129Xe Dynamic Nuclear Polarization Demystified: The Influence of the Glassing Matrix on the Radical Properties.

129Xe dissolution dynamic nuclear polarization (DNP) is a controversial topic. The gold standard technique for hyperpolarized xenon magnetic resonance imaging (MRI) is spin exchange optical pumping, which received FDA approval in 2022. Nevertheless, the versatility of DNP for enhancing the signal of any NMR active nucleus might provide new perspectives for hyperpolarized 129Xe NMR/MRI. Initial publications about 129Xe DNP underlined the increased complexity in the sample preparation and lower polarization levels when compared to more conventional 13C-labeled molecules, at same experimental conditions, despite very close gyromagnetic ratios. Herein, we introduce, using a Custom Fluid Path system, a user-friendly and very robust sample preparation method. Moreover, investigating the radical properties at real DNP conditions by means of LOngitudinal Detected Electron Spin Resonance, we discovered a dramatic shortening of the electron spin longitudinal relaxation time (T1e) of nitroxyl radicals in xenon DNP samples' matrices, with respect to more commonly used water:glycerol ones. Mitigating those challenges through microwave frequency modulation, we achieved over 20% 129Xe polarization without employing any deuterated solvent.

The dataset of duplex ultrasound assessment of the internal mammary artery in women with unilateral mastectomy followed by radiotherapy for breast cancer.

Adjuvant radiotherapy for breast cancer may involve some incidental exposure of the ipsilateral internal mammary artery to ionizing radiation. However, the relevant evidence is limited and inconsistent. The dataset presented in this article contains the information used to assess the effects of accidental radiation exposure on the internal mammary artery in patients with unilateral total mastectomy followed radiotherapy for breast cancer. The study population consists of two groups: the irradiated group and the control group. The left and right internal mammary arteries were assessed through the second intercostal spaces using a computed sonography system (Vivid S6; GE, Tirat Carmel, Israel) equipped with a 5.5 - 11 MHz transducer. The recorded parameters were the diameter, time-averaged maximum velocity, and blood flow of the internal mammary artery. The dataset contains two files of data: a raw and an analyzed data. The raw data file contains the individual information of each participant, including demographic characteristics and the parameters of the internal mammary artery duplex ultrasound imaging. The analyzed data file was made up of R Markdown, a markup language of R. The results of data analysis were presented in the related research article which has been accepted for publication in the Annals of Vascular Surgery. The dataset presented in this article may be reused for further studies in which the internal mammary artery is considered as potential donor or recipient vessels for a vascular bypass or free flap anastomosis.

Duplex Imaging Assessment of the Internal Mammary Arteries in Women after Unilateral Mastectomy and Radiotherapy for Breast Cancer.

BACKGROUND: The effects of incidental radiation exposure on internal mammary arteries remain unclear. The present study was designed to test the hypothesis by comparing diameter and blood flow of the irradiated and nonirradiated internal mammary arteries, using Duplex ultrasound imaging. METHODS: The study was designed as a single-center, transversal, comparative study. The main outcomes were diameter and volumetric blood flow of the internal mammary arteries. The Wilcoxon rank-sum test was used to assess the differences between the irradiated and nonirradiated internal mammary arteries with regard to the diameter and volumetric blood flow. RESULTS: The diameter (median [interquartile range]) of the irradiated internal mammary arteries (0.170 mm [0.160, 0.180]) was smaller than that of the contralateral nonirradiated ones (0.180 mm [0.170, 0.200], P < 0.0001) and that of the internal mammary arteries in the control group (0.180 mm [0.170, 0.190], P < 0.0001). Similarly, blood flow (median [interquartile range]) of the irradiated internal mammary arteries (52.4 ml/min [37.78, 65.57]) was smaller than that of the contralateral nonirradiated ones (62.7 ml/min [46.87, 84.17], P < 0.0001), as well as of the left (56.7 ml/min [46.88, 72.58], P = 0.02) and the right internal mammary arteries in the control group (61.0 ml/min [47.47, 74.52], P = 0 0.0009). CONCLUSIONS: The data indicate that the irradiated internal mammary arteries in patients with a history of total mastectomy followed by radiotherapy for breast cancer had significantly smaller diameter and blood flow compared to the nonirradiated internal mammary arteries.

