Positron Emission Tomography and Computer Tomography (PET/CT) in Prostate, Bladder, and Testicular Cancers.

Positron emission computed tomography (PET) is a functional, noninvasive method for imaging regional metabolic processes that is nowadays most often combined to morphological imaging with computed tomography (CT). Its use is based on the well-founded assumption that metabolic changes occur earlier in tumors than morphologic changes, adding another dimension to imaging. This article will review the established and investigational indications and radiopharmaceuticals for PET/CT imaging for prostate cancer, bladder cancer and testicular cancer, before presenting upcoming applications in radiation therapy.

MRS glucose mapping and PET joining forces: re-evaluation of the lumped constant in the rat brain under isoflurane anaesthesia.

Although numerous positron emission tomography (PET) studies with (18) F-fluoro-deoxyglucose (FDG) have reported quantitative results on cerebral glucose kinetics and consumption, there is a large variation between the absolute values found in the literature. One of the underlying causes is the inconsistent use of the lumped constants (LCs), the derivation of which is often based on multiple assumptions that render absolute numbers imprecise and errors hard to quantify. We combined a kinetic FDG-PET study with magnetic resonance spectroscopic imaging (MRSI) of glucose dynamics in Sprague-Dawley rats to obtain a more comprehensive view of brain glucose kinetics and determine a reliable value for the LC under isoflurane anaesthesia. Maps of Tmax /CMRglc derived from MRSI data and Tmax determined from PET kinetic modelling allowed to obtain an LC-independent CMRglc . The LC was estimated to range from 0.33 ± 0.07 in retrosplenial cortex to 0.44 ± 0.05 in hippocampus, yielding CMRglc between 62 ± 14 and 54 ± 11 μmol/min/100 g, respectively. These newly determined LCs for four distinct areas in the rat brain under isoflurane anaesthesia provide means of comparing the growing amount of FDG-PET data available from translational studies.

Improving breast cancer education: the case of an evolving multidisciplinary module for undergraduate medical students (lausanne medical school, 1993-2008).

Breast cancer is a public health issue in numerous countries. Multidisciplinary collaboration is required for patient care, research, and also education of future physicians. This paper uses Kern's framework for curriculum design to demonstrate how a breast diseases module for undergraduate medical students created in 1993 evolved over 15 years. The main outcomes of program refinements were better integrated course content, the development of electronic course documents, and implementation of computer-aided small group learning. A main future challenge is to further develop efficient instructional strategies in line with well-defined learning needs for undergraduate students.

Generative FDG-PET and MRI model of aging and disease progression in Alzheimer's disease.

The failure of current strategies to provide an explanation for controversial findings on the pattern of pathophysiological changes in Alzheimer's Disease (AD) motivates the necessity to develop new integrative approaches based on multi-modal neuroimaging data that captures various aspects of disease pathology. Previous studies using [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) and structural magnetic resonance imaging (sMRI) report controversial results about time-line, spatial extent and magnitude of glucose hypometabolism and atrophy in AD that depend on clinical and demographic characteristics of the studied populations. Here, we provide and validate at a group level a generative anatomical model of glucose hypo-metabolism and atrophy progression in AD based on FDG-PET and sMRI data of 80 patients and 79 healthy controls to describe expected age and symptom severity related changes in AD relative to a baseline provided by healthy aging. We demonstrate a high level of anatomical accuracy for both modalities yielding strongly age- and symptom-severity- dependant glucose hypometabolism in temporal, parietal and precuneal regions and a more extensive network of atrophy in hippocampal, temporal, parietal, occipital and posterior caudate regions. The model suggests greater and more consistent changes in FDG-PET compared to sMRI at earlier and the inversion of this pattern at more advanced AD stages. Our model describes, integrates and predicts characteristic patterns of AD related pathology, uncontaminated by normal age effects, derived from multi-modal data. It further provides an integrative explanation for findings suggesting a dissociation between early- and late-onset AD. The generative model offers a basis for further development of individualized biomarkers allowing accurate early diagnosis and treatment evaluation.

