Gadolinium-diethylenetriamine Pentaacetic Acid Research Articles

The Protective Impact of Gd-DTPA on Hemolysis in Pulsed Field Ablation for Atrial Fibrillation.

Pulsed field ablation (PFA) is a promising nonthermal method for treating atrial fibrillation. However, the potential for erythrocyte rupture and subsequent hemolysis remains a significant concern, particularly with high-intensity applications. In this study, we explored the protective effects of gadolinium-diethylenetriamine-penta-acetic acid (Gd-DTPA), a common magnetic resonance imaging contrast agent, against PFA-induced hemolysis both invitro and invivo. Our invitro experiments involved subjecting fresh heparinized rat blood to PFA in the presence of various concentrations of Gd-DTPA. We found that Gd-DTPA concentrations of 100μM and 1,000μM significantly mitigated hemolysis caused by PFA application. For invivo studies, rats were administered Gd-DTPA at dosages of 10μmol/kg and 100μmol/kg before PFA. The results indicated that preadministration of Gd-DTPA effectively reduced erythrocyte destruction and intravascular hemolysis after PFA. The protective effect of Gd-DTPA is attributed to its ability to stiffen erythrocyte membranes, rendering them more resistant to the destabilizing effects of PFA-induced electroporation. These findings suggest that Gd-DTPA could play a crucial role in minimizing hemolysis and associated complications in clinical applications of PFA for atrial fibrillation. Further studies are needed to confirm these protective effects in larger animal models and eventually in clinical settings.

Value of hepatic artery digital subtraction angiography in the detection of small hepatocellular carcinoma lesions.

To compare the detection rates of hepatic artery digital subtraction angiography (HA-DSA) and magnetic resonance imaging (MRI) gadolinium diethylenetriaminepentaacetic acid (MRI-Gd-DTPA) and MRI gadolinium diethylenetriaminepentaacetic acid (MRI-Gd-EOB-DTPA) for small (diameter ≤2 cm) hepatocellular carcinoma (HCC) lesions. A prospective analysis of patients admitted to the Tumor Hospital of Guangxi Medical University between January 1, 2015, and December 30, 2016, was conducted. The detection rates of the three methods were analyzed. The diameter of small HCC lesions detected using HA-DSA and MRI-Gd-EOB-DTPA were evaluated. The diagnostic value of HCC Barcelona staging for HA-DSA was analyzed. For 107 small lesions detected in 57 patients, the detection rates of HA-DSA and MRI-Gd-DTPA were 86.0% (92/107) and 71.0% (76/107), respectively (p < .05). Of 77 small lesions detected in 42 patients using MRI-Gd-EOB-DTPA and HA-DSA, 67 were detected using HA-DSA, all of which had a rich blood supply, and 72 were detected using MRI-Gd-EOB-DTPA. The minimum diameter of lesions detected using MRI-Gd-EOB-DTPA was approximately 0.4 cm, whereas that of lesions detected using HA-DSA was approximately 0.5 cm. After HA-DSA, a change in the Barcelona staging occurred in 33.3% (62/186) of cases but not after MRI-Gd-DTPA; HA-DSA was significantly better than MRI-Gd-DTPA for staging (p = .03). HA-DSA and MRI-Gd-EOB-DTPA have high diagnostic values for the detection of small HCC lesions, which is helpful for accurate staging of HCC and provides the most valuable information for patient treatment and prognosis.

3D MR fingerprinting for dynamic contrast-enhanced imaging of whole mouse brain.

Quantitative MRI enables direct quantification of contrast agent concentrations in contrast-enhanced scans. However, the lengthy scan times required by conventional methods are inadequate for tracking contrast agent transport dynamically in mouse brain. We developed a 3D MR fingerprinting (MRF) method for simultaneous T1 and T2 mapping across the whole mouse brain with 4.3-min temporal resolution. We designed a 3D MRF sequence with variable acquisition segment lengths and magnetization preparations on a 9.4T preclinical MRI scanner. Model-based reconstruction approaches were employed to improve the accuracy and speed of MRF acquisition. The method's accuracy for T1 and T2 measurements was validated in vitro, while its repeatability of T1 and T2 measurements was evaluated in vivo (n = 3). The utility of the 3D MRF sequence for dynamic tracking of intracisternally infused gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) in the whole mouse brain was demonstrated (n = 5). Phantom studies confirmed accurate T1 and T2 measurements by 3D MRF with an undersampling factor of up to 48. Dynamic contrast-enhancedMRF scans achieved a spatial resolution of 192 × 192 × 500 μm3 and a temporal resolution of 4.3 min, allowing for the analysis and comparison of dynamic changes in concentration and transport kinetics of intracisternally infused Gd-DTPA across brain regions. The sequence also enabled highly repeatable, high-resolution T1 and T2 mapping of the whole mouse brain (192 × 192 × 250 μm3) in 30 min. We present the first dynamic and multi-parametric approach for quantitatively tracking contrast agent transport in the mouse brain using 3D MRF.

