Diffusion Tensor Imaging of the Superior Thalamic Radiation and Cerebrospinal Fluid Distribution in Idiopathic Normal Pressure Hydrocephalus

Abstract

BACKGROUND AND PURPOSE Ventricular enlargement in elderly raises a challenging differential diagnosis to physicians. While Alzheimer's disease is the most common form of dementia, idiopathic normal pressure hydrocephalus (iNPH) constitutes a potentially reversible syndrome. iNPH has a unique pathophysiology pertaining to cerebrospinal fluid (CSF) dynamics and periventricular white matter. We aimed to determine the effects of iNPH on periventricular white matter bundles and to further characterize its ventricular and sulcal CSF distribution by using diffusion tensor tractography (DTT) and CSF volumetrics on high resolution T1‐weighted magnetic resonance imaging data. METHODS Deterministic DTT and validated volumetric parcellation were performed on 20 healthy elderly, 13 Alzheimer's disease (AD), and 9 iNPH patients. The superior thalamic radiation, corticospinal tract, and dentatorubrothalamic tract were traced and quantified using DTI studio software. Cloud‐based volumetric parcellation was also performed on 138 healthy subjects across the lifespan, 13 AD, and 9 iNPH‐patients. Ventricular and sulcal CSF volumes in the three groups were compared. RESULTS Combining increased mean diffusivity of the superior thalamic radiation with ventricular volume resulted in clear separation of iNPH from the AD and age‐matched healthy subject groups. Additionally, ventricular to sulcal CSF ratio, utilizing fully automated methods, was significantly greater in the iNPH patients compared to AD and healthy age‐matched controls. CONCLUSIONS Combined microstructural (DTT) and macrostructural (ventricular volume) changes is a promising radiological approach in studying ventriculomegaly. Automated estimation of the disproportionate ventricular and sulcal CSF ratio in patients presenting with ventriculomegaly may be important as radiologic markers in differentiating iNPH from other causes of ventriculomegaly.

The role of diffusion tensor imaging in idiopathic normal pressure hydrocephalus: A literature review

“…Many measures were used as assessments of cognitive function (Mini Mental State Examination (MMSE), 21–29,31,32,35–37,43–45,48,49 trail making test A (TMT-A), 23,32,33,35,36,43,49 DemTect test, 25 , 32 Montreal Cognitive Assessment (MOCA) 54 ; learning and memory (Hopkins Verbal Learning Task-Revised (HVLT-R) 39 ); verbal fluency and executive function (COWAT), 20 , 39 Wechsler Memory Scale III (WMS-WL), 20 Rey complex figure test (RCFT), 20 according to Deckersbach et al. 71 ); conceptualization, mental flexibility, motor programming, sensitivity to interference, inhibitory control and environmental autonomy due to frontal lobe dysfunction (frontal assessment battery (FAB) 22,24,33,36,37,41,45,49 ); grade of dementia (Clinical Dementia Rating Scale (CDR), 29,35,36 , Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) 29 ); motor impairment and gait (gait velocity, 43 Timed Up and Go (TUG) test, 22,23,30,35–38,41,…”

“…Additionally, ventricular to sulcal CSF ratio was greater in the iNPH patients compared to AD and healthy controls. 54…”

“…16–17 in 1994, and recently, many papers investigated its role in analyzing white matter (WM) alterations in patients with iNPH. 12 , 18–54 DTI is a non-invasive MR technique that provides information about the orientation and anisotropy of the WM tracts, and may delineate microstructural changes in cerebral WM; high-resolution, multitensor imaging (more than six diffusion directions) is currently combined with various other advanced MR techniques to study connectivity within the brain. In fact, illnesses that disrupt the normal organization or integrity of cerebral WM have a qualitative and quantitative impact on DTI measures.…”

DTI Profiles for Rapid Description of Cohorts at the Clinical-Research Interface

“…As the displacement of fluid in compartments is critical within the NPH spectrum, studies have shown that DTI has been able to demonstrate different patterns of white matter injury consistent with the symptomatology of the NPH disorder (16). DTI has also been found to differentiate NPH from other cohorts such as those with other types of ventriculomegaly, chronic hydrocephalus as well as Alzheimer's disease, Parkinson's disease, and other dementias (17–19). However, there are challenges in DTI acquisition and interpretation that prevent its more widespread uptake at the clinical-research interface.…”

The Normal Anatomy of the Brain Pathways: What the Neuroradiologist Needs to Know (Literature Review)

“…Верхняя таламическая лучистость (superior thalamic radiation) -содержит волокна, связывающие вентральную группу ядер с пре-и постцентральными извилинами, вторичной моторной и сенсорной корой [32].…”