A method for determining a quantitative result CT parameter map in a region of interest of an object under examination is described. The method includes acquiring a sequence of quantitative input CT parameter maps for at least two predetermined times, the sequence being generated by a contrast-enhanced spectral multiphase CT of the region of interest; receiving a sequence of contrast-enhanced MRI image datasets, the MRI datasets having a higher temporal resolution than the sequence of input CT parameter maps; determining a relation between the MRI image datasets and the input CT parameter maps; and determining the result CT parameter map based on the determined relation and the MRI image datasets for at least one additional time, the at least one additional time being different from the predetermined time.

Systems and methods for acquiring magnetic resonance imaging (MRI) images of a subject are provided. The method includes performing a pulse sequence to elicit spin echoes, wherein the pulse sequence includes a radio frequency (RF) excitation pulse and a series of RF refocusing pulses that refocus echoes with flip angles in the series of RF refocusing pulses that are varied. The method also includes scaling MRI data associated with each echo by a correction factor that is determined for each echo to create scaled MRI data and that is not the same for all echoes. The method then includes reconstructing an image of the subject using the scaled MRI data.

The present application provides a compound comprising at least one isotopically labeled nitrogen atom for use in diagnosing a condition or disease in a subject, compositions and kits comprising the compound and methods of using the same.

The ratio of arterial spin labeled (ASL) perfusion to diffusion weighted imaging (DWI) is generally homogeneous in the anoxic/hypoxic injury population. Conversely, the ratio is more heterogeneous in the non-anoxic/hypoxic population. By plotting these ratios in a graphical format in the form of an axial color map of the brain—referred to as a normalized diffusion to perfusion (NDP) ratio colormap—it may be determined whether a patient has suffered from an anoxic/hypoxic injury. Thus, the anoxic and non-anoxic injury patients will have, respectively, homogenous and heterogeneous color maps. Anoxic brain injury patients have a global homogeneously positive relationship between qualitative ASL perfusion and diffusion weighted signal such that areas of restricted diffusion show significantly increased ASL perfusion signal, which may be attributable to BBB integrity. The NDP ratio colormap provides an imaging biomarker to differentiate anoxic brain injury from normal controls and to potentially assess BBB integrity.

The present application provides a system and method for quantifying perfusion using a dictionary matching approach. In some aspects, the method comprises performing a predetermined pulse sequence using an MRI system to acquire MRI data from the subject after having delivered a dose of a contrast agent to the subject. The method also includes comparing the MRI data to a dictionary to determine perfusion information, and generating, using the perfusion information, a report indicative of perfusion within the subject.

The invention provides a method of medical imaging. The method comprises: receiving, for a current active time window (204A-N) and during a brain activity analysis session (200, 500), fMRI data of a region of interest (309) of a subject (318) in an active state. A transverse relaxation, T2*, map may be generated from the fMRI data using a predefined model of fMRI data variations. The generated T2* map may be compared with a reference T2* map. A blood-oxygen-level dependent (BOLD) response of the region of interest (309) during the current active time window (204 A-N) may be estimated using the results of the comparison.

Embodiments include a system for determining cardiovascular information for a patient. The system may include at least one computer system configured to receive patient-specific data regarding a geometry of the patient's heart, and create a three-dimensional model representing at least a portion of the patient's heart based on the patient-specific data. The at least one computer system may be further configured to create a physics-based model relating to a blood flow characteristic of the patient's heart and determine a fractional flow reserve within the patient's heart based on the three-dimensional model and the physics-based model.

The disclosure is directed to an Echo-Planar-Imaging (EPI) magnetic resonance imaging techniques combined with a variable-density undersampling scheme. The technique comprises generating an RF pulse, applying a switched frequency-encoding read out gradient in a variable time interval, and applying simultaneously an intermittently blipped low-magnitude phase-encoding gradient with a variable value of an integral of the phase-encoding gradient. The aforementioned steps are carried out such that the k-space is at least partially undersampled and the time interval of one read out gradient is varied depending on the integral of the phase encoding gradient, such that a ratio between the variable time interval of the read out gradient and the integral of the corresponding phase encoding gradient is kept above or at a predetermined constant value, which is related to a predetermined criteria of image quality.

In contrast-enhanced MRI, a visualization capability of a tissue which a contrast agent reaches is increased, and overall imaging time is shortened. An imaging unit of an MRI apparatus includes a gradient echo pulse sequence for acquiring a T1 weighted image including a fat saturation pulse, and a control unit performs control to generate images of a plurality of phases having different arrival positions of a contrast agent by repeating the pulse sequence for a predetermined time from administration of the contrast agent to the subject by the imaging unit. At this time, a preparation pulse that suppresses a signal from a contrast agent present outside a target tissue (cell) is added prior to a pulse sequence, in a phase immediately before reaching the target tissue.

A method for measuring water exchange across the blood-brain barrier includes acquiring diffusion weighted (DW) arterial spin labeling (ASL) magnetic resonance imaging (MRI) signals. The method further includes determining optimal parameters to separate labeled water in capillary and brain tissue compartments. The method further includes estimating water exchange rate across the blood-brain barrier based on the DW ASL MRI signals and the optimal parameters, using a total generalized variation (TGV) regularized single-pass approximation (SPA) modeling algorithm.