Magnetic Resonance Imaging Guidance Research Articles

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.

Microfluidic synthesis of fibronectin-coated polydopamine nanocomplexes for self-supplementing tumor microenvironment regulation and MR imaging-guided chemo-chemodynamic-immune therapy.

Development of nanomedicines to overcome the hindrances of tumor microenvironment (TME) for tumor theranostics with alleviated side effects remains challenging. We report here a microfluidic synthesis of artesunate (ART)-loaded polydopamine (PDA)/iron (Fe) nanocomplexes (NCs) coated with fibronectin (FN). The created multifunctional Fe-PDA@ART/FN NCs (FDRF NCs) with a mean size of 161.0​nm exhibit desired colloidal stability, monodispersity, r1 relaxivity (4.96​mM-1s-1), and biocompatibility. The co-delivery of the Fe2+ and ART enables enhanced chemodynamic therapy (CDT) through improved intracellular reactive oxygen species generation via a cycling reaction between Fe3+ and Fe2+ caused by the Fe3+-mediated glutathione oxidation and Fe2+-mediated ART reduction/Fenton reaction for self-supplementing TME regulation. Likewise, the combination of ART-mediated chemotherapy and the Fe2+/ART-regulated enhanced CDT enables noticeable immunogenic cell death, which can be collaborated with antibody-mediated immune checkpoint blockade to exert immunotherapy having significant antitumor immunity. The combined therapy improves the efficacy of primary tumor therapy and tumor metastasis inhibition by virtue of FN-mediated specific targeting of FDRF NCs to tumors with highly expressed αvβ3 integrin and can be guided through the Fe(III)-rendered magnetic resonance (MR) imaging. The developed FDRF NCs may be regarded as an advanced nanomedicine formulation for chemo-chemodynamic-immune therapy of different tumor types under MR imaging guidance.

A Multi-Institutional Phase 2 Trial of Ablative 5-Fraction Stereotactic Magnetic Resonance-Guided On-Table Adaptive Radiation Therapy for Borderline Resectable and Locally Advanced Pancreatic Cancer

Magnetic resonance (MR) image guidance may facilitate safe ultrahypofractionated radiation dose escalation for inoperable pancreatic ductal adenocarcinoma. We conducted a prospective study evaluating the safety of 5-fraction Stereotactic MR-guided on-table Adaptive Radiation Therapy (SMART) for locally advanced (LAPC) and borderline resectable pancreatic cancer (BRPC). Patients with LAPC or BRPC were eligible for this multi-institutional, single-arm, phase 2 trial after ≥3 months of systemic therapy without evidence of distant progression. Fifty gray in 5 fractions was prescribed on a 0.35T MR-guided radiation delivery system. The primary endpoint was acute grade ≥3 gastrointestinal (GI) toxicity definitely attributed to SMART. One hundred thirty-six patients (LAPC 56.6%, BRPC 43.4%) were enrolled between January 2019 and January 2022. Mean age was 65.7 (36-85) years. Head of pancreas lesions were most common (66.9%). Induction chemotherapy mostly consisted of (modified)FOLFIRINOX (65.4%) or gemcitabine/nab-paclitaxel (16.9%). Mean CA19-9 after induction chemotherapy and before SMART was 71.7 U/mL (0-468). On-table adaptive replanning was performed for 93.1% of all delivered fractions. Median follow-up from diagnosis and SMART was 16.4 and 8.8 months, respectively. The incidence of acute grade ≥3 GI toxicity possibly or probably attributed to SMART was 8.8%, including 2 postoperative deaths that were possibly related to SMART in patients who had surgery. There was no acute grade ≥3 GI toxicity definitely related to SMART. One-year overall survival from SMART was 65.0%. The primary endpoint of this study was met with no acute grade ≥3 GI toxicity definitely attributed to ablative 5-fraction SMART. Although it is unclear whether SMART contributed to postoperative toxicity, we recommend caution when pursuing surgery, especially with vascular resection after SMART. Additional follow-up is ongoing to evaluate late toxicity, quality of life, and long-term efficacy.

Robotic system for magnetic resonance imaging-guided high-intensity focus ultrasound application: Feasibility of breast fibroadenoma treatment.

