Magnetic Resonance Imaging Guidance Research Articles

Harnessing the Power of Radiotherapy for Lung Cancer: A Narrative Review of the Evolving Role of Magnetic Resonance Imaging Guidance

Compared with computed tomography (CT), magnetic resonance imaging (MRI) traditionally plays a very limited role in lung cancer management, although there is plenty of room for improvement in the current CT-based workflow, for example, in structures such as the brachial plexus and chest wall invasion, which are difficult to visualize with CT alone. Furthermore, in the treatment of high-risk tumors such as ultracentral lung cancer, treatment-associated toxicity currently still outweighs its benefits. The advent of MR-Linac, an MRI-guided radiotherapy (RT) that combines MRI with a linear accelerator, could potentially address these limitations. Compared with CT-based technologies, MR-Linac could offer superior soft tissue visualization, daily adaptive capability, real-time target tracking, and an early assessment of treatment response. Clinically, it could be especially advantageous in the treatment of central/ultracentral lung cancer, early-stage lung cancer, and locally advanced lung cancer. Increasing demands for stereotactic body radiotherapy (SBRT) for lung cancer have led to MR-Linac adoption in some cancer centers. In this review, a broad overview of the latest research on imaging-guided radiotherapy (IGRT) with MR-Linac for lung cancer management is provided, and development pertaining to artificial intelligence is also highlighted. New avenues of research are also discussed.

Optimizing Glioma Resection Outcomes: A Systematic Review of Intraoperative Magnetic Resonance Imaging Guidance in Neurosurgery

Optimizing Glioma Resection Outcomes: A Systematic Review of Intraoperative Magnetic Resonance Imaging Guidance in Neurosurgery

Targeting Hydrogel for Intelligent Recognition and Spatiotemporal Control in Cell-Based Therapeutics.

Smart drug platforms based on spatiotemporally controlled release and integration of tumor imaging are expected to overcome the inefficiency and uncertainty of traditional theranostic modes. In this study, a composite consisting of a thermosensitive hydrogel (polyvinyl alcohol-carboxylic acid hydrogel (PCF)) and a multifunctional nanoparticle (Fe3O4@Au/Mn(Zn)-4-carboxyphenyl porphyrin/polydopamine (FAMxP))is developed to combine tumor immunogenic cell death (ICD)/immune checkpoint blockade (ICB) therapy under the guidance of magnetic resonance imaging (MRI) and fluorescence imaging (FI). It can not only further recognize the target cells through the folate receptor of tumor cells, but also produce thermal dissolution after exposure to near-infrared light to slowly release FAMxP in situ, thereby prolonging the treatment time and avoiding tumor recurrence. As FAMxP entered the tumor cells, it released FAMx in a pH-dependent manner. Chemodynamic, photothermal and photodynamic therapy can cause significant ICD in cancer cells. ICB can thus be further enhanced by injecting anti-programmed cell death ligand 1, improving the effectiveness of tumor treatment. The developed PCF-FAMxP composite hydrogel may represent an updated drug design approach with simple compositions for cooperative MRI/FI-guided targeted therapeutic pathways for tumors.

Motion Accuracy of Pneumatic Stepper Motor-Driven Robotic System Developed for MRI-Guided High-Intensity Focused Ultrasound Treatment of Prostate Disease

The latest advancement in high-intensity focused ultrasound (HIFU) treatment technology integrates magnetic resonance imaging (MRI) guidance for precise treatment of prostate disease. As conventional electromagnetic motors are not applicable for utilization within MRI scanners, we have developed a prototype robotic system driven by pneumatic stepper motors to control the movement of the HIFU transducer within an intrarectal probe during MRI-guided HIFU treatment procedures. These pneumatic stepper motors were constructed entirely from MRI-compatible plastic materials. Assessment of the robotic system’s MRI compatibility was conducted utilizing a 3.0T MRI scanner, revealing no discernible MRI image distortion with a minor decrease in the signal-to-noise ratio (2.8%) during the motor operation. The robotic system enabled the transducer to move inside the probe with two degrees of freedom, allowing both linear and rotational motion. The positional accuracy of the transducer movement was assessed, yielding ±0.20 and ±0.22 mm accuracies in the forward and backward linear movements, respectively, and ±0.79° and ±0.74° accuracies in the clockwise and counterclockwise rotational motions, respectively. Emulation of authentic HIFU procedures involved creating a two-dimensional array of thermal lesions in a tissue-mimicking phantom, achieving positional accuracy within ±1 mm for the generated HIFU focal spots. The prototype robotic system incorporating pneumatic stepper motors fabricated entirely from MRI-compatible plastic materials has demonstrated the requisite positional accuracy necessary for effective HIFU treatment of prostate disease, indicating substantial promise for future clinical application.

