Psychiatric Mental Health Nursing by Videbeck

In magnetic resonance imaging (MRI),a
type of body scan, an energy field is created with a
huge magnet and radio waves. The energy field is
converted to a visual image or scan. MRI produces
more tissue detail and contrast than CT and can
show blood flow patterns and tissue changes such
as edema. It also can be used to measure the size and
thickness of brain structures. Selemon and Goldman-
Rakic (1995) found a 7% reduction in cortical thick-
ness in persons with schizophrenia. The person un-
dergoing an MRI must lie in a small, closed chamber
and remain motionless during the procedure, which
takes about 45 minutes. Those who feel claustropho-
bic or have increased anxiety may require sedation
before the procedure. Clients with pacemakers or
metalimplants, such as heart valves or orthopedic
devices, cannot undergo MRI.
More advanced imaging techniques, such as
positron emission tomography (PET)and sin-

gle photon emission computed tomography

(SPECT),are used to examine the function of the

brain. Radioactive substances are injected into the

blood; the flow of those substances in the brain is

monitored as the client performs cognitive activities

as instructed by the operator. PET uses two photons

simultaneously; SPECT uses a single photon. PET

provides better resolution with sharper and clearer

pictures. A PET scan takes about 2 to 3 hours; SPECT

takes 1 to 2 hours. PET and SPECT are used pri-

marily for research not for the diagnosis and treat-

ment of clients with mental disorders (Karson &

Renshaw, 2000; Malison & Innis, 2000) (Fig. 2-6). A

recent breakthrough is the use of the chemical marker

FDDNP with PET scanning to identify the amyloid

plaques and tangles of Alzheimer’s disease in living

clients; these conditions previously could be diag-

nosed only through autopsy (Small, 2002). These

scans have shown that clients with Alzheimer’s dis-

2 NEUROBIOLOGICTHEORIES ANDPSYCHOPHARMACOLOGY 25

Table 2-2

BRAINIMAGINGTECHNOLOGY

Procedure Imaging Method Results Duration

Computed tomography (CT)

Magnetic resonance

imaging (MRI)

Positron emission tomography

(PET)

Single photon emission computed

tomography (SPECT)

Serial x-rays of brain

Radio waves from brain detected

from magnet

Radioactive tracer injected into

bloodstream and monitored as

client performs activities

Same as PET

Structural image

Structural image

Functional

Functional

20–40 minutes

45 minutes

2–3 hours

1–2 hours

Figure 2-5.Example of computed tomography scan of brain of patient with schizo-

phrenia compared to normal control.