Neuroimaging is crucial in early and accurate assessment of diagnosis, prognosis, and therapy optimization in patients with declining cognitive abilities. Imaging modalities now available for clinical indications related to neurodegenerative processes include Computed Tomography (CT), MR imaging, and PET imaging with 6 positron-emitting radiotracers approved at this time by the US Food and Drug Administration. The central focus of this article is the role of FDG-PET in clinical and research applications of patients with cognitive problems, and how the derived information may be effectively integrated with information acquired from other neuroimaging modalities.
FDG-PET/CT is central to Lugano-based staging, Deauville-scored response assessment, and prognostication across Hodgkin and non-Hodgkin lymphoma subtypes. Quantitative metrics, particularly total metabolic tumor volume, have emerged as powerful independent prognostic biomarkers. In Hodgkin's lymphoma, interim PET successfully guides treatment de-escalation, while in DLBCL, interim PET remains prognostic but not therapeutically actionable. FDG-PET/Ct is a valuable prognostic biomarker for multi-time point assessment during CAR-T therapy, and guides bridging therapy. More sophisticated PET prognostic and response assessment criteria are emerging in the era of targeted therapies with the help of PET radiomics and deep learning, which needs standardization.
2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG) PET remains widely used in neuro-oncology and provides valuable metabolic information in both adult and pediatric brain tumors. In primary central nervous system lymphomas, it plays an important role in diagnosis, staging, prognostic assessment, and treatment monitoring. In gliomas and other brain tumors, because of the high physiologic uptake in normal brain tissue, particularly in the cortex, tumor-to-background contrast may be reduced. Nevertheless, 18F FDG PET can help to characterize tumor aggressiveness, guide biopsy, and detect residual or recurrent disease.
The introduction of 18F-fluorodeoxyglucose (FDG) to medicine has been revolutionary during the past 5 decades, and its impact rivals that of other technical advances that have been made in medicine during the past century. Therefore, it is timely to celebrate the impact of this unique tracer and its critical role in so many domains of medicine, including the assessment and management of many serious diseases and disorders in the brain but also the entire body. FDG has lived up to the title molecule of the century. With the invention of total body PET instruments, the future looks just as promising.
An expanding body of advanced functional neuroimaging research, particularly using fluorodeoxyglucose (FDG) PET, has sought to characterize the neurologic foundations of consciousness. Investigations have examined a broad spectrum of conscious states, as well as experimental methods for inducing alterations in conscious experience. These states range from typical waking awareness to various stages of sleep, the anesthetized brain, and conditions associated with neurologic or psychiatric disorders such as seizures and schizophrenia. This review describes key findings from these lines of inquiry and discusses the methodological limitations and conceptual challenges in studying consciousness through neuroimaging approaches such as FDG PET.
Precise interpretation of brain PET imaging in both clinical and research settings depends on a well-defined understanding of normal variation, which is complicated by the evolving metabolic pattern of brain activity over the life span as well as the dynamic nature of human mental states. This article reviews important technical and neurophysiological factors that influence what constitutes a normal brain PET scan. It highlights the role of different radiopharmaceuticals in measuring cerebral blood flow, glucose metabolism, and neurotransmitter activity, while emphasizing that baseline cognitive, sensory, and emotional conditions-as well as age-related neurologic changes-significantly affect imaging outcomes.
Fluorodeoxyglucose (FDG) PET is a critical functional imaging modality in modern radiation therapy, enabling improved tumor detection, target delineation, and treatment assessment. This review highlights FDG-PET's role in radiotherapy planning, including integration through image registration, PET/computed tomography simulation, and incorporation of quantitative metrics for segmentation and dose optimization. Emerging applications such as adaptive radiotherapy and dose painting are discussed, along with using FDG-PET to assess treatment response. FDG-PET also provides insight into radiation-induced normal tissue changes and prior treatment fields. Collectively, FDG-PET enhances precision in radiotherapy planning and supports more personalized, response-adaptive treatment strategies.
Fluorodeoxyglucose (FDG)-PET/computed tomography (CT) serves a multifaceted role across nonlymphoma hematolymphoid disorders, though its utility varies considerably by disease entity. In multiple myeloma, FDG-PET/CT is the International Myeloma Working Group-preferred imaging modality for response assessment, with standardized interpretation through Italian Myeloma criteria for PET Use/Deauville criteria enabling reproducible evaluation. PET-based complete metabolic response and dual imaging-plus-minimal residual disease negativity provide the strongest prognostic stratification, validated across landmark trials including CASSIOPEIA and FORTE. Important limitations include nonavid disease and inferior sensitivity for diffuse marrow infiltration compared to WB-MR imaging, where evidence for combined FDG-PET/MR imaging is gathering.
