Diffusion-perfusion MRI characterization of post-recanalization hyperperfusion in humans.
BACKGROUND
Animal and human studies have demonstrated that postischemic hyperperfusion may occur both early and late timepoints following acute cerebral ischemia.


OBJECTIVE
To use diffusion-perfusion MRI to characterize hyperperfusion in humans following intra-arterial thrombolysis.


METHODS
MRI were performed before treatment, several hours following vessel recanalization, and at day 7 in patients successfully recanalized with intra-arterial thrombolytics.


RESULTS
Hyperperfusion was visualized in 5 of 12 patients within several hours after recanalization (mean volume, 18 mL; range, 7 to 40 mL), and in 6 of 11 patients at day 7 (mean volume, 28 mL; range, 4 to 45 mL). Within the core region of hyperperfusion, mean cerebral blood flow was 2.1 times greater than in the contralateral homologous region at the early time point, and 3.1 times greater at day 7. Seventy-nine percent of voxels with hyperperfusion at day 7 demonstrated infarction at day 7, whereas only 36% of voxels (within the initial hypoperfusion region) not showing hyperperfusion at day 7 demonstrated infarction at day 7. Mean pretreatment apparent diffusion coefficient (ADC) and perfusion values were more impaired in voxels that subsequently developed hyperperfusion compared with other at-risk voxels (all p values < 0.0001). There were no significant differences in the degree of clinical improvement in patients with regions of hyperperfusion versus those without, although sample size limited power to detect group differences.


CONCLUSIONS
Postischemic hyperperfusion, visualized with perfusion MRI in humans following recanalization by intra-arterial thrombolytic therapy, occurred in about 40% of patients within hours and in about 50% of patients at day 7. Hyperperfusion developed mainly in regions that went on to infarction. Compared with other abnormal regions, tissues that developed postischemic hyperperfusion had greater bioenergetic compromise in pretreatment apparent diffusion coefficient values and greater impairment in pretreatment blood flow measures.
Kidwell
C S
CS
UCLA Stroke Center, UCLA Medical Center, Los Angeles, CA 90095, USA. ckidwell@ucla.edu
Saver
J L
JL
Mattiello
J
J
Starkman
S
S
Vinuela
F
F
Duckwiler
G
G
Gobin
Y P
YP
Jahan
R
R
Vespa
P
P
Villablanca
J P
JP
Liebeskind
D S
DS
Woods
R P
RP
Alger
J R
JR
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply*; D002544:Cerebral Infarction / Q000175:diagnosis* / Q000188:drug therapy; D004058:Diffusion; D004292:Dominance, Cerebral / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000175:diagnosis*; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects; D015427:Reperfusion Injury / Q000175:diagnosis*; D015912:Thrombolytic Therapy; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage; D014568:Urokinase-Type Plasminogen Activator / Q000008:administration & dosage
D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator