Abstract: Systems and methods for measuring macromolecular proton fraction in a subject are provided. A nuclear magnetic resonance apparatus applies a magnetic field to a body region on the subject, and radiofrequency modes are applied to the body region as well. Each radiofrequency mode delivers a plurality of radiofrequency pulses separated by time delays, wherein at least one of the radiofrequency modes causes suppression of signal components from an unwanted tissue, and at least one of the radiofrequency modes causes magnetization exchange between water and macromolecules in tissues in the body region. Amplitudes corresponding to magnetic signals received from the body region are measured and macromolecular proton fraction based on the amplitudes can be calculated.

Abstract: Systems and methods for measuring macromolecular proton fraction in a subject are provided. A nuclear magnetic resonance apparatus applies a magnetic field to a body region on the subject, and radiofrequency modes are applied to the body region as well. Each radiofrequency mode delivers a plurality of radiofrequency pulses separated by time delays, wherein at least one of the radiofrequency modes causes suppression of signal components from an unwanted tissue, and at least one of the radiofrequency modes causes magnetization exchange between water and macromolecules in tissues in the body region. Amplitudes corresponding to magnetic signals received from the body region are measured and macromolecular proton fraction based on the amplitudes can be calculated.

Abstract: A contrast enhancement (CE) agent is infused into blood flowing through a site that is to be imaged with magnetic resonance imaging (MRI). Two double inversion procedures are carried out, forming a quadruple inversion recovery (QIR) pulse sequence. Each double inversion procedure comprises a non-selective and slice-selective inversion RF pulse. The first double inversion procedure is followed by a first predefined inversion delay period, TI1, and the second procedure by a second predefined inversion delay period, TI2. A black-blood image can thus be produced in which blood appears consistently black and tissues surrounding the blood, such as a vessel wall, heart, atherosclerotic plaque, or thrombus, are clearly visible. Unlike the prior art black-blood imaging technique, the QIR method does not require a precise knowledge of the T1 of the blood carrying the CE agent in order to suppress the signal and artifacts caused by the blood flowing through the site.

Abstract: A reduced field-of-view (FOV) imaging technique combines suppression of signals from outer volume and inflowing blood. Both outer volume and blood suppression are achieved using an SFQIR (Small-FOV Quadruple-inversion-Recovery) preparative pulse sequence including two double-inversion pulse pairs separated by appropriate delays. Within each pair, inversion pulses are successively applied to the imaged slice and the slab orthogonal to the imaging plane, with the thickness equal to the FOV size in the phase-encoding direction. Each double-inversion results in a reinversion of the magnetization in a central part of the FOV, while outer areas of the FOV and inflowing blood remain inverted. The SFQIR module was implemented for single-slice and multislice acquisition with a fast spin-echo readout sequence. Timing parameters of the sequence corresponding to the maximal suppression efficiency can be found by minimizing variation of the normalized signal over the entire range of T1 occurring in tissues.

Abstract: A multi-slice double inversion recovery (DIR) pulse sequence with read out of a signal for imaging successive slices implemented on a magnetic resonance image scanner. In the method, when the DIR pulse sequence is applied before imaging each slice, a slab-selective inversion re-inverts the entire slab that includes all of the slices. All slices are imaged within a predefined repetition time (TR). The number, N, of slices acquired per TR controls the inversion time to execute the read out of the signal for imaging each slice at a zero-crossing point of blood. In a test, multi-slice DIR images of carotid arteries were obtained with N ranging from 2-8, for four subjects. The results were compared with those for both standard single-slice DIR, and inflow saturation techniques. Multi-slice DIR with N=2-6 provided blood flow suppression in carotid arteries similar to that of single-slice DIR, and significantly better than inflow saturation.

Abstract: A multi-slice double inversion recovery (DIR) pulse sequence with read out of a signal for imaging successive slices implemented on a magnetic resonance image scanner. In the method, when the DIR pulse sequence is applied before imaging each slice, a slab-selective inversion re-inverts the entire slab that includes all of the slices. All slices are imaged within a predefined repetition time (TR). The number, N, of slices acquired per TR controls the inversion time to execute the read out of the signal for imaging each slice at a zero-crossing point of blood. In a test, multi-slice DIR images of carotid arteries were obtained with N ranging from 2-8, for four subjects. The results were compared with those for both standard single-slice DIR, and inflow saturation techniques. Multi-slice DIR with N=2-6 provided blood flow suppression in carotid arteries similar to that of single-slice DIR, and significantly better than inflow saturation.

Abstract: A contrast enhancement (CE) agent is infused into blood flowing through a site that is to be imaged with magnetic resonance imaging (MRI). Two double inversion procedures are carried out, forming a quadruple inversion recovery (QIR) pulse sequence. Each double inversion procedure comprises a non-selective and slice-selective inversion RF pulse. The first double inversion procedure is followed by a first predefined inversion delay period, TI1, and the second procedure by a second predefined inversion delay period, TI2. A black-blood image can thus be produced in which blood appears consistently black and tissues surrounding the blood, such as a vessel wall, heart, atherosclerotic plaque, or thrombus, are clearly visible. Unlike the prior art black-blood imaging technique, the QIR method does not require a precise knowledge of the T1 of the blood carrying the CE agent in order to suppress the signal and artifacts caused by the blood flowing through the site.