MRI Parametric
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Attributes to the World of p-MRI
Parametric imaging is a diagnostic procedure in MRI, which has capabilities to generate different contrast images and parameters. Parametric images in MRI derived from functional tracer studies enable quantitative estimates of physiologic or biochemical processes in the living body. Functional imaging not only provides unique information related to in vivo physiologic processes, but is also capable of deriving quantitative functional parameters that can be used in the diagnosis of disease, the response therapy, and the evaluation of a drug. The parameter estimation is a discipline that provides tools for mathematically modeling phenomena and the estimation of the constants appearing in these models. Combinations of T2-weighted imaging, diffusion imaging, perfusion (dynamic contrast-enhanced imaging) and spectroscopic imaging have been used in mp-MRI (Multi Parametric-Magnetic Resonance Imaging) for the assessment of disease area.
What is T2* Imaging?
T2*-weighted imaging is spin–spin relaxation, that is, the transverse component of the magnetization vector exponentially decays towards its equilibrium value. It is characterized by the spin–spin relaxation time, known as T2 in an idealized system. Here all nuclei in a given chemical environment, in a magnetic field, relax with the same frequency. However, it is difficult situation in real world due to minor differences in chemical environment which lead to dispersion of magnetic vectors and loss of signal.
What is Diffusion Imaging?
Diffusion-weighted imaging (DWI) is a form of MR imaging based upon analyzing the random Brownian motion of water molecules within a voxel of tissue. It evaluates the molecular function and micro-architecture of the cells within voxel. DWI signal contrast can be quantified by apparent diffusion coefficient maps and it acts as a tool for Response therapy and assessment of disease progression.
What is Perfusion Imaging?
Perfusion imaging is based on the principles of tracer kinetic modeling to assess the microvasculature. Contrast agent is injected into the blood and monitored as it passes through the microvasculature. The vasculature is a key feature in the histopathology diagnosis of disease tissue.
What is Spectroscopy Imaging?
Magnetic Resonance (MR) spectroscopy is a noninvasive diagnostic test for measuring biochemical changes. While MRI helps to identify the anatomical location of a disease area, and MR spectroscopy compares the chemical composition of disease area. Here each nucleus type within disease are has a characteristic frequency when placed in the same magnetic field. During relaxation following excitation, rf signals can be detected which contain information about the magnetic environment experienced by each nucleus, and therefore about the molecules in which they are contained.
mp-MRI
Publication/Patents
Optimizing MRI Scan Time in the Computation of
Pharmacokinetic Parameters (Ktrans) in Breast
Cancer Diagnosis; Amarnath Jena, DNB (NM), Shashi Bhushan Mehta, (PhD), and Sangeeta Taneja, (MD); OURNAL OF MAGNETIC RESONANCE IMAGING 38:573–579 (2013) Link