A Smart Responsive Nanotheranostic System for MRI of Tumor Response to Immunotherapy and Enhanced Synergism of Thermo‐Immunotherapy

AbstractThe challenges associated with the assessment of immune checkpoint inhibitor (ICI) therapy and low immunotherapy response observed in patients with poorly immunogenic tumors are addressed. A smart‐responsive nanoprobe MZF@Gd is synthetized based on magnetic resonance tuning (MRET). The nanoprobe is designed to be targeted and cleaved by granzyme B, a marker of cytotoxic T‐cell activation. MZF@Gd consisted of superparamagnetic Mn‐ and Zn‐doped ferrite magnetic nanoparticles (MZF‐MNPs) with a magnetocaloric effect and a paramagnetic contrast agent gadolinium‐diethylenetriamine penta‐acetic acid (Gd‐DTPA). These components are connected by the granzyme B substrate peptides. The activation of the T1WI signal through MRET, following the cleavage of the probe by granzyme B, enabled the accurate evaluation of the ICI therapeutic effect. Subsequently, an active‐targeting magnetothermally responsive nanotheranostic agent FA‐P(MZF@Gd/JQ1) is fabricated. This agent incorporated the MRET probe MZF@Gd, JQ‐1 (an inhibitor of PD‐L1), the thermosensitive copolymer PCL‐b‐P(MEO2MA‐co‐OEGMA), and folic acid on the surface. Nanotheranostic agents killed tumor cells through magnetocaloric effects, stimulated antitumor immunity, and regulated the drug release, thereby achieving a synergistic effect between hyperthermia and immunotherapy. Moreover, MZF@Gd released from the agent sensitively detected the presence of granzyme B at the tumor site, thereby enabling an effective assessment of therapeutic efficacy.

Efficacy of photodynamic therapy using hematoporphyrin derivative nanomedicine on hepatocellular carcinoma cells.

Objective: To demonstrate the efficacy of photodynamic therapy (PDT) using hematoporphyrin derivative (HPD) nanomedicine in combination with conventional chemotherapy based on gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) magnetic resonance imaging (MRI) for hepatocellular carcinoma (HCC) therapy. Methods: HPD nanomedicine was prepared, and the cytotoxicity of HPD nanomedicine at different concentrations on HCC cells and the half-maximal inhibitory concentration (IC50) were analyzed. Sixty HCC patients who visited our hospital from 2021 to 2023 were retrospectively analyzed. Patient data were analyzed, with 30 cases in control group (CG) receiving conventional chemotherapy for HCC, and 30 cases in observation group (OG) receiving conventional chemotherapy combined with HPD nanomedicine PDT. Gd-DTPA MRI was utilized to monitor the morphological and biological characteristics of the lesions in patients. After treatment completion, the long-term efficacy of patients and the levels of bcl-2 and bax proteins in primary HCC cells were evaluated. Results: The IC50 values of HPD on HepG2 cell proliferation and the cell inhibition rates gradually increased with increasing doses of HPD (50 μM, 25 μM, 12.5 μM, 6.25 μM, 3.13 μM, 1.56 μM, 0.78 μM). HPD exhibited great anti-proliferative effects on HepG2 cells at relatively low concentrations. The differences in expression rates of bcl-2 protein and bax protein between groups were considerable (P<0.05). There were neglectable changes in AST and ALT levels between the two groups before treatment, but they were markedly reduced after treatment versus before treatment (P<0.05), with OG showing considerably lower levels than CG after treatment (P<0.05). Additionally, patients in OG exhibited better survival rates after the course of treatment versus those in CG. Conclusion: This study demonstrates that the combination of conventional chemotherapy based on Gd-DTPA MRI with HPD nanomedicine PDT greatly improves the efficacy of treatment for HCC patients. This combined treatment strategy not only enhances therapeutic outcomes but also alleviates adverse reactions associated with conventional treatment, providing a novel approach for future research in the treatment of HCC.

