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Detection of Acute Ischemia

MRI and CT are both usually normal for several hours after interruption of flow
to the brain as the tissue properties measured by these modalities take time to become
abnormal. SPECT imaging of rCBF is a highly effective means for detecting acute

Table 2. SPECT patterns according to dementia subtype

Percentage of All
Dementias

Most Common Pattern

of SPECT

rCBF Reductions

Alzheimer's disease

50-70

Bilateral parietotemporal
(relative sparing of
sensorimotor cortex, basal
ganglia and cerebellum).

Diffuse Lewy body
dementia

10-20

Like Alzheimer's disease

Vascular dementia
(multi-infarct)

10

Multiple asymmetric
cortical and subcortical
in a vascular distrubution

Frontotemporal
dementia (including
Pick's disease)

5-10

Bilateral anterior frontal
lobes and inferior temporal
lobes

Normal pressure
hydrocephalus

6

Global with an enlarged
subcortical low-flow region

Cortical basal
degeneration

<5

Unilateral cortex, basal
ganglia and thalamus
(contralateral to the affected
limb)

Parkinson's disease

<5

Like Alzheimer's disease

Chronic drug
intoxication

3

Normal

Cerebral trauma

2

Prefrontal and temporal
poles (occasionally occipital
 contre-coup defects)

Huntington's disease

2

Caudate nuclei

HIV encephalopathy

Progressive
palsy

(Steel-Richardson
syndrome Prilosec / Prilosec walgreens)

Normal

Table summarizes data from multiple studies, usually small case series.

stroke. Since reduced blood flow is the primary event Seroquel / Seroquel anxiety.

The clinical usefulness of SPECT rCBF to demonstrate early interruption in
blood flow to the brain is still unclear as no obvious impact in terms of prognostic
information or patient management has emerged. This situation may change if it
can be shown to help guide patient selection for therapies such as thrombolysis.
Successful lysis of blood clots obstructing cerebral blood vessels can dramatically
improve post-stroke functional status if it is achieved in the first few hours. This
benefit is partially offset by a significant risk of intracranial hemorrhage Mestinon / Mestinon sr, and in which vascular cells may have been irreversibly damaged.
Reflow into such vessels is prone to intraparenchymal bleeding with a high rate of
complications related to acutely increased intracranial pressure. Inclusion of SPECT
rCBF studies in stroke protocols to evaluate suitability for thrombolysis will depend
on clinical confirmation that it reliably predicts which patients are at increased risk
of bleeding (Fig. 6). In theory, it should be easy to detect the large, severe decrease in
tracer uptake that would portend a poor outcome.