Prostate cancer: F-18-fluorocholine PET-CT utility. [Cancer de la prostate : utilité de la TEP-TDM à la 18F-fluorocholine.]

In oncology, positron emission computed tomography (PET/CT) has become an essential tool for initial staging, response evaluation and follow-up of cancer patients. Most of the frequent tumors (lung, breast, esophagus, and lymphomas) are highly avid for (18)F-fluorodeoxyglucose ((18)FDG), but prostate cancer has not demonstrated significant uptake of FDG. The development of new tracers labeled with (18)F such as choline analogs allowed already to obtain interesting results particularly in patients with biological relapse and inconclusive conventional imaging workup. The impact of (18)F-flurocholine PET/CT on patient management needs to be validated in large studies, but many centers use already this examination in order to guide further management, including radiotherapy planning. (C) 2011 Elsevier Masson SAS. All rights reserved.

Quantification of Myocardial Blood Flow in Absolute Terms Using (82)Rb PET Imaging: The RUBY-10 Study.

OBJECTIVES: The purpose of this study was to compare myocardial blood flow (MBF) and myocardial flow reserve (MFR) estimates from rubidium-82 positron emission tomography ((82)Rb PET) data using 10 software packages (SPs) based on 8 tracer kinetic models. BACKGROUND: It is unknown how MBF and MFR values from existing SPs agree for (82)Rb PET. METHODS: Rest and stress (82)Rb PET scans of 48 patients with suspected or known coronary artery disease were analyzed in 10 centers. Each center used 1 of 10 SPs to analyze global and regional MBF using the different kinetic models implemented. Values were considered to agree if they simultaneously had an intraclass correlation coefficient >0.75 and a difference <20% of the median across all programs. RESULTS: The most common model evaluated was the Ottawa Heart Institute 1-tissue compartment model (OHI-1-TCM). MBF values from 7 of 8 SPs implementing this model agreed best. Values from 2 other models (alternative 1-TCM and Axially distributed) also agreed well, with occasional differences. The MBF results from other models (e.g., 2-TCM and retention) were less in agreement with values from OHI-1-TCM. CONCLUSIONS: SPs using the most common kinetic model-OHI-1-TCM-provided consistent results in measuring global and regional MBF values, suggesting that they may be used interchangeably to process data acquired with a common imaging protocol.

Évaluation de la perfusion myocardique par TEP-TDM. [Myocardial perfusion imaging using PET/CT.]

For the past decade, PET and PET/CT have been widely studied for myocardial perfusion imaging. Several studies demonstrated the incremental value of PET for the diagnostic and prognostic assessment of patients with coronary artery disease. Moreover, PET allows for non-invasively quantifying myocardial blood flow and myocardial flow reserve, that both are recognized as surrogate marker of cardiac event free survival. By enabling the exploration of epicardial disease and the microvasculature, PET constitutes a unique tool to study pathophysiogical mechanisms leading to atherosclerosis genesis. The recent emergence of high-tech hybrid machines may even provide further incremental information about coronary function and morphology. By taking the best of each modality, a better assessment of patients with coronary artery disease is expected. (C) 2011 Elsevier Masson SAS. All rights reserved.

An international validation study of the EORTC brain cancer module (EORTC QLQ-BN20) for assessing health-related quality of life and symptoms in brain cancer patients.

