Evaluation of average amount of cerebral blood flow measured by brain perfusion index in patients with neuropsychiatric systemic lupus erythematosus.

We used the brain perfusion index (BPI), an indicator of the average amount of cerebral blood flow (CBF), to evaluate the usefulness of the average amount of CBF for neuropsychiatric systemic lupus erythematosus (NPSLE). Of the seventy three SLE patients examined in this study (total 100 scans), 16 patients (23 scans) had already been diagnosed with NPSLE based on clinical symptoms indicative of central nervous system involvement. In addition, 12 patients (17 scans) exhibited the antiphospholipid antibody syndrome (APS). BPI is significantly influenced by age and we therefore used the BPI ratio (ratio of age predicted BPI to measured BPI value) for each assessment. The mean BPI value of 100 scans was 11.2 +/- 2.79, and the mean BPI ratio was 0.99 +/- 0.24 in all SLE patients. The mean BPI ratio among NPSLE (0.84 +/- 0.19) was significantly lower than that of the non-NPSLE patients (1.04 +/- 0.24) (P < 0.0005). However, there was no difference in the mean BPI ratio between APS patients (0.98 +/- 0.24) and non-APS patients (0.99 +/- 0.25). These results indicate that the mean CBF assessed by the BPI ratio using SPECT is of use in the evaluation of central nervous system involvement in SLE patients.