Abstract
Background: Perfusion single-photon emission computed tomography (SPECT) using an acetazolamide is an important clinical tool used to assess cerebrovascular reactivity (CVR) in patients, but its use has been limited to clinical diagnostics. This study aimed to preliminarily evaluate the feasibility of perfusion SPECT using carbon dioxide (CO2). Methods: Ten healthy subjects participated in two consecutive SPECT scans using CO2 inhalation. To evaluate brain perfusion after preprocessing, the voxel-by-voxel CVR values were averaged in 13 subgroup regions of interest (ROIs) based on a template. Subsequently, averaged CVR values of each ROI were analyzed based on both cerebellar hemispheres. Results: CVR values in the eight subgroup ROIs, which included vermis, both insula/cingulate, and frontal cortices, showed significant changes (p < 0.05). CVR values were higher in vermis and right insula/cingulate by 3.34% and 3.15%, respectively. Conclusions: This study showed that quantitative SPECT with CO2 inhalation could be used to evaluate the voxel-based CVR in healthy subjects, which could be beneficial for elucidating induced hypercapnic states and for longitudinally investigating the healthy aging in brain vessels. Furthermore, the cerebrovascular hemodynamic parameters induced by CO2 could play an important role as a biomarker to evaluate treatment progress in patients with cerebrovascular disease.
Highlights
Brain perfusion imaging using technetium 99m-labeled hexamethyl-propyleneamineoxime (99m Tc-HMPAO) single-photon emission computed tomography (SPECT) is used as a standard technique for evaluating and diagnosing cerebrovascular reactivity (CVR) in patients with cerebrovascular disease (CVD) [1,2]
The purpose of this study was to determine the possible use of consecutive 99m TcHMPAO SPECT imaging with 5% CO2 inhalation to evaluate CVR in healthy subjects and to calculate the voxel-based CVR values based on the automated anatomical labeling (AAL)
We aimed to demonstrate the effects of CO2 on a healthy human brain by performing a subgroup region of interest (ROI) analysis using an automated program developed for the quantitative evaluation of CVR
Summary
Brain perfusion imaging using technetium 99m-labeled hexamethyl-propyleneamineoxime (99m Tc-HMPAO) single-photon emission computed tomography (SPECT) is used as a standard technique for evaluating and diagnosing cerebrovascular reactivity (CVR) in patients with cerebrovascular disease (CVD) [1,2]. The extra accumulated absorption of 99m Tc-HMPAO into the brain tissue can be calculated by subtracting it in a subsequent SPECT image. These properties apply to any condition that causes brain perfusion within a short time, such as carbon dioxide (CO2 ) inhalation. To evaluate brain perfusion after preprocessing, the voxel-by-voxel CVR values were averaged in 13 subgroup regions of interest (ROIs) based on a template. Conclusions: This study showed that quantitative SPECT with CO2 inhalation could be used to evaluate the voxel-based
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