NIR-Light-Triggered Mild-Temperature Hyperthermia to Overcome the Cascade Cisplatin Resistance for Improved Resistant Tumor Therapy.

Currently, cisplatin resistance has been recognized as a multistep cascade process for its clinical chemotherapy failure. Hitherto, it remains challenging to develop a feasible and promising strategy to overcome the cascade drug resistance (CDR) issue for achieving fundamentally improved chemotherapeutic efficacy. Herein, a novel self-assembled nanoagent is proposed, which is constructed by Pt(IV) prodrug, cyanine dye (cypate), and gadolinium ion (Gd3+), for systematically conquering the cisplatin resistance by employing near-infrared (NIR) light activated mild-temperature hyperthermia in tumor targets. The proposed nanoagents exhibit high photostability, GSH/H+-responsive dissociation, preferable photothermal conversion, and enhanced cellular uptake performance. In particular, upon 785-nm NIR light irradiation, the generated mild temperature of ≈ 43 °C overtly improves the cell membrane permeability and drug uptake, accelerates the disruption of intracellular redox balance, and apparently enhances the formation of Pt-DNA adducts, thereby effectively overcoming the CDR issue and achieves highly improved therapeutic efficacy for cisplatin-resistant tumor ablation.

Multisize Electrode Field-of-View: Validation by High Resolution Gadolinium-Enhanced Cardiac Magnetic Resonance.

BACKGROUND: Voltage mapping to detect ventricular scar is important for guiding catheter ablation, but the field-of-view of unipolar, bipolar, conventional, and microelectrodes as it relates to the extent of viable myocardium (VM) is not well defined. OBJECTIVES: The purpose of this study was to evaluate electroanatomic voltage-mapping (EAVM) with different-size electrodes for identifying VM, validated against high-resolution ex-vivo cardiac magnetic resonance (HR-LGE-CMR). METHODS: A total of 9 swine with early-reperfusion myocardial infarction were mapped with the QDOT microcatheter. HR-LGE-CMR (0.3-mm slices) were merged with EAVM. At each EAVM point, the underlying VM in multisize transmural cylinders and spheres was quantified from ex vivo CMR and related to unipolar and bipolar voltages recorded from conventional and microelectrodes. RESULTS: In each swine, 220 mapping points (Q1, Q3: 216, 260 mapping points) were collected. Infarcts were heterogeneous and nontransmural. Unipolar and bipolar voltage increased with VM volumes from >175 mm3 up to >525 mm3 (equivalent to a 5-mm radius cylinder with height >6.69 mm). VM volumes in subendocardial cylinders with 1- or 3-mm depth correlated poorly with all voltages. Unipolar voltages recorded with conventional and microelectrodes were similar (difference 0.17 ± 2.66 mV) and correlated best to VM within a sphere of radius 10 and 8 mm, respectively. Distance-weighting did not improve the correlation. CONCLUSIONS: Voltage increases with transmural volume of VM but correlates poorly with small amounts of VM, which limits EAVM in defining heterogeneous scar. Microelectrodes cannot distinguish thin from thick areas of subendocardial VM. The field-of-view for unipolar recordings for microelectrodes and conventional electrodes appears to be 8 to 10 mm, respectively, and unexpectedly similar.

Protease-Mediated T1 Contrast Enhancement of Multilayered Magneto-Gadolinium Nanostructures for Imaging and Magnetic Hyperthermia.

In this work, we constructed a multifunctional composite nanostructure for combined magnetic hyperthermia therapy and magnetic resonance imaging based on T1 and T2 signals. First, iron oxide nanocubes with a benchmark heating efficiency for magnetic hyperthermia were assembled within an amphiphilic polymer to form magnetic nanobeads. Next, poly(acrylic acid)-coated inorganic sodium gadolinium fluoride nanoparticles were electrostatically loaded onto the magnetic nanobead surface via a layer-by-layer approach by employing a positively charged enzymatic-cleavable biopolymer. The positive-negative multilayering process was validated through the changes occurring in surface ζ-potential values and structural characterization by transmission electron microscopy (TEM) imaging. These nanostructures exhibit an efficient heating profile, in terms of the specific absorption rates under clinically accepted magnetic field conditions. The addition of protease enzyme mediates the degradation of the surface layers of the nanostructures with the detachment of gadolinium nanoparticles from the magnetic beads and exposure to the aqueous environment. Such a process is associated with changes in the T1 relaxation time and contrast and a parallel decrease in the T2 signal. These structures are also nontoxic when tested on glioblastoma tumor cells up to a maximum gadolinium dose of 125 µg mL-1, which also corresponds to a iron dose of 52 µg mL-1. Nontoxic nanostructures with such enzyme-triggered release mechanisms and T1 signal enhancement are desirable for tracking tumor microenvironment release with remote T1-guidance and magnetic hyperthermia therapy actuation to be done at the diseased site upon verification of magnetic resonance imaging (MRI)-guided release.

