Nothing conjures up so much dread in the elderly as a diagnosis of Alzheimer's disease. Nothing is more heartrending than to see than a child with an uncontrollable seizure disorder. To share a moment with a victim of Parkinson's disease is to witness the agony of not being able to perform the simplest of physical tasks. Stroke, dementia in its many forms, and brain tumors are other disorders that strike the brain and the very core of our personality.
PET is proving essential for patients with these neurological disorders. CT and MR scans may render exquisite detail about the structure of the brain -- but can tell nothing about its function. With a single PET image, abnormalities of brain function can be found that would otherwise go undetected.
- Suffering from memory loss? PET can determine if the cause is Alzheimer's disease, blood flow shortages, depression, or some other reason.
- PET can localize the brain site of seizure activity. This is especially important for children with uncontrollable seizures who are candidates for hemispherectomy as cure.
- PET can tell if that muscle tremor is Parkinson's disease or another of the "Movement" disorders.
- PET can look at brain tumor and reveal if it's benign or malignant. It is also widely used when recurrence is suspected to show whether structural change is tumor re-growth or merely scar tissue.
- PET can "map" the areas of the brain responsible for movement, speech, and other critical functions. This is a remarkable guide for surgeons who are performing delicate operations on different areas of the brain.
The symptoms are sadly familiar: memory loss, vagueness, losing the point of a conversation, repeating oneself. The decline is steady and downhill. The patient requires increasing levels of care. Alzheimer's disease (AD) is the most common form of late-life dementia, with approximately 4 million stricken in the U.S. alone. Annual cost estimates, including the costs of medical, long-term and home care, as well as caregiver productivity losses, approach $90 billion yearly. As the babyboomers reach the age of 60 and older, the number of Americans who will succumb to this disease may reach 14 million! The impact on people's lives and the economy is staggering.
New drugs are now available for patients with AD in its early stages. Donepezil (also known as Aricept) can temporarily stabilize the decline and improve memory function of patients with mild to moderate Alzheimer's. However, recognition of dementia is particularly difficult in its early stages. Clearly, many patients are not diagnosed and fail to receive treatment, particularly in the early disease stages when intervention may do the most good.
Mohammed Ali and Michael J. Fox are just two of the more than one million people, both men and women, in the United States who suffer from Parkinson's disease (PD). The symptoms are progressive and by now familiar to most of us: the frozen face that is part of the rigid body posture, the tremor that is often uncontrollable, the difficulty with walking and the instability of posture. PD was first described in 1817 by an English physician, Dr. James Parkinson, who called it "Shaking Palsy." It wasn't until the 1960's that pathological and biochemical brain changes were identified as the cause, specifically the degeneration of the brain areas that produce dopamine.
Administration of the drug leveodopa, which is converted by the brain into levodopa, has been the standard treatment for PD. A common problem has been how to get a high enough concentration of the drug to reach the brain without causing side effects. Other drugs have been developed to enhance this process.
How Does PET/CT make a Difference?
- PET can definitively diagnose Parkinson's disease.
- Research using PET has been responsible for many of the discoveries about how the disease affects the brain. PET is being used by researchers searching for a cure.
Dementia isn't really a disease but a group of symptoms certain diseases have in common. According to the Alzheimer's Association, dementia is a loss of mental function to the extent that it interferes with a person's daily life. This could include loss of memory, intellect, rationality, social skills and normal emotional reactions. Alzheimer's disease is the most common cause of dementia. Other dementias include Parkinson's disease, vascular dementia, Pick's disease, Huntington's disease, and structural brain problems such as head injury or brain tumor. PET is able to diagnose all of these diseases.
Vascular dementia is the second most common cause of dementia. It refers to problems with the circulation of blood to the brain that are usually the result of many small strokes or decreased blood flow. Dementia may occur when one of these strokes damages a strategic area of the brain responsible for a memory or emotion function.