Aims: The psychometric properties of the EORTC QLQ-BN20, a brain cancer-specific HRQOL questionnaire, have been previously determined in an English-speaking sample of patients. This study examined the validity and reliability of the questionnaire in a multi-national, multi-lingual study. Methods: QLQ-BN20 data were selected from two completed phase III EORTC/NCIC clinical trials in brain cancer (N=891), including 12 languages. Experimental treatments were surgery followed by radiotherapy (RT) and adjuvant PCV chemotherapy or surgery followed by concomitant RT plus temozolomide (TMZ) chemotherapy and adjuvant TMZ chemotherapy. Standard treatment consisted of surgery and postoperative RT alone. The psychometrics of the QLQ-BN20 were examined by means of multi-trait scaling analyses, reliability estimation, known groups validity testing, and responsiveness analysis. Results: All QLQ-BN20 items correlated more strongly with their own scale (r>0.70) than with other QLQ-BN20 scales. Internal consistency reliability coefficients were high (all alpha0.70). Known-groups comparisons yielded positive results, with the QLQ-BN20 distinguishing between patients with differing levels of performance status and mental functioning. Responsiveness of the questionnaire to changes over time was acceptable. Conclusion: The QLQ-BN20 demonstrates adequate psychometric properties and can be recommended for use in conjunction with the QLQ-C30 in assessing the HRQOL of brain cancer patients in international studies.

TEP/TDM en radiothérapie : indications et perspectives [PET/CT and radiotherapy: indications and potential applications].

The implementation of new techniques of imaging in the daily practice of the radiation oncologist is a major advance in these last 10 years. This allows optimizing the therapeutic intervals and locoregional control of the disease while limiting side effects. Among them, positron emission tomography (PET) offers an opportunity to the clinician to obtain data relative to the tumoral biological mechanisms, while benefiting from the morphological images of the computed tomography (CT) scan. Recently hybrid PET/CT has been developed and numerous studies aimed at optimizing its use in the planning, the evaluation of the treatment response and the prognostic value. The choice of the radiotracer (according to the type of cancer and to the studied biological mechanism) and the various methods of tumoral delineation, require a regular update to optimize the practices. We propose throughout this article, an exhaustive review of the published researches (and in process of publication) until December 2011, as user guide of PET/CT in all the aspects of the modern radiotherapy (from the diagnosis to the follow-up): biopsy guiding, optimization of treatment planning and dosimetry, evaluation of tumor response and prognostic value, follow-up and early detection of recurrence versus tumoral necrosis. In a didactic purpose, each of these aspects is approached by primary tumoral location, and illustrated with representative iconographic examples. The current contribution of PET/CT and its perspectives of development are described to offer to the radiation oncologist a clear and up to date reading in this expanding domain.

Peritoneal Carcinomatosis in Primary Ovarian Cancer Staging: Comparison Between MDCT, MRI, and 18F-FDG PET/CT.

PURPOSE: The aim of this study was to compare multidetector CT (MDCT), MRI, and FDG PET/CT imaging for the detection of peritoneal carcinomatosis (PC) in ovarian cancer. PATIENTS AND METHODS: Fifteen women with ovarian cancer and suspected PC underwent MDCT, MRI, and FDG PET/CT, shortly before surgery. Nine abdominopelvic regions were defined according to the peritoneal cancer index. We applied lesion size scores on MDCT and MR and measured FDG PET/CT standard uptake. We blindly read MDCT, MR, and PET/CT before joint review and comparison with histopathology. Receiver operating characteristics analysis was performed. RESULTS: Ten women had PC (67%). Altogether, 135 abdominopelvic sites were compared. Multidetector CT, MRI, and FDG PET/CT had a sensitivity of 96%, 98%, and 95%, and specificity was 92%, 84%, and 96%, respectively. Corresponding receiver operating characteristics area was 0.94, 0.90, and 0.96, respectively, without any significant differences between them (P = 0.12). FDG PET/CT detected supradiaphragmatic disease in 3 women (20%) not seen by MDCT or MRI. CONCLUSIONS: Although MRI had the highest sensitivity and FDG PET/CT had the highest specificity, no significant differences were found between the 3 techniques. Thus, MDCT, as the fastest, most economical, and most widely available modality, is the examination of choice, if a stand-alone technique is required. If inconclusive, PET/CT or MRI may offer additional insights. Whole-body FDG PET/CT may be more accurate for supradiaphragmatic metastatic extension.

The activity of the anti-apoptotic fragment generated by the caspase-3/p120 RasGAP stress-sensing module displays strict Akt isoform specificity.