Comprehensive Analysis of the Spatial Distribution of Gadolinium, Iron, Manganese, and Phosphorus in the Brain of Healthy Rats After High-Dose Administrations of Gadodiamide and Gadobutrol.

OBJECTIVES: After the administration of gadolinium-based contrast agents (GBCAs), residual gadolinium (Gd) has been detected in a few distinct morphological structures of the central nervous system (CNS). However, a systematic, comprehensive, and quantitative analysis of the spatial Gd distribution in the entire brain is not yet available. The first aim of this study is to provide this analysis in healthy rats after administration of high GBCA doses. The second aim is to assess the spatial distributions and possible Gd colocalizations of endogenous iron (Fe), manganese (Mn), and phosphorus (P). In addition, the presence of Gd in proximity to blood vessels was assessed by immunohistochemistry. MATERIALS AND METHODS: Male rats were randomly assigned to 3 groups (n = 3/group): saline (control), gadodiamide (linear GBCA), and gadobutrol (macrocyclic GBCA) with cumulative Gd doses of 14.4 mmol/kg of body mass. Five weeks after the last administration, the brains were collected and cryosectioned. The spatial distributions of Gd, Fe, Mn, and P were analyzed in a total of 130 sections, each covering the brain in 1 of the 3 perpendicular anatomical orientations, using laser ablation coupled with inductively coupled plasma mass spectrometry. Quantitative spatial element maps were generated, and the concentrations of Gd, Fe, and Mn were measured in 31 regions of interest covering various distinct CNS structures. Correlation analyses were performed to test for possible colocalization of Gd, Fe, and Mn. The spatial proximity of Gd and blood vessels was studied using metal-tagged antibodies against von Willebrand factor with laser ablation coupled with inductively coupled plasma mass spectrometry. RESULTS: After administration of linear gadodiamide, high Gd concentrations were measured in many distinct structures of the gray matter. This involved structures previously reported to retain Gd after linear GBCA, such as the deep cerebellar nuclei or the globus pallidus, but also structures that had not been reported so far including the dorsal subiculum, the retrosplenial cortex, the superior olivary complex, and the inferior colliculus. The analysis in all 3 orientations allowed the localization of Gd in specific subregions and layers of certain structures, such as the hippocampus and the primary somatosensory cortex. After macrocyclic gadobutrol, the Gd tissue concentration was significantly lower than after gadodiamide. Correlation analyses of region of interest concentrations of Gd, Fe, and Mn revealed no significant colocalization of Gd with endogenous Fe or Mn in rats exposed to either GBCA. Immunohistochemistry revealed a colocalization of Gd traces with vascular endothelium in the deep cerebellar nuclei after gadobutrol, whereas the majority of Gd was found outside the vasculature after gadodiamide. CONCLUSIONS: In rats exposed to gadodiamide but not in rats exposed to gadobutrol, high Gd concentrations were measured in various distinct CNS structures, and structures not previously reported were identified to contain Gd, including specific subregions and layers with different cytoarchitecture and function. Knowledge of these distinct spatial patterns may pave the way for tailored functional neurological testing. Signs for the localization of the remaining Gd in the vascular endothelium were prominent for gadobutrol but not gadodiamide. The results also indicate that local transmetalation with endogenous Fe or Mn is unlikely to explain the spatial patterns of Gd deposition in the brain, which argues against a general role of these metals in local transmetalation and release of Gd ions in the CNS.

Holmium (III)-doped multifunctional nanotheranostic agent for ultra-high-field magnetic resonance imaging-guided chemo-photothermal tumor therapy.