MRI-Based Interstitial Fluid Velocity Analysis for Drug Delivery Efficiency Evaluation in Tumor.

There are many flow behaviors in solid tumors, including intravascular, bloodstream, and interstitial convection. Studies have shown that tumor interstitial fluid (TIF) is an important part of tumor microenvironment regulation and affects drug delivery and metabolism between tumor cells. Magnetic resonance imaging (MRI) is suitable for detecting the flow rates of liquids in tissues. Clinical phase contrast PC-MRI technology has been designed to observe the blood flow in large vessels such as arteries and veins; however, it is not sensitive enough to deal with slow flow velocity. Our previously developed vertical plane echo PC-MRI technology, the Velocity Mapping sequence, improved the signal-to-noise ratio (SNR) for measuring slow interstitial fluid rate. In this study, this sequence was used to determine the TIF flow rate in MDA-MB-231 human breast tumor cells used in BALB/c nude male mice. Two different sizes of contrast agents were intravenously injected, and the relationship between their distribution and the TIF flow rate was studied for the first time. Combining the results of clinical scanning showed that small-molecule DTPA-Gd (diethylenetriaminepentaacetic acid-gadolinium) was distributed immediately around the tumor margin after the injection. This distribution was positively correlated to the high flow rate area of the TIF before administration. In contrast, nanoparticles NaGdF4-PEG (polyethylene glycol) entered the tumor and reached their peak at 3 h. Drug distribution was negatively correlated with the high-flow-rate region of the TIF. Investigation of the TIF velocity can help better understand the fluid behavior in tumors and its role in drug delivery.

Single-Atom Gadolinium Nano-Contrast Agents with High Stability for Tumor T1 Magnetic Resonance Imaging

Gadolinium chelates for tumor magnetic resonance imaging (MRI) face challenges such as inadequate sensitivity, lack of selectivity, and risk of Gd leakage. This study presents a single-atom Gd nano-contrast agent (Gd-SA) that enhances tumor MRI. Isolated Gd atoms coordinated by six N atoms and two O atoms are atomically dispersed on a hollow carbon nanosphere, allowing the maximum utilization of Gd atoms with reduced risk of toxic Gd ion leakage. Owning to the large surface area and fast exchange of relaxed water molecules, Gd-SA shows excellent T1-weighted magnetic resonance enhancement with a r1 value of 11.05 mM-1 s-1 at 7 T, which is 3.6 times that of the commercial gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). In vivo MRI results show that the Gd-SA has a higher spatial resolution and a wider imaging time window for tumors than Gd-DTPA, with low hematological, hepatic, and nephric toxicities. These advantages demonstrate the great potential of single-atom Gd-based nanomaterials as safe, efficient, and long-term MRI contrast agents for cancer diagnosis.

Primary Malignant Lymphoma of the Cauda Equina Diagnosed after Decompression for Lumbar Spinal Stenosis: A Case Report.

Primary malignant lymphoma confinement to the cauda equina is rare. Only 14 cases of primary malignant lymphoma in the cauda equina have been reported. In these cases, the clinical features were similar to those of lumbar spinal canal stenosis (LSCS). This report describes a case of diffuse large B-cell lymphoma of the cauda equina that was diagnosed after decompression surgery for LSCS. An 80-year-old man presented with gait disturbance due to progressive muscle weakness in the lower extremities over the previous two months. He was diagnosed with LSCS, and decompression surgery was performed. However, the muscle weakness worsened after surgery; therefore, he was referred to our department. Plain magnetic resonance imaging (MRI) revealed swelling of the cauda equina. It demonstrated marked homogenous enhancement by gadolinium-diethylenetriamine pentaacetic acid. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) revealed diffuse accumulation of 18F-FDG in the cauda equina. These imaging findings were consistent with those of cauda equina lymphomas. To confirm the diagnosis, we performed an open biopsy of the cauda equina. Histological examination indicated diffuse large B-cell lymphoma. Considering the patient's age and activities of daily living, further treatment was not performed. The patient died four months after the first surgery. Rapid progression of muscle weakness, which cannot be prevented by decompression surgery, and swollen cauda equina on MRI may be signs of this disorder. Gadolinium-enhanced MRI, 18F-FDG PET, and histological investigation of the cauda equina should be performed for diagnosing primary malignant lymphoma of the cauda equina.