The caspase-3/p120 RasGAP module acts as a stress sensor that promotes pro-survival or pro-death signaling depending on the intensity and the duration of the stressful stimuli. Partial cleavage of p120 RasGAP generates a fragment, called fragment N, which protects stressed cells by activating Akt signaling. Akt family members regulate many cellular processes including proliferation, inhibition of apoptosis and metabolism. These cellular processes are regulated by three distinct Akt isoforms: Akt1, Akt2 and Akt3. However, which of these isoforms are required for fragment N mediated protection have not been defined. In this study, we investigated the individual contribution of each isoform in fragment N-mediated cell protection against Fas ligand induced cell death. To this end, DLD1 and HCT116 isogenic cell lines lacking specific Akt isoforms were used. It was found that fragment N could activate Akt1 and Akt2 but that only the former could mediate the protective activity of the RasGAP-derived fragment. Even overexpression of Akt2 or Akt3 could not rescue the inability of fragment N to protect cells lacking Akt1. These results demonstrate a strict Akt isoform requirement for the anti-apoptotic activity of fragment N.

Eye lens monitoring for interventional radiology personnel: dosemeters, calibration and practical aspects of H p (3) monitoring. A 2015 review.

A thorough literature review about the current situation on the implementation of eye lens monitoring has been performed in order to provide recommendations regarding dosemeter types, calibration procedures and practical aspects of eye lens monitoring for interventional radiology personnel. Most relevant data and recommendations from about 100 papers have been analysed and classified in the following topics: challenges of today in eye lens monitoring; conversion coefficients, phantoms and calibration procedures for eye lens dose evaluation; correction factors and dosemeters for eye lens dose measurements; dosemeter position and influence of protective devices. The major findings of the review can be summarised as follows: the recommended operational quantity for the eye lens monitoring is H p (3). At present, several dosemeters are available for eye lens monitoring and calibration procedures are being developed. However, in practice, very often, alternative methods are used to assess the dose to the eye lens. A summary of correction factors found in the literature for the assessment of the eye lens dose is provided. These factors can give an estimation of the eye lens dose when alternative methods, such as the use of a whole body dosemeter, are used. A wide range of values is found, thus indicating the large uncertainty associated with these simplified methods. Reduction factors from most common protective devices obtained experimentally and using Monte Carlo calculations are presented. The paper concludes that the use of a dosemeter placed at collar level outside the lead apron can provide a useful first estimate of the eye lens exposure. However, for workplaces with estimated annual equivalent dose to the eye lens close to the dose limit, specific eye lens monitoring should be performed. Finally, training of the involved medical staff on the risks of ionising radiation for the eye lens and on the correct use of protective systems is strongly recommended.

Gamma oscillations in V1 are correlated with GABAA receptor density: A multi-modal MEG and Flumazenil-PET study.

High-frequency oscillations in the gamma-band reflect rhythmic synchronization of spike timing in active neural networks. The modulation of gamma oscillations is a widely established mechanism in a variety of neurobiological processes, yet its neurochemical basis is not fully understood. Modeling, in-vitro and in-vivo animal studies suggest that gamma oscillation properties depend on GABAergic inhibition. In humans, search for evidence linking total GABA concentration to gamma oscillations has led to promising -but also to partly diverging- observations. Here, we provide the first evidence of a direct relationship between the density of GABAA receptors and gamma oscillatory gamma responses in human primary visual cortex (V1). By combining Flumazenil-PET (to measure resting-levels of GABAA receptor density) and MEG (to measure visually-induced gamma oscillations), we found that GABAA receptor densities correlated positively with the frequency and negatively with amplitude of visually-induced gamma oscillations in V1. Our findings demonstrate that gamma-band response profiles of primary visual cortex across healthy individuals are shaped by GABAA-receptor-mediated inhibitory neurotransmission. These results bridge the gap with in-vitro and animal studies and may have future clinical implications given that altered GABAergic function, including dysregulation of GABAA receptors, has been related to psychiatric disorders including schizophrenia and depression.