Ultra-high-field (UHF) MRI has shown great advantages over low-field magnetic resonance imaging (MRI). Despite being the most commonly used MRI contrast agents, gadolinium chelates perform poorly in high magnetic fields, which significantly weakens their T1 intensity. In comparison, the rare element Holmium (Ho)-based nanoparticles (NPs) have demonstrated great potential as T2-weighted MRI contrast agents in UHF MRI due to their extremely short electron relaxation times (∼ 10-13s). In this study, a multifunctional nanotherapeutic probe was designed for UHF MRI-guided chemotherapy and photothermal therapy. The Ho (III)-doped mesoporous polydopamine (Ho-MPDA, HM) nanosphere was loaded with the chemotherapeutic drug mitoxantrone (MTO) and then coated with 4T1 cell membranes to enhance active targeting delivery to breast cancer. The prepared nanotherapeutic probe MTO@HMM@4T1 (HMM@T) exhibited good biocompatibility, high drug-loading capability and great potential as Ho (III)-based UHF MRI contrast agents. Moreover, the biodegradation of HMM@T in response to the intratumor pH and glutathione (GSH) promotes MTO release. Near-infrared (NIR) light irradiation of HM induced photothermal therapy and further enhanced drug release. Consequently, HMM@T effectively acted as an MRI-guided tumor-targeting chemo-photothermal therapy against 4T1 breast cancer. STATEMENT OF SIGNIFICANCE: Ultra-high-field (UHF) MRI has shown great advantages over low-field magnetic resonance imaging (MRI). Although gadolinium chelates are the most commonly used MRI contrast agents in clinical practice, they exhibit a significantly decreased T1 relaxivity at UHF. Holmium exhibits outstanding UHF magnetic resonance capabilities in comparison with gadolinium chelates currently used in clinic. Herein, a theranostic nanodrug (HMM@T) was designed for UHF MRI-guided chemo-photothermal therapy. The nanodrug possessed remarkable UHF T2 MRI properties (r2 = 152.13 mM-1s-1) and high drug loading capability of 18.4 %. The biodegradation of HMM@T NPs under triple stimulations of pH, GSH, and NIR led to an efficient release of MTO in tumor microenvironment. Our results revealed the potential of a novel UHF MRI-guided multifunctional nanosystem in cancer treatment.

Hydrogen-Bonded Organic Frameworks Chelated Manganese for Precise Magnetic Resonance Imaging Diagnosis of Cancers.

Magnetic resonance imaging (MRI) is an important tool in the diagnosis of many cancers. However, clinical gadolinium (Gd)-based MRI contrast agents have limitations, such as large doses and potential side effects. To address these issues, we developed a hydrogen-bonded organic framework-based MRI contrast agent (PFC-73-Mn). Due to the hydrogen-bonded interaction of water molecules and the restricted rotation of manganese ions, PFC-73-Mn exhibits high longitudinal relaxation r1 (5.03 mM-1 s-1) under a 3.0 T clinical MRI scanner. A smaller intravenous dose (8 µmol of Mn/kg) of PFC-73-Mn can provide strong contrast and accurate diagnosis in multiple kinds of cancers, including breast tumor and ultrasmall orthotopic glioma. PFC-73-Mn represents a prospective new approach in tumor imaging, especially in early-stage cancer.

Investigating the possibility of extending the BWR cycle length for 15 years of operation by mixing highly enriched UO2 fuel with burnable absorbers.

This paper investigates the possibility to extend the cycle length of boiling water reactor bundles to 15 years of operation with three different burnable poisons; gadolinium, erbium, and boron carbide. This can be carried out by mixing highly enriched UO2 fuel (15-19.9% U-235) with high concentrations of Gadolinium oxide (3-14% Gd2O3) or Erbium oxide (2-4% Er2O3).The boron carbide B4C was modeled as (Al2O3-B4C) rods in the bundle guide tubes. MCNPX code 2.7 was used to evaluate infinite multiplication factor (K-inf), power distribution, peaking factor, void reactivity coefficient, fuel cycle length, depletion of U-235, and fissile inventory ratio for the three designs at 40% void. The MCNPX simulation showed that introducing gadolinium rods at the bundle periphery has the advantage of lowering reactivity swing throughout the exposure range. The uniform distribution of erbium in all fuel rods contributed to the flattening of peaking factor at all the burnup stages. For the B4C design, the author found that the assembly with B4C-Al performs best in terms of reactivity flattening when five of the B4C-AL2O3 rods are positioned in the central region of the assembly. Furthermore, the fuel temperature coefficient is more negative for gadolinium design at all burnup stages. On the other hand, the boron model delivers the lowest control rod worth. Finally, the moderator temperature coefficient is more negative for erbium and WABA designs due to the enhanced thermal neutrons capture by the effect of the strategic arrangement of WABA rods and the uniform distribution of erbium.

Immunological gadolinium-doped mesoporous carbon nanoparticles for tumor-targeted MRI and photothermal-immune co-therapy.

Photothermal therapy (PTT) is an effective and well-documented approach to thermally ablate tumors. However, the side effect of distal metastasis and recurrence limit its further expansion. At the same time as PTT was developed, the employment of imaging to monitor the treatment of tumors also became meaningful. Herein, as a proof of concept, gadolinium-doped mesoporous carbon nanoparticles (Gd-MCNs) were prepared as nanocarriers, MRI contrast agents, and PTT agents by a one-step hard template method, which realized Gd doping and carbon filling simultaneously, while retaining enough pore space for drug loading. After loading the immune adjuvant, R837, and the coating of tumor extracellular vesicle, the obtained biomimetic nanoparticles (EV@Gd-MCNs-R837) not only allowed tumor MRI, but also inhibited the primary tumor and its metastasis with long-term immune memory in vivo. This study provides proof for the potential of Gd-MCNs-based biomimetic nanoparticles for targeted PTT/immune-enhanced synergistic theranostic of tumors.

