RCBF-quantification with 99mTc-HMPAO-SPECT: theory and first results

Area of Science:

• Nuclear Medicine
• Cerebrovascular Physiology
• Medical Imaging

Background:

• Assessing regional cerebral blood flow (rCBF) is crucial for diagnosing and managing various neurological conditions.
• Existing methods for rCBF measurement have limitations, necessitating the development of novel, accurate techniques.

Purpose of the Study:

• To evaluate the efficacy of a new method for calculating rCBF using technetium-99m-labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) SPECT.
• To compare the results obtained from the novel SPECT method with a standard technique (133Xe inhalation).

Main Methods:

• SPECT imaging was performed on 25 patients after intravenous injection of 99mTc-HMPAO.
• Cardiac output and mean cerebral transit times were measured using 195mAu first pass studies.
• A three-compartment model was utilized to calculate the mean retention fraction of 99mTc-HMPAO in the brain.
• rCBF was calculated using brain activity concentration, cardiac output, and retention fraction.
• Comparison was made with the 133Xe inhalation method in 15 patients.

Main Results:

• A method was developed to calculate rCBF from 99mTc-HMPAO brain activity concentration, cardiac output, and retention fraction.
• A significant correlation (r=0.73) was found between the mean hemisphere CBF derived from the 99mTc-HMPAO SPECT method and the mean hemisphere grey matter CBF from the 133Xe inhalation method.

Conclusions:

• The novel 99mTc-HMPAO SPECT method provides a reliable estimation of regional cerebral blood flow.
• This technique offers a promising alternative for rCBF assessment, correlating well with established methods.