Cornerstone for MRI-compatible robots: A continuous pneumatic actuator with easy-to-connect prismatic/revolute and bidirectional encoder modules

The exceptional imaging capability of magnetic resonance imaging (MRI) enables the applications of robot-assisted surgery under MRI guidance. Essential to these robotic systems are the MRI-compatible robotic joint actuators. Among various actuation methods using MRI-compatible materials, pneumatic actuators are considered the most suitable for this application scenario due to their sterility, safety, and reliability. Yet, the current pneumatic actuators are either bulky, inefficient, or cannot achieve accurate bidirectional continuous motion. As a step forward, a novel high-performance continuous MRI-compatible pneumatic motor is proposed, along with quick-connect revolute/prismatic motion output modules and high accurate bidirectional encoder modules. The high performance of the pneumatic rotary and linear actuators are evaluated through experimental testing, where the rotary actuator can provide up to 2 Nm of output torque and over 28 W of output power, while the linear variant can deliver over 50 N of thrust, which surpass the SOTA competitors. Corresponding dynamic models are established and verified via experiments, with a maximum error of only 2.01%. Closed-loop control experiments demonstrate the high control precision and fast response frequency of the proposed pneumatic actuators, promoting the performance of joint actuators of various MRI-compatible surgical robots.

The impact of motion on onboard MRI-guided pencil beam scanned proton therapy treatments

Objective. Online magnetic resonance imaging (MRI) guidance could be especially beneficial for pencil beam scanned (PBS) proton therapy of tumours affected by respiratory motion. For the first time to our knowledge, we investigate the dosimetric impact of respiratory motion on MRI-guided proton therapy compared to the scenario without magnetic field. Approach. A previously developed analytical proton dose calculation algorithm accounting for perpendicular magnetic fields was extended to enable 4D dose calculations. For two geometrical phantoms and three liver and two lung patient cases, static treatment plans were optimised with and without magnetic field (0, 0.5 and 1.5 T). Furthermore, plans were optimised using gantry angle corrections (0.5 T +5° and 1.5 T +15°) to reproduce similar beam trajectories compared to the 0 T reference plans. The effect of motion was then considered using 4D dose calculations without any motion mitigation and simulating 8-times volumetric rescanning, with motion for the patient cases provided by 4DCT(MRI) data sets. Each 4D dose calculation was performed for different starting phases and the CTV dose coverage V 95% and homogeneity D 5%–D 95% were analysed. Main results. For the geometrical phantoms with rigid motion perpendicular to the beam and parallel to the magnetic field, a comparable dosimetric effect was observed independent of the magnetic field. Also for the five 4DCT(MRI) cases, the influence of motion was comparable for all magnetic field strengths with and without gantry angle correction. On average, the motion-induced decrease in CTV V 95% from the static plan was 17.0% and 18.9% for 1.5 T and 0.5 T, respectively, and 19.9% without magnetic field. Significance. For the first time, this study investigates the combined impact of magnetic fields and respiratory motion on MR-guided proton therapy. The comparable dosimetric effects irrespective of magnetic field strength indicate that the effects of motion for future MR-guided proton therapy may not be worse than for conventional PBS proton therapy.

Transcutaneous Ablation of Lung Tissue in a Porcine Model Using Magnetic-Resonance-Guided Focused Ultrasound (MRgFUS).

