functional Brain Imaging:

oday, there is not a single person who has not suffered or experienced emotional or psychological difficulties, either personally or in close others. Depression, youth suicide and addictions have reached epidemic proportions; panic attacks, obsessive-compulsive thinking or having experienced a horrific event, only to be left with nightmares, flashbacks or social avoidance (PTSD), are almost commonplace.

Sadly, there are a proportion of those suffering from these conditions who failed to seek help, whilst amongst those that do, a significant percentage fail to respond to the medical and psychological interventions, despite the best efforts of all involved. Until recently, the medical profession have been unable to fully comprehend patient's symptoms or uncharacteristic behaviours in terms of what was actually happening to the neuro-chemistry within their brains! This in part, was due to the unavailability of the ‘normal’ functioning brain data bases which could then be used as a comparison for patients suffering from a range of psychiatric disorders, such anxiety or depression.

Fortunately, the evolution of advanced imaging cameras and computer technology has seen the advent of such (sex and age corrected) data-bases, so allowing clinicians now to see how patient symptoms, such as obsessions or road rage might occur as an alteration of brain functioning.

Today, the increased knowledge gained from functional brain imaging has provided clinicians with an added tool of scientific information to compliment their clinical assessment, particularly in the group of the more difficult patient group often labelled, treatment resistant.

Finally, the consequence of such medical progress has allowed clinicians to better understand their patients and their symptoms. In so doing, they are achieving better outcomes than previously due to such advancements which has allowed them to tailor-make medication and treatment programs more appropriately suited to the individual’s needs.

functional Brain Imaging Gallery -- 3D Surface Brain:

What is SPECT?

[Single Photon Emission Computerized Tomography]

SPECT is a functional nuclear medicine study that looks directly at the flow of blood to the different regions of brain [cerebral blood flow] and indirectly at a patient’s brain cell’s metabolism and chemical [neurotransmitter] activity. In other words, how their brain is working.

A harmless radioactive isotope bound to molecules is injected into the patient’s blood stream, whereupon it travels to the brain to be taken up differentially in different sites depending on the activity of the neurone’s receptors at that site.

The patient then lies still for approximately 15 minutes while the SPECT camera takes its images which are reconstructed into coloured 3-D images and slices by modern computer technology. With these sophisticated images physicians are able to map and then identify certain patterns of brain activity that correlate with psychiatric and neurological conditions.

functional Brain Imaging Case Study:

Paul, a 27-year-old IT consultant presents to his family doctor 24 hours after being involved in what he describes, as a minor motor vehicle accident. His main complaint was that of persistent headaches since the accident. Further enquiry revealed that on impact, Paul who was not wearing a seatbelt at the time, was thrown forward, hitting his head on the dashboard and losing consciousness for only a few seconds.

The Family Physician initially referred Paul for a skull x-ray to determine whether there had been any bony damage to the skull [i.e. a fracture] and at the same time ordered a MRI [Magnetic Resonance Imaging] to examine the brain. As it turned out both of these investigations were normal, but when Paul’s headaches persisted for six months and were associated with being unable to concentrate as well as prior to the accident and feeling somewhat irritable and anxious, his doctor referred him to a specialist Neurologist who thought it advisable for him to undertake a SPECT Scan.[see below]

Skull x-rays, CAT scans and MRI's demonstrate brain structure or anatomy, just like a digital photograph and while being useful in detecting lesions such as tumours or cysts, they do not tell us what is actually happening in the brain at a cellular level. On the other hand functional studies such as SPECT allow the opportunity to see how the various geographical areas of the brain actually function or work.

SPECT: (Single Photon Emission Computed Tomography)

The brain, as with any organ in the body, is dependant on its blood supply for function and survival. The brain however, is more vulnerable than most, not just for it is oxygen supply, but also for its total energy requirements - it is the only organ in the body which cannot store and conserve its own energy supply.

As an example, just imagine you went for a jog around the block; obviously you would need very little blood to your stomach, as you are not digesting a meal and a greater volume of blood to the calves of your legs, in order that they may have the oxygen and nutrients needed to continue to run. So to when the brain is in balance, an appropriate distribution of cerebral blood flow [CBF] reaches each individual region depending on its requirements and in doing so the metabolism and neurochemical functioning at that site is said to be “normal”. The simplified equations underpinning the differential blood flow to various regions of the brain is: Cerebral Blood Flow [CBF] to any region is proportionate to the cellular activity occurring in that region [i.e. the metabolism in the basic building blocks of the brain such as neurones etc]. This cellular metabolism in turn indirectly equates to be neurochemical activity [neurotransmitter] in the region.

It is this formulation which allows the clinician to interpret the findings on SPECT and correlate the patient’s symptoms in the light of the alteration in neurotransmitter activity responsible for these changes in brain functioning. This in turn enables the clinician to put in place the most appropriate treatment profile possible.

So it is when the brain’s normal functioning becomes disturbed, as seen in a case of Paul, the neurochemical balance in a specific area (e.g. the frontal lobes) became compromised by his head trauma causing Paul’s symptoms of headaches and anxiety. It is interesting that on further enquiry Paul admitted to subtle changes in his impulse control, judgment and attention, much akin to a person suffering from Attention Deficit/ Hyper-activity Disorder.

It is now well-known from numerous research studies utilising functional brain imaging techniques such as PET, SPECT and functional MRI, that in certain neurological and psychiatric disorders, defined areas of altered brain functioning occurs. Alzheimer’s disease for example, not uncommonly has areas of under-perfusion [hypo-perfusion] in the temporal and parietal regions while obsessive-compulsive disorder (OCD) reveals over-perfusion [hyper-perfusion] in the caudate nuclei of the basal ganglia and the anterior cingulate gyrus and areas on the cortical region.

These changes in brain function can be seen in the functional imaging “pictures” as colourful areas of increased or decreased CBF perfusion. In other words, the amount of blood flowing to a particular region of the brain is visually represented on a coloured sliding scale. [The colour scale may vary from one functional brain imaging Centre to another as this depends on the preference and computerised programme employed by the nuclear physician.]

It is now well-known from numerous research studies utilising functional brain imaging techniques such as PET, SPECT and functional MRI, that in certain neurological and psychiatric disorders, defined areas of altered brain functioning occurs. Alzheimer’s disease for example, not uncommonly has areas of under-perfusion [hypo-perfusion] in the temporal and parietal regions while obsessive-compulsive disorder (OCD) reveals over-perfusion [hyper-perfusion] in the caudate nuclei of the basal ganglia and the anterior cingulate gyrus and areas on the cortical region. Hence, the clinician can examine patient’s SPECT Scan images and detect variations of CBF to specific brain regions which are considered to be outside the ‘normal’ range. These regions are said to be hyper-perfused, “hot” or receiving “too much” CBF or alternatively, under-perfused, “cold” or are receiving "too little" blood supply.

functional Brain Imaging- Clinical Applications:

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