute kidney injury (AKI) frequently complicates major surgery and can be associated with hypertension and progress to chronic kidney disease, but reports on blood pressure normalization in AKI are conflicting. In the present study, we investigated the effects of an angiotensin-converting enzyme inhibitor, enalapril, and a soluble epoxide hydrolase inhibitor, 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl)urea (TPPU), on renal inflammation, fibrosis, and glomerulosclerosis in a mouse model of ischemia-reperfusion injury (IRI)-induced AKI. Male CD1 mice underwent unilateral IRI for 35 min.

Integration and evaluation of a gradient-based needle navigation system for percutaneous MR-guided interventions.

The purpose of the present study was to integrate an interactive gradient-based needle navigation system and to evaluate the feasibility and accuracy of the system for real-time MR guided needle puncture in a multi-ring phantom and in vivo in a porcine model. The gradient-based navigation system was implemented in a 1.5T MRI.