Korean J Nucl Med.  2000 Aug;34(4):322-335.

Quantification of Cerebrovascular Reserve Using Tc-99m HMPAO Brain SPECT and Lassen's Algorithm

• Kim KM
• Lee DS
• Kim SK
• Lee JS
• Kang KW
• Yeo JS
• Chung JK
• Lee MC

Abstract

PURPOSE: For quantitative estimation of cerebrovascular reserve (CVR), we estimated the cerebral blood flow (CBF) using Lassen's nonlinearity correction algorithm and Tc-99m HMPAO brain SPECT images acquired with consecutive acquisition protocol. Using the values of CBF in basal and acetazolamide (ACZ) stress states, CBF increase was calculated. MATERALS AND METHODS: In 9 normal subjects (age: 72+/-4 years), brain SPECT was performed at basal and ACZ stress states consecutively after injection of 555 MBq and 1,110 MBq of Tc-99m HMPAO, respectively. Cerebellum was automatically extracted as reference region on basal SPECT image using threshold method. Assuming basal CBF of cerebellum as 55 ml/100 g/min, CBF was calculated for every pixel at basal states using Lassen's algorithm. Cerebellar blood flow at stress was estimated comparing counts of cerebellum at rest and ACZ stress and Lassen's algorithm. CBF of every pixel at ACZ stress state was calculated using Lassen's algorithm and ACZ cerebellar count. CVR was calculated by subtracting basal CBF from ACZ stress CBF for every pixel. The percent CVR was calculated by dividing CVR by basal CBF. The CBF and percentage CVR parametric images were generated.
RESULTS
The CBF and percentage CVR parametric images were obtained successfully in all the subjects. Global mean CBF were 49.6+/-5.5 ml/100g/min and 64.4+/-10.2 ml/100g/min at basal and ACZ stress states, respectively. The increase of CBF at ACZ stress state was 14.7+/-9.6 ml/100g/min. The global mean percent CVR was 30.7% and was higher than the 13.8% calculated using count images.
CONCLUSION
The blood flow at basal and ACZ stress states and cerebrovascular reserve were estimated using basal/ACZ Tc-99m-HMPAO SPECT images and Lassen's algorithm. Using these values, parametric images for blood flow and cerebrovascular reserve were generated.

Keyword

Tc-99m HMPAO; Quantification; Cerebral blood flow; Cerebrovascular reserve; Lassen's algorithm

MeSH Terms

Acetazolamide
Brain*
Cerebellum
Technetium Tc 99m Exametazime*
Tomography, Emission-Computed, Single-Photon*
Acetazolamide
Technetium Tc 99m Exametazime