MRI Guidance Research Articles

360° open-ended and navigated magnetic resonance-guided microwave ablation for hepatic tumors in risk areas.

Image-guided local ablation has becoming a promising treatment option for patients unsuitable for surgical resection. Currently, magnetic resonance (MR) imaging has been used as guidance for ablation due to its good soft-tissue contrast, high image quality and absence of ionizing radiation. However, the limited operating space and interrupted and delayed imaging of the conventional MR equipment increased the difficulty of puncture during operation. Therefore, we utilized an easy-to-use optical navigation system with a 0.4 T 360° open MR system to perform MR-guided microwave ablation (MWA) to treat liver tumor patients in risk areas. To evaluate the safety and efficacy of MR-guided MWA in treating liver tumors using a 0.4 T open and navigated MR system. A retrospective analysis was performed on 19 liver tumor patients who underwent MR-guided MWA between August 2014 and August 2017. The complications, complete ablation, and long-term outcomes were analyzed and evaluated. It was found that navigated MRI guidance allowed for precise needle placement in the targeted tumor, and ablation was successfully performed in all patients without serious intraoperative complications and death. Additionally, complete ablation was reached at 94.74% (18/19), with only one patient discovered with residual tumor, and therefore received another MWA session within three months. 360° open MR system combined with navigation systems conveniently enhanced the operation of MR-guided ablation, producing effective outcomes. Therefore, this option may be a safe and effective therapy for liver tumors in patients, especially for those situated in risk areas and those not visible to identify by ultrasound or computerized tomography.

Guiding and monitoring focused ultrasound mediated blood–brain barrier opening in rats using power Doppler imaging and passive acoustic mapping

The blood–brain barrier (BBB) prevents harmful toxins from entering brain but can also inhibit therapeutic molecules designed to treat neurodegenerative diseases. Focused ultrasound (FUS) combined with microbubbles can enhance permeability of BBB and is often performed under MRI guidance. We present an all-ultrasound system capable of targeting desired regions to open BBB with millimeter-scale accuracy in two dimensions based on Doppler images. We registered imaging coordinates to FUS coordinates with target registration error of 0.6 ± 0.3 mm and used the system to target microbubbles flowing in cellulose tube in two in vitro scenarios (agarose-embedded and through a rat skull), while receiving echoes on imaging transducer. We created passive acoustic maps from received echoes and found error between intended location in imaging plane and location of pixel with maximum intensity after passive acoustic maps reconstruction to be within 2 mm in 5/6 cases. We validated ultrasound-guided procedure in three in vivo rat brains by delivering MRI contrast agent to cortical regions of rat brains after BBB opening. Landmark-based registration of vascular maps created with MRI and Doppler ultrasound revealed BBB opening inside the intended focus with targeting accuracy within 1.5 mm. Combined use of power Doppler imaging with passive acoustic mapping demonstrates an ultrasound-based solution to guide focused ultrasound with high precision in rodents.

Challenges in MRI-Guided Breast Biopsy and Some Suggested Strategies: Case Based Review.

With the increasing use of MRI in clinical practice, the need for MRI-guided intervention is also increasing. Indeterminate lesions identified on MRI without mammographic or sonographic correlates will need to be approached under MRI guidance. MRI-guided biopsy is a skill that can be acquired with proper training and guidance. These procedures have their own set of challenges and issues; some of them are specific to the patient habitus in this region. Adequate knowledge and understanding of the challenges can help the radiologist to be better equipped to face these issues and solve them promptly during the procedure, thus increasing the overall success rate of the procedure. Not much local data from Asian countries is available on this front. This paper aims to share common challenges one may face while performing MRI-guided biopsy and share some tips and tricks to address these problems. Hopefully, this will help the readers achieve a higher success rate for MRI-guided interventions in their clinical practice.

Comparison of Diagnostic Accuracies of USG, MG and MRI Modalities Defined with BI-RADS Classification System.

