Research Lines

Susceptibility

Is a physical property defined as the degree of magnetization of a material as a response to an applied magnetic field. Susceptibility-based MRI techniques can be used to measure the inhomogeneities of the magnetic field, or the presence of certain chemical species in the brain such as iron.

Quantitative Susceptibility Mapping (QSM)

Is a technique that has drawn the attention of many researchers, due to its ability to map the susceptibility values of tissues as a function of space. A more challenging susceptibility technique is Susceptibility Tensor Imaging (STI) which finds magnitude and directionality of the susceptibility as a function of space.

Diffusion

Is the process by which molecules randomly move from regions of higher to lower concentration. MRI is sensitivity to this motion and several techniques have been developed to make use of this sensitivity. Diffusion Weighted (DW) MRI finds the bulk diffusion coefficient as a function of space. Analogously to STI, Diffusion Tensor Imaging (DTI) finds the directionality of the diffusion as a function of space. DTI and diffusion-based techniques have been used to investigate the structural connectivity of the brain and myelination or demyelination processes.

Both signals, susceptibility and diffusion, are promising biomarkers for schizophrenia and other mental disorders, since they would provide crucial information about the neurochemically-rich nuclei of the brainstem.

General objective

To use and develop new MRI-based technology focusing on human brainstem nuclei to develop new biomarkers for early schizophrenia, a paradigmatic case of a severe mental disorder.

Specific objectives

  1. To design new brainstem MRI-based biomarkers related to treatment response in patients with first episode of schizophrenia.
  2. To design new brainstem imaging-based biomarkers that could inform risk to psychosis in a cohort of patients with the 22q11 deletion syndrome.
  3. To develop a deep learning reconstruction approach for QSM and STI that could reduce the variability of current reconstruction methods due to artifact propagations and due to arbitrary heuristics needed for parameter setting.
  4. To develop an STI reconstruction method using DTI as a priori information.
  5. To adapt the developed QSM, STI, DTI reconstruction methods (at 3 Tesla) for lower field data (at 1.5 Tesla), and multi-vendor MRI scanners (Philips and Siemens).
  6. To train students (at undergraduate and graduate level), researchers and professionals from both engineering (biomedical, electrical, etc.) and health sciences (radiology, psychiatry, neurology, genetics etc.) in an interdisciplinary environment.
  7. To enhance our existing national and international collaborations and to enlarge our international collaboration network.
  8. To disseminate our knowledge to the community through different outreach strategies.

General Hypothesis

Susceptibility-based and diffusion-based MRI measurements of the brainstem nuclei could be used as biomarkers to inform the clinical course in early schizophrenia.

Specific hypothesis

  1. Susceptibility-based measurement of the neurochemical composition of the substantia nigra is related to treatment-response in first-episode schizophrenia.
  2. Susceptibility tensor imaging -informing the structural organization of the substantia nigra- can differentiate 22q11 deletion syndrome patients with a history of schizophreniform psychosis from those without.
  3. Deep learning will allow us to unify into a single process the reconstruction pipeline of QSM
  4. DTI information plus deep learning techniques will allow the acquisition and reconstruction of STI without significantly lengthening the scan and avoiding tilting the head of the patient.