Redox ferrocenylseleno compounds modulate longitudinal and transverse relaxation times of FNPs-Gd MRI contrast agents for multimodal imaging and photo-Fenton therapy.

Developing a feasible way to feature longitudinal (T1) and transverse (T2) relaxation performance of contrast agents for magnetic resonance imaging (MRI) is important in cancer diagnosis and therapy. Improved accessibility to water molecule is essential for accelerating the relaxation rate of water protons around the contrast agents. Ferrocenyl compounds have reversible redox property for modulating the hydrophobicity/hydrophilicity of assemblies. Thus, they could be the candidates that can change water accessibility to the contrast agent surface. Herein, we incorporated ferrocenylseleno compound (FcSe) with Gd3+-based paramagnetic UCNPs, to obtain FNPs-Gd nanocomposites using T1-T2 MR/UCL trimodal imaging and simultaneous photo-Fenton therapy. When the surface of NaGdF4:Yb,Tm UNCPs was ligated by FcSe, the hydrogen bonding between hydrophilic selenium and surrounding water molecules accelerated their proton exchange to initially endow FNPs-Gd with high r1 relaxivity. Then, hydrogen nuclei from FcSe disrupted the homogeneity of the magnetic field around the water molecules. This facilitated T2 relaxation and resulted in enhanced r2 relaxivity. Notably, upon the near-infrared light-promoted Fenton-like reaction in the tumor microenvironment, hydrophobic ferrocene(II) of FcSe was oxidized into hydrophilic ferrocenium(III), which further increased the relaxation rate of water protons to obtain r1 = 1.90±0.12 mM-1 s-1 and r2 = 12.80±0.60 mM-1 s-1. With an ideal relaxivity ratio (r2/r1) of 6.74, FNPs-Gd exhibited high contrast potential of T1-T2 dual-mode MRI in vitro and in vivo. This work confirms that ferrocene and selenium are effective boosters that enhance the T1-T2 relaxivities of MRI contrast agents, which could provide a new strategy for multimodal imaging-guided photo-Fenton therapy of tumors. STATEMENT OF SIGNIFICANCE: T1-T2 dual-mode MRI nanoplatform with tumor-microenvironment-responsive features has been an attractive prospect. Herein, we designed redox ferrocenylseleno compound (FcSe) modified paramagnetic Gd3+-based UCNPs, to modulate T1-T2 relaxation time for multimodal imaging and H2O2-responsive photo-Fenton therapy. Selenium-hydrogen bond of FcSe with surrounding water molecules facilitated water accessibility for fast T1 relaxation. Hydrogen nucleus in FcSe perturbed the phase coherence of water molecules in an inhomogeneous magnetic field and thus accelerated T2 relaxation. In tumor microenvironment, FcSe was oxidized into hydrophilic ferrocenium via NIR light-promoted Fenton-like reaction which further increased both T1 and T2 relaxation rates; Meanwhile, the released toxic •OH performed on-demand cancer therapy. This work confirms that FcSe is an effective redox mediate for multimodal imaging-guided cancer therapy.

Cardiovascular Magnetic Resonance Imaging in Patients With Ibrutinib-Associated Cardiotoxicity.

Importance: Ibrutinib has been associated with serious cardiotoxic arrhythmias. In preclinical models, these events are paralleled or proceeded by diffuse myocardial injury (inflammation and fibrosis). Yet whether this is seen in patients or has implications for future cardiotoxic risk is unknown. Objective: To assess the incidence and outcomes of myocardial injury among patients with ibrutinib-related cardiotoxicity. Design, Setting, and Participants: This cohort study included consecutive patients treated with ibrutinib from 2012 to 2019, phenotyped using cardiovascular magnetic resonance (CMR) from a large US Comprehensive Cancer Center registry. Exposures: Ibrutinib treatment for cancer control. Main Outcomes and Measures: The primary outcome was the presence of late gadolinium enhancement (LGE) fibrosis. The secondary outcome was the occurrence of major adverse cardiac events (MACE), defined as atrial fibrillation, heart failure, symptomatic ventricular arrhythmias, and sudden death of probable or definite ibrutinib association after CMR. We also assessed parametric-mapping subclinical fibrosis (native-T1, extracellular volume fraction) and inflammation/edema (max-T2) measures. Cardiovascular magnetic resonance measures were compared with those obtained in similar consecutive patients with cancer without ibrutinib treatment (pretreatment controls). Observed measures were also compared with similar-aged broad population rates (general-population controls) and a broader pool of cardiovascular disease (CVD) risk-matched cancer controls. Multivariable regression was used to assess the association between CMR measures and MACE. Results: Overall, 49 patients treated with ibrutinib were identified, including 33 imaged after treatment initiation (mean [SD] age, 65 [10] years, 9 [27%] with hypertension, and 23 [69.7%] with index-arrhythmias); median duration of ibrutinib-use was 14 months. The mean (SD) pretreatment native T1 was 977.0 (73.0) ms, max-T2 56.5 (4.0) ms, and 4 (13.3%) had LGE. Posttreatment initiation, mean (SD) native T1 was 1033.7 (48.2) ms, max-T2 61.5 (4.8) ms, and 17 (54.8%) had LGE (P < .001, P = .01, and P < .001, respectively, pre- vs post-ibrutinib treatment). Native T12SDs was elevated in 9 (28.6%), and max-T22SDs in 21 (63.0%), respectively. Cardiovascular magnetic resonance measures were highest in those with suspected toxic effects (P = .01 and P = .01, respectively). There was no association between traditional CVD-risk or cancer-treatment status and abnormal CMR measures. Among those without traditional CVD, 16 (58.6%) had LGE vs 38 (13.3%) in matched-controls (relative-risk, 4.8; P < .001). Over a median follow-up of 19 months, 13 (39.4%) experienced MACE. In multivariable models inclusive of traditional CVD risk factors, LGE (hazard ratio [HR], 4.9; P = .04), and native-T12SDs (HR, 3.3; P = .05) associated with higher risks of MACE. Conclusions and Relevance: In this cohort study, myocardial injury was common in ibrutinib users, and its presence was associated with higher cardiotoxic risk.