Mechanism of extracellular space changes in cryptococcal brain granuloma revealed by MRI tracer.

This study aimed to investigate the changes in extracellular space (ECS) in cryptococcal brain granuloma and its pathological mechanism. The animal model of cryptococcal brain granuloma was established by injecting 1 × 106 CFU/ml of Cryptococcus neoformans type A suspension into the caudate nucleus of Sprague-Dawley rats with stereotactic technology. The infection in the brain was observed by conventional MRI scanning on days 14, 21, and 28 of modeling. The tracer-based MRI with a gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) as a magnetic tracer was performed on the rats with cryptococcal granuloma and the rats in the control group. The parameters of ECS in each area of cryptococcal brain granuloma were measured. The parameters of ECS in the two groups were compared by independent sample t-test, and the changes in ECS and its mechanism were analyzed. Up to 28 days of modeling, the success rate of establishing the brain cryptococcal granuloma model with 1 × 106 CFU/ml Cryptococcus neoformans suspension was 60%. In the internal area of cryptococcal granuloma, the effective diffusion coefficient D* was significantly higher than that of the control group (t = 2.76, P < 0.05), and the same trend showed in the volume ratio α (t = 3.71, P < 0.05), the clearance rate constant k (t = 3.137, P < 0.05), and the tracer half-life T1/2 (t = 3.837, P < 0.05). The tortuosity λ decreased compared with the control group (t = -2.70, P < 0.05). At the edge of the cryptococcal granuloma, the D* and α decreased, while the λ increased compared with the control group (D*:t = -6.05, P < 0.05; α: t = -4.988, P < 0.05; λ: t = 6.222, P < 0.05). The internal area of the lesion demonstrated a quicker, broader, and more extended distribution of the tracer, while the edge of the lesion exhibited a slower and narrower distribution. MRI tracer method can monitor morphological and functional changes of ECS in pathological conditions and provide a theoretical basis for the treatment via ECS.

Inhibition of calcium‐dependent phospholipase A2 improves blood‐brain barrier integrity in ApoE4 carrying mice

AbstractBackgroundBlood‐brain barrier (BBB) is essential for neural health and function. Degradation of BBB is observed in Alzheimer’s disease (AD) and is more pronounced in individuals carrying the apolipoprotein E4 (ApoE4) allele, which is a major genetic risk factor for AD. ApoE4 increases the activation of calcium‐dependent phospholipase A2 (cPLA2), which is linked to BBB function. Here, we asked if cPLA2 inhibition in ApoE4 carrying mice could repair BBB integrity and if the changes could be observed in vivo by dynamic contrast‐enhanced MRI (DCE‐MRI).Method16‐month‐old ApoE4 targeted replacement (ApoE4‐TR) mice were divided into a control group treated with vehicle (n=4) and an experimental group treated with a cPLA2 inhibitor ASB‐14780 (n=4). All imaging was performed using a 7T MRI scanner. DCE‐MRI protocol involved acquisition of baseline images (5min), mice receiving a bolus of gadolinium diethylenetriaminepentaacetic acid (Gd‐DTPA, 0.3mmol/kg, i.v.)) and followed by post‐bolus scans for 20min. Regions of interest (ROIs), such as the hippocampus and isocortex, were manually defined using T2‐weighted (FSE) anatomical scans in ImageJ. Volume transfer constants (KTrans) of the contrast agent uptake were calculated for each subject from the dynamic DCE‐MRI scan using the Patlak model on the Rocketship software (MATLAB).ResultKTrans values for the isocortex and the hippocampus were calculated for two animals from the control group and three animals from the experimental group. The mean KTrans value in the hippocampus region was 60% lower for the mice treated with cPLA2 inhibitor than controls (p=0.056), 0.0459 ± 0.0168 min‐1 and 0.117 ± 0.030 min‐1 respectively. Similarly, the mean KTrans value in the isocortex for the treated mice was 50% lower than the controls (p=0.89), 0.0554 ± 0.018 min‐1 and 0.110 ± 0.028 min‐1 respectively.ConclusionWe observed that cPLA2 inhibition decreased KTrans values implying increased BBB function. Thus, cPLA2 inhibition can be a possible therapeutic path towards reversing some of the damage to the brain due to AD. Currently, we are validating this observation with larger sample sizes and by analyzing the brains of these mice for changes in molecular signatures of BBB.