BI-RADS classification facilitates the information related to diagnosis for radiologists. It allows radiologists to interpret mammograms accurately. We aimed to compare the diagnostic accuracy of the three modalities, USG, MG and MRI, with the BI-RADS classification system according to their imaging findings. This study included 82 patients who underwent Tru-Cut biopsy under the guidance of USG, MG, and MRI. Mammography, sonography and MRI were performed in the prone position. Of the patients, 46.3%, 14.6%, and 39.0% were assessed in 4A, 4B, and 5 MRI BI-RADS categories, respectively. Based on the variable surgical/pathological diagnosis, 50%, 28.0%, and 22.0% of the patients were categorized as having malignant findings, benign findings, and infectioninflammation- mastitis, respectively. The determination of the endpoints for the parameter of long-axis diameter (mm) was found to be statistically significant according to ROC analysis as a gold standard based on specificity levels of benign and malignant findings (p<0.05). A significant correlation was detected between the gold standard and the categorical variable MRI BI-RADS (χ2=46.380, p<0.01). When the specificity and sensitivity of all three modalities in surgical/pathological diagnosis were compared, MRI was concluded to be superior to the other modalities and a valuable method for the prediction of lesion malignancy and determination of biopsy prediction and priority.

In-bore MR prostate biopsy - initial experience.

The introduction of multiparametric MRI (mpMRI) has been a breakthrough in the diagnosis of noninvasive clinically significant prostate cancer. Currently, MR-guided prostate biopsy (in-bore biopsy) is the only biopsy method that uses real-time MRI in patients with suspected prostate cancer. The aim of the study was a retrospective analysis of the correlation between MRI results and histological findings of prostate samples suspected of malignancy, which were taken during MRI-guided biopsy. Thirty-nine patients with 57 lesion biopsies were enrolled in the study. Patients were aged 48-84 years (mean age 67.2 ± 9.4 years). Cancer was histologically confirmed in 24 lesions, including primary cancer in 14 lesions and local recurrence in 10 lesions. Cancer was not detected in the remaining lesions (n = 33). Malignancy was confirmed in 90% of lesions previously reported as PI-RADS 5. Only one Prostate Imaging and Reporting and Data System (PI-RADS 5) lesion was histologically negative (prostatitis). Cancer was detected in 50% of lesions defined as PI-RADS 4. Cancer cells were not found in any of 23 lesions defined as PI-RADS 3 (53.5%). Most of the lesions assessed as PI-RADS 3 were located in the transitional zone (n = 19). Only four PI-RADS 3 lesions were found in the peripheral zone. Large lesions or lesions feasible for cognitive TRUS biopsy were not referred for MRI biopsy, which resulted in a higher proportion of lesions assessed as PI-RADS 3. Fourteen lesions suspected of local recurrence were assessed in our study. Cancer was found in approximately 72% of the lesions. Performing prostate biopsy under the guidance of real-time MRI allows precise collection of material for histological examination (even from a very small lesion). As a result, both primary cancer and local recurrence after previous radiotherapy of prostate cancer can be confirmed.

An MR-Conditional Needle Driver for Robot-Assisted Spinal Injections: Design Modifications and Evaluations.

This paper introduces design modifications to our MR-Conditional, 2-degree-of-freedom (DOF), remotely-actuated needle driver for MRI-guided spinal injections. The new needle driver should better meet cleaning and sterilization guidelines needed for regulatory approval, preserve the sterile field during intraoperative needle attachment, and offer better ergonomics and intuitiveness when handling the device. Dy-namic and static force and torque required to properly install the needle driver onto our 4-DOF robot base are analyzed, which provide insight into the risks of intraoperative tool attachment in the setting of robot-assisted spinal injections under MRI guidance.

