Revolutionary impact of PET and PET-CT on the day-to-day practice of medicine and its great potential for improving future health care

In this communication, we present an overview of the impact and advantages of PET and PET-CT fusion imaging in the practice of medicine. We also discuss the evolution of this promising molecular imaging technique since its inception and the future prospects of the combined structure-function approach. Superior contrast resolution, accurate quantification and above all optimal image quality aid in improved diagnosis of many serious disorders including cancer. We speculate that this powerful imaging approach will almost completely replace most other conventional methods in the future. Currently, 18[F]-fluorode- -oxyglucose (FDG) is the main radiopharmaceutical employed for PET studies around the globe. With the availability of high quality PET images on a routine basis in most centres around the world and the likelihood that several other useful PET tracers will be approved in the near future for routine clinical applications, this technique will likely become essential in almost any medical disorder

Evolving role of PET imaging in assessment of atherosclerosis

Department of Radiology, Perelman School of Medicine, Hospital of the University of Pennsylvania, Philadelphia, USA, The IVth Congress of Radiology and Medical Imaging of the Republic of Moldova with international participation, Chisinau, May 31 – June 2, 2018Background: Atherosclerosis is a major health problem and a leading cause of cardiovascular disease worldwide. The disease frequently coexists in more than one vascular bed and the clinical outcome and therapeutic options are largely dependent on early diagnosis. Content: Atherosclerosis represents a dynamic inflammatory process, therefore many principles of diagnostic imaging studies can be directed at the biological composition and inflammatory state of atherosclerotic lesions. FDG-PET/CT holds great potential in the diagnostic work-up of atherosclerosis, by enabling both functional imaging reflecting the inflammatory activity within the atherosclerotic plaques and structural whole-body imaging reflecting local arterial wall thickening and the degree of arterial stenosis. Functional imaging becomes especially relevant knowing that vascular FDG uptake and calcification do not overlap significantly. Studies also show that FDG PET may be useful in evaluating and individualizing therapeutic interventions as the arterial FDG activity attenuates after administration of lipidlowering medication or life style interventions. The presentation provides a brief overview of animal and clinical studies illustrated with relevant images on this topic. Conclusion: Data from both animal and human studies show that FDG-PET has great potential for assessing large artery atherosclerosis and evaluating the effect of therapeutic interventions. However, new studies are needed for further validation and standardization of imaging protocols before FDG-PET imaging of atherosclerosis can be adopted in clinical practice

Unparalleled contributions of FDG-PET imaging to medicine over the past 4 decades

Department of Radiology, Perelman School of Medicine, Hospital of the University of Pennsylvania, Philadelphia, USA, The IVth Congress of Radiology and Medical Imaging of the Republic of Moldova with international participation, Chisinau, May 31 – June 2, 2018Background: Positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) is currently one of the most widely used imaging modalities. Both the technology and the radiopharmaceutical were conceived in the 1970s, facing a variety of challenges. Nowadays, a variety of PET techniques using partial volume correction and segmentation allow accurate quantification of metabolic activity in different tissues of the human body in normal and disease states. Content: The presentation reviews the long journey of FDG-PET from its origin up to date with a large number of case illustrations, including the first images obtained personally while working on developing the modality in the 1970’s. A brief summary of the imaging equipment and its evolution as well as the main contributions of FDG-PET imaging to medical practice and research activities are also discussed. Conclusion: FDG-PET-CT imaging has had a substantial impact on research and on the day to day practice of medicine. This has resulted in minimizing pain and suffering for millions of patients and in reducing the cost of health care worldwide

Evolving role of FDG-PET in detecting and characterizing infectious and inflammatory disorders