Study of folate receptor-targeted macromolecular gadolinium complex tumor contrast agent

Targeted drug delivery can improve efficacy and reduce dose, so targeted drug delivery is a very ideal diagnostic imaging approach, and it is necessary to develop magnetic resonance imaging contrast agents with targeted effects. In this study, nuclear magnetic resonance contrast agent folic acid-chitosan/chitosan-diethylenetriaminepentaacetic acid-gadolinium nanoparticles (FA-CS/CS-DTPA-Gd NPs) was combined with folic acid (FA) group modified chitosan (CS) and diethylenetriaminepentaacetic acid-gadolinium complex (DTPA-Gd) modified chitosan. FA-CS/CS-DTPA-Gd NPs were characterized by fourier transform spectroscopy (FT-IR), nuclear magnetic resonance (1H NMR), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The in vitro magnetic properties, cytotoxicity, and targeting to HeLa tumor cells of the nanoparticles were al so evaluated. The results showed that the prepared FA-CS/CS-DTPA-Gd NPs had uniform spheroid shape with particle size of 120.12 ± 1.29 nm; they had good magnetic properties with relaxation rate of 7.5 mM−1·s−1, which was 2.5 times that of DTPA-Gd; they had good in vitro cellular MR imaging and cell safety and could specifically target folic acid-overexpressing tumor cells. The results showed that nanoparticles could be used as targeted magnetic resonance imaging contrast agents in medical diagnostic imaging pathways.

Spontaneous Thoracic Spinal Epidural Hematoma During Pregnancy

Spontaneous Thoracic Spinal Epidural Hematoma During Pregnancy

Dual-modal polypeptide-containing contrast agents for magnetic resonance/fluorescence imaging

Dual-modal magnetic resonance/fluorescent imaging (MRI/FI) attracts moreandmoreattentions in diagnosis of tumors. A corresponding dual-modal imaging agent with sufficient tumor sensitivity and specificity should be matched to improve imaging quality. Tripeptide (RGD) and pentapeptide (YIGSR) were selected as the tumor-targeting groups and attached to gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) and rhodamine B (RhB), and then make two novel polypeptide-based derivatives (RGD-Gd-DTPA-RhB and YIGSR-Gd-DTPA-RhB), respectively. These derivatives were further characterized and their properties, such as cell uptake, cell cytotoxicity, MRI and FI assay, were measured. YIGSR-Gd-DTPA-RhB and RGD-Gd-DTPA-RhB had high relaxivity, good tumor-targeting property, low cell cytotoxicity and good red FI in B16F10 melanoma cells. Moreover, YIGSR-Gd-DTPA-RhB and RGD-Gd-DTPA-RhB possessed high uptake to B16F10 melanoma, and then achieve highly enhanced FI and MRI of tumors in mice for a prolonged time. Therefore, YIGSR-Gd-DTPA-RhB and RGD-Gd-DTPA-RhB can be applied as the potential agents for tumor targeted MRI/FI in vivo.

Mapping single-nephron filtration in the isolated, perfused rat kidney using magnetic resonance imaging.

