Using ultrasonography to diagnose middle cerebral artery stenosis

• Main Authors: Li-Wei Wang, 王麗雯
• Other Authors: 謝政哲
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/as4d6m

碩士 === 國立中興大學 === 生命科學院碩士在職專班 === 102 === Background：Carotid ultrasound and transcranial color- coded duplex sonography (TCCS) are widely-used, non-invasive tools for detecting cerebral artery stenosis. The reference range of cerebral blood flow velocity was based on the literature reports from Caucasian populations. In addition, using the same reference range of flow velocities in young adults might lead to misdiagnosis since age significantly affects cerebral blood flow. The present study aims to establish the normal range of cerebral blood flow velocities in Taiwanese population. Methods：Carotid ultrasound and TCCS were performed in 332 healthy, asymptomatic subjects. The participants were divided into three age groups (<40 y/o, 40-60 y/o and ≧60 y/o) to evaluate the associations between age and cerebral blood flow velocities. Sex-specific analysis was also performed. Based on the distribution of flow velocities obtained from healthy subjects, we proposed new diagnostic criteria for middle cerebral artery (MCA) stenosis. Brain magnetic resonance angiography (MRA) of 233 stroke patients was reviewed. The severity of MCA stenosis of each participant was determined by MRA. The sensitivity, specificity, positive and negative predictive values of ultrasound diagnostic criteria were calculated. Results：Sex and age are significantly associated with cerebral blood flow. The average flow velocities for MCA in subjects younger than 40 y/o, 40-60 y/o, and ≧ 60 y/o are 109.8 ± 22.7, 98.2 ± 23.6, 89.7 ± 23.5 cm/sec respectively (ANOVA p <0.001). Women has significantly higher cerebral blood flow than men, especially in women younger than 60 y/o. We proposed MCA / ICA PSV index (i.e. the ratio of flow velocities between extracranial internal carotid artery and intracranial MCA) to be the new diagnostic criteria for MCA stenosis. A MCA/ICA index higher than 1.58 in subjects younger than 60 y/o suggested MCA stenosis; whereas an index higher than 1.93 in subjects elder than or equal to 60 y/o suggested MCA stenosis. We then applied the diagnostic criteria to stroke patients to evaluate its validity. Using MRA as golden standard, the sensitivity, specificity, positive and negative predictive values for ultrasound are 48%, 76%, 21%, and 92% respectively. Conclusions：Carotid ultrasound and TCCS are useful, screening tools for detecting intracranial cerebral artery stenosis. The influence of age and sex should be considered in the interpretation of cerebral blood flow velocities.