Influence of DNP Polarizing Agents on Biochemical Processes: TEMPOL in Transient Ischemic Stroke.

Hyperpolarization of 13C by dissolution dynamic nuclear polarization (dDNP) boosts the sensitivity of magnetic resonance spectroscopy (MRS), making possible the monitoring in vivo and in real time of the biochemical reactions of exogenously infused 13C-labeled metabolic tracers. The preparation of a hyperpolarized substrate requires the use of free radicals as polarizing agents. Although added at very low doses, these radicals are not biologically inert. Here, we demonstrate that the presence of the nitroxyl radical TEMPOL influences significantly the cerebral metabolic readouts of a hyperpolarized [1-13C] lactate bolus injection in a mouse model of ischemic stroke with reperfusion. Thus, the choice of the polarizing agent in the design of dDNP hyperpolarized MRS experiments is of great importance and should be taken into account to prevent or to consider significant effects that could act as confounding factors.

Multi-sample/multi-nucleus parallel polarization and monitoring enabled by a fluid path technology compatible cryogenic probe for dissolution dynamic nuclear polarization.

Low throughput is one of dissolution Dynamic Nuclear Polarization (dDNP) main shortcomings. Especially for clinical and preclinical applications, where direct 13C nuclei polarization is usually pursued, it takes hours to generate one single hyperpolarized (HP) sample. Being able to hyperpolarize more samples at once represents a clear advantage and can expand the range and complexity of the applications. In this work, we present the design and performance of a highly versatile and customizable dDNP cryogenic probe, herein adapted to a 5 T "wet" preclinical polarizer, that can accommodate up to three samples at once and, most importantly, it is capable of monitoring the solid-state spin dynamics of each sample separately, regardless of the kind of radical used and the nuclear species of interest. Within 30 min, the system was able to dispense three HP solutions with high repeatability across the channels (30.0 ± 1.2% carbon polarization for [1-13C]pyruvic acid doped with trityl radical). Moreover, we tested multi-nucleus NMR capability by polarizing and monitoring simultaneously 13C, 1H and 129Xe. Finally, we implemented [1-13C]lactate/[1-13C]pyruvate polarization and back-to-back dissolution and injection in a healthy mouse model to perform multiple-substrate HP Magnetic Resonance Spectroscopy (MRS) at 14.1 T.

Segmenting electroencephalography wires reduces radiofrequency shielding artifacts in simultaneous electroencephalography and functional magnetic resonance imaging at 7 T.

PURPOSE: Simultaneous scalp electroencephalography and functional magnetic resonance imaging (EEG-fMRI) enable noninvasive assessment of brain function with high spatial and temporal resolution. However, at ultra-high field, the data quality of both modalities is degraded by mutual interactions. Here, we thoroughly investigated the radiofrequency (RF) shielding artifact of a state-of-the-art EEG-fMRI setup, at 7 T, and design a practical solution to limit this issue. METHODS: Electromagnetic field simulations and MR measurements assessed the shielding effect of the EEG setup, more specifically the EEG wiring. The effectiveness of segmenting the wiring with resistors to reduce the transmit field disruption was evaluated on a wire-only EEG model and a simulation model of the EEG cap. RESULTS: The EEG wiring was found to exert a dominant effect on the disruption of the transmit field, whose intensity varied periodically as a function of the wire length. Breaking the electrical continuity of the EEG wires into segments shorter than one quarter RF wavelength in air (25 cm at 7 T) reduced significantly the RF shielding artifacts. Simulations of the EEG cap with segmented wires indicated similar improvements for a moderate increase of the power deposition. CONCLUSION: We demonstrated that segmenting the EEG wiring into shorter lengths using commercially available nonmagnetic resistors is effective at reducing RF shielding artifacts in simultaneous EEG-fMRI. This prevents the formation of RF-induced standing waves, without substantial specific absorption rate (SAR) penalties, and thereby enables benefiting from the functional sensitivity boosts achievable at ultra-high field.

How to improve the efficiency of a traditional dissolution dynamic nuclear polarization (dDNP) apparatus: Design and performance of a fluid path compatible dDNP/LOD-ESR probe.

