[Pitfalls in diagnosing cerebrovascular diseases using magnetic resonance angiography].

Magnetic resonance angiography (MRA) is one of the important methods for neurological imaging. Currently, time-of-flight (TOF) MRA, phase contrast (PC) MRA, and contrast-enhanced MRA are being studied for their potential for diagnosing cerebrorascular diseases. Many specific flow signal patterns and artifacts are observed on MRI. MRA has recently been developed on the basis of the studies on the MR flow phenomenon. However, flow artifacts are observed even in MRA, and most of the pitfalls associated with MRA have arisen due to the MR flow phenomenon. To avoid false-negative and false-positive results in MRA, it is very important to understand the MR flow phenomenon and flow artifacts. The purpose of this paper is to explain the MR flow phenomenon, flow artifacts, and the principle of MRA. Furthermore, the technical development of TOF MRA and the pitfalls observed while evaluating clinical cases have been discussed. This paper also clarifies MR flow artifacts and the current status of cerebral 3D TOF MRA, and explains how to avoid false negative and false positive results in MRA.