Myocardial Characterization with Extracellular Volume Mapping with a First-Generation Photon-counting Detector CT with MRI Reference.

Background Photon-counting detector (PCD) CT provides comprehensive spectral data with every acquisition, but studies evaluating myocardial extracellular volume (ECV) quantification with use of PCD CT compared with an MRI reference remain lacking. Purpose To compare ECV quantification for myocardial tissue characterization between a first-generation PCD CT system and cardiac MRI. Materials and Methods In this single-center prospective study, adults without contraindication to iodine-based contrast media underwent same-day cardiac PCD CT and MRI with native and postcontrast T1 mapping and late gadolinium enhancement for various clinical indications for cardiac MRI (the reference standard) between July 2021 and January 2022. Global and midventricular ECV were assessed with use of three methods: single-energy PCD CT, dual-energy PCD CT, and MRI T1 mapping. Quantitative comparisons among all techniques were performed. Correlation and reliability between different methods of ECV quantification were assessed with use of the Pearson correlation coefficient (r) and the intraclass correlation coefficient. Results The final sample included 29 study participants (mean age ± SD, 54 years ± 17; 15 men). There was a strong correlation of ECV between dual- and single-energy PCD CT (r = 0.91, P < .001). Radiation dose was 40% lower with dual-energy versus single-energy PCD CT (volume CT dose index, 10.1 mGy vs 16.8 mGy, respectively; P < .001). In comparison with MRI, dual-energy PCD CT showed strong correlation (r = 0.82 and 0.91, both P < .001) and good to excellent reliability (intraclass correlation coefficients, 0.81 and 0.90) for midventricular and global ECV quantification, but it overestimated ECV by approximately 2%. Single-energy PCD CT showed similar relationship with MRI but underestimated ECV by 3%. Conclusion Myocardial tissue characterization with photon-counting detector CT-based quantitative extracellular volume analysis showed a strong correlation to MRI. © RSNA, 2023 Supplemental material is available for this article.

18F-FET-PET imaging in high-grade gliomas and brain metastases: a systematic review and meta-analysis.

PURPOSE: To provide a summary of the diagnostic performance of 18F-FET-PET in the management of patients with high-grade brain gliomas or metastases from extracranial primary malignancies. METHODS: MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews databases were searched for studies that reported on diagnostic test parameters in radiotherapy planning, response assessment, and tumour recurrence/treatment-related changes differentiation. Radiomic studies were excluded. Quality assessment was performed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool and the GRADE approach. A bivariate, random-effects model was used to produce summary estimates of sensitivity and specificity. RESULTS: Twenty-six studies with a total of 1206 patients/lesions were included in the analysis. For radiotherapy planning of glioma, the pooled proportion of patients from 3 studies with 18F-FET uptake extending beyond the 20 mm margin from the gadolinium enhancement on standard MRI was 39% (95% CI, 10-73%). In 3 studies, 18F-FET-PET was also shown to be predictive of early responders to treatment, whereas MRI failed to show any prognostic value. For the differentiation of glioma recurrence from treatment-related changes, the pooled sensitivity and specificity of TBRmax 1.9-2.3 from 6 studies were 91% (95% CI, 74-97%) and 84% (95% CI, 69-93%), respectively. The respective values for brain metastases from 4 studies were 82% (95% CI, 74-88%) and 82% (95% CI, 74-88%) using TBRmax 2.15-3.11. CONCLUSION: While 18F-FET shows promise as a complementary modality to standard-of-care MRI for the management of primary and metastatic brain malignancies, further validation with standardized image interpretation methods in well-designed prospective studies are warranted.

