Assessment of bypass patency using transcranial Doppler sonography: correlations with computerized tomography angiography findings in patients with moyamoya disease

High-resolution magnetic resonance vessel wall imaging provides new insights into Moyamoya disease

Moyamoya disease (MMD) is a rare condition that affects the blood vessels of the central nervous system. This cerebrovascular disease is characterized by progressive narrowing and blockage of the internal carotid, middle cerebral, and anterior cerebral arteries, which results in the formation of a compensatory fragile vascular network. Currently, digital subtraction angiography (DSA) is considered the gold standard in diagnosing MMD. However, this diagnostic technique is invasive and may not be suitable for all patients. Hence, non-invasive imaging methods such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are often used. However, these methods may have less reliable diagnostic results. Therefore, High-Resolution Magnetic Resonance Vessel Wall Imaging (HR-VWI) has emerged as the most accurate method for observing and analyzing arterial wall structure. It enhances the resolution of arterial walls and enables quantitative and qualitative analysis of plaque, facilitating the identification of atherosclerotic lesions, vascular entrapment, myofibrillar dysplasia, moyamoya vasculopathy, and other related conditions. Consequently, HR-VWI provides a new and more reliable evaluation criterion for diagnosing vascular lesions in patients with Moyamoya disease.

Usefulness of STA ultrasonography parameters after STA-MCA bypass in patients with moyamoya disease: A short review

STA bypass assessment by ultrasonography after bypass surgery in patients with moyamoya disease is minimally invasive and can be performed repeatedly. With STA bypass assessment by ultrasonography, it was shown that in the short term, blood flow that passes through the STA peaks approximately 5 days after the bypass surgery and then gradually decreases over 7 days. In the medium and long terms, it has been shown that the blood flow through the bypass decreases, compared with that during the first postoperative week, and continues for approximately half a year. The ultrasonographic STA parameters can also clearly indicate bypass patency, but there remains some discussion regarding bypass function. Although some reports have tried to show that these parameters are also useful for predicting acute-phase TNEs and predicting the future of bypass function, no studies have yet examined these parameters in detail in relation to the state of cerebral circulation or degree of residual antegrade flow, and additional studies are needed in the future.