Focused ultrasound (FUS) is a minimally invasive treatment that utilizes high-energy ultrasound waves to thermally ablate tissue. Magnetic resonance imaging (MRI) guidance may be combined with FUS (MRgFUS) to increase its accuracy and has been proposed for lung tumor ablation/debulking. However, the lungs are predominantly filled with air, which attenuates the strength of the FUS beam. This investigation aimed to test the feasibility of a new approach using an intentional lung collapse to reduce the amount of air inside the lung and a controlled hydrothorax to create an acoustic window for transcutaneous MRgFUS lung ablation. Eleven pigs had one lung mechanically ventilated while the other lung underwent a controlled collapse and subsequent hydrothorax of that hemisphere. The MRgFUS lung ablations were then conducted via the intercostal space. All the animals recovered well and remained healthy in the week following the FUS treatment. The location and size of the ablations were confirmed one week post-treatment via MRI, necropsy, and histological analysis. The animals had almost no side effects and the skin burns were completely eliminated after the first two animal studies, following technique refinement. This study introduces a novel methodology of MRgFUS that can be used to treat deep lung parenchyma in a safe and viable manner.

A multi-mode Rhein-based nano-platform synergizing ferrotherapy/chemotherapy-induced immunotherapy for enhanced tumor therapy

Ferroptosis has emerged as a promising strategy for treating triple-negative breast cancer (TNBC) due to bypassing apoptosis and triggering immunogenic cell death (ICD) of tumor cells. However, the antitumor efficacy has been limited by the insufficient intracellular ferrous iron concentration required for ferroptosis and inadequate antitumor immune response. To address these limitations, we designed a multi-mode nano-platform (MP-FA@R-F NPs), which exhibited a synergistic effect of ferroptosis, apoptosis and induced immune response for enhanced antitumor therapy. MP-FA@R-F NPs target folate receptors, which are over-expressed on the tumor cell's surface to promote intracellular uptake. The cargoes, including Rhein and Fe3O4, would be released in intracellular acid, accelerating by NIR laser irradiation. The released Rhein induced apoptosis of tumor cells mediated by the caspase 3 signal pathway, while the released Fe3O4 triggered ferroptosis through the Fenton reaction and endowed the nanoplatform with magnetic resonance imaging (MRI) capabilities. In addition, ferroptosis-dying tumor cells could release damage-associated molecular patterns (DAMPs) to promote T cell activation and infiltration for immune response and induce immunogenic cell death (ICD) for tumor immunotherapy. Together, MP-FA@R-F NPs represent a potential synergistic ferro-/chemo-/immuno-therapy strategy with MRI guidance for enhanced antitumor therapy. Statement of significanceThe massive strategies of cancer therapy based on ferroptosis have been emerging in recent years, which provided new insights into designing materials for cancer therapy. However, the antitumor efficacy of ferroptosis is still unsatisfactory, mainly due to insufficient intracellular pro-ferroptotic stimuli. In the current study, we designed a multi-mode nano-platform (MP-FA@R-F NPs), which represented a potential synergistic ferro-/chemo-/immuno-therapy strategy with MRI guidance for enhanced antitumor therapy.

Design and Analysis of an MRI-Compatible Soft Needle Manipulator

Needle manipulation with the guidance of magnetic resonance imaging (MRI) plays a key role in minimally invasive procedures such as biopsy and ablation. However, the confined bore and strong magnetic field of the MR environment pose great challenges in developing a robotic system that fulfills the needle manipulation function. This paper presents the design and analysis of a soft needle manipulator (SoNIM) that can achieve needle manipulation in the MR environment. This pneumatically actuated manipulator consists of two bending actuators and one elongation actuator that are completely made of non-magnetic materials. These soft pneumatic actuators can generate flexible movements while maintaining a compact design, ensuring that the SoNIM is accommodated within the MRI bore. The kinematic modeling and closed-loop control of the SoNIM are investigated to achieve the position control of the needle tip. Experiments showed that the SoNIM was capable of directing the needle tip to reach the targets with a satisfactory accuracy of 2.9 ± 0.98 mm. Furthermore, the functionality and MRI compatibility of the SoNIM were validated in the clinical setting, demonstrating the capability of the SoNIM to perform needle manipulation in the MRI bore with negligible degradation to the image quality. With excellent MRI compatibility, compact design, and flexible movements, the SoNIM provides a promising solution for manipulating surgical needles in MRI-guided minimally invasive surgeries.

