When drawing lesions, it is sometimes the case that the lesion will be visible on one modality, but not on the other (i.e. lesion may be visible on a diffusion scan but not the T2 weighted structural scan). 

Since it is preferable to draw the VOI in the same space and resolution as the T2 (and assuming the diffusion and T2 are coregistered properly) it would be great to be able to draw your region on the diffusion scan and have it simultaneously be drawn on the coregistered/open T2. 

Adding a 'draw on all yoked images' option, perhaps next to the 'yoke' option, or else in the Draw dropdown would be fantastic.