Table 1:

Recommended Acquisition Protocols for Perfusion-Weighted (PWI) and Diffusion-Weighted (DWI) MR Imaging

	PWI	DWI
Sequence	Single-shot gradient-echo echoplanar imaging	Single-shot diffusion-weighted spin-echo echoplanar imaging
Image acquisition parameters	TR≤1500 ms^*	TR≥4000 ms but can be as high as needed to fit all slices
	TE=35 to 45 ms @ 1.5T	TE minimum (partial Fourier)
	TE=25 to 30 ms @ 3T	b=0 and 1000 sec/mm²
	flip angle α=60 to 90° @ 1.5T, 60° @ 3.0T	(at least 3 orthogonal directions) eddy current correction (dual-spin echo or postprocessing)
	Parallel imaging and coil selected at the discretion of the site
Image acquisition duration	90 to 120 seconds image acquisition started 10 seconds before initiation of injection to achieve at least 10 to 12 baseline images and also record slow uptake in stroke regions	90 to 260 seconds
Coverage and slice thickness	Whole brain coverage using ≥12 slices slice thickness 5 mm gap 0 to 1 mm^* matrix size 128×128^* phase-encoding along A/P direction field of view ≈24 cm	Whole brain coverage using ≥12 slices slice thickness 5 mm gap 0 to 1 mm matrix size 128×128 phase-encoding along A/P direction field of view ≈24 cm
Slice orientation	Parallel to hard palate	Parallel to hard palate (ideally perpendicular to the scanner bore)
Contrast material	Standard gadolinium-based contrast material	…
Contrast volume	Single dose (for half-molar agent, ≈20 mL for 100 kg person) followed by 20 to 40 mL saline flush	…
Injection rate	4 to 6 mL per second (power injector required) same injection rate for contrast and saline	…
IV access	18 to 20 gauge IV line right antecubital vein preferred	…
Miscellaneous	PWI can be performed before or after MR-angiography	…

MRI scanner: 1.5T or 3T (MRI scanners with 512 image limit per series should be excluded).
* Interslice gap can be increased and matrix size can be decreased to achieve whole-brain coverage (TR can also be optimized to afford entire brain coverage but should be ≤1500 to 2000 ms).