Abstract A005: A multi-institutional randomized phase III trial of chemotherapy alone versus chemotherapy and ablative 5-fraction MRI-guided adaptive radiation therapy for locally advanced pancreatic cancer (LAP-ABLATE)

Abstract Background: Prospective studies demonstrate that chemotherapy and non-ablative radiation therapy (RT) achieve superior locoregional control (LRC) although have not improved overall survival (OS) relative to chemotherapy alone for patients with locally advanced pancreatic cancer (LAPC). Emerging data suggest that significant radiation dose escalation may further enhance LRC, and it has been hypothesized that in a subset of patients this may improve OS. However, delivering ablative radiation dose in 5 or fewer fractions with computerized tomography (CT) guidance is associated with unacceptable rates of grade 3-5 toxicity. Safe dose escalation can be facilitated by radiation delivery systems that utilize magnetic resonance image (MRI) guidance and on-table adaptive replanning. A growing body of literature describes promising efficacy and safety of ablative 5-fraction stereotactic MRI-guided adaptive radiation therapy (SMART) for LAPC compared to historical non-ablative outcomes. Based on these encouraging results, the LAP-ABLATE trial has been designed to test the hypothesis that ablative SMART improves OS. Methods: The LAP-ABLATE trial is a multi-institutional group sequential randomized phase III study for patients with LAPC. Patients are eligible after first receiving 4-6 months of (modified)FOLFIRINOX or gemcitabine/nab-paclitaxel with either stable or responding disease. Other key eligibility criteria include CA 19-9 <180 U/mL and no contraindication to undergoing MRI scans. Patients are randomized (1:2) to receiving no ablative SMART (arm A) versus ablative SMART (arm B), with subsequent systemic therapy or surgery being optional in both arms. Ablative SMART will be delivered using the MRIdian Linac, a 0.35 Tesla MRI-guided linear accelerator. The prescribed dose is 50 Gy to gross disease and 33 Gy to elective regions in 5 fractions using a simultaneous integrated boost (SIB). The primary objective is to compare 2-year OS with secondary objectives including assessment of LRC, distant metastasis free survival (DMFS), progression-free survival (PFS), quality of life (QOL), and toxicity. Randomization will be stratified by participating center, baseline CA 19-9 level and induction chemotherapy regimen. Target accrual is 267 patients (arm A: 89, arm B: 178). Discussion: The LAP-ABLATE trial is the first prospective randomized phase III study designed to compare OS in LAPC patients following induction systemic therapy randomized to with or without ablative 5-fraction RT. Citation Format: Michael D. Chuong, Jessica M. Frakes, Kathryn E. Mittauer, James Good, Josh Kim, Daniel Chang, Dae Won Kim, Stefanie Corradini, Luca Boldrini, Mokenge Malafa, Eileen O'Reilly. A multi-institutional randomized phase III trial of chemotherapy alone versus chemotherapy and ablative 5-fraction MRI-guided adaptive radiation therapy for locally advanced pancreatic cancer (LAP-ABLATE) [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A005.

Magnetic resonance imaging-guided radiofrequency ablation of breast cancer: a current state of the art review.

With a gradual increase in breast cancer incidence and mortality rates and an urgent need to improve patient prognosis and cosmetology, magnetic resonance imaging (MRI)-guided radiofrequency ablation (RFA) therapy has attracted wide attention as a new treatment method for breast cancer. MRI-RFA results in a higher complete ablation rate and extremely low recurrence and complication rates. Thus, it may be used as an independent treatment for breast cancer or adjuvant to breast-conserving surgery to reduce the extent of breast resection. Furthermore, with MRI guidance, accurate control of RFA can be achieved, and breast cancer treatment can enter a new stage of minimally invasive, safe, and comprehensive therapy. With progress in MR thermometry technology, the applications of MRI are expected to broaden.

Functional Outcomes of Patients Who Underwent Anorectal Malformation Repair Using MRI Guidance

BackgroundDespite the initiation of minimally invasive laparoscopic techniques, the majority of patients who undergo anorectal malformation repair still experience functional bowel issues in childhood, including constipation and fecal incontinence. In this study, we evaluate the functional outcomes of a procedure in which magnetic resonance imaging guidance is used during initial laparoscopic repair to better locate the epicenter of the sphincter muscle complex and pelvic floor with the goal of more accurate placement of the neoanus and improved functional outcomes. MethodsA retrospective chart review evaluated demographic, operative, and outcome details for patients who underwent this procedure. A telephone survey was employed to determine levels of social continence using the validated Baylor Continence Scale and to determine what type of bowel management is used. ResultsTwenty-six patients were included. Median age at operation was 7 months, and median age at follow-up was 4 years old, with a range of 1–9. Bowel management regimen results revealed that 19 % (n = 5) use no bowel management regimen, 58 % (n = 15) use laxatives only, and 23 % (n = 6) use enemas. Enema use was not associated with different spine or sacral anomalies (p = 0.77). Fifteen patients (58 %) answered the Baylor Continence Scale questions and had a median score of 14. No difference was found in scores when accounting for lesion level (p = 0.43), quality of needle placement (p = 0.46), or quality of sphincter muscles (p = 0.75). ConclusionsUsing MRI guidance in the repair of anorectal malformations shows promise in both the qualitative and quantitative functional outcomes of this complex patient population. Level of EvidenceLevel III.