Department of Radiology, Perelman School of Medicine, Hospital of the University of Pennsylvania, Philadelphia, USA, The IVth Congress of Radiology and Medical Imaging of the Republic of Moldova with international participation, Chisinau, May 31 – June 2, 2018Background: Because of its ability to quantify the rate of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) uptake, FDG PET/CT can provide valuable information related to the degree of inflammatory activity, its location and extension even before morphological changes may become evident. It is not surprising that the modality is being used as a diagnostic tool in a variety of infectious and inflammatory disorders. Content: Due to its high sensitivity and whole-body approach, FDG PET has been used for detecting culprit lesions and/or evaluation of disease activity in systemic infections and inflammations, fever of unknown origin, chronic osteomyelitis, prosthetic joint infections, vasculitis, spinal infections, diabetic foot infections, inflammatory bowel disease (IBD), degenerative joint disease, active granulomatous diseases such as sarcoidosis, as well as in a variety of non-infectious/inflammatory or proliferative conditions such as radiation pneumonitis and post-lung transplant lymphoproliferative disorders. Novel PET radiopharmaceuticals for imaging infection and inflammation tracers are also being tested. The presentation reviews the current state of this very important application of FDG-PET imaging. Relevant FDG PET/CT and PET/MRI images showing the pattern of FDG uptake in common infectious and inflammatory disorders are also provided. Conclusion: FDG-PET/CT imaging represents a perspective modality for evaluation of infectious and inflammatory disorders that can provide valuable information in the appropriate clinical setting

What can and what cannot be accomplished with PET: clarifying ongoing misconceptions

Department of Radiology, Perelman School of Medicine, Hospital of the University of Pennsylvania, Philadelphia, USA, The IVth Congress of Radiology and Medical Imaging of the Republic of Moldova with international participation, Chisinau, May 31 – June 2, 2018Background: The introduction of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) in 1976 as a joint effort of the University of Pennsylvania and Brookhaven National Laboratory opened new perspectives in medical imaging. Although FDG PET/CT has become a unique cornerstone of molecular imaging and one of the most widely used imaging modalities, familiarity with its limitations is of paramount importance for avoiding unnecessary examinations. Content: FDG PET and PET/CT are now widely used in many oncologic diseases for tumor staging/re-staging and monitoring of disease activity as well as for evaluating the response to administered therapy. However, FDG is a nonspecific tracer and can also accumulate at the sites of many benign processes. Even though dual time-point imaging of FDG PET may be helpful in differentiating malignant from benign processes, exceptions exist, and some authors have even demonstrated significant overlap of FDG uptake patterns in malignant and benign lesions. A variety of other PET radiopharmaceuticals such as FLT, 60Cu-ATSM, 18F-EF5, 18F-FMISO, FIAU, FHBG, FHPG, 11C-Acetate, 18F-Fuoride, 94mTc-MIBI, 18F or 11C -labeled Choline are increasingly being used in various disorders and their area of clinical applications is expanding. In this context, the lecture is also approaching various controversial domains such as PET applications for imaging islets in pancreas, detecting plaques and tangles in Alzheimer’s disease or bacteria at sites of infection. Last, but not least, the presentation provides a brief summary related to novel quantitative techniques such as partial volume correction and global disease assessment. Conclusion: At the end of the lecture attendees would expand their knowledge about what can and what cannot be accomplished with FDG PET/CT imaging

Achievements and beyond: Scientific trajectory of Professor Mohammad A. Rafi

This biography highlights the scientific trajectory of Professor Mohammad A. Rafi, Ph.D., who, in particular, has greatly advanced the field of neurodegenerative disorders during his long and successful tenure at Jefferson Medical College, Thomas Jefferson University. This Editorial recognizes, above all, Professor Rafi's significant contributions to the study of lysosomal storage disorders as they relate to Krabbe Disease

Regional differences in the coupling between resting cerebral blood flow and metabolism may indicate action preparedness as a default state.