This paper presents a high-intensity focus ultrasound (HIFU) robotic system for treating breast fibroadenoma under the guidance of magnetic resonance imaging (MRI). Based on the thermal and mechanical effects of ultrasound, the system aims to deliver ultrasound energy to a target precisely without damaging the normal tissue. The temperature elevation can be monitored in real time by MRI, and the treatment plan can be adjusted during the procedure. The requirements, design specifications, control system and registration of the robotic system are specified. The robotic system was designed with a 3 degrees of freedom manipulator with limit switches and encoders, a customised MRI-compatible breast coil, a water bladder with sets of breast-conforming brackets, and a probe capable of generating ultrasound. Twenty volunteers were recruited for this study, and their data were analysed to provide more precise data for the design. The accuracy of the robot was evaluated in free space using a coordinate measuring machine, phantom and ex vivo porcine tissue in MRI room. The study also verified the signal-to-noise ratio (SNR) of the MRI with the effect of the robotic system. The research findings revealed that the manipulator exhibited a translational precision of 0.10±0.14mm, a rotational fidelity around the X direction of 0.11±0.09°, and an oscillatory exactness around the Y direction of 0.10±0.08°. The investigation of positioning accuracy demonstrated that the robot's error in free space was 0.26±0.07mm. When subjected to MRI room with agar-silica phantom and ex vivo porcine tissue, the positioning accuracy amounted to 1.11±0.47mm and 1.57±0.52mm. In the presence of the robotic system, the SNR of the MRI experienced a 4.2% reduction, which had a negligible impact on image quality. The conducted experiments validate the efficacy of the proposed MRI-guided HIFU robotic system in executing agar-silica phantom and ex vivo porcine tissue investigations with adequate positioning accuracy. Consequently, this system exhibits certain feasibility for the treatment of breast fibroadenomas.

Review of Robot-Assisted HIFU Therapy.

This paper provides an overview of current robot-assisted high-intensity focused ultrasound (HIFU) systems for image-guided therapies. HIFU is a minimally invasive technique that relies on the thermo-mechanical effects of focused ultrasound waves to perform clinical treatments, such as tumor ablation, mild hyperthermia adjuvant to radiation or chemotherapy, vein occlusion, and many others. HIFU is typically performed under ultrasound (USgHIFU) or magnetic resonance imaging guidance (MRgHIFU), which provide intra-operative monitoring of treatment outcomes. Robot-assisted HIFU probe manipulation provides precise HIFU focal control to avoid damage to surrounding sensitive anatomy, such as blood vessels, nerve bundles, or adjacent organs. These clinical and technical benefits have promoted the rapid adoption of robot-assisted HIFU in the past several decades. This paper aims to present the recent developments of robot-assisted HIFU by summarizing the key features and clinical applications of each system. The paper concludes with a comparison and discussion of future perspectives on robot-assisted HIFU.

Evaluation of the Efficiency of Neuronavigation in Patients with Glioblastoma

Objective: To investigate the effect of neuronavigation use on mortality in patients with glioblastoma. Methods: For each of the 26 patients that underwent neuronavigation-assisted supratotal resection for glioblastoma between 2018 and 2020, one patient that underwent supratotal resection without navigation was selected. Results: Radiographic radicality was observed in 35% of the cases in the neuronavigation-assisted surgery group and 29% of those in the conventional surgery group. Absolute and relative residual tumor volumes were significantly lower in the neuronavigation-assisted surgery group. Radical tumor resection was associated with a very significant increase in survival. There was no significant difference in the survival rates between the patients that underwent surgery with and without neuronavigation. This was attributed to the small number of participants and supratotal resection being performed in all statistically determined patients The low median survival period of glioblastoma may have also contributed to this finding. Conclusions: Surgery plays an important role in the treatment of glioblastoma. A combination of techniques including intraoperative magnetic resonance imaging, neuronavigation, ultrasound, and fluorescence guidance allows for safe and maximum surgical resection, leading to better outcomes in terms of survival and postoperative functional recovery. However, despite maximal surgical resection and adjuvant chemotherapy-radiotherapy, most cases develop tumor recurrence within 10 months, which is considered to be due to established cancer stem cells. Therefore, there is an urgent need to develop more effective treatment strategies for glioblastoma.

Deformable cardiac surface tracking by adaptive estimation algorithms

This study presents a particle filter based framework to track cardiac surface from a time sequence of single magnetic resonance imaging (MRI) slices with the future goal of utilizing the presented framework for interventional cardiovascular magnetic resonance procedures, which rely on the accurate and online tracking of the cardiac surface from MRI data. The framework exploits a low-order parametric deformable model of the cardiac surface. A stochastic dynamic system represents the cardiac surface motion. Deformable models are employed to introduce shape prior to control the degree of the deformations. Adaptive filters are used to model complex cardiac motion in the dynamic model of the system. Particle filters are utilized to recursively estimate the current state of the system over time. The proposed method is applied to recover biventricular deformations and validated with a numerical phantom and multiple real cardiac MRI datasets. The algorithm is evaluated with multiple experiments using fixed and varying image slice planes at each time step. For the real cardiac MRI datasets, the average root-mean-square tracking errors of 2.61 mm and 3.42 mm are reported respectively for the fixed and varying image slice planes. This work serves as a proof-of-concept study for modeling and tracking the cardiac surface deformations via a low-order probabilistic model with the future goal of utilizing this method for the targeted interventional cardiac procedures under MR image guidance. For the real cardiac MRI datasets, the presented method was able to track the points-of-interests located on different sections of the cardiac surface within a precision of 3 pixels. The analyses show that the use of deformable cardiac surface tracking algorithm can pave the way for performing precise targeted intracardiac ablation procedures under MRI guidance. The main contributions of this work are twofold. First, it presents a framework for the tracking of whole cardiac surface from a time sequence of single image slices. Second, it employs adaptive filters to incorporate motion information in the tracking of nonrigid cardiac surface motion for temporal coherence.