O-230 Newer non-invasive modalities in fibroid management

Abstract Fibroids are highly prevalent and may cause abnormal menstrual bleeding, pain, mass in pelvis, infertility or pregnancy complications. For years, surgery such as myomectomy or hysterectomy have been the main treatment option. However, the high costs, morbidity and often long hospitalization and recovery time have driven the need for more conservative options. Today, there is a paradigm shift in our approach to the management of fibroids. Depending on the age of the woman, number and location of fibroids, symptoms and her desire for fertility, one can choose a suitable option. Medical options such as progestin’s, GnRh analogues, GnRH antagonists, selective progesterone receptor modulators like ulipristal, mifepristone, aromatase inhibitors or the use of an intra uterine progestin releasing device give good relief of symptoms and temporarily shrink the fibroid. Many high intensity focussed ultrasound options with or without MRI guidance are now available. Uterine artery embolization has stood the test of time. Innovative new techniques such as transvaginal doppler guided vascular clamp, intrauterine ultrasound guided radio frequency ablation, percutaneous microwave ablation are now available to treat this common, often symptomatic and recurrent problem.

Evaluating breast biopsy practice and breast biopsy marker utilisation in the clinical setting.

Breast Screen Australia and Breast Screen Aotearoa guidelines recommend breast biopsy marker (BBM) use in indicated patients. This study aims to evaluate breast biopsy practice and BBM utilisation by modality. An online survey was disseminated to radiologists who identified 'breast imaging' as their area of practice in the Royal Australian and New Zealand College of Radiologists (RANZCR) customer relationship management system. Survey questions addressed participant demographics and factors relating to BBM use. Most respondents (72%) place between 1 and 4 BBMs per week. Almost all (99%) respondents perform ultrasound-guided biopsy of the breast or axillary nodes, with 85% performing stereotactic or tomosynthesis-guided breast biopsy and 27% performing MRI-guided breast biopsy. BBM utilisation differs by modality, with 97% respondents always placing a BBM post-MRI-guided breast biopsy, 50% always placing a BBM post-stereotactic-guided biopsy and 3% always placing a BBM post-ultrasound-guided breast biopsy. Almost all radiologists perform breast biopsy using ultrasound, stereotactic/tomosynthesis or MRI guidance. BBM utilisation varies by modality, with 72% of respondents placing between 1 and 4 clips per week. Reasons for placing or not placing BBM aligned with prior studies. This is the first study to evaluate the number of breast biopsies performed by radiologists on a weekly or monthly basis, providing a useful platform for comparison in the local setting.

Patient reported outcomes for quality of life (QOL) by Expanded Prostate Cancer Index (EPIC) on average 15 years post treatment

Objective/purposePreviously patient reported quality of life (QOL) was reported in men with prostate cancer a mean 2 and 6 years post treatment with open radical prostatectomy (RP), 3D conformal radiation therapy (3D CRT), or 125I low dose rate (LDR) brachytherapy (BT). Herein we update the results 15 years post-treatment QOL. Materials/methodsThe Expanded Prostate Cancer Index (EPIC) domains were scored with differences evaluated at a median 15.8 years follow up based upon mean EPIC summary domains by ANOVA with pairwise post-hoc comparisons adjusted for age. Patient differences of current survey from first cross-section are reported as median change in summary score for each treatment group at median of 2.2 and 6.0, and 15.8 years. ResultsAmong men still alive response rate was 52% in BT, 60% in 3D CRT, and 62% in RP resulting in 30, 41, and 330 QOL questionnaires to evaluate for each corresponding modality at median follow up of 15.8 years. Men were a mean 75.3, 83.6, and 79.3 years of age after RP, 3DCRT, and BT, respectively.At a median of 15.8 years, there were largely persistent differences in EPIC domains without substantial evolution in QoL from middle time points. Persistent worsening in urinary irritative and bowel domain with 3DRT or BT compared to RP. Trend towards worse urinary incontinence with RP were noted without statistical differences within radiotherapy options. ConclusionAs the EPIC patient reported outcomes with the longest follow-up, these data uniquely reveal temporal trends from 2 to 15 years post treatment. However, the treatment modalities of open RP, 3D CRT without image guidance or intensity modulation, and BT without peripheral loading or MRI guidance may not reflect modern techniques.

