MR-angiography allows defining severity grades of cerebral vasospasm in an experimental double blood injection subarachnoid hemorrhage model in rats.
OBJECTIVE
Magnetic resonance (MR) imaging has been used for the detection of cerebral vasospasm (VSP) related infarction in experimental subarachnoid hemorrhage (eSAH) in rats. Conventional angiography is generally used to visualize VSP, which is an invasive technique with a possible increase in morbidity and mortality. In this study we evaluated the validity of MR-angiography (MRA) in detecting VSP and its feasibility to define VSP severity grades after eSAH in rats.


METHODS
SAH was induced using the double-hemorrhage model in 12 rats. In two rats, saline solution was injected instead of blood (sham group). MR was performed on day 1, 2 and on day 5. T1-, T2-, T2*-weighted and time-of-flight MR sequences were applied, which were analyzed by two blinded neuroradiologists. Vessel narrowing of 25-50% was defined as mild, 50-75% as moderate and >75% as severe VSP.


RESULTS
We performed a total of 34 MRAs in 14 rats. In 14 rats, MRA was performed on day 2 and day 5. In six rats MRA was additionally performed on day1 before the blood injection. A good visualization of cerebral vessels was possible in all cases. No VSP was seen in the sham group neither on day 2 nor on day 5. We found vasospasm on day 2 in 7 of the 14 rats (50%) whereas all 7 rats had mild and one rat had additionally moderate and severe vasospasm in one vessel, respectively. On day 5 we found vasospasm in 8 of the 14 rats (60%) whereas 4 rats had severe vasospasm, 1 rat had moderate vasospasm and 3 rats demonstrated mild vasospasm. In 4 of the 14 rats (30%) an ischemic lesion was detected on day 5. Three of these rats had severe vasospasm and one rat had mild vasospasm. Severe vasospasm on day 5 was statistically significant correlated with the occurrence of ischemic lesions (Fisher's Exact test, OR 19.5, p = 0.03).


CONCLUSIONS
MRA is a noninvasive diagnostic tool, which allows a good visualization of the cerebral vasculature and provides reproducible results concerning the detection of VSP and the differentiation into three severity grades in rats. Future studies are needed to directly compare MRA with conventional angiography.
Department of Neurosurgery, Georg August University Göttingen, Germany.
Vesna
V
Malinova
Department of Neuroradiology, Georg August University Göttingen, Germany.
Marios N
MN
Psychogios
Department of Neuroradiology, Georg August University Göttingen, Germany.
Ioannis
I
Tsogkas
Department of Neurology, Georg August University Göttingen, Germany.
Birte
B
Koennecke
Department of Neurosurgery, Georg August University Göttingen, Germany.
Kim
K
Bleuel
Department of Neurosurgery, Georg August University Göttingen, Germany.
Bogdan
B
Iliev
Department of Neurosurgery, Georg August University Göttingen, Germany.
Veit
V
Rohde
Department of Neurosurgery, Georg August University Göttingen, Germany.
Dorothee
D
Mielke
D000818:Animals; D002533:Cerebral Angiography / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D020301:Vasospasm, Intracranial / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology