MRE-IA in Liver Disease and Neurovascular Imaging
Condition: Diffuse and Focal Liver Diseases, Cerebral Function
MeSH terms: Liver Diseases
Study type: Interventional

Summary: 
      The objective of this research project is to develop Magnetic Resonance Elastography by
      Intrinsic Activation (MRE-IA) imaging methods at two imaging centers (CRCHUS and CRCHUM) for
      use in ongoing studies in liver disease and neurovascular imaging. MRE is a developing MR
      imaging modality that provides detailed maps of tissue's mechanical properties, based on
      displacement measurements made during the propagation of low amplitude vibrations through the
      region of interest. MRE-IA uses the pressure pulses of the cardiac cycle to induce the
      vibrations needed for MRE image reconstruction.

      MRE-IA has already been demonstrated based on the use of existing, clinically approved MR
      imaging sequences, and once this capability has been established at the two centers, initial
      trials will be done to demonstrate the method's potential in liver and neurovascular imaging.
      In the case of the liver, this pilot project funding will be used to perform MRE-IA imaging
      in patients with chronic liver disease and focal liver lesions. Results will be analyzed to
      establish the relationship between the mechanical properties mentioned above and disease
      stage. In the neurovascular case, imaging will be conducted under basic visual and motor
      stimulus conditions in healthy subjects, and results compared non-stimulus control images to
      determine changes in the above properties based on brain function. In addition, MRE-IA images
      will be compared with BOLD imaging to investigate the role of fluid conductivity in fMRI
      results.
    

Detailed description: 
      Unlike current MRE methods which require the application of cyclical mechanical excitations
      with an external driver, MRE-IA is a recently developed MRE modality that uses the naturally
      occurring cardiac pressure cycle to generate the displacements used for elastic property
      reconstruction. With no external activation, MRE-IA provides a simple pathway towards in-vivo
      elastography results that avoids the discomfort, poor coupling, and high attenuation often
      observed in MRE extrinsic vibration drivers.

      Goals: The principal goal of this project is to establish Magnetic Resonance Elastography by
      Intrinsic Activation (MRE-IA) imaging methods at the imaging centers of the Centre de
      recherche du centre hospitalier universitaire de Sherbrooke (CRCHUS) and the Centre de
      recherche du centre hospitalier universitaire de Montréal (CRCHUM). Each imaging center will
      then focus on separate sub-goals: improving liver disease assessment with MRE-IA (CRCHUM) and
      evaluating the role of fluid conductivity and changes in elastic properties with mental tasks
      (CRCHUS).

      Hypothesis: There are two main hypotheses underlying this project: (1) that internal
      activation provides an effective, robust displacement source for MRE image reconstruction
      that eliminates the problems of discomfort, high attenuation, artefact sensitivity, and low
      signal to noise associated with traditional extrinsic MRE methods; and (2) that the advanced
      material property maps provided by MRE-IA, such as viscoelastic damping, poroelastic effects
      and anisotropy, will lead to better classification and understanding of both diseased and
      healthy tissue states.

      Methods: The image acquisition methodology for this project will be identical at both imaging
      centers. Intrinsic activation MRE displacement data will be obtained through the use the
      Q-Flow angiographic sequence available on the Philips 3T systems at both the CRCHUS and
      CRCHUM.

      MRE-IA for diffuse and focal liver disease (CRCHUM): The objective of this study is to
      demonstrate the feasibility of MRE-IA imaging in the assessment of liver disease. MRE-IA will
      be performed in three populations (10 healthy volunteers, 25 patients with diffuse liver
      disease and 10 patients with focal liver lesions)

      Intrinsic MRE: MRE-IA images are reconstructed from phase-contrast sequences that are
      currently available on MRI scanners at CHUM and CHUS. Post-processing of the images with
      finite element analysis (FEA) mechanical simulations allows calculation of
      poroviscoelasticity parameters (i.e. porosity, bulk modulus, storage modulus [G'], and loss
      modulus [G'']). These poroviscoelasticity parameters will be correlated with
      histopathological markers of disease severity (fibrosis, inflammation, fat) in patients with
      chronic liver disease and with the final diagnosis (type of liver lesion).

      Cerebral function imaging via MRE-IA (CRCHUS): The objective of this study is to investigate
      the changes in mechanical properties during the performance of mental tasks and the role of
      inherent fluid conductivity in the BOLD imaging used in fMRI methods. Multiple imaging
      sessions will be performed to investigate changes to MRE-IA property maps to visual (V1)
      stimulation. Imaging sessions will be include either V1 (n=6) or non-stimulus (n=3) cases.
      Each case will include both MRE-IA and fMRI acquisitions.
    

Intervention name(s): Stimuli; No stimuli
Intervention type(s): Other; Other
Intervention description(s): Visual stimulation while using additional sequencing; Additional sequencing only
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: Additional sequences during magnetic resonance elastography by intrinsic activation with or without stimuli
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: Magnetic resonance elastography; Intrinsic activation; Liver disease; Cerebral function