2020-910 SEQUENCE DESIGNS FOR CONCURRENT X-NUCLEI AND H-NUCLEI MRI

SUMMARY

Researchers from the Department of Radiology at UCLA have identified an alternative approach to imaging H- and X- nuclei simultaneously. This thereby retains the flexibility to perform independent sequences on each nucleus in the MRI scanner.

BACKGROUND

Magnetic resonance imaging (MRI) is clinically performed on hydrogen nuclei as it is the most abundant element in the human body in the form of water. However other nuclei are also visible with MRI. These are referred to as X nuclei, where X can stand for several different elements. Potentially useful elements for medical imaging are X=Na (sodium), X=F (fluorine) and X=P (phosphorus), which play key roles in biochemistry. The relative low abundance of X nuclei compared to proton makes them difficult to see above the background noise. Researchers have spent considerable efforts to optimize the signal to noise ratio. As such, X-nucleus MRI examinations are on the order of 30 minutes. X-nucleus imaging, however, is never done in isolation but always in conjunction with proton imaging so the total time would increase to an hour. Since there is virtually no interaction between the two measurement processes, it would be feasible to take measurements simultaneously and reduce the scan time in half.

INNOVATION

A recent study (Zidan Yu 2019) described perfectly synchronous hydrogren and X-nucleus imaging, in which identical instructions were sent to both imaging nuclei. This is efficient but of limited clinical value since it requires the same pattern of instructions (or “sequence” in MRI terminology) to be transmitted to the H- and X-nuclei. Clinical imaging uses many different sequences that are sensitive to different lesion types so it would be clinically a non-starter to limit the H- imaging component this way.

Researchers at UCLA describe an alternative approach to imaging H- and X- at the same time. These involve various ways of interleaving the sets of instructions - or sequence building blocks (SBB) - that are used on the H- and the X-nuclei. This retains the flexibility to perform independent sequences on each nucleus in the MRI scanner.

APPLICATIONS

• Useful for medical imaging and biochemistry
• Optimizes the clinical MRI examination of X-nucleus imaging
• Interleaves sequences for efficient MRI scans

ADVANTAGES

• Decreases MRI scan time in half
• Decreases cost associated with MRI scan

State of Development: The present invention has been submitted with three various acquisition strategies to acquire H and X nuclei images simultaneously including details of the expected X and X building blocks.

Related Papers (from the inventors only)

1. Zidan Yu, Guillaume Madelin, Daniel K. Sodickson, Martijn A. Cloos. Simultaneous proton magnetic resonance fingerprinting and sodium MRI. DOI: 10.1002/mrm.28073 (2019)
2. Keith R. Thulborn. Quantitative sodium MR imaging: A review of its evolving role in medicine. NeuroImage 168 (2018) 250–268
3. Guillaume Madelin, Ravinder R. Regatte. Biomedical Applications of Sodium MRI In Vivo. J Magn Reson Imaging. 38:511–529 (2013)
4. Paul A. Bottomley. Sodium MRI in Man: Technique and Findings. eMagRes, 2012, Vol 1: 353–366. DOI 10.1002/9780470034590.emrstm1252
5. Stephen C. Jones, Alexander Kharlamov, Boris Yanovski, D. Kyle Kim, PhD, Kirk A. Easley, Victor E. Yushmanov, Scott K. Ziolko, Fernando E. Boada. Stroke Onset Time Using Sodium MRI in Rat Focal Cerebral Ischemia. Stroke. 2006;37:883-888
6. E. Neumaier-Probst, S. Konstandin, J. Ssozi, C.Groden, M. Hennerici, L. R. Schad, and M. Fatar. A double-tuned 1H/23Na resonator allows 1H-guided 23Na-MRI in ischemic stroke patients in one session. International Journal of Stroke, 10:56–61, 2015
7. Friedrich Wetterling, Lindsay Gallagher, I. Mhairi Macrae, Sven Junge, Andrew J. Fagan.Regional and Temporal Variations in Tissue Sodium Concentration During the Acute Stroke Phase. Magnetic Resonance in Medicine 67:740–749 (2012)