Assessment of hepatocellular carcinoma using apparent diffusion coefficient and diffusion kurtosis indices: preliminary experience in fresh liver explants

Objectives

The objective was to perform ex vivo evaluation of non-Gaussian diffusion kurtosis imaging (DKI) for assessment of hepatocellular carcinoma (HCC), including presence of treatment-related necrosis, using fresh liver explants.

Methods

Twelve liver explants underwent 1.5-T magnetic resonance imaging using a DKI sequence with maximal b-value of 2000 s/mm². A standard monoexponential fit was used to calculate apparent diffusion coefficient (ADC), and a non-Gaussian kurtosis fit was used to calculate K, a measure of excess kurtosis of diffusion, and D, a corrected diffusion coefficient accounting for this non-Gaussian behavior. The mean value of these parameters was measured for 16 HCCs based upon histologic findings. For each metric, HCC-to-liver contrast was calculated, and coefficient of variation (CV) was computed for voxels within the lesion as an indicator of heterogeneity. A single hepatopathologist determined HCC necrosis and cellularity.

Results

The 16 HCCs demonstrated intermediate-to-substantial excess diffusional kurtosis, and mean corrected diffusion coefficient D was 23% greater than mean ADC (P=.002). HCC-to-liver contrast and CV of HCC were greater for K than ADC or D, although these differences were significant only for CV of HCCs (P≤.046). ADC, D and K all showed significant differences between non-, partially and completely necrotic HCCs (P≤.004). Among seven nonnecrotic HCCs, cellularity showed a strong inverse correlation with ADC (r=−0.80), a weaker inverse correlation with D (− 0.24) and a direct correlation with K (r= 0.48).

Conclusions

We observed non-Gaussian diffusion behavior for HCCs ex vivo; this DKI model may have added value in HCC characterization in comparison with a standard monoexponential model of diffusion-weighted imaging.     

Molecular association and function of arabinogalactan protein complexes from tree exudates

Gum arabic is an exudate from the Acacia trees found in the arid conditions of the Sahelian belts of Africa. The particular gum discussed here is from the species Acacia senegal is a complex polydisperse molecule and is widely used in the food industry, mainly as a natural emulsifier. It is the high molecular weight arabinogalactan protein (AGP) component which is responsible for its emulsification functionality. A process is described which can increase the content and molecular weight of this component and as a result a new series of commercial gum arabic products have been produced, designated Acacia senegal(sey)SUPERGUM. The maturation process used to prepare these products is similar to that which occurs in the natural state of the tree. The paper describes how aggregation of the AGP can be controlled whereby low molecular weight components can be associated to form stable products. The mechanism of this association is discussed and explained in terms of inter-molecular equilibria. The results satisfactorily account for the large variation found in natural gum arabic and in commercial samples. Since this molecular variation can adversely affect the effectiveness of the gum arabic as an emulsifier, it is important that it can now be standardized and enhanced. There are indications that the basic building block of Acacia senegal is ca 400,000 Da but that aggregates of this unit can form depending on local conditions and commercial processing methods.     

Introduction

These are the proceedings of an international meeting on “Structural Aspects of the Intercellular Matrices of Plants and Animals”, June 23–26, 2008 in St. Tropez, France. The meeting was sponsored by the Matrix Biology Institute (Edgewater, New Jersey, USA) and Phillips Hydrocolloids Research Ltd, London, UK, and organized by Janet Denlinger and Glyn Phillips (co-editors of this Special Issue), with Endre A. Balazs at Villas Nifnaha and Hylan, Parc de la Moutte, St. Tropez, France.

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Diophantine approximation with multiplicative functions

Let σ(n) denote the sum of divisors function. Our main result shows that, given any real α > 1 there are infinitely many integers n such that

The pseudoscalar mass spectrum as evidence for gluons,anomalies and topological charge

The complete set of anomalous Ward identities for the spontaneous breaking of U(3) × U(3) applied to the pseudoscalar nonet spectrum is shown to provide evidence for gluons, gluon anomalies and non-trivial topological charge. Solutions of the Ward identities give estimates both of the average topological charge of QCD and the underlying pure Yang-Mills theory of gluons. The application of one of the Ward identities ignored in previous phenomenological analyses leads to a clearer understanding of the decays ψ→ηγ and η'γ, and explains the enhancement of SU(3) breaking effects in these decays.     

Synthesis and structural characterization of cis-Pt(SH)2(PPh3)2 and related alkyl and aryl thiolato complexes

The synthesis and spectroscopic characterization of the complexes cis-Pt(SR)₂(PPh₃)₂ (R = H. Me, n-Bu and Ph) are reported, together with the single crystal X-ray crystallographic characterization of cis-Pt(SH)₂(PPh₃)₂. The ability of these complexes to act as bidentate ligands towards other metal centres is also briefly described.