A new bimodal approach for sentinel lymph node imaging in prostate cancer using a magnetic and fluorescent hybrid tracer

PurposeTo obtain initial data on sentinel lymph node (SLN) visualisation by pre-operative magnetic resonance imaging (MRI) and intra-operative bimodal SLN identification using a new magnetic fluorescent hybrid tracer in prostate cancer (PCa) patients.MethodsTen patients at > 5% risk for lymph node (LN) invasion were included. The day before surgery, a magnetic fluorescent hybrid tracer consisting of superparamagnetic iron oxide nanoparticles (SPION) and indocyanine green was transrectally injected into the prostate. Five hours after injection, transversal pelvic MRI scans were recorded and T2*-weighed images were screened for pelvic LNs with SPION uptake. Intra-operatively, magnetically active and/or fluorescent SLNs were detected by a handheld magnetometer and near-infrared fluorescence imaging (FI). Extended pelvic lymph node dissection (PLND) and radical prostatectomy completed the surgery. All resected specimens were checked ex situ for magnetic activity and fluorescence and were histopathologically examined.ResultsPre-operative MRI identified 145 pelvic LNs with SPION uptake. In total, 75 (median 6, range 3‒13) magnetically active SLNs were resected, including 14 SLNs not seen on MRI. FI identified 89 fluorescent LNs (median 8.5, range 4‒13) of which 15 LNs were not magnetically active. Concordance of the different techniques was 70% for pre-operative MRI vs. magnetometer-guided PLND and 88% for magnetic vs. fluorescent SLN detection.ConclusionThese are the first promising results of bimodal, magnetic fluorescent SLN detection in PCa patients. Our magnetic fluorescent hybrid approach provides the surgeon a pre-operative lymphatic roadmap by using MRI and intra-operative visual guidance through the application of a fluorescent lymphatic agent. The diagnostic accuracy of our new hybrid approach has to be evaluated in further studies.Trial registrationDRKS00032808. Registered 04 October 2023, retrospectively registered.

An MR Compatible Vascular Stenosis Method Based on Fiber Bragg Grating

Progressive stenosis of blood vessels is an important cause of cardiovascular diseases. Traditional intervention methods rely on fluoroscopy, which exposes both patients and operators to ionizing radiation. In this paper, we propose a real-time detection method for vascular stenosis intervention based on Fiber Bragg Grating (FBG) sensors that can be used under magnetic resonance imaging (MRI) guidance. An FBG sensor array with 5 sensors is developed and validated using a vascular flow phantom that simulates the morphological features of stenoses. We first verify the sensor for measuring vascular stenosis through flow rate and profile using the FBG sensor array, followed by a detailed assessment of the MRI compatibility of the sensor in terms of imaging artefact and changes in SNR, The error of FBG array is within the range of ±10με, the SNR variation is 3.608%, indicating that the FBG sensor array has excellent MR image compatibility. Experiment results show a good correlation between the degrees of stenoses with strain measurements, thus offering real-time information to aid MR guided vascular intervention.

Evaluation of synthetically generated computed tomography for use in transcranial focused ultrasound procedures.

