An empirical equation for the magnetization transfer (MT)FLASH signal is derived by analogy to dual-excitation FLASH, introducing a novel semiquantitative parameter for MT, the percentage saturation imposed by one MT pulse during TR. This parameter is obtained by a linear transformation of the inverse signal, using two reference experiments of proton density and T 1 weighting. The influence of sequence parameters on the MT saturation was studied. An 8.5-min protocol for brain imaging at 3 T was based on nonselective sagittal 3D-FLASH at 1.25 mm isotropic resolution using partial acquisition techniques (TR/TE/ ␣ ‫؍‬ 25ms/4.9ms/5°or 11ms/4.9ms/15°for the T 1 reference). A 12.8 ms Gaussian MT pulse was applied 2.2 kHz off-resonance with 540°flip angle. The MT saturation maps showed an excellent contrast in the brain due to clearly separated distributions for white and gray matter and cerebrospinal fluid. Magnetization transfer (MT) is a contrast mechanism in tissue that is based on cross-relaxation or chemical exchange between protons in bulk water and rotationally immobilized macromolecules (1,2). In clinical MRI, MT contrast is invoked by application of a T 2 -selective RF pulse applied prior to slice excitation. The "MT pulse" saturates specifically the macromolecular magnetization, and MT is then observed as a reduction in image intensity. Its normalized value, the MT ratio (MTR), is commonly taken as a measure for the strength of the MT effect, and hence interpreted as a surrogate parameter for macromolecular content or myelination. However, the MTR is not an absolute measure, but depends on the sequence parameters and is influenced by T 1 relaxation and flip angle inhomogeneities.This limitation can be overcome by quantitative Z-spectroscopy measurements to obtain parameter estimates for the binary spin-bath (BSB) model and suitable absorption line shapes (3,4). On clinical MR systems, pulsed MT is combined with spoiled gradient echo sequences (FLASH, fast low angle shot) and suitable adaptations of Henkelman's continuous wave model (5-7). Alternatively, pulsed MT experiments can be approximated by instantaneous events of saturation separating intervals free of irradiation (8). Since brain tissue is characterized by conditions of fast-exchange, this "free" evolution can be described by two exponential time courses, the common T 1 relaxation and the MT. The latter is observed as a reduction of the longitudinal magnetization of free water subsequent to the MT pulse (9). This MT-related saturation increases in time until the exchange equilibrium in the BSB model is restored.The concept of separating T 1 relaxation and MT has been previously applied to progressive partial saturation by repetitive MT pulses (10). Here, it is transferred to the MT-w(eighted) FLASH sequence. A phenomenological signal equation is derived by analogy from a FLASH experiment with two interleaved excitations and recovery times. This equation represents the effects of excitation and relaxation during TR, while any additional saturation du...

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Objective: To determine the forces and moments delivered to a maxillary central incisor during rotation by three different thermoplastic appliances with identical thickness. Materials and Methods: Five identical appliances were manufactured from each of three materials (Ideal Clear 1.0 mm, Erkodur 1.0 mm, Biolon 1.0 mm). An upper central incisor fixed in a measuring device was rotated around its central axis in 0.5-degree steps to 62.5 degrees, 65 degrees, and 67.5 degrees (equivalent to an activation of 60.17 mm, 60.34 mm, and 60.51 mm of the incisor edge) in the clockwise and anticlockwise directions with the respective appliance fixed in place. For statistical analysis, the moments Tz (rotation) and forces Fz (intrusion) were tested. Means and standard deviations for Tz and median and 25% and 75% quantiles for Fz were calculated. An analysis of variance (ANOVA) was performed. Results: The minimal moment was determined at a rotation of 20.17 mm (27.3 Nmm, 60.8), and the maximal moment at a deflection of 20.51 mm (271.8 Nmm. 62.5) was recorded. The minimal value for Fz was measured at an activation of 20.17 mm (0.0 N), and the highest intrusive forces were evaluated for a rotation of 20.51 mm (25.8 N). The particular material sometimes had a significant (P , .05) influence on the forces delivered and the moments. Conclusions: During rotation with aligners, an intrusive force can also be observed. The direction of rotation, and the materials used all exert an influence on the force delivery properties of the appliance.

Attempts to optimize the magnetization transfer ratio (MTR) obtained from spoiled gradient echo MRI have focused on the properties of the magnetization transfer pulse. In particular, continuous-wave models do not explicitly account for the effects of excitation and relaxation on the MTR. In this work, these were modeled by an approximation of free relaxation between the radiofrequency pulses and of an instantaneous saturation event describing the magnetization transfer pulse. An algebraic approximation of the signal equation can be obtained for short pulse repetition time and small flip angles. This greatly facilitated the mathematical treatment and understanding of the MTR. The influence of inhomogeneous radiofrequency fields could be readily incorporated. The model was verified on the human brain in vivo at 3 T by variation of flip angle and pulse repetition time. The corresponding range in MTR was similar to that observed by a 4-fold increase of magnetization transfer pulse power. Choice of short pulse repetition time and larger flip angles improved the MTR contrast and reduced the influence of radiofrequency inhomogeneity. Optimal contrast is obtained around an MTR of 50%, and noise progression is reduced when a high reference signal is obtained. Magn Reson Med 64:177-185,

Aims Health data captured by commercially available smart devices may represent meaningful patient‐reported outcome measures (PROMs) in heart failure (HF) patients. The purpose of this study was to test this hypothesis by evaluating the feasibility of a new telemonitoring concept for patients following initial HF hospitalization. Methods and results We designed a cardio patient monitoring platform (CPMP) that comprised mobile iOS‐based applications for patients' smartphone/smartwatch and the equivalent application on a physicians' tablet. It allowed for safe and continuous data transmission of self‐measured physiological parameters, activity data, and patient‐reported symptoms. In a prospective feasibility trial with 692 patient days from 10 patients hospitalized for newly diagnosed HF with reduced ejection fraction (mean left ventricular ejection fraction (LVEF) 26.5 ± 9.8%), we examined the CPMP during the first 2 months following discharge (69 ± 15 observation days per patient). The mean daily step count recorded by the mobile devices emerged as a promising new PROM. Its 14 day average increased over the study period (3612 ± 3311 steps/day at study inclusion and 7069 ± 5006 steps/day at end of study; P < 0.0001). It is unique for continuously reflecting real‐life activity and correlated significantly with traditional surrogate parameters of cardiac performance including LVEF ( r = 0.44; 95% CI 0.07–0.71; P = 0.0232), 6 min walk test ( r = 0.67; 95% CI 0.38–0.84; P = 0.0002), and scores in health‐related quality of life questionnaires. Conclusions We provide the first patient monitoring platform for HF patients that relies on commercially available iOS/watchOS‐based devices. Our study suggests it is ready for implementation as a tool for recording meaningful PROMs in future HF trials and telemonitoring.