The Diagnostic Value of 1.5T Versus 3.0T Magnetic Resonance Imaging Intratympanic Gadolinium Inner Ear Enhancement in Patients with Meniere's Disease.

BACKGROUND: A comparative study of 1.5T and 3.0T magnetic resonance imaging inner ear gadolinium enhancement was carried out to further explore the practicality and universality of 1.5T magnetic resonance imaging in the diagnosis of inner ear labyrinthine hydrops positive imaging. METHODS: This dual case-control study was conducted on 25 patients with Meniere's disease (experimental group), diagnosed by People's Hospital of Ordos Dongsheng District between April 2017 and April 2019 and 51 patients with Meniere's disease (control group), diagnosed by People's Hospital Affiliated to Fujian University of Traditional Chinese Medicine between March 2010 and February 2011 and published on Chinese Medical Journal in 2011. Both groups were injected with gadolinium diluent into bilateral tympanic chambers through the tympanic membrane, and 3 dimensional-Fluid Attenuated Inversion Recovery (FLAIR) magnetic resonance imaging scanning of the inner ear was performed 24 hours later. The results of the 2 groups were observed, calculated, and statistically processed. RESULTS: The positive rate of membranous labyrinthine hydrops was 96% (24/25) in the experimental group and 96.1% (49/51) in the control group. The results are very close. CONCLUSION: In clinical diagnoses of Meniere's disease, 1.5T magnetic resonance imaging and 3.0T magnetic resonance imaging have the same value and significance.

Effective mitigation of gadolinium deposition using the bidentate hydroxypyridinone ligand Me-3,2-HOPO.

With the extensive usage of gadolinium-based contrast agents (GBCAs) in magnetic resonance imaging (MRI), gadolinium deposition has been observed in the brain, kidneys, liver, etc., and this is also closely related to the development of nephrogenic systemic fibrosis (NSF) in patients with renal dysfunction. Chelation, thereby promoting the elimination of deposited Gd(III), seems to be promising for alleviating these problems. Despite many ligands suitable for chelation therapy having been studied, the decorporation of transition metals (e.g. iron, copper, lead, etc.) and actinides (e.g. uranium, plutonium, etc.) has long been a primary concern, whereas the study of Gd(III) has been extremely limited. Due to their excellent metal binding abilities in vivo and therapeutic effects toward neurodegenerative diseases, bidentate hydroxypyridinone ligands are expected to be able to remove Gd(III) from the brain, kidneys, bones, and liver. Herein, the Gd(III) decorporation efficacy of a bidentate hydroxypyridinone ligand (Me-3,2-HOPO) has been evaluated. The complexation behavior between Me-3,2-HOPO and Gd(III) in solution and solid states was characterized with the assistance of potentiometric titration and X-ray diffraction techniques, respectively. Solution-based thermodynamic studies illustrate that the dominant species of complex between Gd(III) and Me-3,2-HOPO (HL) is GdL2+ (log ß120 = 11.8 (3)) at pH 7.4. The structure of the Gd-Me-3,2-HOPO crystal obtained from a room temperature reaction reveals the formation of a Gd(III) dimer that is chelated by four ligands as a result of metal ion hydration and ligand complexation. Cellular Gd(III) removal assays illustrate that Me-3,2-HOPO could effectively reduce final amounts of gadolinium by 77.6% and 66.1% from rat renal proximal tubular epithelial (NRK-52E) cells and alpha mouse liver 12 (AML-12) cells, respectively. Our current results suggest the potential of bidentate HOPO ligands as an effective approach to treat patients suffering from Gd(III) toxicity.

In vivo evaluation of the effects of combined boron and gadolinium neutron capture therapy in mouse models.

While boron neutron capture therapy (BNCT) depends primarily on the short flight range of the alpha particles emitted by the boron neutron capture reaction, gadolinium neutron capture therapy (GdNCT) mainly relies on gamma rays and Auger electrons released by the gadolinium neutron capture reaction. BNCT and GdNCT can be complementary in tumor therapy. Here, we studied the combined effects of BNCT and GdNCT when boron and gadolinium compounds were co-injected, followed by thermal neutron irradiation, and compared these effects with those of the single therapies. In cytotoxicity studies, some additive effects (32‒43%) were observed when CT26 cells were treated with both boron- and gadolinium-encapsulated PEGylated liposomes (B- and Gd-liposomes) compared to the single treatments. The tumor-suppressive effect was greater when BNCT was followed by GdNCT at an interval of 10 days rather than vice versa. However, tumor suppression with co-injection of B- and Gd-liposomes into tumor-bearing mice followed by neutron beam irradiation was comparable to that observed with Gd-liposome-only treatment but lower than B-liposome-only injection. No additive effect was observed with the combination of BNCT and GdNCT, which could be due to the shielding effect of gadolinium against thermal neutrons because of its overwhelmingly large thermal neutron cross section.