Magnetic Resonance Imaging–Guided vs Computed Tomography–Guided Stereotactic Body Radiotherapy for Prostate Cancer

Magnetic resonance imaging (MRI) guidance offers multiple theoretical advantages in the context of stereotactic body radiotherapy (SBRT) for prostate cancer. However, to our knowledge, these advantages have yet to be demonstrated in a randomized clinical trial. To determine whether aggressive margin reduction with MRI guidance significantly reduces acute grade 2 or greater genitourinary (GU) toxic effects after prostate SBRT compared with computed tomography (CT) guidance. This phase 3 randomized clinical trial (MRI-Guided Stereotactic Body Radiotherapy for Prostate Cancer [MIRAGE]) enrolled men aged 18 years or older who were receiving SBRT for clinically localized prostate adenocarcinoma at a single center between May 5, 2020, and October 1, 2021. Data were analyzed from January 15, 2021, through May 15, 2022. All patients had 3 months or more of follow-up. Patients were randomized 1:1 to SBRT with CT guidance (control arm) or MRI guidance. Planning margins of 4 mm (CT arm) and 2 mm (MRI arm) were used to deliver 40 Gy in 5 fractions. The primary end point was the incidence of acute (≤90 days after SBRT) grade 2 or greater GU toxic effects (using Common Terminology Criteria for Adverse Events, version 4.03 [CTCAE v4.03]). Secondary outcomes included CTCAE v4.03-based gastrointestinal toxic effects and International Prostate Symptom Score (IPSS)-based and Expanded Prostate Cancer Index Composite-26 (EPIC-26)-based outcomes. Between May 2020 and October 2021, 156 patients were randomized: 77 to CT (median age, 71 years [IQR, 67-77 years]) and 79 to MRI (median age, 71 years [IQR, 68-75 years]). A prespecified interim futility analysis conducted after 100 patients reached 90 or more days after SBRT was performed October 1, 2021, with the sample size reestimated to 154 patients. Thus, the trial was closed to accrual early. The incidence of acute grade 2 or greater GU toxic effects was significantly lower with MRI vs CT guidance (24.4% [95% CI, 15.4%-35.4%] vs 43.4% [95% CI, 32.1%-55.3%]; P = .01), as was the incidence of acute grade 2 or greater gastrointestinal toxic effects (0.0% [95% CI, 0.0%-4.6%] vs 10.5% [95% CI, 4.7%-19.7%]; P = .003). Magnetic resonance imaging guidance was associated with a significantly smaller percentage of patients with a 15-point or greater increase in IPSS at 1 month (6.8% [5 of 72] vs 19.4% [14 of 74]; P = .01) and a significantly reduced percentage of patients with a clinically significant (≥12-point) decrease in EPIC-26 bowel scores (25.0% [17 of 68] vs 50.0% [34 of 68]; P = .001) at 1 month. In this randomized clinical trial, compared with CT-guidance, MRI-guided SBRT significantly reduced both moderate acute physician-scored toxic effects and decrements in patient-reported quality of life. Longer-term follow-up will confirm whether these notable benefits persist. ClinicalTrials.gov Identifier: NCT04384770.

Ovalbumin-loaded paramagnetic nano-triangles for enhanced dendritic cell stimulation, T1-MR imaging, and antitumor immunity

Vaccine-based cancer immunotherapy has demonstrated a significant potential for cancer treatment in clinics. Although the efficiencies of vaccines are limited, they can be enhanced by a well-designed antigen delivery system that promotes sufficient antigen presentation of dendritic cells (DCs) for initiating high T cell immunity. Herein, antigen-loaded manganese oxide (Mn3O4) triangular-shaped ultrasmall nanoparticles were prepared to stimulate DC-based immunotherapy under the guidance of T1 magnetic resonance imaging. The FDA-approved triblock copolymer Pluronic® F-68 was used not only to transfer the phase from hydrophobic to hydrophilic but also to enrich antigen loading and improve the biocompatibility of the prepared nanoparticles. Ovalbumin (OVA), a model antigen, was adsorbed on the surface of polymer-coated nanoparticles through electrostatic interaction to form Mn3O4@PF68-OVA nanoparticle-antigen complexes to stimulate DC-based immunization and antigen-specific T cell immunity. The Mn3O4@PF68-OVA nanovaccine (NV) induces negligible toxicity effects against 4T1 and bone marrow-derived dendritic cells (BMDCs) by conventional methods supports the proliferation of intestine organoids, which are an innovative three-dimensional cytotoxicity evaluation system, thereby indicating their potential safety for in vivo cancer therapies. The designed paramagnetic nanovaccine possessed excellent OVA delivery to dendritic-regulated antigen-specific T cells in vitro by stimulating the maturation level of BMDCs. In addition, Mn3O4@PF68-OVA NVs enhance immunity in vivo by increasing the T-cells and M1 macrophages, which suggests improved immunity. Excitingly, vaccination with Mn3O4@PF68-OVA offer complete protection in the prophylactic group and significant tumor inhibition in the therapeutic group against B16-OVA tumor. In addition, the designed nanovaccine demonstrated high T1-MR imaging in the tumor, further justifying enhanced tumor accumulation and capability to real-time monitor the treatment procedure. This study presents a promising nanosystem to design an effective nanovaccine for T1-MR imaging-guided tumor immunotherapy.

