The
Present and Near Future of Functional Imaging of: Brain "Injury"
Dr. J Michael
Uszler
Asst. Clin. Professor, UCLA, Santa Monica
Abstract:
Brain "injury" of all types, including trauma,
stroke, and developmental conditions, is becoming more prevalent - or is it that
we are more aware of its frequent occurrence in the lives of people right around
us, including family and friends?
This awareness, along with the increasing application
of hyperbaric oxygen and other forms of therapy for acute and long-term brain
injury, has propelled the development of forms of non-invasive brain imaging to
enable seeing the effects of these therapies on brain function.
Medical doctors are trained with a primary focus on
anatomy, and thus MRI and CT scanning of the brain are used commonly in brain
injury. However, the clinical challenge is that in many forms of subtle/chronic
brain injury, the brain's anatomy pattern is not significantly changed. Thus the
MRI or CT looks "normal" in many cases in which the person has
neurological dysfunction.
Thus more recently we and others have used the
functional types of imaging SPECT and PET - to visualize the dysfunctional
changes in the presence of "normal" brain anatomy. Both of these
involve the use of radioisotopes that are normally distributed into the brain in
relation to the actual functional levels of different brain regions. SPECT is
much more widely clinically available than PET, and is increasingly used to
evaluate brain injury and resultant dysfunction before and after hyperbaric
oxygen, pharmacologic and nutritional therapies.
In the next 2-4 years SPECT imaging will be directly
matched to two types of MRI imaging so as to achieve the best combination of
function and anatomy information in many cases of brain injury. The first usage
of MRI involves "FUSION" imaging, namely a direct computer matching of
the SPECT function and the MRI anatomy data throughout different regions of the
brain. We have begun to employ this type of "fusion" imaging in both
paediatric and adult age chronic brain injury.
A second type of MRI, called "fMRI;' so-called
functional MRI, is being developed and analyzed in its ability to contribute
brain function information. Presently its main limitation is that it requires
the person being scanned to not only to hold their head still, but also to
perform a specific, voluntary task while being scanned. Unfortunately many
people with brain injury cannot do one or both of these. This is most obvious in
the paediatric age range, and thus includes CP and autism.
Thus, SPECT brain imaging with quantitative analysis
and "fusion" will continue to be the predominant form of functional
brain imaging of brain injury.
Dr. J Michael
Uszler
Asst. Clin. Professor, UCLA, Santa Monica