Theranostics, the integration of diagnostic imaging and targeted radionuclide therapy, has transformed oncological practice. While receptor-targeted tracers such as somatostatin receptor PET/computed tomography (CT) and prostate-specific membrane antigen PET/CT anchor most theranostic workflows, 18F-fluorodeoxyglucose (FDG) PET/CT retains an indispensable role across the spectrum of theranostic diseases. FDG PET images glucose metabolism and thereby captures biological information that receptor-targeted tracers cannot. This review synthesizes current evidence, guideline recommendations, and emerging applications, including total-body PET, AI-assisted quantification, radiomics, and novel fibroblast activation protein inhibitor targeted theranostics, to define the evolving position of FDG-PET/CT as a gatekeeper in the theranostic oncological workflow.
Fluorodeoxyglucose positron emission tomography (FDG PET), particularly when fused with computed tomography (CT) or MRI, has become an essential component in the oncologic evaluation of hepatobiliary and pancreatic malignancies. These tumors collectively represent some of the most challenging cancers to diagnose and treat, often presenting at advanced stages with dismal prognosis. FDG PET exploits the upregulated glycolytic activity of tumor cells, offering functional characterization that complements and frequently surpasses the capabilities of anatomical imaging. This review focuses on the value of 18F-FDG PET/CT in the assessment and treatment of hepatobiliary and pancreatic malignancies.
18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) is an important but unevenly useful tool in pediatric oncology. Its clearest role is in lymphoma, especially Hodgkin lymphoma, where metabolic imaging informs staging and response-adapted therapy. In sarcoma, neuroblastoma, CNS tumors, Langerhans cell histiocytosis, germ cell tumors, and Wilms tumor, FDG PET is best used selectively as an adjunct to anatomic imaging, disease-specific tracers, and pathology. This review summarizes practical indications, limitations, pediatric protocol issues, and case-image scenarios in which FDG PET adds clinically meaningful information.
Esophageal and gastric cancers carry high mortality due to late-stage diagnosis, necessitating accurate staging and response assessment. Fluorine-18 fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) integrates metabolic and anatomic imaging, playing a pivotal role in detecting occult metastases, guiding therapy decisions, and assessing early treatment response. It is particularly effective in esophageal cancer and intestinal-type gastric adenocarcinoma, but has limited sensitivity in diffuse and mucinous subtypes. PET/CT enhances radiotherapy planning and distinguishes recurrence from post-treatment changes.
Fluorodeoxyglucose PET/computed tomography plays a central role in the management of melanoma and soft-tissue sarcoma by enabling comprehensive metabolic imaging for staging, response assessment, and prognostication. It improves detection of distant disease and guides clinical decision-making, particularly in advanced stages. Quantitative PET parameters enhance prognostic evaluation, while emerging applications such as radiomics and artificial intelligence are shaping its role in precision oncology. Careful interpretation is required to account for limitations, including false-positive findings and atypical response patterns associated with immunotherapy.
Dedicated breast positron emission imaging modalities including planar positron emission mammography and volumetric ring-type dedicated breast PET represent advanced high-resolution molecular imaging architectures specifically designed to overcome the spatial resolution and sensitivity limitations of conventional whole-body positron emission tomography/computed tomography clinical scanners. Utilizing 2-[18F]fluoro-2-deoxy-D-glucose or emerging receptor-targeted radiopharmaceuticals, these dedicated breast systems provide highly detailed functional cartography of breast tissue with a spatial resolution of 1.5 to 2.4 mm, enabling the detection of subcentimetric primary lesions, intraductal disease components, and separate synchronous malignant foci.
Lung cancer, the most commonly diagnosed malignancy, is the leading cause of cancer-related mortality worldwide. Advancements in molecular imaging have expanded the role of [18F] 2-Fluoro-2-deoxy-glucose (FDG) PET/CT in the management of lung cancer, from the evaluation of pulmonary nodules (including solitary pulmonary nodule) to staging, radiotherapy planning and response evaluation. This review summarizes updates on the utility of FDG PET in non-small-cell lung cancer and expands on the current and future potential of artificial intelligence and radiogenomics in molecular imaging.
