TABLE 2.

- Definition of hemodynamic descriptors involved in the analysis.

WSS-based descriptors
Time-Averaged WSS ($\text{TAWSS}$)	$\text{TAWSS}=\frac{1}{T}\underset{0}{\overset{T}{{\displaystyle \int }}}\left|\mathbf{WSS}\right|dt$
Oscillatory Shear Index ($\text{OSI}$)	$\text{OSI}=0.5 \left[1-\left(\frac{\left|{{\displaystyle \int }}_0^T\mathbf{WSS}dt\right|}{{{\displaystyle \int }}_0^T\left|\mathbf{WSS}\right|dt}\right)\right]$
Relative Residence Time ($\text{RRT}$)	$\text{RRT}=\frac{1}{\text{TAWSS}\cdot \left(1-2\cdot \text{OSI}\right)}=\frac{1}{\frac{1}{T}\left|{{\displaystyle \int }}_0^T\mathbf{WSS}dt\right|}$
Transverse WSS (transWSS)	$\text{transWSS}=\frac{1}{T}\underset{0}{\overset{T}{{\displaystyle \int }}}\left|\mathbf{WSS}\cdot \left(\mathbf{n}\times \frac{{{\displaystyle \int }}_0^T\mathbf{WSS}dt}{\left|{{\displaystyle \int }}_0^T\mathbf{WSS}dt\right|}\right)\right|dt$
Helicity-based descriptors
Local Normalized Helicity (LNH)	$\text{LNH}=\frac{\mathbf{v}\cdot \mathbf{\omega }}{\left|\mathbf{v}\right|\cdot \left|\mathbf{\omega }\right|}=\cos \gamma$
Average helicity ($h_1$)	$h_1=\frac{1}{TV}{\displaystyle \underset{\mathit{T}\mathit{V}}{\iint }\mathbf{v}\cdot \mathbf{\omega }dVdt}$
Average helicity intensity ($h_2$)	$h_2=\frac{1}{TV}{\displaystyle \underset{TV}{\iint }\left|\mathbf{v}\cdot \mathbf{\omega }\right| dVdt}$
Signed balance of counter-rotating helical flow structures ($h_3$)	$h_3=\frac{h_1}{h_2} -1 \le h_3\le 1$
Unsigned balance of counter-rotating helical flow structures ($h_4$)	$h_4=\frac{\left|h_1\right|}{h_2} 0 \le h_4\le 1$

WSS is the WSS vector; T is the period of the cardiac cycle; n is the unit vector normal to the arterial surface at each element; v is the velocity vector; ω is the vorticity vector; γ is the angle between velocity and vorticity vectors; V is the arterial volume.