Multidimensional diffusion (MDD) MRI is a novel imaging technique that provides information enabling
better discrimination of the average rate, microscopic anisotropy, and orientation of diffusion within microscopic tissue environments. We share our experience in the evaluation of MDD’s clinical feasibility in various brain pathologies, where we employed Diffusion Tensor Distribution (DTD) imaging to retrieve nonparametric intravoxel DTDs. DTD allows separation of tissue-specific diffusion profiles of the main brain components, e.g., white matter, grey matter, cerebrospinal fluid and pathological tissue environments such as edema through so-called ‘bins’, namely the ‘thin’, ‘thick’, ‘big’, and the new fourth bin, ‘sparse’. Microscopic anisotropy is not confounded by cell alignment over the voxel scale, unlike conventional fractional anisotropy. Long processing times (a few hours) are needed to generate DTD maps. Current MDD sequences, albeit optimized, feature longer TE compared to conventional diffusion sequences. This imposes a lower image resolution (3x3 mm2) in order to maintain reasonable signal-to-noise ratio. Distortion artefacts could be corrected upon acquisition of a reverse phase-encoding b0 image (for ‘topup’ processing).
1. Basic physics underlying MDD MRI
2. Pros and cons of the sequence
3. Highlight key differential diagnostic points in different brain indications: infections – tuberculomas and cysticercosis, sudden onset of loss of balance, fits, radiation damage and seizures.
The poster can be viewed here: MDD_EE_poster
