Changes of Fractional Anisotropy and Apparent Diffusion Coefficient in Patients with Idiopathic Normal Pressure Hydrocephalus

Abstract

Since ventricular dilation and periventricular abnormal intensities are commonly seen in patients with idiopathic normal pressure hydrocephalus (INPH) on magnetic resonance imaging (MRI), dysfunction of white matter may have an important role in the mechanism causing symptoms of INPH. To clarify the pathophysiology of INPH, we analyzed axonal water dynamics using diffusion tensor MRI. Thirty-six patients with possible INPH were included. Regional fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in several white matter regions before and 24 h after a cerebrospinal fluid tap test (CSF-TT). The patients were divided into two groups: patients who showed significant improvements in neurological status after the CSF-TT (positive, n = ;17) and those with no neurological improvement (negative, n = 19). After CSF-TT, ADC values were significantly decreased in the frontal periventricular region and the body of the corpus callosum in the positive group (p < 0.05), whereas no significant change was shown in the negative group. FA values were significantly increased in the body of the corpus callosum in both groups after CSF-TT (p < 0.05). After CSF-TT, water molecules at the extracellular space could move to the intraventricular space, resulting in decreased ADC values. This suggests that changes of water dynamics in white matter may have a role in the mechanism causing symptoms of INPH.

The role of diffusion tensor imaging and fractional anisotropy in the evaluation of patients with idiopathic normal pressure hydrocephalus: a literature review

“…9,22,27,34,43,46 Some of these studies have reported that CSF drainage significantly increases FA in the periventricular WM and the CC and also significantly decreases ADC in these areas.…”

“…9 The patients were separated into 2 groups: those who had significant neurological improvement after the CSF tap test (17 patients) and those who had no improvement (19 patients). A statistically significant decrease (p < 0.05) in ADCs was detected only for the patients with neurological improvement.…”

“…In contrast, a significant increase (p < 0.05) in FA after the CSF tap test was observed in both groups. 9 Jurcoane et al studied 2 groups of patients with iNPH after they had undergone CSF drainage via a spinal tap: the first group comprised 12 patients whose gait significantly improved 3 days after the CSF drainage, and the second group consisted of 14 patients whose gait did not improve. 22 The authors performed DTI and magnetization transfer ratio (MTR) measurements in the CSTs after the CSF drainage in both patient groups.…”

The effects of hydrocephalus on the periventricular white matter in intracerebral hemorrhage: a diffuser tensor imaging study

“…This selective restriction of water molecule movement allows physical changes in periventricular white matter caused by hydrocephalus to be explored by diffusion anisotropy. Many DTI studies have reported the effect of hydrocephalus on periventricular white matter in patients with normal pressure hydrocephalus and in patients with hydrocephalus caused by a congenital anomaly [8][9][10][11][12][13][14][15][16][17]. However, little is known about hydrocephalus following stroke [18,19].…”

Change in fractional anisotropy during treatment of diabetic ketoacidosis in children

“…Diffusion-weighted MRI, by using magnetic field gradients to spatially label water molecules, reflects changes in water diffusion in tissues and is therefore considered sensitive to changes in the cerebral microstructure (11). Diffusion tensor imaging (DTI) measurements are sensitive to both absolute water diffusion and the direction of diffusion; for example, movement of water in normal pressure hydrocephalus from the white matter extracellular space to the intraventricular space is associated with a decrease in the apparent diffusion coefficient (ADC) (12). The fractional anisotropy (FA) changes in a wide variety of neurological disease states have been described (9,10).…”