Question

Why do MRS Imaging Scientists take the “area underneath a chemical shift peak” rather than the peak height as an estimate of molecule concentration? DEMONSTRATE MATHEMATICALLY.

Answer 1

Proton magnetic resonance spectroscopy(MRS) have very much importance in clinical and experimental work in human. it is a powerful tool to provide clinically relevant information for several diseases such as brain tumors, metabollic disorders and systemic diseases. Most available MRS method is proton spectroscopy.

  MR imaging maps the distribution and interaction of water (its hydrogen atoms) with tissue.  In contrast, 1 H MRS analyzes signal of the hydrogen protons attached to other molecules. Whereas for MRI only a single peak (water) is being mapped, The result of MRS is a collection of peaks at different radiofrequencies (RF) representing proton nuclei in different chemical environments. MRS is restricted to the analysis of individual regions of interest (ROI) much larger than the resolution of MRI.The height of a peak is equivalent to the strength of the signal. The position on the x -axis (or chemical shift axis) measures the chemical shift relative to a reference (tetramethylsilane (TMS) at 0 ppm) and can be used to identify chemicals. The water peak would be at 4.7 ppm. However, the water peak is suppressed in MRS sequences as it would be several orders of magnitude larger than any of the other peaks.