The kidney has an extraordinary ability to maintain glomerular filtration despite natural fluctuations in blood pressure and nephron loss. This is partly due to local coordination between single-nephron filtration and vascular perfusion. An improved understanding of the three-dimensional (3-D) functional coordination between nephrons and the vasculature may provide a new perspective of the heterogeneity of kidney function and could inform targeted therapies and timed interventions to slow or prevent the progression of kidney disease. Here, we developed magnetic resonance imaging (MRI) tools to visualize single-nephron function in 3-D throughout the isolated perfused rat kidney. We used an intravenous slow perfusion of a glomerulus-targeted imaging tracer [cationized ferritin (CF)] to map macromolecular dynamics and to identify glomeruli in 3-D, followed by a bolus of a freely filtered tracer (gadolinium diethylenetriamine penta-acetic acid) to map filtration kinetics. There was a wide intrakidney distribution of CF binding rates and estimated single-nephron glomerular filtration rate (eSNGFR) between nephrons. eSNGFR and CF uptake rates did not vary significantly by distance from the kidney surface. eSNGFR varied from ∼10 to ∼100 nL/min throughout the kidney. Whole single-kidney GFR was similar across all kidneys, despite differences in the distributions eSNGFR of and glomerular number, indicating a robust adaptive regulation of individual nephrons to maintain constant single-kidney GFR in the presence of a natural variation in nephron number. This work provides a framework for future studies of single-nephron function in the whole isolated perfused kidney and experiments of single-nephron function in vivo using MRI.NEW & NOTEWORTHY We report MRI tools to measure and map single-nephron function in the isolated, perfused rat kidney. We used imaging tracers to identify nephrons throughout the kidney and to measure the delivery and filtration of the tracers at the location of the glomeruli. With this technique, we directly measured physiological parameters including estimated single-nephron glomerular filtration rate throughout the kidney. This work provides a foundation for new studies to simultaneously map the function of large numbers of nephrons.

Carboxymethyl chitosan-assisted MnOx nanoparticles: Synthesis, characterization, detection and cartilage repair in early osteoarthritis

While the early detection and repair of cartilage lesions are crucial in the treatment of osteoarthritis (OA), they remain challenging because neither clinically used medicines nor magnetic resonance (MR) contrast agents can achieve detection and repair simultaneously. Here, we conjugated carboxymethyl chitosan (CMC) with a cartilage-targeting peptide (WYRGRL, termed WY) and then synthesized CMC-assisted manganese oxide nanoparticles (MnOx NPs). The resultant WY-CMC-MnOx NPs demonstrated an excellent biocompatibility and a good T1 relaxivity of 1.72 mM−1·s−1. Owing to their ultrasmall size and cartilage-targeting ability, the WY-CMC-MnOx NPs considerably increased the MR imaging quality of cartilage lesions compared to non-cartilage-targeting NPs. In contrast, clinically used gadolinium-diethylenetriamine pentaacetic acid (Gd-DPTA) failed to detect the cartilage lesions. Furthermore, WY-CMC-MnOx promoted chondrogenesis in mesenchymal stem cells, thereby enhancing OA therapy through efficient cartilage regeneration after intraarticularly injection in destabilization of medial meniscus (DMM) rat models. Our results indicate that WY-CMC-MnOx NPs are promising for use in the diagnosis and treatment of early OA.

Red Blood Cell Membrane-Coated Ultrasmall NaGdF4 Nanoprobes for High-Resolution 3D Magnetic Resonance Angiography.

Enhanced angiography based on magnetic resonance imaging (MRI) has emerged as a noninvasive, robust, and high-resolution imaging technique for the clinical evaluation of vascular diseases. However, the effects of clinical Gd-chelating contrast agents are unsatisfactory for MRI contrast enhancement owing to their short blood half-life caused by rapid vascular extravasation, especially in microvessels. To address these issues, nanoprobes based on red blood cell membrane-coated ultrasmall NaGdF4 nanoparticles that exhibit much higher longitudinal molar relaxivity (r1) than the clinically used contrast agent gadolinium diethylenetriaminepentaacetic acid have been developed. Furthermore, the appropriate hydrodynamic diameter and stealth nature aid the nanoprobes to reside longer within the blood vessels without extravasation, thereby increasing the contrast between the blood vessels and surrounding tissues. Through probe-enhanced three-dimensional (3D) dynamic contrast-enhanced MR angiography, the main arteries and veins of the mouse were readily discernible, and even tiny vessels with sub-millimeter diameters could be clearly depicted. With this level of outstanding MR angiography performance, the embolization and recanalization processes of the carotid artery can be serially monitored with high imaging resolution using only a single injection. Additionally, the results of clearance studies and the toxicity tests further highlight the safety features of the nanoprobe. To summarize, the nanoprobes used in this study exhibit less extravascular leakage and a longer blood half-life, thus successfully overcoming the defects of the conventional low-molecular-weight Gd-based contrast agents and demonstrating their potential usefulness in enhanced MR angiography.

