Brain functional involvement by perfusion SPECT in systemic sclerosis and Behçet's disease.

Involvement of the central nervous system is frequent in systemic immune-mediated diseases, such as systemic lupus erythematosus, Behçet's disease (BD), and systemic sclerosis (SSc). Structural brain examinations, such as computed tomography and magnetic resonance imaging, may be useful in diagnosing and following-up these cerebral syndromes in some cases, but they are more often inconclusive. Single photon emission computed tomography (SPECT) with perfusion tracers is a powerful method that can disclose brain involvement in many clinical situations, even in patients with subtle neurological symptoms. In fact, perfusion tracers can disclose regional hypoperfusion caused by both ischemia due to vascular narrowing and neuronal metabolic derangement due to direct neuronal damage. The latter phenomenon occurs because the blood flow to the brain is strictly regulated by metabolic demands, so that hypometabolism is reflected by hypoperfusion in most instances. SPECT findings in 42 mainly neurologically asymptomatic patients with SSc and in eight mainly neurologically symptomatic patients with BD are reported. SPECT was shown to be very sensitive and disclosed brain functional deficits in approximately half of SSc patients without neurological complaints and in all patients with BD, who had various neurological symptoms but usually inconclusive structural brain examinations.