Stereotactic MRI-guided radiation therapy for localized prostate cancer (SMILE): a prospective, multicentric phase-II-trial

BackgroundNormofractionated radiation regimes for definitive prostate cancer treatment usually extend over 7–8 weeks. Recently, moderate hypofractionation with doses per fraction between 2.2 and 4 Gy has been shown to be safe and feasible with oncologic non-inferiority compared to normofractionation. Radiobiologic considerations lead to the assumption that prostate cancer might benefit in particular from hypofractionation in terms of tumor control and toxicity. First data related to ultrahypofractionation demonstrate that the overall treatment time can be reduced to 5–7 fractions with single doses > 6 Gy safely, even with simultaneous focal boosting of macroscopic tumor(s). With MR-guided linear accelerators (MR-linacs) entering clinical routine, invasive fiducial implantations become unnecessary. The aim of the multicentric SMILE study is to evaluate the use of MRI-guided stereotactic radiotherapy for localized prostate cancer in 5 fractions regarding safety and feasibility.MethodsThe study is designed as a prospective, one-armed, two-stage, multi-center phase-II-trial with 68 patients planned. Low- and intermediate-risk localized prostate cancer patients will be eligible for the study as well as early high-risk patients (cT3a and/or Gleason Score ≤ 8 and/or PSA ≤ 20 ng/ml) according to d’Amico. All patients will receive definitive MRI-guided stereotactic radiation therapy with a total dose of 37.5 Gy in 5 fractions (single dose 7.5 Gy) on alternating days. A focal simultaneous integrated boost to MRI-defined tumor(s) up to 40 Gy can optionally be applied. The primary composite endpoint includes the assessment of urogenital or gastrointestinal toxicity ≥ grade 2 or treatment-related discontinuation of therapy. The use of MRI-guided radiotherapy enables online plan adaptation and intrafractional gating to ensure optimal target volume coverage and protection of organs at risk.DiscussionWith moderate hypofractionation being the standard in definitive radiation therapy for localized prostate cancer at many institutions, ultrahypofractionation could be the next step towards reducing treatment time without compromising oncologic outcomes and toxicities. MRI-guided radiotherapy could qualify as an advantageous tool as no invasive procedures have to precede in therapeutic workflows. Furthermore, MRI guidance combined with gating and plan adaptation might be essential in order to increase treatment effectivity and reduce toxicity at the same time.

Current State of MRI-Guided Endovascular Arterial Interventions: A Systematic Review of Preclinical and Clinical Studies.

MRI guidance of arterial endovascular interventions could be beneficial as it does not require radiation exposure, allows intrinsic blood-tissue contrast, and enables three-dimensional and functional imaging, however, clinical applications are still limited. To review the current state of MRI-guided arterial endovascular interventions and to identify the most commonly reported challenges. Systematic review. Pubmed, Embase, Web of Science, and The Cochrane Library were systematically searched to find relevant articles. The search strategy combined synonyms for vascular pathology, endovascular therapy, and real-time MRI guidance. No field strength or sequence restrictions were applied. Two reviewers independently identified and reviewed the original articles and extracted relevant data. Results of the included original articles are reported. A total of 24,809 studies were identified for screening. Eighty-eight studies were assessed for eligibility, after which data were extracted from 43 articles (6 phantom, 33 animal, and 4 human studies). Reported technical success rates for animal and human studies ranged between 42% to 100%, and the average complication rate was 5.8% (animal studies) and 8.8% (human studies). Main identified challenges were related to spatial and temporal resolution as well as safety, design, and scarcity of current MRI-compatible endovascular devices. MRI guidance of endovascular arterial interventions seems feasible, however, included articles included mostly small single-center case series. Several hurdles remain to be overcome before larger trials can be undertaken. Main areas of research should focus on adequate imaging protocols with integrated tracking of dedicated endovascular devices.

Fe(III)-Chelated Polydopamine Nanoparticles for Synergistic Tumor Therapies of Enhanced Photothermal Ablation and Antitumor Immune Activation.