Dexamethasone does not affect endolymphatic hydrops (EH) in patients with Meniere's disease within 24 h, and intratympanic administration of gadolinium plus dexamethasone simplifies high-quality imaging of EH using a novel protocol of 7 min

BackgroundIntratympanic administration of gadolinium chelate allows for a better visualization of endolymphatic hydrops (EH) using MRI than intravenous injection and was recently further improved to facilitate high-quality imaging of EH in 7 min. The aim of the present study was to simplify the intratympanic administration protocol by mixing gadolinium chelate with therapeutic dexamethasone and to evaluate the effects of this mixture on the visualization of EH in MRI. Materials and methodsIn an in vitro study, the potential impact of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) on the stability of dexamethasone was evaluated by analyzing dynamic changes in dexamethasone with high-performance liquid chromatography (HPLC) after mixing with Gd-DTPA. Ten patients with definite Meniere's disease (MD) were recruited to study the potential interference of dexamethasone on MRI visualization of EH, and 49 patients with MD were recruited to evaluate the effect of intratympanic injection of Gd-DTPA mixed with dexamethasone on MRI of EH using a 3T MR machine and a novel heavily T2-weighted 3-dimensional fluid-attenuated inversion recovery reconstructed using a magnitude plus zero-filled interpolation (hT2FLAIR-MZFI) sequence. ResultsThe retention times and peak area of dexamethasone in HPLC were not modified by the addition of Gd-DTPA. EH grading in the cochlea and vestibule was not influenced in any ear by intratympanic injection of dexamethasone. Excellent inner ear images were obtained from all patients, and EHs with various grades were displayed. There were significant correlations between diagnosis and cochlear EH (p < 0.01, Spearman's Rho), between diagnosis and vestibular EH (p < 0.01, Spearman's Rho), and between cochlear and vestibular EH (p < 0.01, Spearman's Rho). The distribution of Gd-DTPA plus dexamethasone negatively correlated with the grade of vestibular EH. Injury of the endolymph-perilymph barrier was detected in one cochlea and three vestibules of 59 inner ears with MD. ConclusionsIntratympanic administration of Gd-DTPA plus dexamethasone yielded high-quality MRI images of EH in patients with MD using a novel 7-min protocol and simplified the clinical application. Intratympanic administration of Gd-DTPA plus dexamethasone might be used to test its therapeutic effect in future work. Level of evidence3.

Integration of PEG-conjugated gadolinium complex and superparamagnetic iron oxide nanoparticles as T 1-T 2 dual-mode magnetic resonance imaging probes.

The T1−T2 dual-mode probes for magnetic resonance imaging (MRI) can non-invasively acquire comprehensive information of different tissues or generate self-complementary information of the same tissue at the same time, making MRI a more flexible imaging modality for complicated applications. In this work, three Gadolinium-diethylene-triaminepentaaceticacid (Gd-DTPA) complex conjugated superparamagnetic iron oxide (SPIO) nanoparticles with different Gd/Fe molar ratio (0.94, 1.28 and 1.67) were prepared as T1–T2 dual-mode MRI probes, named as SPIO@PEG-GdDTPA0.94, SPIO@PEG-GdDTPA1.28 and SPIO@PEG-GdDTPA1.67, respectively. All SPIO@PEG-GdDTPA nanocomposites with 8 nm spherical SPIO nanocrystals showed good Gd3+ chelate stability. SPIO@PEG-GdDTPA0.94 nanocomposites with lowest Gd/Fe molar ratio show no cytotoxicity to Raw 264.7 cells as compared to SPIO@PEG-GdDTPA1.28 and SPIO@PEG-GdDTPA1.67. SPIO@PEG-GdDTPA0.94 nanocomposites with r1 (8.4 mM−1s−1), r2 (83.2 mM−1s−1) and relatively ideal r2/r1 ratio (9.9) were selected for T1–T2 dual-mode MRI of blood vessels and liver tissue in vivo. Good contrast images were obtained for both cardiovascular system and liver in animal studies under a clinical 3 T scanner. Importantly, one can get high-quality contrast-enhanced blood vessel images within the first 2 h after contrast agent administration and acquire liver tissue anatomy information up to 24 h. Overall, the strategy of one shot of the dual mode MRI agent could bring numerous benefits not only for patients but also to the radiologists and clinicians, e.g. saving time, lowering side effects and collecting data of different organs sequentially.

