Design, construction and validation of a magnetic particle imaging (MPI) system for human brain imaging.

Magnetic Particle Imaging (MPI) was introduced in 2005 as a promising, tracer-based medical imaging modality with the potential for high sensitivity and spatial resolution. Since then, numerous preclinical devices have been built but only a few human-scale devices, none of which targeted functional neuroimaging. In this work, we probe the challenges of scaling the technology to meet the needs of human functional neuroimaging with sufficient sensitivity for detecting the hemodynamic changes following brain activation with a spatio-temporal resolution comparable to current functional Magnetic Resonance Imaging (fMRI) approaches.

Quantum Speed Limit in Quantum Sensing.

Quantum sensors capitalize on advanced control sequences for maximizing sensitivity and precision. However, protocols are not usually optimized for temporal resolution. Here, we establish the limits for time-resolved sensing of dynamical signals using qubit probes.

Charge and Spin Dynamics and Destabilization of Shallow Nitrogen-Vacancy Centers under UV and Blue Excitation.

Shallow nitrogen-vacancy (NV) centers in diamond offer opportunities to study photochemical reactions, including photogeneration of radical pairs, at the single-molecule regime. A prerequisite is a detailed understanding of charge and spin dynamics of NVs exposed to the short-wavelength light required to excite chemical species. Here, we investigate the charge and spin dynamics of shallow NVs under 445 and 375 nm illumination.

Functional magnetic particle imaging (fMPI) of cerebrovascular changes in the rat brain during hypercapnia.

Non-invasive functional brain imaging modalities are limited in number, each with its own complex trade-offs between sensitivity, spatial and temporal resolution, and the directness with which the measured signals reflect neuronal activation. Magnetic particle imaging (MPI) directly maps the cerebral blood volume (CBV), and its high sensitivity derives from the nonlinear magnetization of the superparamagnetic iron oxide nanoparticle (SPION) tracer confined to the blood pool. Our work evaluates functional MPI (fMPI) as a new hemodynamic functional imaging modality by mapping the CBV response in a rodent model where CBV is modulated by hypercapnic breathing manipulation.

Toward quantum sensing of chiral induced spin selectivity: Probing donor-bridge-acceptor molecules with NV centers in diamond.

Photoexcitable donor-bridge-acceptor (D-B-A) molecules that support intramolecular charge transfer are ideal platforms to probe the influence of chiral induced spin selectivity (CISS) in electron transfer and resulting radical pairs. In particular, the extent to which CISS influences spin polarization or spin coherence in the initial state of spin-correlated radical pairs following charge transfer through a chiral bridge remains an open question. Here, we introduce a quantum sensing scheme to measure directly the hypothesized spin polarization in radical pairs using shallow nitrogen-vacancy (NV) centers in diamond at the single- to few-molecule level.

Diamond surface engineering for molecular sensing with nitrogen-vacancy centers.

Quantum sensing using optically addressable atomic-scale defects, such as the nitrogen-vacancy (NV) center in diamond, provides new opportunities for sensitive and highly localized characterization of chemical functionality. Notably, near-surface defects facilitate detection of the minute magnetic fields generated by nuclear or electron spins outside of the diamond crystal, such as those in chemisorbed and physisorbed molecules. However, the promise of NV centers is hindered by a severe degradation of critical sensor properties, namely charge stability and spin coherence, near surfaces (< 10 nm deep).

Single-Nitrogen-Vacancy NMR of Amine-Functionalized Diamond Surfaces.

Nuclear magnetic resonance (NMR) imaging with shallow nitrogen-vacancy (NV) centers in diamond offers an exciting route toward sensitive and localized chemical characterization at the nanoscale. Remarkable progress has been made to combat the degradation in coherence time and stability suffered by near-surface NV centers using suitable chemical surface termination. However, approaches that also enable robust control over adsorbed molecule density, orientation, and binding configuration are needed.

Parallel detection and spatial mapping of large nuclear spin clusters.

Nuclear magnetic resonance imaging (MRI) at the atomic scale offers exciting prospects for determining the structure and function of individual molecules and proteins. Quantum defects in diamond have recently emerged as a promising platform towards reaching this goal, and allowed for the detection and localization of single nuclear spins under ambient conditions. Here, we present an efficient strategy for extending imaging to large nuclear spin clusters, fulfilling an important requirement towards a single-molecule MRI technique.

A sensitive, stable, continuously rotating FFL MPI system for functional imaging of the rat brain.