Magnetic resonance imaging-guided ultrasound ablation for prostate cancer - A contemporary review of performance.

Prostate cancer (PCa) is one of the most common malignancies in men, but patient outcomes are varied depending on extent of disease. Radical, whole-gland therapies, such as prostatectomy or radiotherapy, are definitive treatments for PCa, but they are associated with significant morbidity, including erectile dysfunction and urinary incontinence. Focal therapies for PCa, whereby the part of gland harboring disease is selectively treated, spares the normal surrounding structures, and minimizes the morbidity associated with whole gland treatment. The use of magnetic resonance imaging (MRI) guidance provides advantages over ultrasound guidance, such as better localization and targeting of clinically significant PCa (csPCa), as well as MRI thermometry which optimizes tissue ablation temperatures. This review will discuss two MRI-guided high-intensity focused ultrasound (HIFU) techniques - transrectal MR-guided focused ultrasound (MRgFUS) and TULSA (transurethral ultrasound ablation) ablation for localized PCa. Overall, recent major trials for MRgFUS and TULSA have shown promising oncological and functional results in the treatment of low- to intermediate-risk PCa. Recent Phase II MRgFUS trials have shown better oncologic outcomes than the published results for focal ultrasound guided HIFU and may justify the additional costs associated with MRI guidance. While initial studies on TULSA have focused on subtotal gland ablation, recent trials assessing oncological outcomes for focal treatment of angular sectors have shown promise.

Optimisation of path planning for minimally invasive interventions on prostate using MR-robot: Application to on-live pets

The robot-assisted biopsy system under Magnetic Resonance Imaging (MRI) guidance is a promising candidate for prostate cancer diagnosis in terms of improving the reliability and accuracy of reaching micro-lesions of perineum organ tissues. This has been explored for the last decade. A pre-requisite for effective interventional diagnosis is an accurate intervention planning that is difficult to achieve manually. This is due to multiple factors mainly, the fact that the insertion needles trajectories should avoid organs at risk and limited manoeuvrability, under clinician control. Thus, Biopsy-robot is a feasible solution to improve targeting accuracy. However, the planned trajectories should be consistent with the needle-driven robot's kinematics capabilities. To eliminate these problems, we present an integrated concept composed of MRI-robot and Brachytherapy (BT) path planning algorithm, allowing to minimise the number of entry points of BT needles, from a physical grid to reach all the treatable volume of the prostate gland. This means minimising the number of inserted needles from the perineum, compared to a conventional straight insertion of multiple needles. Indeed, the proposed method is able to set-up safe percutaneous routes defined by a set of oblique straight-line paths linking a minimum number of feasible entry points and desired finite target points, defined within the prostate volume. By adopting such a procedure, the aim is to contribute in minimising tissue damage and patient trauma, and risk of infection, and shortening recovery time. A combinatorial approach is proposed for the minimisation of the insertion point. The development, implementation, and experimental evaluation of the needle path planning method for the 5 Degree of Freedom (DoF) robot guide is presented and performed within a 1.5 Tesla MRI to evaluate how the proposed approach is efficient and reliable on-live pets.

Magnetic Resonance Imaging Guidance for Percutaneous Needle Intervention

Magnetic Resonance Imaging Guidance for Percutaneous Needle Intervention

High Intensity Focused Ultrasound for Treatment of Bone Malignancies—20 Years of History

High Intensity Focused Ultrasound (HIFU) is the only non-invasive method for percutaneous thermal ablation of tissue, with treatments typically performed either under magnetic resonance imaging or ultrasound guidance. Since this method allows efficient heating of bony structures, it has found not only early use in treatment of bone pain, but also in local treatment of malignant bone tumors. This review of 20 years of published studies shows that HIFU is a very efficient method for rapid pain relief, can provide local tumor control and has a very patient-friendly safety profile.