Radiological detection of dissolved cocaine

Introduction: Smuggling dissolved drugs, especially cocaine, in bottled liquids is a problem at borders nowadays. Common fluoroscopy of packages at the border cannot detect contaminated liquids. To find a dissolved drug, an immunological test using a drug-test panel has to be performed. This means that a control sample of the cargo must be opened to perform the test. As it is not possible to open all boxes, and as smugglers hide the drugcontaining boxes between regularly filled boxes, contaminated cargos can be overlooked. Investigators sometimes cannot perform the drug-test panel because they try not to arouse the smugglers' suspicion in order to follow the cargo and to find the recipient. Aims: The objective of our studies was to define non-invasive examination techniques to investigate cargos that are suspicions to contain dissolved cocaine without leaving traces on the samples. We examined vessels containing cocaine by radiological cross-section techniques such as multidetector computed tomography (MDCT) and magnetic resonance spectroscopy (MRS). Methods: In a previous study, we examined bottles of wine containing dissolved cocaine in different quantities using an MDCT unit. To distinguish between bottles containing red wine and those where cocaine was solved in the wine, cross sectional 2D-images have been reconstructed and the absorption of X-rays was quantified by measuring the mean density of the liquid inside the bottles. In our new study, we investigated phantoms containing cocaine dissolved in water with or without ethanol as well as cocaine dissolved in different sorts of commercially available wine by the use of a clinical magnetic resonance unit (3 tesla). To find out if dissolved cocaine could be detected, magnetic resonance spectroscopy (1H MRS) was performed. Results: By using a MDCT-unit and measuring the mean attenuation of X-rays, it is possible to distinguish weather substances are dissolved in a liquid or not, if a comparative liquid without any solutions is available. The increase of the mean density indicates the presence of dissolved substances without the possibility to identify the substance. By using magnetic resonance spectroscopy, dissolved cocaine can be clearly identified because it produces distinctive resonances in the spectrum. In contrast to MDCT, this technique shows a high sensitivity (detection of 1 mM cocaine in wine). Conclusions: Cross-sectional imaging techniques such as MDCT and MRS appropriated to examine cargos that are suspicious to contain dissolved cocaine. They allow to perform non-invasive investigations without leaving any trace on the cargo. While an MDCT scan can detect dissolved substances in liquids, identification of cocaine can be obtained by MR-spectroscopy. Acknowledgment: This work was supported by the Centre d'Imagerie BioMédicale (CIBM) of the University of Lausanne (UNIL), the Swiss Federal Institute of Technology Lausanne (EPFL), the University of Geneva (UniGe), the Centre Hospitalier Universitaire Vaudois (CHUV), the Hôpitaux Universitaire de Genève (HUG) and the Leenaards and the Jeantet Foundations.

Self-similarity properties of natural images resemble those of turbulent flows

We show that the statistics of an edge type variable in natural images exhibits self-similarity properties which resemble those of local energy dissipation in turbulent flows. Our results show that self-similarity and extended self-similarity hold remarkably for the statistics of the local edge variance, and that the very same models can be used to predict all of the associated exponents. These results suggest using natural images as a laboratory for testing more elaborate scaling models of interest for the statistical description of turbulent flows. The properties we have exhibited are relevant for the modeling of the early visual system: They should be included in models designed for the prediction of receptive fields.