Method for multimodal tissue imaging based on resonance raman effect on metal based mri contrast agents and method for ionizing laser plumes through atmospheric pressure chemical ionization

Abstract

Disclosed herein is a method for multimodal imaging during a medical procedure using magnetic resonance imaging (MRI) and Raman optical imaging which involves administering an MRI imaging contrast agent that a chemical structure having charge-transfer electronic transitions. The tissue is imaged using and MRI device and the tissue is illuminated with excitation light that has spectral components that are approximately tuned close to one of the charge-transfer electronic transitions thereby producing enhanced Raman optical signals which are analyzed to produce Raman imaging data followed by registering the MRI and Raman imaging data. The present disclosure also provides a method for ionizing laser plumes through atmospheric pressure chemical ionization.

1 . A mass spectrometry system for analyzing molecular composition of a sample in a condensed phase, comprising:
 a pulsed laser capable of ablating the surface of said sample atmospheric pressure thereby producing an ablation plume containing analyte molecules;   a gas delivery system for delivering a gas jet to the ablation plume, wherein said gas jet contains dopant molecules;   a metal object with a sharp tip placed in the vicinity of said gas jet;   a high voltage generator that is electrically connected to said metal object thereby creating a corona discharge at said sharp tip, wherein said corona discharge ionizes said dopant molecules in said gas jet;   and wherein said gas jet intercepts said laser ablation plume whereby at least one of subsequent direct or indirect collisions between said ionized dopant molecules and said analyte molecules results in ionization of several of said analyte molecules; and   directing said ionized analyte molecules towards a mass spectrometer wherein said ionized analyte molecules are analyzed providing information about a molecular composition of said sample.   
     
     
         2 . The system according to  claim 1  where said gas delivery system includes a capillary connected with a tubing connected to a source of compressed gas. 
     
     
         3 . The system according to  claim 2  where said source of compressed gas is a gas cylinder or gas compressor. 
     
     
         4 . The system according to  claim 1  wherein said metal object with a sharp tip has a form of a sharp needle that is placed within said capillary. 
     
     
         5 . The system according to  claim 1  wherein said dopant is any one of air, water vapour, N 2 , a noble gas, toluene, or a mixture of any of these gases. 
     
     
         6 . The system according to  claim 1  wherein said high voltage source is any one of a pulsed, modulated, or constant high voltage source. 
     
     
         7 . The system according to  claim 1  wherein said gas delivery system jet includes a pulsed valve.