[The contribution of single-photon emission-computed tomography in cerebral function diagnosis]

Area of Science:

• Neuroscience
• Medical Imaging
• Radiochemistry

Background:

• Single photon emission computed tomography (SPECT) enables visualization of physiological and chemical brain processes.
• SPECT utilizes single photon emitting nuclides, such as 99m technetium and 123 iodine, tagged to compounds or 133xenon.
• The technique involves measuring radioactivity from a rotating gamma-camera to compute tracer distribution in tomographic slices.

Purpose of the Study:

• To present clinical experience with SPECT using N-isopropyl-(123I)-p-iodoamphetamine (123I-IMP) and 99mTc hydroxymethyl-propylene-amine-oxime (99mTc-HMPAO).
• To highlight the application of SPECT in studying cerebrovascular disease, epilepsy, and Alzheimer's disease.
• To explore the potential of SPECT in psychiatric diseases and parkinsonism, with future interest in receptor ligands.

Main Methods:

• Administration of radiopharmaceutical agents (123I-IMP, 99mTc-HMPAO) that distribute according to regional cerebral blood flow (rCBF).
• Measurement of radioactivity using a rotating gamma-camera from multiple directions.
• Computation of tracer distribution and transformation into tomographic brain slices.

Main Results:

• SPECT has improved understanding of pathophysiological processes and dynamics after ischemic infarction.
• In epilepsy, SPECT can identify foci of reduced or enhanced tracer activity in interictal and ictal stages.
• SPECT demarcates zones of diminished neuronal activity in temporo-parietal and frontal cortex in early Alzheimer's disease.

Conclusions:

• SPECT is a valuable tool for visualizing brain function and aiding in the diagnosis of neurological and psychiatric conditions.
• The method provides essential insights into the pathophysiology of diseases like stroke, epilepsy, and Alzheimer's.
• Future research directions include the application of SPECT with receptor ligands for a broader range of clinical studies.