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PURPOSE: To develop a high temporal resolution functional MRI (fMRI) method for tracking repeating events in the brain. METHODS: We developed a novel fMRI method using Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT), termed EVEnt-Recurring SWIFT (EVER-SWIFT). The method is able to image similar repeating events with sub-second temporal resolution. Here, we demonstrate the use of EVER-SWIFT for detecting fMRI responses during deep brain stimulation (DBS) of the medial septal nucleus (MSN) and during spontaneous isoflurane-induced burst suppression in the rat brain at 9.4 T with 200-ms temporal resolution. RESULTS: EVER-SWIFT showed that the shapes and time-to-peak values of the response curves to DBS stimulation significantly differed between downstream brain regions connected to the MSN, resembling findings obtained with traditional 2-s temporal resolution. In contrast, EVER-SWIFT allowed for detailed temporal measurement of a spontaneous isoflurane-induced bursting activity pattern, which was not achieved with traditional temporal resolution. CONCLUSION: EVER-SWIFT enables sub-second 3-dimensional imaging of both stimulated and spontaneously recurring brain activities, and thus holds great potential for studying the mechanisms of neuromodulation and spontaneous brain activity.

© 2017 International Society for Magnetic Resonance in Medicine Purpose: Conventional T2-weighted MRI produces a hypointense signal from iron-labeled cells, which renders quantification unfeasible. We tested a SWeep Imaging with Fourier Transformation (SWIFT) MRI pulse sequence to generate a quantifiable hyperintense signal from iron-labeled cells. Methods: Mesenchymal stem cells (MSCs) were labeled with different concentrations of iron oxide particles and examined for cell viability, proliferation, and differentiation. The SWIFT sequence was optimized to detect and quantify the amount of iron in the muscle tissue after injection of iron oxide solution and iron-labeled MSCs. Results: The incubation of MSCs with iron oxide and low concentration of poly-L-lysine mixture resulted in an internalization of up to 22 pg of iron per cell with no adverse effect on MSCs. Phantom experiments showed a dependence of SWIFT signal intensity on the excitation flip angle. The hyperintense signal from iron-labeled cells or solutions was detected, and an amount of the iron oxide in the tissue was quantified with the variable flip angle method. Conclusions: The SWIFT sequence can produce a quantifiable hyperintense MRI signal from iron-labeled cells. The graft of 18 x 106 cells was detectable for 19 days after injection and the amount of iron was quantifiable. The proposed protocol simplifies the detection and provides a means to quantify cell numbers. Magn Reson Med 78:1900–1910, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

Modification of a commercial computer-controlled high-resolution NMR spectrometer Tesla BS-587A and specially designed interface circuits are described, which allow the original ADT-4700 computer to be replaced by a modern IBM PC compatible personal computer. © 1998 MAHK Hayka/Interperiodica Publishing.

An active system of temperature regulation and temperature gradient in a sample on the example NMR sensor is described in this work. By supporting the given average temperature, the system of temperature-stabilization allows one to set and supervise the size and direction of the temperature gradient along a sample. The temperature of a sample is maintained with on accuracy of about ±0.1°C in a temperature interval of-150 to +200°C with a longitudinal temperature gradient no more than ±0.2°C. The value of the temperature gradient is established in the range of 0° to 10°C/cm in both directions. © 1998 MAHK Hayka/Interperiodica Publishing.

Spin-lattice and spin-spin NMR relaxation was studied in a series of segmented polyurethanes based on poly(diethylene glycol adipate), 2,4-tolylene diamine, and 2,4-toluene diisocyanate. It was concluded that NMR relaxation is determined by physical interactions between rigid blocks and also between rigid and flexible blocks. The dependence of the degree of segregation on the molecular weights of rigid and flexible blocks was determined. A quite high degree of segregation in the investigated systems and the related manifestations of individual features of flexible blocks allowed us to follow the dynamics of the molecular chain with fixed end and study variation of the glass transition temperature and the activation energy of the segmental motion of this chain as a function of its molecular weight.

A new technique based on the Goldman-Shen pulse sequence with varying preparation interval is proposed for the study of domain morphology of segmented polyurethanes. The results of numerical calculations of the magnetization recovery in different models of domain morphology show that the method provides new information about the domain morphology which is beyond the reach of the conventional Goldman-Shen experiment. A close agreement of the theoretical predictions with the experimental data on samples of segmented polyurethanes with a fixed molecular mass of the hard blocks and variable molecular mass of the soft blocks reinforces the above statement. The resulting structural parameters obtained by this new NMR technique are compared with the data from the small-angle X-ray scattering (SAXS) method.

Data from three-pulse NMR experiments, namely, the Goldman-Shen pulse sequence and the stimulated-echo sequence, on partially crystallized poly(ethylene glycol) and tetrafunctional dimethylsiloxane networks are presented. A dipole echo has been observed after a third radiofrequency pulse. Quantum mechanical calculations of the response of the spin system to the three-pulse sequences have been performed, considering only thez-zcomponent of the dipole-dipole spin coupling. The resulting expression suggests dipole-echo formation and is in agreement with experimental data. © 1995.

The effect of the content of rigid blocks on the phase state and structure of rigid domains in segmented polyurethane based on polyethylenebutyleneglycol adipate, 1,4-butandiol, and 4,4′-diphenylmethane diisocyanate is studied with the aid of pulsed 1H NMR. It is shown from an analysis of free induction decays and using the Goldman-Shen technique that in the specimen having the minimum rigid block length a microphase is formed whose domains have sharp boundaries without intermediate regions. With increase in rigid block length, a second type of domain appears together with the first, consisting of a central part and an intermediate region of high molecular mobility. The ratio of the number of domains of different types depends on the temperature. The dimensions of the domains and intermediate regions are evaluated, and possible structural models are considered. © 1989.

Pulse NMR methods have been employed to investigate the phase state and the process of phase separation in segmented PUs based on 1,4-butanediol and 4,4′-diphenylmethane diisocyanate with crystallizable (polybutylene glycol adipate) and non-crystallizable as part of PU (polybutylene ethylene glycol adipate) polyesters. For both samples the same Tg of flexible blocks (-20°C) and temperature of the disappearance of the microphase of the rigid blocks (110°C) are observed. The segregation process was found to have two stages with acceleration as the temperature rises in a certain interval. The crystallization processes of the flexible blocks were found to influence the rate of segregation of the rigid blocks. © 1990.