Biology Reference
In-Depth Information
and monkeys (
12
). Interestingly, several studies have used a different
ultrasound technique to visualize intravascular fl ow in rodents
(
13, 14
). In these studies, rodents were imaged through a cranial
window after intravenous injection of various contrast agents
(
13, 14
). These ultrasound probes were able to identify arterial
narrowing as well as disruption of the blood-brain barrier by
detecting these contrast agents (
13, 14
).
3. Cerebral
Angiography
Cerebral angiography is considered the gold standard for diagnos-
ing cerebral vasospasm in humans (
15
). This modality typically
involves cannulating a large distal artery and threading the catheter
proximally into the carotid and/or vertebral artery. Contrast agent
is injected, and sequential radiographs are taken to visualize the
movement of the contrast agent through the intracranial blood
vessels. The presence of arterial narrowing signifi es the presence of
vasospasm (
15
).
Cerebral angiography provides important spatial and temporal
information not offered by other modalities (
16
). Additionally, it
is less susceptible to artifact from bone and surrounding tissue
compared to other techniques (
16
). However, major disadvan-
tages exist, including invasiveness and requirement for large vessel
access (
16
). This can lead to signifi cant vascular injury and even
stroke (
16
). This procedure can also be diffi cult in smaller
animals.
Cerebral angiography has been used to evaluate vasospasm in
several studies, including rodent (
17
), rabbit (
18
), canine (
19
),
and primate models (
20, 21
). Hartmut et al. used a double hemor-
rhage model to evaluate the time course of vasospasm in rats (
17
).
In this study, autologous blood was obtained from the femoral
artery and injected into the cisterna magna on consecutive days (
17
).
The presence of vasospasm was assessed in the vertebral-basilar
system by cannulating the femoral artery and selectively inserting
a microcatheter into the vertebral artery (
17
). After injection of
contrast agent, imaging was obtained using biplane digital sub-
traction angiography equipment (
17
). Peak vasospasm occurred
on day 5 in this model (
17
). Salvetti et al. (
18
) performed a similar
procedure to evaluate vasospasm in the posterior circulation of
rabbits. Peak vasospasm occurred 3 days after injection of autolo-
gous blood in this study (
18
). Quan et al. (
19
) evaluated vasos-
pasm in dogs after injection of autologous blood using a double
hemorrhage technique. Vasospasm occurred on day 3 and peaked
on day 7 using digital subtraction angiography (
19
). In monkeys,
the peak period of arterial narrowing occurred 7 days after SAH
(
20, 21
).
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