Signal Changes in the Brain on Susceptibility-Weighted Imaging Under Reduced Cerebral Blood Flow: A Preliminary Study

OBJECTIVES To reveal the characteristics of susceptibility-weighted imaging (SWI) under low cerebral blood flow (CBF) induced by hyperventilation (HV). MATERIALS AND METHODS This study was approved by the institutional review board. Informed consent was obtained. Six healthy volunteers (5 men, 1 woman; mean age, 29 years; range, 24-33 years) underwent SWI and arterial spin labeling perfusion imaging under normal ventilation (NV) and HV at 3.0 T. Regions of interest (ROIs) were placed on gray matter (GM) and white matter (WM) of the frontal lobe (FL) and occipital lobe (OL). Intensities of ROIs were compared between NV and HV. Contrast of veins compared with adjacent cerebral parenchyma (CV) was also compared between NV and HV. RESULTS CBF during HV (CBF(HV)) was decreased compared with CBF during NV (CBF(NV)) (29.1 +/- 4.6%). FL-GM(HV) and OL-GM(HV) showed significant signal decreases compared with FL-GM(NV) and OL-GM(NV), respectively (P = .018, .017). CV(HV) was significantly increased compared with CV(NV) (164.1 +/- 29.9%) (P = .00019). CONCLUSIONS SWI sensitively reflects HV-induced decreases in CBF. The present results might assist in the interpretation of SWI in clinical practice, since CBF decreases might also influence signal changes on SWI.