Dissolution Dynamic Nuclear Polarization (dDNP) was invented almost twenty years ago. Ever since, hardware advancement has observed 2 trends: the quest for DNP at higher field and, more recently, the development of cryogen free polarizers. Despite the DNP community is slowly migrating towards "dry" systems, many "wet" polarizers are still in use. Traditional DNP polarizers can use up to 100 L of liquid helium per week, but are less sensitive to air contamination and have higher cooling power. These two characteristics make them very versatile when it comes to new methods development. In this study we retrofitted a 5 T/1.15 K "wet" DNP polarizer with the aim of improving cryogenic and DNP performance. We designed, built, and tested a new DNP insert that is compatible with the fluid path (FP) technology and a LOgitudinal Detected Electron Spin Resonance (LOD-ESR) probe to investigate radical properties at real DNP conditions. The new hardware increased the maximum achievable polarization and the polarization rate constant of a [1-13C]pyruvic acid-trityl sample by a factor 1.5. Moreover, the increased liquid He holding time together with the possibility to constantly keep the sample space at low pressure upon sample loading and dissolution allowed us to save about 20 L of liquid He per week.

Preservation of internal iliac artery flow during endovascular aortic aneurysm repair in a patient with bilateral absence of common iliac artery.

Bilateral absence of the common iliac artery is an extremely rare congenital vascular malformation in which the distal aorta divides directly into two external iliac arteries and two internal iliac arteries. In the case of the presence of this vascular malformation in association with an aortic aneurysm, preservation of the internal iliac artery flow during endovascular aortic repair represents a technical challenge. We have reported a case in which the bilateral absence of the common iliac artery associated with an infrarenal abdominal aortic aneurysm was successfully treated by endovascular aortic repair using commercially available iliac branched devices to maintain pelvic perfusion.

Evaluating the potential of hyperpolarised [1-13C] L-lactate as a neuroprotectant metabolic biosensor for stroke.

Cerebral metabolism, which can be monitored by magnetic resonance spectroscopy (MRS), changes rapidly after brain ischaemic injury. Hyperpolarisation techniques boost 13C MRS sensitivity by several orders of magnitude, thereby enabling in vivo monitoring of biochemical transformations of hyperpolarised (HP) 13C-labelled precursors with a time resolution of seconds. The exogenous administration of the metabolite L-lactate was shown to decrease lesion size and ameliorate neurological outcome in preclinical studies in rodent stroke models, as well as influencing brain metabolism in clinical pilot studies of acute brain injury patients. The aim of this study was to demonstrate the feasibility of measuring HP [1-13C] L-lactate metabolism in real-time in the mouse brain after ischaemic stroke when administered after reperfusion at a therapeutic dose. We showed a rapid, time-after-reperfusion-dependent conversion of [1-13C] L-lactate to [1-13C] pyruvate and [13C] bicarbonate that brings new insights into the neuroprotection mechanism of L-lactate. Moreover, this study paves the way for the use of HP [1-13C] L-lactate as a sensitive molecular-imaging biosensor in ischaemic stroke patients after endovascular clot removal.

Leaf photosynthesis of 'Cat Hoa Loc' mango (Mangifera indica L.) and 'Nam Roi' pummelo (Citrus grandis (L.) Osbeck.) in the rainy season.

With an EARS--Plant photosynthesis meter we determined gross photosynthesis (P) of leaves of 'Cat Hoa Loc' mango on 4 years old trees planted in the Fruit Tree Experiment and Production Station, Campus 2, Department of Crop Science, College of Agriculture, Can Tho University in the rainy season of the year 2000. The same experiment was conducted on 'Nam Roi' pummelo on a farm located in the Binh Minh district, Vinh Long province. In the rainy season the calculated gross photosynthesis of 'Cat Hoa Loc' mango leaves at flowering stage was higher than that at the vegetative stage. However, the photosynthetically active radiation and quantum yield of 'Cat Hoa Loc' mango leaves in both stages did not reach the light saturation point when compared with values from estimated equation of photosynthetic light curve. The same holds true for 'Nam Roi' pummelo in the vegetative stage.