Prediction of Ovarian Follicular Dominance by MRI Phenotyping of Hormonally Induced Vascular Remodeling

In the mammalian female, only a small subset of ovarian follicles, known as the dominant follicles (DFs), are selected for ovulation in each reproductive cycle, while the majority of the follicles and their resident oocytes are destined for elimination. This study aimed at characterizing early changes in blood vessel properties upon the establishment of dominance in the mouse ovary and application of this vascular phenotype for prediction of the follicles destined to ovulate. Sexually immature mice, hormonally treated for induction of ovulation, were imaged at three different stages by dynamic contrast-enhanced (DCE) MRI: prior to hormonal administration, at the time of DF selection, and upon formation of the corpus luteum (CL). Macromolecular biotin-bovine serum albumin conjugated with gadolinium-diethylenetriaminepentaacetic acid (b-BSA-GdDTPA) was intravenously injected, and the dynamics of its extravasation from permeable vessels as well as its accumulation in the antral cavity of the ovarian follicles was followed by consecutive T1-weighted MRI. Permeability surface area product (permeability) and fractional blood volume (blood volume) were calculated from b-BSA-GdDTPA accumulation. We found that the neo-vasculature during the time of DF selection was characterized by low blood volume and low permeability values as compared to unstimulated animals. Interestingly, while the vasculature of the CL showed higher blood volume compared to the DF, it exhibited a similar permeability. Taking advantage of immobilized ovarian imaging, we combined DCE-MRI and intravital light microscopy, to reveal the vascular properties of follicles destined for dominance from the non-ovulating subordinate follicles (SFs). Immediately after their selection, permeability of the vasculature of DF was attenuated compared to SF while the blood volume remained similar. Furthermore, DFs were characterized by delayed contrast enhancement in the avascular follicular antrum, reflecting interstitial convection, whereas SFs were not. In this study, we showed that although DF selection is accompanied by blood vessel growth, the new vasculature remained relatively impermeable compared to the vasculature in control animal and compared to SF. Additionally, DFs show late signal enhancement in their antrum. These two properties may aid in clinical prediction of follicular dominance at an early stage of development and help in their diagnosis for possible treatment of infertility.

High-quality imaging of endolymphatic hydrops acquired in 7 minutes using sensitive hT2W\u20133D\u2013FLAIR reconstructed with magnitude and zero-filled interpolation

BackgroundIt is still challenging to detect endolymphatic hydrops (EH) in patients with Meniere’s disease (MD) using MRI. The aim of the present study was to optimize a sensitive technique generating strong contrast enhancement from minimum gadolinium–diethylenetriamine pentaacetic acid (Gd–DTPA) while reliably detecting EH in the inner ear, including the apex.Materials and methodsAll imaging was performed using a 3.0 T MR system 24 h after intratympanic injection of low-dose Gd–DTPA. Heavily T2-weighted 3-dimensional fluid-attenuated inversion recovery reconstructed with magnitude and zero-filled interpolation (hT2W–FLAIR–ZFI) was optimized and validated in phantom studies and compared with medium inversion time inversion recovery imaging with magnitude reconstruction (MIIRMR). The following parameters were used in hT2W–FLAIR–ZFI: repetition time 14,000 ms, echo time 663 ms, inversion time 2900 ms, flip angle 120°, echo train length 271, and field of view 166 × 196 mm2.ResultsMRI obtained using hT2W–FLAIR–MZFI yielded high-quality images with sharper and smoother borders between the endolymph and perilymph and a higher signal intensity ratio and more homogenous perilymph enhancement than those generated with MIIRMR (p < 0.01). There were predominantly grade II EHs in the cochleae and grade III EHs in the vestibule in definite MD. EH was detected in the apex of 11/16 ipsilateral ears, 3/16 contralateral ears in unilateral definite MD and 3/6 ears in bilateral MD.ConclusionsThe novel hT2W–FLAIR–MZFI technique is sensitive and demonstrates strong and homogenous enhancement by minimum Gd–DTPA in the inner ear, including the apex, and yields high-quality images with sharp borders between the endolymph and perilymph.