Joint Program in Nuclear Medicine

Brain SPECT Imaging in Dementia

Alexander Matthies, MD
Finn Mannting, MD, PhD

February 18, 1997

Presentation

An 82 year old female with no significant past medical history presented with a 2 year history of slowly progressive decline, initially mainly short term memory loss. However the decline recently accelerated, especially due to severe word finding and orientation difficulties, visual and auditory hallucinations.

Imaging Findings

A brain SPECT study (axial view and coronal view) revealed bilateral temporo-parietal perfusion defects, which were more prominent in the left hemisphere. These findings indicate the diagnosis of Alzheimer's disease.

Diagnosis

Alzheimer's Disease

Discussion

Dementia is one of the major causes of morbidity in the elderly generation. It’s prevalence is believed to be between 2 and 25% above the age of 65 (depending on sampling technique and country). It has a very significant impact on society and heath care systems.

The most common types of primary dementia include:

Very rare types of primary dementia include: However dementia due to secondary causes has always to be considered. The most common types are:

Several new approaches have been developed in recent years to enable a faster diagnosis of dementing processes. While the CT and MRI are excellent tools to exclude secondary, in particular anatomic causes of dementia, they are of limited value in defining primary degenerative brain diseases, especially in the early stages.

In recent years functional brain SPECT imaging with several tracers has been applied for the evaluation of early clinical symptoms of dementia.

While early research and clinical studies were performed with Xe-133 and I-123-iodoamphetamine, currently the most common agents are Tc-99m labeled tracer HMPAO and ECD.

Brain SPECT in Alzheimer's disease

A large part of brain SPECT imaging has focused on the early detection of Alzheimer's disease. This is in part related to the large portion of dementia patients, that are ultimately diagnosed with Alzheimer's disease, but also to the lack of laboratory test for the disease.

Early stages of the disease may have normal or only unilateral perfusion defects. Bilateral areas of hypoperfusion are seen in the moderate to severe cases.

Holman et al. studied 132 patients with brain scans. A final diagnosis was established in 113 patients. Among these were 52 patients with Alzheimer's disease, 11 with Parkinson's disease dementia, 11 with vascular dementia, 14 with AIDS dementia, 2 with Pick's disease and 23 with other diagnoses.

Bilateral temporoparietal defects with or without additional defects had a probability of 77 % and 82 % respectively. If Parkinson's disease dementia is excluded, which can have the same appearance as AD, the likelihood of Alzheimer's disease is over 90 %. Unilateral, frontal or multiple small defects were not predictive of AD.

These findings were confirmed by other authors.

References

1. Harrison’s Principles of Internal Medicine. 13th ed. McGraw-Hill. 1994, pp 2269-2275.

2. Greenfield’s Neuropathology, 6th ed. New York, Wiley, 1966. 3. Brain Disease of the Nervous System. Walton J (editor), Oxford 1993.

4. Dementia Disorders. Katona CL (editor): 1st ed. London, Chapman and Hall, 1989.

5. Holman BL et al: The Scintigraphic Appearance of Alzheimer’s Disease: A prospective study Using Technetium-99m-HMPAO SPECT. JNM 1992; 33:181-185.

6. Holman BL and Devous MD: Functional Brain SPECT: The Emergence of A Powerful Clinical Method. JNM 1992; 33:1888-1904.

7. Bonte FJ et al: Single Photon Tomography in Alzheimer’s Disease and the Dementias. Semin Nuc Med 1990; 20:342-352.

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J. Anthony Parker, MD PhD, Tony_Parker@bidmc.harvard.edu