Both the low energy density of near-infrared (NIR) photothermal conversion during treatment and the recurrence and metastasis after local treatment have been the main obstacles and conundrums in polydopamine-mediated tumor photothermal therapy (PTT). Herein, On the basis of the enhancement of NIR absorption by ligand to metal charge transfer (LMCT) in transition-metal complexes and the activation of antitumor immunity by an appropriate concentration of Fe(III) ions, Fe(III)-chelated PDA nanoparticles (Fe-PDA NPs) with high loading and responsive release of iron ions were synthesized through a prechelation-polymerization method. First, Fe(III) chelated with the catechol groups in DA to form a mono-dopa-Fe(III) chelate, and then the polymerization of dopamine was initiated under alkaline conditions. The results revealed that the mono-dopa-Fe(III) chelate was still the main form of the Fe ion existing in Fe-PDA and was able to greatly enhance the light absorption behaviors of PDA in NIR, resulting a superior photothermal conversion ability (η = 55.5%). Moreover, the existence of Fe(III) also gave Fe-PDA a T1-weighted MRI contrast-enhancement performance (r1 = 7.668 mM-1 s-1) and it would enable the accurate ablation of primary tumors in vivo with Fe-PDA under NIR irradiation by means of the guidance of MRI and thermal imaging. Furthermore, Fe-PDA exhibited better H2O2-responsive biodegradability in comparison to PDA and easily released Fe ions in tumors, which could effectively promote the tumor-associated macrophage (TAM) repolarization to the M1 mode. TAM repolarization combined with the immunogenic cell death (ICD) induced by PTT could effectively enhance the efficacy of immunotherapy, preventing tumor recurrence and metastasis. The design of Fe-PDA nanoparticles should provide more inspiration for structural and functional improvements of melanin-based materials in tumor suppression.

The role for MRI-guided transurethral ultrasound ablation in the continuum of prostate cancer care.

Prostate cancer continues to have a negative impact on the duration and quality of life for males and their families. MRI is transforming the pathway of prostate cancer detection, diagnosis, staging, and surveillance, backed by multiple Level 1 studies and robust reporting standards. This evolving paradigm of MRI-directed care is now being expanded to include in-bore MRI-guided prostate tissue ablation techniques, which reduce the burden of genitourinary complications associated with standard-of-care treatments, without sacrificing cancer control. The workflow for MRI-guided transurethral ultrasound ablation relies on intraprocedural MRI guidance for treatment planning, automated and physician-monitored treatment delivery, and post-treatment assessment at both immediate and long-term time points. Our early experience has identified several procedure refinements, and aligns with early evidence from prospective clinical studies using transurethral ultrasound ablation for treatment of patients with either primary or recurrent disease. Driven by quantitative real-time imaging, MRI-guided ablative interventions provide rich datasets for developing technical refinements and predictive models that will progressively improve patient outcomes as these novel techniques become part of a new standard-of-care.

Pathological outcomes of pancreatic adenocarcinoma (PA) after preoperative high biological effective dose (BED) magnetic resonance image-guided radiation therapy (MRgRT).

