Assessment of informative value of effective cerebral blood flow calculation technique according to 99mTc-HMPAO polyphase scintigraphy data

Abstract

Background. According to single-photon emission computed tomography (SPECT) data, the most common technique to calculate volume cerebral blood flow (VCBF) is N.A. Lassen method. Following it, VCBF in different segments of the brain is assessed in comparison with blood flow in the cerebellum, where it is considered to be constant. However, this approach does not take into account that in some pathologies, in particular, injuries, occlusions of blood vessels, VCBF of the cerebellum also does change. Therefore, an original technique of calculating regional VCBF based on polyphase scintigraphy has been developed, which will make it possible to make a more accurate assessment of the effective perfusion of the brain. Purpose – to evaluate the clinical informative value of the developed technique for calculating effective cerebral blood flow according to 99mTc-HMPAO (hexamethylpropyleneaminoxime) polyphase brain scintigraphy data. Materials and methods. The study is focused on analyzing two groups of patients: Group A represented by patients with signs of chronic cerebral ischemia and Group B enrolling patients in the interim and long term of explosive minor brain injury (n=22). Group A patients were divided into two subgroups, depending on the presence of structural and hemodynamic changes in the vertebral arteries (VA) according to ultrasound (US) of the major vessels of the brain. I-A subgroup (n=13) was made up by those patients who had structural lesions of the vertebrobasilar basin; II-A (n=27) patients had no relevant signs. All patients underwent a comprehensive clinical examination including neuropsychological testing, ultrasound of major vessels, magnetic resonance imaging, single-photon emission computed tomography (SPECT). Effective volume cerebral blood flow (VCBF), according to the SPECT data, was calculated based on the original technique (VCBFSB). VCBFSB values were compared with the SPECT data using N.A. Lassen (VCBFLassen) method and the ultrasound data. Results and discussion. Analysing the data of the groups of patients with hemodynamic impairment in the vertebro-basilar basin shows that, according to the scintigraphy of VCBF, I-A group patients differ from II-A group on average 1.82± 0.06 times the amount for CBFSB and 0.95± 0.04 for CBFLassen. The total mean blood flow in the carotid and vertebral arteries of I-A group patients was 748.19±198.42 mL/min, II-A group patients – 1112.23±63.71 mL/min. Comparing the mean values of the hemodynamic parameters of the brain of Group B patients with the data of Group II-A patients, VCBFSB was 1.33±0.25-fold decreased, while CBFLassen showed 1.03±0.14-fold decrease of perfusion (in total average blood flow of vertebral and carotid arteries according to US of Group B – 1760±580 ml/min). Conclusions. Preliminary clinical studies, using the developed technique for calculating volume cerebral blood flow according to 99mTc-HMPAO scintigraphy data with the corresponding software, showed a rather high sensitivity in assessing VCBF in case of pathological changes in the brain, especially, in occlusion of the major vessels of the brain and contusions resulting from battle trauma, whereas N.A. Lassen method was insufficiently informative. The regression analysis of US data, SPECT data and neuropsychological testing shows clear linear correlation relationships, but they do also differ in sign depending on the diagnosis and the degree of pathological changes.

Keywords

• brain
• perfusion
• cerebral blood flow
• 99mtc-hmpao
• cerebral ischemia
• filtration
• superposition of images
• postconcussional syndrome