BSA-templated ultrasmall Ag/Gd2O3 as a self-enabled nanotheranostic for MR/CT/PA tri-modality imaging and photothermal therapy.

It is becoming more and more important to effectively integrate multiple complementary diagnostic imaging and synergistic therapies into a nano-platform, but it is still challenging. Here, we used bovine serum albumin (BSA) as a template to prepare ultra-small Ag/Gd2O3 (Ag/Gd@BSA) hybrid nanoparticles with high water dispersion by a biomineralization strategy for magnetic resonance (MR)/computed tomography (CT)/photoacoustic (PA) imaging-guided photothermal therapy (PTT). Compared with commercial MR and CT contrast agents, we showed that these well-characterized BSA-templated nanotheranostics possessed higher r1 relaxivity (5.84 mM-1 s-1) and HU values. In addition, these nanotheranostics have an excellent NIR absorption feature and outstanding photothermal conversion efficiency (47.4%) in the solution phase. The in vivo imaging experiment demonstrated that the Ag/Gd@BSA hybrid nanoparticles could serve as tri-modality imaging contrast agents to enable precise diagnosis of tumors. Meanwhile, it was also revealed that Ag/Gd@BSA had ability to be an ideal nanotherapeutic agent to achieve a satisfactory tumor treatment effect through PTT. Also, we showed the good biocompatibility of Ag/Gd@BSA nanoparticles. Overall, these results indicated that Ag/Gd@BSA was an effective nanotheranostic, which could accurately identify tumor sites and realize complete tumor elimination, having great potential in clinical transformation.

Treatment with natalizumab during pregnancy in multiple sclerosis: The experience of implementing a clinical practice protocol (NAP-30).

BACKGROUND: Pregnancy planning in women with highly active multiple sclerosis (HAMS) who need a high-efficacy disease-modifying therapy (heDMT) currently requires a careful risk-benefit evaluation. This includes minimizing fetal drug toxicity and preventing MS reactivation. We describe our experience with natalizumab in women with HAMS and unplanned pregnancy by implementing a clinical practice protocol (NAP-30) designed to maintain the effectiveness of natalizumab during pregnancy, reduce fetal exposure and prevent complications. METHODS: This was an observational retrospective study including women with HAMS on active treatment with natalizumab who became unexpectedly pregnant in the period 2018-2021 and continued this treatment during pregnancy according to the NAP-30 protocol. MS clinical and radiological variables were analyzed before and during pregnancy and in the postpartum period, along with maternal and fetal toxicity during pregnancy and safety findings in newborns. We also describe the NAP-30 protocol, which includes the use of a bridging dose to adjust and maintain natalizumab infusions every 6 weeks during pregnancy up to week 30 and scheduled delivery at week 40. RESULTS: Six women (one in her first gestation) with a median age of 31.5 years at the onset of pregnancy (min-max: 24-37 years) were included. All were negative for anti-John Cunningham virus (JCV) antibodies and were on treatment with intravenous natalizumab 300 mg every 4 weeks. At the time of conception, three patients had received 12, 17 and 53 infusions of natalizumab, respectively, while for the remaining three patients natalizumab was their first DMT (two patients had received 6 infusions and one patient had received 3 infusions of natalizumab). All six patients received 6 doses of natalizumab during pregnancy according to the NAP-30 protocol. After delivery, all six patients restarted natalizumab every 4 weeks (median: 3 days; range: 2-4 days). No patients had relapses during pregnancy or at 6 months postpartum, nor did they develop any general health or laboratory abnormalities. The MRI scan performed at 4-6 months postpartum showed no new T2 lesions or gadolinium-enhancing lesions. No miscarriages or threatened miscarriages were reported. One of the patients underwent elective preterm delivery at week 35 after mild-to-moderate anemia was detected by fetal Doppler scan. The newborn had low birth weight (2080 g) and mild anemia, which resolved within two months with oral iron supplementation. The other infants were born with normal birth weight and showed no blood count abnormalities. After a median follow-up of 10 months, all six babies showed normal development with no complications detected. CONCLUSIONS: Based on our experience, the implementation of the NAP-30 protocol in women with HAMS and unplanned pregnancy undergoing treatment with natalizumab allows the continuation of natalizumab during pregnancy, with a very favorable clinical and radiological effectiveness and maternal-fetal safety profile during pregnancy and postpartum. Both in pregnancy with HAMS and in general, and particularly for successful implementation of the NAP-30 protocol, obstetric support and monitoring is essential for adequate pregnancy management.