Transcranial focused ultrasound (tFUS) is a therapeutic ultrasound method that focuses sound through the skull to a small region noninvasively and often under magnetic resonance imaging (MRI) guidance. CT imaging is used to estimate the acoustic properties that vary between individual skulls to enable effective focusing during tFUS procedures, exposing patients to potentially harmful radiation. A method to estimate acoustic parameters in the skull without the need for CT is desirable. We synthesized CT images from routinely acquired T1-weighted MRI using a 3D patch-based conditional generative adversarial network and evaluated the performance of synthesized CT (sCT) images for treatment planning with tFUS. We compared the performance of sCT with real CT (rCT) images for tFUS planning using Kranion and simulations using the acoustic toolbox, k-Wave. Simulations were performed for 3 tFUS scenarios: (1)no aberration correction, (2)correction with phases calculated from Kranion, and (3)phase shifts calculated from time reversal. From Kranion, the skull density ratio, skull thickness, and number of active elements between rCT and sCT had Pearson's correlation coefficients of 0.94, 0.92, and 0.98, respectively. Among 20 targets, differences in simulated peak pressure between rCT and sCT were largest without phase correction () and smallest with Kranion phases (). The distance between peak focal locations between rCT and sCT was for all simulation cases. Real and synthetically generated skulls had comparable image similarity, skull measurements, and acoustic simulation metrics. Our work demonstrated similar results for 10 testing cases comparing MR-sCTs and rCTs for tFUS planning. Source code and a docker image with the trained model are available at https://github.com/han-liu/SynCT_TcMRgFUS.

Mn2+ /Ir3+ -Doped and CaCO3 -Covered Prussian Blue Nanoparticles with Indocyanine Green Encapsulation for Tumor Microenvironment Modulation and Image-Guided Synergistic Cancer Therapy.

The development of smart theranostic nanoplatforms has gained great interest in effective cancer treatment against the complex tumor microenvironment (TME), including weak acidity, hypoxia, and glutathione (GSH) overexpression. Herein, a TME-responsive nanoplatform named PMICApt /ICG, based on PB:Mn&Ir@CaCO3 Aptamer /ICG, is designed for the competent synergistic photothermal therapy and photodynamic therapy (PDT) under the guidance of photothermal and magnetic resonance imaging. The nanoplatform's aptamer modification targeting the transferrin receptor and the epithelial cell adhesion molecule on breast cancer cells, and the acid degradable CaCO3 shell allow for effective tumor accumulation and TME-responsive payload release in situ. The nanoplatform also exhibits excellent PDT properties due to its ability to generate O2 and consume antioxidant GSH in tumors. Additionally, the synergistic therapy is achieved by a single wavelength of near-infrared laser. RNA sequencing is performed to identify differentially expressed genes, which show that the expressions of proliferation and migration-associated genes are inhibited, while the apoptosis and immune response gene expressions are upregulated after the synergistic treatments. This multifunctional nanoplatform that responds to the TME to realize the on-demand payload release and enhance PDT induced by TME modulation holds great promise for clinical applications in tumor therapy.

Optimal Strategies for Managing Prostate-specific Antigen Recurrence After Primary Radiotherapy in Prostate Cancer: The Finnish Perspective

Biochemical recurrence after radiotherapy for prostate cancer is a clinical dilemma. Patients at low risk of disease progression can be safely monitored. In Finland, options for those with reasonable life expectancy include salvage high-dose-rate brachytherapy and transurethral ultrasound ablation under magnetic resonance imaging guidance.

Magnetic Resonance-guided Procedures: Consensus on Rationale, Techniques, and Outcomes

Magnetic resonance (MR) image guidance has demonstrated significant potential in the field of interventional radiology in several applications. This article covers the main points of MR-guided hepatic tumor ablation as a representative of MR-guided procedures. Patient selection and appropriate equipment utilization are essential for successful MR-guided tumor ablation. Intra-procedural planning imaging enables the visualization of the tumor and surrounding anatomical structures in most cases without application of contrast agent, ensuring optimal planning of the applicator tract. MRI enables real-time, multiplanar imaging, thus simultaneous observation of the applicator and target tumor is possible during targeting with adaptable slice angulations in case of challenging tumor positions. Typical ablation zone appearance during therapy monitoring with MRI enables save assessment of the therapy result, resulting in a high primary efficacy rate. Recent advancements in ablation probes have shortened treatment times, while technical strategies address applicator visibility issues. MR-imaging immediately after the procedure is used to rule out complications and to assess technical success. Especially in smaller neoplasms, MRI-guided liver ablation demonstrates positive outcomes in terms of technical success rates, as well as promising survival and recurrence rates. Additionally, percutaneous biopsy under MR guidance offers an alternative to classic guidance modalities, providing high soft tissue contrast and thereby increasing the reliability of lesion detection, particularly in cases involving smaller lesions. Despite these advantages, use of MR-guidance in clinical routine is still limited to few indications and centers, due to by high costs, extended duration, and the need for specialized expertise. In conclusion, MRI-guided interventions could benefit from ongoing advancements in hardware, software and devices. Such progress has the potential to expand diagnostic and treatment options in the field of interventional radiology.

