Age-Dependent Changes in the Histogram of Apparent Diffusion Coefficients Values in Magnetic Resonance Imaging

Abstract

The aim of this study was to develop a fast method for estimating whether a brain volume loss is within the normal range for the respective age of the patient. A readout-segmented diffusion-weighted echo-planar imaging sequence was performed as part of the routine examination at a 3-T scanner. Data without (b0-image) and with diffusion weighting (1000 s/mm2) from 492 patients were examined (in the age from 3 to 89 years). One hundred and seventy-three data-sets had to be excluded due to brain lesions or to pathological enlarged cerebrospinal fluid spaces. In the remaining 319 data-sets, apparent diffusion coefficients (ADCs) values were calculated for all pixels exceeding a combined threshold in the diffusion-weighted data and in the non-diffusion-weighted data. The first part of the histogram represents pixels containing mostly brain tissue. The percentage of number of pixels in this part of the ADC histograms was evaluated for all patients and was correlated with the age of the patients. In all the areas examined, a monotone change of relative pixel numbers with the age of the patients was found. The reduction of the contribution of pixels containing mostly brain tissue accelerated with age and was found to be 0.18%/year in the age of 20, 0.34%/year in the age of 50, and 0.50%/year in the age of 80. The observed decrease of the relative number of pixels from the brain tissue with increasing age corresponds to previously published results based on more time-consuming 3-D measurements. The presented technique uses a conventional clinical sequence and might be helpful in deciding whether an observed brain volume loss in a patient is within the normal range for the age of the patient.

Longitudinal Characterisation of Healthy Ageing in Rats using Multimodal Magnetic Resonance Imaging

“…Complimentary to the observed volume changes in grey and white matter, an increase in the size of CSF compartments with chronological ageing is consistently observed, but there is a discrepancy between whether this relationship is linear or curvilinear (Good et al, 2001;Walhovd et al, 2005;Michielse et al, 2010). Diffusion data also demonstrate increased CSF volume; in particular, histograms generated from the ADC values across all brain voxels showed a lower peak ADC in old brains, and histograms from old brains had a longer tail, indicating a decrease in restricted diffusion and an increase in free diffusion due to a larger relative proportion of the brain being fluid rather than tissue (Klose et al, 2013).…”

Parameterization of the Age-Dependent Whole Brain Apparent Diffusion Coefficient Histogram

“…All these groups did not include an age dependence of the ADC histogram in their model estimations. Recent studies showed a strong influence of age on the shape of the whole brain histogram [ 19 , 20 ]. In particular, the relative content of cerebrospinal fluid in the brain is increasing with age and this has an effect on the ADC histogram.…”