摘要:
MRI based molecular imaging is strongly supported by the accurate quantification of contrast agents. According to an exemplary embodiment of the present invention, contrast agent is applied on the basis of a multiple injection application scheme, during which changes in relaxation rate are determined. This may provide for an accurate determination of tumor vascularity via MRI relaxometry.
摘要:
The invention relates to an MR method for the quantitative determination of local relaxation time values in an examination volume. Firstly, a plurality of echo signals (1, 2, 3) with different echo time values (t1, t2, t3) are recorded in a phase-sensitive manner. From these echo signals (1, 2, 3), complex MR images (4, 5, 6) are then reconstructed for the different echo time values (t1, t2, t3). Next, local resonant frequency values (7) are calculated for each image point from the echo-time-dependent change in the phases of the complex image values, and then preliminary local magnetic field inhomogeneity values (8) are calculated from the local resonant frequency values (7). The invention proposes that the local relaxation time values (10) be determined from the echo-time-dependent change in the amplitudes of the image values and correction of the local relaxation time values (10) be carried out taking account of final local magnetic field inhomogeneity values. The preliminary magnetic field inhomogeneity values (8) are used as start values for an iterative optimization procedure (19) for determining the final local magnetic field inhomogeneity values.
摘要:
MRI based molecular imaging is strongly supported by the accurate quantification of contrast agents. According to an exemplary embodiment of the present invention, contrast agent is applied on the basis of a multiple injection application scheme, during which changes in relaxation rate are determined. This may provide for an accurate determination of tumor vascularity via MRI relaxometry.
摘要:
The invention relates to a device for magnetic resonance imaging of a body (7). The device (1) comprises means (2) for establishing a substantially homogeneous main magnetic field in the examination volume, means (3, 4, 5) for generating switched magnetic field gradients superimposed upon the main magnetic field, means (6) for radiating RF pulses towards the body (7), control means (12) for controlling the generation of the magnetic field gradients and the RF pulses, means (10) for receiving and sampling magnetic resonance signals, and reconstruction means (14) for forming MR images from the signal samples. In accordance with the invention, the device is arranged to a) generate a series of MR echo signals (20) by subjecting at least a portion of the body (7) to an MR imaging sequence of RF pulses and switched magnetic field gradients, b) acquire the MR echo signals for reconstructing an MR image data set (21) therefrom, c) calculate a gradient map (22) by computing echo shift parameters (SPx, SPy, SPz) from subsets of the MR image data set, the echo shift parameters (SPx, SPy, SPz) indicating magnetic field gradient induced shifts of the echo positions in k-space, wherein each subset comprises a number (n) of spatially adjacent pixel or voxel values of the MR image data set (21).
摘要:
MRI based molecular imaging is strongly supported by the accurate quantification of contrast agents. According to an exemplary embodiment of the present invention, contrast agent is applied on the basis of a multiple injection application scheme, during which changes in relaxation rate are determined. This may provide for an accurate determination of rumor vascularity via MRI relaxometry.
摘要:
The invention relates to a device for magnetic resonance imaging of a body (7). The device (1) comprises means (2) for establishing a substantially homogeneous main magnetic field in the examination volume, means (3, 4, 5) for generating switched magnetic field gradients superimposed upon the main magnetic field, means (6) for radiating RF pulses towards the body (7), control means (12) for controlling the generation of the magnetic field gradients and the RF pulses, means (10) for receiving and sampling magnetic resonance signals, and reconstruction means (14) for forming MR images from the signal samples. In accordance with the invention, the device is arranged to a) generate a series of MR echo signals (20) by subjecting at least a portion of the body (7) to an MR imaging sequence of RF pulses and switched magnetic field gradients, b) acquire the MR echo signals for reconstructing an MR image data set (21) therefrom, c) calculate a gradient map (22) by computing echo shift parameters (SPx, SPy, SPz) from subsets of the MR image data set, the echo shift parameters (SPx, SPy, SPz) indicating magnetic field gradient induced shifts of the echo positions in k-space, wherein each subset comprises a number (n) of spatially adjacent pixel or voxel values of the MR image data set (21).
摘要:
The present disclosure is directed to a new technique for MR measurement of ultrashort T2* relaxation utilizing spin-echo acquisition. The ultrashort T2* relaxometry can be used for the quantification of highly concentrated iron labeled cells in cell trafficking and therapy. In an exemplary embodiment, a signal is induced by a low flip angle RF pulse. Following excitation pulse, a gradient readout is applied to form an echo. The time between the RF pulse and the center of the gradient readout is defined as TE. In tissues with highly concentrated iron labeled cells, T2* could be below 1 millisecond. Therefore, the signal can be decayed to a noise level with an echo time of a couple milliseconds. Because T2 is much longer in SPIO labeled cells, the signal acquired by spin echo is much bigger than that from the gradient echo, thus avoiding the negative effects associated with the massive signal loss in the image. The ultrashort T2* relaxation map can then by overlaid on the regular T2* map to generate the final T2* map of the field of view.
摘要:
MR based molecular imaging is used for the quantification of contrast agent concentrations. According to an exemplary embodiment of the present invention, a difference between R2 and R2* relaxation rates of a contrast agent is determined on the basis of data measured after contrast agent application. This may provide for an in vivo information relating to a compartmentalization or binding status of the contrast agent, and thus may improve the significance of the examination result.
摘要:
A medical imaging system (2) excites multiple nuclei through a single RF amplifier (24). The medical imaging system (2) includes a magnet (10) that generates a main magnetic field (Bo) in an examination region. A gradient coil (14) superimposes magnetic field gradients (G) on the main magnetic field Bo. At least one transmitter (28) generates multi-nuclei excitation pulses associated with at least two different isotopes and two different frequency spectra. The single amplifier (24) sends the multi-nuclei excitation pulses to a RF coil (18, 20) for application to the examination region.
摘要:
The present invention relates to novel methods and compounds for combined opticalultrasound imaging. The compounds of the present invention relate to particles comprising fluorescence donor and acceptor molecules for energy exchange via FRET. The methods of the present invention use ultrasound to modify the distance between donor and acceptor molecules present on the particles, and to consequently modify the fluorescence emitted by the donor and acceptor. The compounds and methods of the present invention are useful in medical or diagnostic imaging.