Discrepancy between regional cerebral blood flow and glucose metabolism of the brain in systemic lupus erythematosus patients with normal brain magnetic resonance imaging findings

Abstract

Objective

In this study, 2 updated brain-imaging modalities, technetium-99m hexamethylpropylene amine oxime–single-photon–emission computed tomography (HMPAO-SPECT) and fluorine-18 2-fluoro-2-deoxy-D-glucose–positron emission tomography (FDG-PET), were used to simultaneously detect regional cerebral blood flow (rCBF) and glucose metabolism of the brain in patients with systemic lupus erythematosus (SLE).

Methods

Twenty-five female SLE patients, ages 25–40 years, were enrolled in this study and assigned to 1 of 2 groups. Group 1 consisted of 13 patients with neuropsychiatric manifestations (7 had major and 6 had minor manifestations). Group 2 consisted of 12 patients without neuropsychiatric manifestations. Serum levels of anticardiolipin antibodies (aCL) and anti–ribosomal P antibodies (anti-P) were measured. All patients had normal brain magnetic resonance imaging (MRI) findings. Ten healthy female volunteers also underwent brain MRI, HMPAO-SPECT, and FDG-PET for comparison.

Results

^99mTc-HMPAO-SPECT revealed hypoperfusion lesions in 11 (44%) of 25 SLE patients, including 9 (69%) of the 13 patients in group 1, 7 (100%) of the 7 patients with major manifestations, 2 (33%) of the 6 patients with minor manifestations, and 2 (17%) of the 12 patients in group 2. Parietal lobes were the areas most commonly involved. FDG-PET revealed hypometabolism in 7 (54%) of the group 1 patients, 6 (86%) of the 7 patients with major manifestations, and 1 (17%) of the 6 patients with minor manifestations. Temporal lobes were the most commonly involved areas. However, no significant hypometabolism brain lesions were found in group 2 patients. All of the 4 patients with headaches and dizziness or headaches alone had normal findings on HMPAO-SPECT and FDG-PET. Nine (36%) of the 25 patients were positive for aCL. However, the presence of aCL was not related to neuropsychiatric manifestations or to HMPAO-SPECT or FDG-PET findings. Five (20%) of the 25 patients had anti-P antibodies and psychosis/depression.

Conclusion

In patients with normal brain MRI findings, decreases in glucose metabolism coupled with decreases in rCBF are associated with serious neuropsychiatric SLE (NPSLE) presentations, while normal glucose metabolism with decreases in rCBF may be found in SLE patients with or without NPSLE.