Combined use of pulsed arterial spin-labeling and susceptibility-weighted imaging in stroke at 3T.
OBJECTIVE
In acute stroke it is no longer sufficient to detect simply ischemia, but also to try to evaluate reperfusion/recanalization status and predict eventual hemorrhagic transformation. Arterial spin labeling (ASL) perfusion may have advantages over contrast-enhanced perfusion-weighted imaging (cePWI), and susceptibility weighted imaging (SWI) has an intrinsic sensitivity to paramagnetic effects in addition to its ability to detect small areas of bleeding and hemorrhage. We want to determine here if their combined use in acute stroke and stroke follow-up at 3T could bring new insight into the diagnosis and prognosis of stroke leading to eventual improved patient management.


METHODS
We prospectively examined 41 patients admitted for acute stroke (NIHSS >1). Early imaging was performed between 1 h and 2 weeks. The imaging protocol included ASL, cePWI, SWI, T2 and diffusion tensor imaging (DTI), in addition to standard stroke protocol.


RESULTS
We saw four kinds of imaging patterns based on ASL and SWI: patients with either hypoperfusion and hyperperfusion on ASL with or without changes on SWI. Hyperperfusion was observed on ASL in 12/41 cases, with hyperperfusion status that was not evident on conventional cePWI images. Signs of hemorrhage or blood-brain barrier breakdown were visible on SWI in 15/41 cases, not always resulting in poor outcome (2/15 were scored mRS = 0-6). Early SWI changes, together with hypoperfusion, were associated with the occurrence of hemorrhage. Hyperperfusion on ASL, even when associated with hemorrhage detected on SWI, resulted in good outcome. Hyperperfusion predicted a better outcome than hypoperfusion (p = 0.0148).


CONCLUSIONS
ASL is able to detect acute-stage hyperperfusion corresponding to luxury perfusion previously reported by PET studies. The presence of hyperperfusion on ASL-type perfusion seems indicative of reperfusion/collateral flow that is protective of hemorrhagic transformation and a marker of favorable tissue outcome. The combination of hypoperfusion and changes on SWI seems on the other hand to predict hemorrhage and/or poor outcome.
Viallon
Magalie
M
Department of Radiology, Geneva University Hospital, 24 rue Micheli-du-Crest, Geneva, Switzerland.
Altrichter
Stephen
S
Pereira
Vitor Mendes
VM
Nguyen
Duy
D
Sekoranja
Lucka
L
Federspiel
Andrea
A
Kulcsar
Zsolt
Z
Sztajzel
Roman
R
Ouared
Rafik
R
Bonvin
Christophe
C
Pfeuffer
Josef
J
Lövblad
Karl-Olof
KO
D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003952:Diagnostic Imaging / Q000145:classification / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013113:Spin Labels; D020521:Stroke / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods
D013113:Spin Labels