Pick's disease is a disorder affecting the frontal and temporal lobes of the brain, causing progressive and irreversible decline much like Alzheimer's. Disturbances of personality, behavior and language may be noticed first and even be more severe than memory defects. Depending on the lobe affected, symptoms may include loss of social and sexual inhibition, impaired judgment, hoarding items, roaming, difficulties with attention and motivation, aphasia, repetitive speech patterns or the tendency to repeat anything heard. Named for Dr. Arnold Pick who reported the first case in 1892, the onset of the disease is typically in the mid-to-late 50's, and the disease averages about 10 years from onset to death. The cause remains unknown, and until PET the only way to diagnose Pick's disease was after autopsy.
Huntington's disease (HD) is an inherited, degenerative brain disease that affects the mind and body. It slowly diminishes the affected individual's ability to walk, think, talk and reason. Named for Dr. George Huntington who first described this hereditary disorder in 1872, HD is now recognized as one of the more common genetic disorders. More than a quarter of a million Americans have HD or are at risk of inheriting the disease from an affected parent. Early symptoms may include depression, mood swings, forgetfulness, clumsiness, involuntary twitching and lack of coordination. As the disease progresses, concentration and short-term memory diminish and involuntary movements of the head, trunk and limbs increase. Walking, speaking and swallowing abilities deteriorate. HD typically begins in mid-life, between the ages of 30 and 45. In 1993, the HD gene was isolated, and a direct genetic test was developed which can accurately determine whether a person carries the HD gene. The test cannot predict when symptoms will begin. Since the discovery of the gene, HD research has accelerated and much has been added to our understanding of the disease. PET has been instrumental in this breakthrough HD research.
How Does PET/CT make a Difference?
- PET is the only imaging technique that can differentiate between the dementias, ruling out Alzheimer's for example, and positively diagnosing a metabolic pattern for Pick's and Huntington's disease. This is extremely important for directing patient treatment programs, since most dementias are not yet curable. PET is also being used by scientists searching for answers to these diseases. Hopefully, there will be a cure soon.
- Brain tumor evaluation was the first demonstrated clinical application of PET and is now used to grade the degree of malignancy, check for recurrence--especially differentiating surgical changes like scar tissue fromm recurrent tumor, provide physicians with prognostic information, and pinpoint the most active tissue for biopsy.
Approximately two million adults and 500,000 children have been diagnosed with epilepsy (seizure disorder) in the United States. Epilepsy is a devastating condition that encroaches upon every facet of the patient's life - it is difficult to work, many are not allowed to drive, and most all sufferers feel the effects of its negative stigma. Epilepsy is a generic term used to define many different types of seizure disorders. A person that has recurring seizures is said to have epilepsy. A seizure is a disturbance of the electrical activity in the brain. Most often the cause of these seizures is unknown.
From 75 - 85% of patients with epilepsy can be treated with medication that controls or eliminates the debilitating seizures. The rest aren't so lucky - medications do not control the recurring seizures. For these patients, surgery to remove the portion of the brain that is causing the electrical disturbance may be the only option to control their epilepsy. PET helps determine if surgery can be useful.
How Does PET/CT make a Difference?
- Thanks to PET, focal areas of seizures can be identified. This is helpful to determine whether or not brain surgery to remove the seizure site is a treatment option. Generally, surgery is only an option when the center of the electrical disturbance is confined to a small focal area in the brain.
- With the help of PET, scientists have discovered that a child's brain has the ability to compensate for itself, even when a major portion is surgically removed. This knowledge has allowed surgeons to help children with uncontrollable seizures. An entire hemisphere of the brain can be surgically removed and the child will still be able to grow and function quite well.
- PET identifies abnormal areas even if the brain looks normal on a CT or MR scan. Doctors depend on PET to show the area responsible for the seizures AND confirm that there are not other focal areas that produce similar electrical disturbances.
- Without PET, patients may have to undergo an additional open-brain surgery to localize the cause of the seizure activity - a costly and risky undertaking. Now, many curative surgeries can be planned and avoided in others - without that risk and cost.
For more information about the PET/CT scanner or to make an appointment, call the Division of Nuclear Medicine at (410) 328-6891.
This page was last updated: May 10, 2013