Optimizing TMS Coil Placement Approaches for Targeting the Dorsolateral Prefrontal Cortex in Depressed Adolescents: An Electric Field Modeling Study.

High-frequency repetitive transcranial magnetic stimulation (rTMS) to the left dorsolateral prefrontal cortex (L-DLPFC) shows promise as a treatment for treatment-resistant depression in adolescents. Conventional rTMS coil placement strategies include the 5 cm, the Beam F3, and the magnetic resonance imaging (MRI) neuronavigation methods. The purpose of this study was to use electric field (E-field) models to compare the three targeting approaches to a computational E-field optimization coil placement method in depressed adolescents. Ten depressed adolescents (4 females, age: 15.9±1.1) participated in an open-label rTMS treatment study and were offered MRI-guided rTMS five times per week over 6-8 weeks. Head models were generated based on individual MRI images, and E-fields were simulated for the four targeting approaches. Results showed a significant difference in the induced E-fields at the L-DLPFC between the four targeting methods (χ2=24.7, p<0.001). Post hoc pairwise comparisons showed that there was a significant difference between any two of the targeting methods (Holm adjusted p<0.05), with the 5 cm rule producing the weakest E-field (46.0±17.4V/m), followed by the F3 method (87.4±35.4V/m), followed by MRI-guided (112.1±14.6V/m), and followed by the computational approach (130.1±18.1V/m). Variance analysis showed that there was a significant difference in sample variance between the groups (K2=8.0, p<0.05), with F3 having the largest variance. Participants who completed the full course of treatment had median E-fields correlated with depression symptom improvement (r=-0.77, p<0.05). E-field models revealed limitations of scalp-based methods compared to MRI guidance, suggesting computational optimization could enhance dose delivery to the target.

Percutaneous Imaging-guided Cryoablation of Endometriosis Scars of the Anterior Abdominal Wall

To evaluate the safety and clinical efficacy of percutaneous imaging-guided cryoablation for the management of anterior abdominal wall endometriosis. Patients with abdominal wall endometriosis underwent percutaneous imaging-guided cryoablation and had a 6-month follow-up. Data dealing with patients' and anterior abdominal wall endometriosis (AAWE) characteristics, cryoablation, and clinical and radiologic outcomes were retrospectively collected and analyzed. Twenty-nine consecutive patients underwent cryoablation from June 2020 to September 2022. Interventions were performed under US/computed tomography (CT) guidance or magnetic resonance imaging (MRI) guidance. Cryoprobes were directly inserted into the AAWE, and cryoablation was performed with a single 5 to 10 minute freezing cycle, which was stopped when the iceball expanded 3 to 5 mm beyond AAWE borders as assessed on intra-procedural cross-sectional imaging. Fifteen patients (15/29; 51.7%) had prior endometriosis, 28 (28/29; 95.5%) had previous cesarian section, and 22 (22/29; 75.9%) referred association between symptoms and menses. Cryoablation was performed under local (16/29; 55.2%) or general anesthesia (13/29; 44.8%) and mainly in an out-patient basis (18/20; 62%). There was only one (1/29; 3.5%) minor procedure-related complication. Complete symptom relief was recorded in 62.1% (18/29) and 72.4% (21/29) patients at 1 and 6 months, respectively. In the whole population, pain significantly dropped at 6 months compared to the baseline (1.1 ± 2.3; range 0-8 vs 7.1 ± 1.9; range 3-10; p <.05). Eight (8/29; 27.6%) patients presented residual symptoms at 6 months, and 4 (4/29; 13.8%) had an MRI-confirmed residual/recurring disease. Contrast-enhanced MRI obtained for the first 14 (14/29; 48.3%) patients of the series, all without signs of residual/recurring disease, demonstrated a significantly smaller ablation area compared to the baseline volume of the AAWE (1.0 cm3 ± 1.4; range 0-4.7; vs 11.1 ± 9.9 cm3; range 0.6-36.4; p <.05). Percutaneous imaging-guided cryoablation of AAWE is safe and clinically effective in achieving pain relief.