Pre-and postoperative cerebral blood flow changes in patients with idiopathic normal pressure hydrocephalus measured by computed tomography (CT)-perfusion.

In idiopathic normal pressure hydrocephalus (iNPH), the cerebral blood flow (CBF) is of pathophysiological interest and a potential biomarker. Computed tomography perfusion (CTP), an established technique with high spatial resolution and quantitative measurements, has not yet been used in the iNPH context. If CTP were sensitive to the CBF levels and changes in iNPH, this technique might provide diagnostic and prognostic absolute perfusion thresholds. The aim of this work was to determine the applicability of CTP to iNPH. CBF measurements of 18 patients pre- and 17 three months postoperatively, and six healthy individuals (HI) were evaluated in 12 cortical and subcortical regions of interest. Correlations between CBF and symptomatology were analyzed in shunt-responders. Compared to HI, the preoperative CBF in iNPH was significantly reduced in normal appearing and periventricular white matter (PVWM), the lentiform nucleus and the global parenchyma. No CBF differences were shown between responders and non-responders. In responders, the CBF recovered postoperatively by 2.5-32% to approximately the level of HI, but remained significantly decreased in the PVWM of non-responders. The pre- and postoperative CBF of cortical and subcortical regions correlated with the intensity of symptoms. In spite of limited spatial coverage, CTP can measure CBF changes in iNPH.