[Chronological changes in MR angiography of a case with isolated angiitis of the CNS].

Isolated angiitis of the central nervous system (IAC) is a disease of unknown etiology, and is restricted to the small-to-medium-sized blood vessels of the central nervous system. We report serial MR angiography findings in a case of IAC. A 51-year-old female came to our hospital because of severe headache. Computed tomography (CT) 6 days after the onset didn't show anything particular, and MR angiography 8 days after the onset revealed segmental stenosis of the bilateral anterior cerebral arteries. However, we couldn't diagnose it as IAC. Thirteen days after the onset, the patient's headache worsened. Subsequent MRA revealed severe stenosis of the bilateral anterior and middle cerebral arteries. After that, steroid therapy was initiated. Her headache was disappeared immediately. Twenty-nine days after the onset, MRA showed the improvement of stenosis. Seventy-three days after the onset, stenosis of the cerebral arteries was disappeared. Interestingly, in another case report of IAC, MRA showed improvement of the stenosis one month after the onset, and disappearance of the stenosis two months after the onset.