573 Background: Pre-operative radiotherapy (RT) for PA has the potential to reduce positive surgical margin rates and increase pathologic tumor response, which has been associated with improved survival. Increasing the BED can improve local control and overall survival for patients with unresectable PA. Use of stereotactic body radiation therapy (SBRT) to achieve a higher BED has been limited by toxicity to adjacent radiosensitive structures, but this can be mitigated by MRgRT. We describe our use of MRgRT prior to potentially curative resection of localized PA. Methods: We performed a single institution retrospective analysis of all patients with localized PA who received high BED SBRT on the MR Linac followed by surgical resection with curative intent. Toxicity was evaluated according to Common Terminology Criteria for Adverse Events, version 5.0. Tumor response was evaluated according to the College of American Pathologists tumor regression grading criteria (CAP-TRG), ranging from CAP 0 indicating pathologic complete response to CAP grade 3 indicating no response. Ordinal logistic regression model was used to assess the association between time from RT to surgery and TRG. Follow up included MRI or CT scans at least every three months. Results: We analyzed 26 patients with borderline resectable (80.8%), locally advanced (11.5%), and resectable (7.7%) tumors who received high BED MRgRT followed by surgical resection. Median age at diagnosis was 68 years (34 - 86). Most patients received chemotherapy (80.8%) prior to RT, with 81% of these receiving FOLFINIRNOX and 19% receiving gemcitabine/nab-paclitaxel. All patients received MR-guided high BED SBRT to a median dose of 50 Gy (40 - 50) in 5 fractions. On-table adaptive replanning was performed in 88% of patients, with 74% having all 5 fractions adapted. No acute grade 2+ toxicity associated with RT was observed. The median time to resection was 50 days (37 – 115), and the procedure types included: Whipple (69%), distal (23%), or total pancreatectomy (8%). The R0 resection rate was 96% and no perioperative deaths occurred within 90 days. Complete (0) or near-complete (1) pathologic response was observed in 35% of cases and the time from RT to surgery was positively associated with TRG (R2= 0.22, p = 0.0003). The median follow-up after RT was 16.5 months (3.9- 26.2) during which 9 patients recurred, and 3 patients died of disease. The derived median progression-free survival from RT was 13.2 months. Conclusions: These initial pathology outcomes following high BED MR-guided SBRT are encouraging and suggest that the time from SBRT to surgical resection is associated with response. This finding is consistent with results from other preoperative GI tumor sites and results from prospective studies using high BED SBRT with MRI guidance in combined modality therapy against PA are eagerly awaited.

Real-Time Control of Active Catheter Signals for Better Visual Profiling During Cardiovascular Interventions Under MRI Guidance

In MR-guided interventional procedures, RF coils can be attached to the instruments to provide a positive MR signal for device tracking. The signal from these coils can vary strongly over the procedure and mask the surrounding anatomy. The purpose of this study is to introduce and demonstrate a low-cost, vendor- and device-independent interface circuit that allows the interventionalist to adjust the active device signal intensity. In this work a variable attenuator circuit was constructed to control the tip signal of an active coronary artery catheter in real-time from within the MR scanner room. Performance of the attenuator circuit and the active catheter was characterized on the test bench, in a phantom model, and in vivo. The system was used in a pig model at 3T during the introduction of the catheter into the left coronary artery. The circuit could attenuate the amplitude of the tracking coil signal by up to 20 dB. Without attenuation, the tracking coil signal intensity was masking anatomical details of the coronary ostium making it impossible to reliably introduce the catheter into the artery. After interactive adjustment, which was performed in a few seconds by the interventionalist, the improved visualization of the vascular anatomy enabled a rapid insertion of the catheter into the coronary ostium. The vendor-independent variable attenuator provides real-time control of the catheter signal without interrupting the image acquisition. Even though most MRI systems can control the individual signal levels from coils by software, the attenuator hardware is advantageous as it can be integrated into any MR-system, and it provides a direct interface for the interventionalist at the magnet.

Focused ultrasound as a non-invasive method with therapeutic potential in patients with Alzheimer's disease

Alzheimer's disease (AD) is a common, progressive neurodegenerative disease characterized by abnormal deposition of β-amyloid (Aβ) and hyperphosphorylated tau protein. Despite the fact that biomarkers and methods of treating AD are currently being actively studied, there is still no therapy that can significantly reduce the progression of this disease. Therefore, the search for therapeutic disease-modifying strategies is becoming increasingly popular. One such strategy is the use of focused ultrasound (FUS) under MRI guidance using a contrast agent (microbubbles). Under the influence of low-intensity FUS, the blood-brain barrier (BBB) is temporarily opened, which is the main obstacle to the effective delivery of therapeutic compounds to the brain, imposing dimensional and biochemical restrictions on the passage of molecules. One of the processes associated with AD is BBB dysfunction, and therefore the study of the effects of FUS in patients with AD is of interest. The literature data show the effectiveness of FUS in animal models of AD. The researchers attribute the effectiveness of the method to the fact that exposure to FUS induces the opening of BBB and reduces the number of amyloid plaques. It has also been demonstrated that FUS can facilitate the delivery of therapeutic drugs to the brain. This allows considering FUS as a new non-invasive method of treatment. Further research is needed to assess the effectiveness of this method in patients with AD.

