M. Andorrà¹ , M. Ramos² , E. Martinez¹ ,
E. Lampert¹ , P. Rodrigues² ,
P. Villoslada¹ , V. Prckovska¹
¹ Institut d ́Investigacions Biomèdiques August Pi i Sunyer,
² MintLabs, S.L., Barcelona, Spain
framework for MS
Limitations of Connectivity Matrices
The classical representation of connectivity among ROI pairs is an N by N
square simetric matrix.
It has some human interpretation limitations:
We defined an elemental connectome as the most simple possible
connectome representing one single track between two particular ROIs.
This way, any connectome can be understood as a lineal combination of this
elemental connectomes. For an N ROIs connectome we can decompose as:
If we consider the scalar weights αifor each elemental connectome we
have what we call the connectivity spectrum. Its amplitude is given by:
Each number of tracks has been normalized by the maximum connectivity
order and then, represented in logaritmic terms to enhance the
Cohort: 10 healthy controls, 5 MS patients
Data: 3T Siemens MRI (0.9mm T1-MPRAGE; 60 directions HARDI)
Deterministic tracking (MRtrix3): DTI, CSD6 and CSD8.1
T1 Segmentation: 'Desikan-Killiany’ (Freesurfer 5.3)2
Healthy template spectrum
One healthy control spectrum with DTI, CSD6 and CSD8.
MS patient spectrum comparison
Healthy averaged template spectrum and one MS patient spectrum.
•Connectivity spectrum is a 2D plot easier to analyze than connectivity
matrices plots to human eyes.
•Peaks and valleys are consistent. Amplitude has subtle changes.
• Moving from CSD of order 6 to 8 doesn’t change a lot the results.
•MS patients has the same shape of controls but lower amplitude as a
• Overlaying MS patient to control’s template give us a quick first idea of
which connections are highly affected by WM lesions.
•This method can be used also to make patients template for those
diseases that are anatomically lesion consistent.
1. An automated labeling system for subdividing the human cerebral cortex on
MRI scans into gyral based regions of interest. Desikan et al. 2006.
2. Fibre-tracking was performed using the MRtrix package. Tournier et al.