Magnetic particle imaging noninvasively maps the distribution of superparamagnetic iron oxide nanoparticles with high sensitivity. Since the particles are confined to the blood pool within the brain, it may be well-suited for cerebral blood volume (CBV)-based functional neuroimaging with MPI (fMPI). Here, we present a magnetic particle imaging system designed to detect the CBV modulation at the hemodynamic timescale (~5 sec) in rodents.

Concept for using magnetic particle imaging for intraoperative margin analysis in breast-conserving surgery.

Breast-conserving surgery (BCS) is a commonly utilized treatment for early stage breast cancers but has relatively high reexcision rates due to post-surgical identification of positive margins. A fast, specific, sensitive, easy-to-use tool for assessing margins intraoperatively could reduce the need for additional surgeries, and while many techniques have been explored, the clinical need is still unmet. We assess the potential of Magnetic Particle Imaging (MPI) for intraoperative margin assessment in BCS, using a passively or actively tumor-targeted iron oxide agent and two hardware devices: a hand-held Magnetic Particle detector for identifying residual tumor in the breast, and a small-bore MPI scanner for quickly imaging the tumor distribution in the excised specimen.

Broadband radio-frequency transmitter for fast nuclear spin control.

The active manipulation of nuclear spins with radio-frequency (RF) coils is at the heart of nuclear magnetic resonance (NMR) spectroscopy and spin-based quantum devices. Here, we present a miniature RF transmitter designed to generate strong RF pulses over a broad bandwidth, allowing for fast spin rotations on arbitrary nuclear species. Our design incorporates (i) a planar multilayer geometry that generates a large field of 4.

Tracking the precession of single nuclear spins by weak measurements.

Nuclear magnetic resonance (NMR) spectroscopy is a powerful technique for analysing the structure and function of molecules, and for performing three-dimensional imaging of their spin densities. At the heart of NMR spectrometers is the detection of electromagnetic radiation, in the form of a free induction decay signal, generated by nuclei precessing around an applied magnetic field. Whereas conventional NMR requires signals from 10 or more nuclei, recent advances in sensitive magnetometry have dramatically lowered the required number of nuclei to a level where a few or even individual nuclear spins can be detected.

Three-Dimensional Nuclear Spin Positioning Using Coherent Radio-Frequency Control.

Distance measurements via the dipolar interaction are fundamental to the application of nuclear magnetic resonance (NMR) to molecular structure determination, but they provide information on only the absolute distance r and polar angle θ between spins. In this Letter, we present a protocol to also retrieve the azimuth angle ϕ. Our method relies on measuring the nuclear precession phase after the application of a control pulse with a calibrated external radio-frequency coil.

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard.

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than g with g=2.002644=g·(1+162ppm) with a relative uncertainty of 15ppm.

Perioperative management of patients with myasthenia gravis: prevention, recognition, and treatment.

Myasthenia gravis (MG) is an autoimmune disease characterized by weakness and fatigability of skeletal muscles, with improvement following rest. The disease was so named because of a frequently fatal outcome. As recently as 30 years ago, 25% of patients with MG died of the disease.

Temporomandibular joint pain and dysfunction.

Pain caused by temporomandibular disorders originates from either muscular or articular conditions, or both. Distinguishing the precise source of the pain is a significant diagnostic challenge to clinicians, and effective management hinges on establishing a correct diagnosis. This paper examines terminology and regional anatomy as it pertains to functional and dysfunctional states of the temporomandibular joint and muscles of mastication.

Benzocaine-induced methemoglobinemia.

A case is reported in which a patient developed methemoglobinemia-induced cyanosis while under general anesthesia during surgery for multiple fascial space infections. The cause of methemoglobinemia was 20% benzocaine spray used for local anesthesia before intubation. Acutely developing methemoglobinemia is infrequently encountered in clinical practice.

Comparison of bone scintigraphy with bone markers in the diagnosis of bone metastasis in lung carcinoma patients.

This study was designed to evaluate the utility of the bone markers total alkaline phosphatase (TAP), bone-specific alkaline phosphatase (BAP), aminoterminal propeptide of type I collagen (PINP), carboxyterminal propeptide of type I collagen (PICP), pyridinoline crosslinks (PYD), deoxypyridinoline crosslinks (DPD), cross-linked carboxyterminal telopeptide of type I collagen (ICTP), cross-linked carboxyterminal telopeptide of type I collagen (CTx, beta-CrossLaps) and tartrate-resistant acid phosphatase 5b (TRAP 5b) in comparison with bone scintigraphy for the diagnosis of bone metastasis in lung carcinoma patients. The study population consisted of 49 patients with bone metastasis confirmed by plain radiography and/or computed tomography, 89 patients without bone metastasis, 12 patients with benign lung diseases and 18 healthy persons. All patients were of male gender.