Hyperosmolar blood-brain barrier opening using intra-arterial injection of hyperosmotic mannitol in mice under real-time MRI guidance.

The blood-brain barrier (BBB) is the main obstacle to the effective delivery of therapeutic agents to the brain, compromising treatment efficacy for a variety of neurological disorders. Intra-arterial (IA) injection of hyperosmotic mannitol has been used to permeabilize the BBB and improve parenchymal entry of therapeutic agents following IA delivery in preclinical and clinical studies. However, the reproducibility of IA BBB manipulation is low and therapeutic outcomes are variable. We demonstrated that this variability could be highly reduced or eliminated when the procedure of osmotic BBB opening is performed under the guidance of interventional MRI. Studies have reported the utility and applicability of this technique in several species. Here we describe a protocol to open the BBB by IA injection of hyperosmotic mannitol under the guidance of MRI in mice. The procedures (from preoperative preparation to postoperative care) can be completed within ~1.5 h, and the skill level required is on par with the induction of middle cerebral artery occlusion in small animals. This MRI-guided BBB opening technique in mice can be utilized to study the biology of the BBB and improve the delivery of various therapeutic agents to the brain.

Anatomical and fMRI-network comparison of multiple DLPFC targeting strategies for repetitive transcranial magnetic stimulation treatment of depression

BackgroundThe efficacy of repetitive transcranial magnetic stimulation (rTMS) for depression may vary depending on the subregion stimulated within the dorsolateral prefrontal cortex (DLPFC). Clinical TMS typically uses scalp-based landmarks for DLPFC targeting, rather than individualized MRI guidance. ObjectiveIn rTMS patients, determine the brain systems targeted by multiple DLPFC stimulation rules by computing several surrogate measures: underlying brain targets labeled with connectivity-based atlases, subgenual cingulate anticorrelation strength, and functionally connected networks. MethodsForty-nine patients in a randomized controlled trial of rTMS therapy for treatment resistant major depression underwent structural and functional MRI. DLPFC rules were applied virtually using MR-image guidance. Underlying cortical regions were labeled, and connectivity with the subgenual cingulate and whole-brain computed. ResultsScalp-targeting rules applied post hoc to these MRIs that adjusted for head size, including Beam F3, were comparably precise, successful in directly targeting classical DLPFC and frontal networks, and anticorrelated with the subgenual cingulate. In contrast, all rules involving fixed distances introduced variability in regions and networks targeted. The 5 cm rule targeted a transitional DLPFC region with a different connectivity profile from the adjusted rules. Seed-based connectivity analyses identified multiple regions, such as posterior cingulate and inferior parietal lobe, that warrant further study in order to understand their potential contribution to clinical response. ConclusionEEG-based rules consistently targeted DLPFC brain regions with resting-state fMRI features known to be associated with depression response. These results provide a bridge from lab to clinic by enabling clinicians to relate scalp-targeting rules to functionally connected brain systems.

Development of an MRI-Guided Approach to Selective Internal Radiation Therapy Using Holmium-166 Microspheres.

