Regional dissociation between the cerebral blood flow and gray matter density alterations in idiopathic normal pressure hydrocephalous: results from SINPHONI-2 study.

Purpose: The purpose of this study was to elucidate the specific regional cerebral blood flow (rCBF) alterations for idiopathic normal pressure hydrocephalus (iNPH) by comparing the proportional rCBF and gray matter change from those of a normal database at the same point of SPECT and MRI examinations.
Methods: Thirty subjects with iNPH underwent both CBF SPECT and MRI. After normalization, voxel-wise two-sample t tests between patients and 11 normal controls were conducted to compare the regional alteration in the gray matter density and rCBF.
Results: The rCBF reduction and the gray matter decrease were seen in almost similar regions surrounding Sylvian fissure, the left parietotemporal region and frontal lobes, whereas we did not find rCBF increase at the top of the high convexity, where the increase of the gray matter density was the highest (p < 0.05).
Conclusion: Our study showed regional associations and dissociations between the relative gray matter density and rCBF in patients with iNPH.