Clinical Research Imaging Facility

Rationale and Objectives. The impact of varying image acquisition parameters on the precision of measurements using quantitative computed tomography is currently based on studies performed before the advent of helical image acquisition and multidetector-row scanners. The aim of this study was to evaluate helical multidetector-row quantitative computed tomography to determine the factors contributing to the overall precision of measurements on quantitative computed tomography conducted using current vintage computed tomographic (CT) scanners.

Using positron emission tomography and (18-F)-fluorodeoxyglucose, we studied cerebral glucose metabolism in 10 anorectic girls within their underweight state and after weight gain. Ten age-and sex-matched healthy volunteers were used as controls. Both groups were scanned during rest, eyes closed and with low ambient noise. In absolute values, the underweight anorectic patients, when compared to control subjects, showed a global (p = 0.002) and regional (p <-0.001) hypometabolism of glucose which normalized with weight gain. In relative values, no global difference could be assessed between underweight anorectic patients and controls but a trend can, nevertheless, be observed toward parietal and superior frontal cortex hypometabolism associated with a relative hypermetabolism in the caudate nuclei and in the inferior frontal cortex. After weight gain, all regions normalized for absolute and relative values, although a trend appears toward relative parietal hypometabolism and inferior frontal cortex hypermetabolism in weight gain anorectic patients. Absolute brain glucose hypometabolism might result from neuroendocrinological or morphological aspects of anorexia nervosa or might be the expression of altered neurotransmission following deficient nutritional state. As some differences exists in relative values in underweight patients and tend to persist in weight gain states, this could support a potential abnormal cerebral functioning, a different reaction to starvation within several regions of the brain or different restoration rates according to the region.

Rationale-Human CD34 + cells have been used in clinical trials for treatment of myocardial infarction (MI). However, it is unknown how long the CD34 + cells persist in hearts, whether the improvement in cardiac function is sustained, and what are the underlying mechanisms.

There is an urgent global need for effective and affordable approaches to cervical cancer screening and diagnosis. In developing nations, cervical malignancies remain the leading cause of cancer-related deaths in women. This reality may be difficult to accept given that these deaths are largely preventable; where cervical screening programs have been implemented, cervical cancer-related deaths have decreased dramatically. In developed countries, the challenges of cervical disease stem from high costs and overtreatment. The National Cancer Institute-funded Program Project is evaluating the applicability of optical technologies in cervical cancer. The mandate of the project is to create tools for disease detection and diagnosis that are inexpensive, require minimal expertise, are more accurate than S7 existing modalities, and can be feasibly implemented in a variety of clinical settings. This article presents the status and long-term goals of the project. (Gend Med. 2012;9:S7-S24)

This report describes techniques and protocols imple* mented at the Geneva Canton University Hospitals (HUG) for the combination of various biomedical imaging modalities and sensors including electromagnetic tomography, to study, assess, and Iocalize neurological (dys)function. The interest for this combination stems from the broad variety of information brought out by (functional) magnetic resonance imaging, magnetic resonance spectroscopy, computed tomography, single-photon emission tomography, positron emission tomography, and electromagnetic tomography. Combining these data allows morphology, metabolism, and function to be studied simultaneously, the complementary nature of the information from these modalities becoming evident when studying pathologies reflected by metabolic or electrophysiologic dysfunctions. Compared with other current multimodality approaches, the one at the HUG is totally compatible with both clinical and research protocols, and efficiently addresses the multidimensional registration and visualization issues. It also smoothly integrates electrophysiology and related data as fully featured modalities.