Although most functional neuroimaging studies examine task effects, interest intensifies in the "default" resting brain. Resting conditions show consistent regional activity, yet oxygen extraction fraction constancy across regions. We compared resting cerebral metabolic rates of glucose (CMRgl) measured with 18F-labeled 2-fluoro-2-deoxy-D-glucose to cerebral blood flow (CBF) 15O-H2O measures, using the same positron emission tomography scanner in 2 samples (n = 60 and 30) of healthy right-handed adults. Region to whole-brain ratios were calculated for 35 standard regions of interest, and compared between CBF and CMRgl to determine perfusion relative to metabolism. Primary visual and auditory areas showed coupling between CBF and CMRgl, limbic and subcortical regions--basal ganglia, thalamus and posterior fossa structures--were hyperperfused, whereas association cortices were hypoperfused. Hyperperfusion was higher in left than right hemisphere for most cortical and subcallosal limbic regions, but symmetric in cingulate, basal ganglia and somatomotor regions. Hyperperfused regions are perhaps those where activation is anticipated at short notice, whereas downstream cortical modulatory regions have longer "lead times" for deployment. The novel observation of systematic uncoupling of CBF and CMRgl may help elucidate the potential biological significance of the "default" resting state. Whether greater left hemispheric hyperperfusion reflects lateral dominance needs further examination

Atherosclerosis imaging with 18F-sodium fluoride PET: state-of-the-art review

Purpose: We examined the literature to elucidate the role of 18F-sodium fluoride (NaF)-PET in atherosclerosis. Methods: Following a systematic search of PubMed/MEDLINE, Embase, and Cochrane Library included articles underwent subjective quality assessment with categories low, medium, and high. Of 2811 records, 1780 remained after removal of duplicates. Screening by title and abstract left 41 potentially eligible full-text articles, of which 8 (about the aortic valve (n = 1), PET/MRI feasibility (n = 1), aortic aneurysms (n = 1), or quantification methodology (n = 5)) were dismissed, leaving 33 published 2010-2012 (n = 6), 2013-2015 (n = 11), and 2016-2018 (n = 16) for analysis. Results: They focused on coronary (n = 8), carotid (n = 7), and femoral arteries (n = 1), thoracic aorta (n = 1), and infrarenal aorta (n = 1). The remaining 15 studies examined more than one arterial segment. The literature was heterogeneous: few studies were designed to investigate atherosclerosis, 13 were retrospective, 9 applied both FDG and NaF as tracers, 24 NaF only. Subjective quality was low in one, medium in 13, and high in 19 studies. The literature indicates that NaF is a very specific tracer that mimics active arterial wall microcalcification, which is positively associated with cardiovascular risk. Arterial NaF uptake often presents before CT-calcification, tends to decrease with increasing density of CT-calcification, and appears, rather than FDG-avid foci, to progress to CT-calcification. It is mainly surface localized, increases with age with a wide scatter but without an obvious sex difference. NaF-avid microcalcification can occur in fatty streaks, but the degree of progression to CT-calcification is unknown. It remains unknown whether medical therapy influences microcalcification. The literature held no therapeutic or randomized controlled trials. Conclusion: The literature was heterogeneous and with few clear cut messages. NaF-PET is a new approach to detect and quantify microcalcification in early-stage atherosclerosis. NaF uptake correlates with cardiovascular risk factors and appears to be a good measure of the body's atherosclerotic burden, potentially suited also for assessment of anti-atherosclerotic therapy

Facts and Fictions About [18F]FDG versus Other Tracers in Managing Patients with Brain Tumors: It Is Time to Rectify the Ongoing Misconceptions.

peer reviewedMRI is the first-choice imaging technique for brain tumors. Positron emission tomography can be combined together with multiparametric MRI to increase diagnostic confidence. Radiolabeled amino acids have gained wide clinical acceptance. The reported pooled specificity of [18F]FDG positron emission tomography is high and [18F]FDG might still be the first-choice positron emission tomography tracer in cases of World Health Organization grade 3 to 4 gliomas or [18F]FDG-avid tumors, avoiding the use of more expensive and less available radiolabeled amino acids. The present review discusses the additional value of positron emission tomography with a focus on [18F]FDG and radiolabeled amino acids