Francois Serge Nicolas

Development and characterization of a dual-energy subtraction imaging system for chest radiography based on CsI:Tl amorphous silicon flat-panel technology

Dual-energy subtraction imaging increases the sensitivity and specificity of pulmonary nodule detection in chest radiography by reducing the contrast of overlying bone structures. Recent development of a fast, high-efficiency detector enables dual-energy imaging to be integrated into the traditional workflow. We have modified a GE RevolutionTM XQ/i chest imaging system to construct a dual-energy imaging prototype system. Here we describe the operating characteristics of this prototype and evaluate image quality. Empirical results show that the dual-energy CNR is maximized if the dose is approximately equal for both high and low energy exposures. Given the high detector DQE, and allocation of dose between the two views, we can acquire dual-energy PA and conventional lateral images with total dose equivalent to a conventional two-view film chest exam. Calculations have shown that the dual-exposure technique has superior CNR and tissue cancellation than single-exposure CR systems. Clinical images obtained on a prototype dual-energy imaging system show excellent tissue contrast cancellation, low noise, and modest motion artefacts. In summary, a prototype dual-energy system has been constructed which enables rapid, dual-exposure imaging of the chest using a commercially available high-efficiency, flat-panel x-ray detector. The quality of the clinical images generated with this prototype exceeds that of CR techniques and demonstrates the potential for improved detection and characterization of lung disease through dual-energy imaging.

Revisiting the framework of the National Institute on Aging-Alzheimer's Association diagnostic criteria

In 2011, the National Institute on Aging and the Alzheimers Association (NIA‐AA) proposed revising the criteria for diagnosing Alzheimers disease (AD), which had been established more than 25 years earlier by the National Institute on Neurologic and Communicative Disorders and Stroke (NINCDS) and the Alzheimers Disease and Related Disorders Association (ADRDA), now called the Alzheimers Association. The NIA‐AA initiative also built upon research criteria for AD proposed by the International Working Group (IWG) in 2007 and updated in 2010. These efforts to revise the criteria reflect the need to improve diagnostic accuracy, facilitate clinical trials, and establish a common set of criteria that are universally accepted across domains of clinical practice, research, and drug development. To ensure that the proposed NIA‐AA criteria remain as current as possible, the Alzheimers Association Research Roundtable convened a meeting in Washington, DC, on October 1 and 2, 2012, bringing together international stakeholders from industry, academia, and regulatory agencies to identify areas of agreement and research gaps respective of NIA‐AA criteria and IWG recommendations.