Efforts to develop adenovirus vectors suitable for genetic interventions in humans have identified three major limitations of the most frequently used vector prototype, human adenovirus serotype 5 (Ad5). These limitations-widespread preexisting anti-Ad5 immunity in humans, the high rate of transduction of normal nontarget tissues, and the lack of target-specific gene delivery-justify the exploration of other Ad serotypes as vector prototypes. In this paper, we describe the development of an alternative vector platform using simian Ad serotype 24 (sAd24). We found that sAd24 virions formed unstable complexes with blood coagulation factor X and, because of that, transduced the liver and other organs at low levels when administered intravenously. The overall pattern of biodistribution of sAd24 particles was similar, however, to that of Ad5, and the intravenously injected sAd24 was cleared by Kupffer cells, leading to their depletion. We modified the virus's fiber protein to design a Her2-specific derivative of sAd24 capable of infecting target human tumor cells in vitro. In the presence of neutralizing anti-Ad5 antibodies, Her2mediated infection with targeted sAd24 compared favorably to that with the Ad5-derived vector. When used to target Her2-expressing tumors in animals, this fiber-modified vector achieved a higher level of gene transfer to metastasis-containing murine lungs than to tumor-free lungs. In aggregate, these studies provide important insights into sAd24 biology, identify its advantages and limitations as a vector prototype, and are thus essential for further development of an sAd24-based gene delivery platform.

The recently developed GATE ͑GEANT4 application for tomographic emission͒ Monte Carlo package, designed to simulate positron emission tomography ͑PET͒ and single photon emission computed tomography ͑SPECT͒ scanners, provides the ability to model and account for the effects of photon noncollinearity, off-axis detector penetration, detector size and response, positron range, photon scatter, and patient motion on the resolution and quality of PET images. The objective of this study is to validate a model within GATE of the General Electric ͑GE͒ Advance/Discovery Light Speed ͑LS͒ PET scanner. Our three-dimensional PET simulation model of the scanner consists of 12 096 detectors grouped into blocks, which are grouped into modules as per the vendor's specifications. The GATE results are compared to experimental data obtained in accordance with the National Electrical Manufactures Association/Society of Nuclear Medicine ͑NEMA/SNM͒, NEMA NU 2-1994, and NEMA NU 2-2001 protocols. The respective phantoms are also accurately modeled thus allowing us to simulate the sensitivity, scatter fraction, count rate performance, and spatial resolution. In-house software was developed to produce and analyze sinograms from the simulated data. With our model of the GE Advance/Discovery LS PET scanner, the ratio of the sensitivities with sources radially offset 0 and 10 cm from the scanner's main axis are reproduced to within 1% of measurements. Similarly, the simulated scatter fraction for the NEMA NU 2-2001 phantom agrees to within less than 3% of measured values ͑the measured scatter fractions are 44.8% and 40.9± 1.4% and the simulated scatter fraction is 43.5± 0.3%͒. The simulated count rate curves were made to match the experimental curves by using deadtimes as fit parameters. This resulted in deadtime values of 625 and 332 ns at the Block and Coincidence levels, respectively. The experimental peak true count rate of 139.0 kcps and the peak activity concentration of 21.5 kBq/ cc were matched by the simulated results to within 0.5% and 0.1% respectively. The simulated count rate curves also resulted in a peak NECR of 35.2 kcps at 10.8 kBq/ cc compared to 37.6 kcps at 10.0 kBq/ cc from averaged experimental values. The spatial resolution of the simulated scanner matched the experimental results to within 0.2 mm.

We describe methods and issues that are relevant to the measurement of change in tumor uptake of 18 Ffluorodeoxyglucose (FDG) or other radiotracers, as measured from positron emission tomography/computed tomography (PET/CT) images, and how this would relate to the establishment of PET/CT tumor imaging as a biomarker of patient response to therapy. The primary focus is on the uptake of FDG by lung tumors, but the approach can be applied to diseases other than lung cancer and to tracers other than FDG. The first issue addressed is the sources of bias and variance in the measurement of tumor uptake of FDG, and where there are still gaps in our knowledge. These are discussed in the context of measurement variation and how these would relate to the early detection of response to therapy. Some of the research efforts currently underway to identify the magnitude of some of these sources of error are described. In addition, we describe resources for these investigations that are being made available through the Reference Image Database for the Evaluation of Response project. Measures derived from PET image data that might be predictive of patient response as well as the additional issues that each of these metrics may encounter are described briefly. The relationship between individual patient response to therapy and utility for multicenter trials is discussed. We conclude with a discussion of moving from assessing measurement variation to the steps necessary to establish the efficacy of PET/CT imaging as a biomarker for response.