Diffusion Kurtosis Imaging: A Possible MRI Biomarker for AD Diagnosis?

Abstract

The purpose of this explorative study was to investigate whether diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) parameter changes are reliable measures of white matter integrity changes in Alzheimer’s disease (AD) patients using a whole brain voxel-based analysis (VBA). Therefore, age- and gender-matched patients with mild cognitive impairment (MCI) due to AD (n = 18), dementia due to AD (n = 19), and age-matched cognitively healthy controls (n = 14) were prospectively included. The magnetic resonance imaging protocol included routine structural brain imaging and DKI. Datasets were transformed to a population-specific atlas space. Groups were compared using VBA. Differences in diffusion and mean kurtosis measures between MCI and AD patients and controls were shown, and were mainly found in the splenium of the corpus callosum and the corona radiata. Hence, DTI and DKI parameter changes are suggestive of white matter changes in AD.

Diffusion kurtosis imaging allows the early detection and longitudinal follow-up of amyloid-β-induced pathology

“…The latter corresponds to our results. However, they also reported reduced MK [33], which contrasts with our finding of an increased MK in many of the cortical ROIs. Reduced MK in the hippocampus of patients with AD was also observed by Wang et al [54].…”

“…This drawback is less apparent in human studies, because the voxel size is much larger in humans, and therefore most voxels share the same degree of pathology. For comparison, we used an isotropic voxel size of 78 μm (0.00047 mm 3 ), whereas in a study done in humans, Struyfs et al used an isotropic voxel size of 2.2 mm (10.64 mm 3 ) [33]. In contrast, when an ROIbased approach is used, the variation in obtained DKI metrics will be smaller because the degree of pathology is averaged across many voxels.…”

“…Clinically, researchers in only a few recent human studies have examined the usefulness of DKI in this context. For example, Struyfs et al [33] compared patients with AD with healthy control subjects and reported reduced FA in many regions, among which was the splenium of the corpus callosum. The latter corresponds to our results.…”

Diffusion Kurtosis Imaging Shows Similar Cerebral Axonal Damage in Patients with HIV Infection and Multiple Sclerosis

“…However, in the absence of direct examination of brain tissue, it is difficult to ascertain the specific pathological abnormalities underlying this WM injury. In this study, we sought to further investigate the pathophysiology of WM damage in HIV using DKI‐derived WMTI metrics that have been shown to be more pathologically specific than DTI‐derived metrics in patients with MS …”

“…Diffusion kurtosis imaging (DKI) is an extension of DTI that enables the quantification of non‐Gaussian diffusion through the estimation of the diffusional kurtosis . DKI allows for the quantification of WM tract integrity (WMTI) metrics such as intra‐ and extra‐axonal diffusivities, axonal water fraction, and tortuosity, which have been shown to be more specific than standard DTI to pathological processes in both experimental models and neurological diseases . In a recent study, we have applied the WMTI technique to patients with multiple sclerosis (MS) who are characterized by extensive and pathologically heterogeneous abnormalities of the WM.…”