Marzia Mortilla MD, Presenter: Nothing to Disclose

Antonio Ciccarone MD, PhD, Abstract Co-Author: Nothing to Disclose

Marco Esposito, Abstract Co-Author: Nothing to Disclose

Claudio Fonda MD, Abstract Co-Author: Nothing to Disclose

Our purpose was to identify a MRI method for quantifying the degree to which water diffusion in biologic tissues is non-Gaussian. DWI depends on the the b-values used during acquisition. At b-values lower than 500s/mm2 the signal attenuation is bi-exponential and it is influenced by both diffusion and perfusion. At b-values higher than 1000 s/mm2 the signal attenuation is influenced by restricted water diffusion and hence allows a non-Gaussian distribution. Diffusion Kurtosis Imaging (DKI) provides quantifiable information about the deviation from Gaussian distribution in water diffusion processes. Our aim was to use DKI in different pediatric brain pathologies in order to evaluate its feasibility in detecting those pathologies.

The method is an extension of conventional DWI that requires higher b-values. We used 5 b-values: from 0 to 2500 s/mm2 with step 500. Fitting all b-values we were able to discriminate Diffusion and kurtosis parameters. We modified image post-processing procedure and we developed home made software for post-processing and DWI, ADC, AKC maps. We have examined 47 children (aged 15 days - 14yrs) with different pathologies (12 tumors, 4 vascular, 9 metabolic, 7 cognitive defects) and with no pathology (15).

AKC maps revealed additional information for tissue characterization. For example in hypoxic-ischemic lesions AKC revealed more details about pathologic tissue changes and provided some information about prognosis. In brain tumors, AKC maps were used for discriminating low-grade from high grade lesions showing more accuracy than conventional diffusion parameters. The 15 patients with no pathology were used to create a set of normal values for specific anatomic regions.

ADCk and AKC are non invasive methods to study brain lesions in pediatric patients. Our results suggest that these maps provide a more detailed characterization of neural tissue in clinical context. The post-processing required to generate maps is more time consuming than traditional DWI maps (2 min for each slice) but this acquisition and post-processing method provide more complete characterization of water displacement inside parenchyma in DWI.

The application of DKI in pathological conditions in a pediatric population provides additional  information about microstructural tissue changes, differential diagnosis and prognosis.

Mortilla, M, Ciccarone, A, Esposito, M, Fonda, C, 3T Apparent Kurtosis Coefficient (AKC) in Pediatric Brain: Preliminary Results.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13021754.html