Long-term Gadolinium Retention in the Healthy Rat Brain: Comparison between Gadopiclenol, Gadobutrol, and Gadodiamide.

Background Safety concerns caused by gadolinium retention call for the development of high-relaxivity gadolinium-based contrast agents (GBCAs) allowing minimal dosing. Purpose To investigate brain gadolinium retention in healthy rats after exposure to gadopiclenol (Elucirem, Guerbet; macrocyclic GBCA) compared with gadobutrol (Gadovist or Gadavist, Bayer; macrocyclic GBCA) and gadodiamide (Omniscan, GE Healthcare; linear GBCA) over 1 year. Materials and Methods In this study conducted between May 2018 and April 2020, 9-week-old healthy Sprague Dawley rats received five injections of either gadopiclenol, gadobutrol, or gadodiamide (2.4 mmol of gadolinium per kilogram of body weight for each), or saline (control animals) over a period of 5 weeks. Rats were randomly assigned to different groups (six female and six male rats per group). MRI examinations were performed before euthanasia at 1, 3, 5, or 12 months after the last injection. Brains were sampled to determine the total gadolinium content via inductively coupled plasma mass spectrometry (ICP-MS), to characterize gadolinium species with size exclusion chromatography (SEC)-ICP-MS, and to perform elemental mapping with laser ablation (LA)-ICP-MS. Mann-Whitney tests were performed on pairwise comparisons of the same time points. Results For both macrocyclic agents, no T1 signal hyperintensities were observed in the cerebellum, and approximately 80% of gadolinium washout was found between 1 month (gadobutrol, 0.30 nmol/g; gadopiclenol, 0.37 nmol/g) and 12 months (gadobutrol, 0.062 nmol/g; gadopiclenol, 0.078 nmol/g). After 12 months, only low-molecular-weight gadolinium species were detected in the soluble fraction. Gadodiamide led to significantly higher gadolinium concentrations after 1 month in the cerebellum (gadodiamide, 2.65 nmol/g; P < .001 vs both macrocyclics) combined with only 15% washout after 12 months (gadodiamide, 2.25 nmol/g) and with gadolinium detected bound to macromolecules. Elemental bioimaging enabled visualization of gadolinium deposition patterns colocalized with iron. Conclusion Gadopiclenol and gadobutrol demonstrated similar in vivo distribution and washout of gadolinium in the healthy rat brain, markedly differing from gadodiamide up to 12 months after the last injection. © RSNA, 2022 Online supplemental material is available for this article.

Metallo-Dye-Based Supramolecular Nanoassembly for NIR-II Cancer Theranostics.

Retaining intrinsic photophysical performance and efficient therapeutic efficacy of cyanine dyes in the second near-infrared (NIR-II) biowindow are challenges in the biomedical field. Herein, we develop a metal ion-assisted NIR-II fluorophore assembly strategy to modulate molecular arrangement behavior, thus overcoming the drawbacks and retaining the photophysical performance of cyanine dyes in aqueous media for cancer phototheranostics. By screening a series of metal ion-assisted fluorophore assemblies, we remarkably found gadolinium-based metallo-dye-supramolecular nanoassembly (denoted as Gd@IR1064) with the intrinsic optical properties of NIR-II cyanine dye (IR1064). Most intriguingly, the as-prepared Gd@IR1064 not only exhibits deep-tissue-penetrating NIR-II photoacoustic, fluorescence, and magnetic resonance imaging ability but also possesses enhanced photothermal conversion performance-induced hyperthermia, achieving a significant tumor elimination effect. Our study provides a promising guide for modulating dye arrangement with unique photophysical performance for biomedical applications.

Magnetic vortex nanoring coated with gadolinium oxide for highly enhanced T1-T2 dual-modality magnetic resonance imaging-guided magnetic hyperthermia cancer ablation.

Nowadays, about 30% of magnetic resonance imaging (MRI) exams need contrast agents (CAs) to improve the sensitivity and quality of the images for accurate diagnosis. Here, a multifunctional nano-agent with ring-like vortex-domain iron oxide as core and gadolinium oxide as shell (vortex nanoring Fe3O4 @Gd2O3, abbreviated as VNFG) was firstly designed and prepared for highly enhanced T1-T2 dual-modality magnetic resonance imaging (MRI)-guided magnetic thermal cancer therapy. After thorough characterization, the core-shell structure of VNFG was confirmed. Moreover, the excellent heat generation property (SAR=984.26 W/g) of the proposed VNFG under alternating magnetic fields was firmly demonstrated. Furthermore, both in vitro and in vivo studies have revealed a good preliminary indication of VNFG's biological compatibility, dual-modality enhancing feature and antitumor efficacy. This work demonstrates that the proposed VNFG can be a high-performance tumor diagnosis and theranostic treatment agent and may have great potential for clinical application in the future.