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Emerging Imaging

Development of Zero TE MRI to visualise cranial bones, nerves and vessels

Project ID: 2022_002

1st Supervisor: Steve Williams, King’s College London 2nd Supervisor: Gareth Barker, King’s College London Additional Supervisor: Toby Wood, King’s College London Industry Supervisor: Florian Wiesinger, GE Healthcare Clinical Supervisor: Tara Renton, Peter Goadsby, Steve Connor

Project summary:

  • Conventional wisdom states that MRI can only be used to image soft tissues and that to image hard tissues a CT is required. This is no longer true, as Zero Echo-Time (ZTE) MRI can image bone and soft tissues in a single combined scan. In addition, ZTE is robust against common MRI artefacts such as flow and off-resonance, and serendipitously is also close to silent where conventional MRI is noisy.
  • However, ZTE is technically challenging and so it is only recently that is has begun to be used in the clinic. This PhD will exploit the unique properties of ZTE MRI to develop improved MRI scans of bones, blood vessels and nerves in the head and neck for use in surgical planning for maxillofacial surgery. These structures outside the brain have long been considered challenging to image and there is great scope to improve that quality of diagnostic information being provided to clinicians.
  • The project will focus on the optimization of the ZTE sequence for bone imaging, incorporation of novel magnetization preparation modules for improved contrast between tissues, and development of automated tissue classification and segmentation methods to automatically highlight anatomy.
Aim of the PhD Project:

  • Exploit the unique properties of the Zero Echo-Time (ZTE) MRI sequence to accurately visualise cranial anatomy (bone, blood vessels, cranial nerves) that is difficult or impossible with conventional imaging.
  • Demonstrate the clinical benefit of ZTE anatomical imaging for surgical and radiation planning.

Project description/background A primary use of medical imaging is planning clinical procedures including surgery or radiation therapy for cancer. As surgical procedures become ever more advanced, medical imaging techniques must keep pace to provide detailed, personalised anatomical information. A particularly demanding example is maxillofacial surgery, which is key in the management of dental pain and debilitating headaches. Although the brain can be imaged in exquisite detail with MRI, the surrounding anatomy including the skull, jaw, teeth, cranial nerves, and major blood vessels is highly challenging due to intricate structures and different tissue types. While conventional MRI and CT can provide some contrasting information about soft tissue and bone respectively, it is not currently possible for either to provide the necessary images of all tissue types simultaneously. This project will utilise a unique form of MR called Zero Echo-Time (ZTE) imaging. Significant advantages of ZTE imaging include the ability to detect signal from bone, teeth & calcifications, improved visualisation of vessels, and robustness to magnetic susceptibility artefacts (1). ZTE hence gives a unique opportunity to image all aspects of anatomy in the head and neck in an integrated way in a single scanning session, while avoiding the use of X-rays inherent in a CT scan.  An additional benefit of ZTE is that the sequence is near-silent, thus increasing patient comfort during scanning (2). The successful candidate will work with a team of expert MRI physicists and clinicians to create a ZTE examination suitable for imaging the fine anatomical structures outside of the brain. They will design suitable contrast preparation schemes and reconstruction techniques to highlight desired – or suppress irrelevant – features of anatomy. This will require close collaboration with clinicians to understand the specific needs for multiple applications. The project will suit a candidate with a background in physics, electrical engineering, biomedical engineering, or related discipline.

Top row – a typical ZTE MR image. Bottom row – the same image with inverted colour scale, showing CT-like contrast with excellent delineation of bones and teeth

Top row – a typical ZTE MR image. Bottom row – the same image with inverted colour scale, showing CT-like contrast with excellent delineation of bones and teeth

If you wish to find out further information about the project before applying, please contact Steve Williams.

References

  1. Ljungberg E, Damestani NL, Wood TC, Lythgoe DJ, Zelaya F, Williams SCR, Solana AB, Barker GJ, Wiesinger F. Silent zero TE MR neuroimaging: Current state-of-the-art and future directions. Prog Nucl Magn Reson Spectrosc. 2021 Apr;123:73-93.
  2. Wood TC, Damestani NL, Lawrence AJ, Ljungberg E, Barker GJ, Solana AB, Wiesinger F, Williams SCR. Silent myelin-weighted magnetic resonance imaging. Wellcome Open Res. 2020 Aug 13;5:74.

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