Simple SummarySelective internal radiation therapy (SIRT) is a treatment for patients with liver cancer that involves the injection of radioactive microspheres into the liver artery. For a successful treatment, it is important that tumours are adequately covered with these microspheres; however, there is currently no method to assess this intraoperatively. As holmium microspheres are paramagnetic, MRI can be used to visualize the holmium deposition directly after administration, and possibly to adapt the treatment if necessary. In order to exploit this advantage and provide a personally optimized approach to SIRT, the administration could ideally be performed within a clinical MRI scanner. It is, however, unclear whether all materials (catheters, administration device) used during the procedure are safe for use in the MRI suite. Additionally, we explore the capability of MRI to visualize the microspheres in near real-time during injection, which would be a requirement for successful MRI-guided treatment. We further illustrate our findings with an initial patient case.Selective internal radiation therapy (SIRT) is a treatment modality for liver tumours during which radioactive microspheres are injected into the hepatic arterial tree. Holmium-166 (166Ho) microspheres used for SIRT can be visualized and quantified with MRI, potentially allowing for MRI guidance during SIRT. The purpose of this study was to investigate the MRI compatibility of two angiography catheters and a microcatheter typically used for SIRT, and to explore the detectability of 166Ho microspheres in a flow phantom using near real-time MRI. MR safety tests were performed at a 3 T MRI system according to American Society for Testing of Materials standard test methods. To assess the near real-time detectability of 166Ho microspheres, a flow phantom was placed in the MRI bore and perfused using a peristaltic pump, simulating the flow in the hepatic artery. Dynamic MR imaging was performed using a 2D FLASH sequence during injection of different concentrations of 166Ho microspheres. In the safety assessment, no significant heating (ΔTmax 0.7 °C) was found in any catheter, and no magnetic interaction was found in two out of three of the used catheters. Near real-time MRI visualization of 166Ho microsphere administration was feasible and depended on holmium concentration and vascular flow speed. Finally, we demonstrate preliminary imaging examples on the in vivo catheter visibility and near real-time imaging during 166Ho microsphere administration in an initial patient case treated with SIRT in a clinical 3 T MRI. These results support additional research to establish the feasibility and safety of this procedure in vivo and enable the further development of a personalized MRI-guided approach to SIRT.

Comparison of Cost vs. Reimbursement for Definitive Radiotherapy in Locally Advanced Cervical Cancer Using Time-Driven Activity-Based Costing

In the last several decades, utilization of standard of care brachytherapy (BT) for locally advanced cervical cancer has declined, with increasing use of external alternatives associated with suboptimal outcomes. Emerging evidence implicates under-reimbursement but is incomplete, as prior studies have relied on surveys and lacked indirect costs. The impact of the upcoming Radiation Oncology Alternative Payment Model (RO-APM) on these trends is also unclear. This study used time-driven activity-based costing (TDABC) to compare the true cost of standard of care external beam radiotherapy (EBRT) plus BT boost with current and proposed reimbursement policy. We hypothesized that TDABC would reveal under-reimbursement of BT, which will be worsened under the RO-APM.TDABC was used to map out the entire patient care cycle, accounting for both direct and indirect costs. Costs were estimated by multiplying prospectively collected timestamps from a 66-patient cohort with nationally derived capacity cost rates for personnel, space, equipment, consumables, and overhead. Current fee-for-service (FFS) and proposed RO-APM rates were derived from Current Procedural Terminology (CPT) codes and public notices and used to calculate reimbursement-cost ratios.The direct cost of standard of care radiotherapy was $16435. Indirect costs and MRI guidance added $6690 and $1280. BT and EBRT total costs were higher than previously estimated using direct cost, survey based TDABC ($13663 vs $8609 and $9462 vs $4090, respectively). Although BT cost 44% more than EBRT, under FFS policy, it was reimbursed 12% less ($16145 vs $19769; 45% vs 55% of total payment), resulting in a > 4-fold lower margin. The reimbursement-cost ratio for BT vs EBRT was 1.18 vs 2.09. Switching to the RO-APM reduced these ratios to 0.76 vs 1.34 (using the FFS 45% vs 55% split in payment). Physician payment was less than cost of care (BT = 0.70).Unlike traditional measurements indexed on charges, TDABC more accurately estimates the true cost of care, particularly when using prospective timestamps and indirect costs. Current FFS rates undervalue the cost of BT relative to EBRT, which may be exacerbated by the RO-APM, incentivizing external alternatives (such as external boosts) over definitive care. TDABC can help policymakers align reimbursement with cost to mitigate declining BT usage, which may be worsening patient outcomes in an already underserved population.