Positron emission tomography (PET) is a nuclear imaging technology (also referred to as molecular imaging) that enables visualization of metabolic processes in the body. The basics of PET imaging is that the technique detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (also called radiopharmaceuticals, radionuclides or radiotracer). The tracer is injected into a vein on a biologically active molecule, usually a sugar that is used for cellular energy. PET systems have sensitive detector panels to capture gamma ray emissions from inside the body and use software to plot to triangulate the source of the emissions, creating 3-D computed tomography images of the tracer concentrations within the body.
Indeterminate lesion on PET/CT classified by PET/MRI for 53-y-old man with lung cancer. Contrast-enhanced CT (A), PET (B), and fused 18F-FDG PET/CT (C) images are displayed in comparison with contrast-enhanced T1-weighted MRI (D), PET, and fused 18F-FDG PET/MRI (F) images. In CT (A), hyperdense, subcentimeter liver lesion (arrows) in segment VII is suggestive of transient hepatic attenuation difference or small hemangioma. As malignancy cannot be excluded, it needs further investigation. On PET/MRI, lesion is clearly classified as metastasis because of contrast enhancement and tracer uptake due to later acquisition time point. Follow-up CT confirmed diagnosis after 78 d. Images created by Ole Martin, University Dusseldorf, Medical Faculty and Benedikt Schaarschmidt, University Hospital Essen.
a) Includes scintigraphy and PET with and without concomitant CT. b) Includes conventional radiography, dual-energy x-ray absorptiometry, fluoroscopy, and radiography performed during radiologic interventions. c) Includes general, cardiothoracic, maxillary, plastic, and orthopedic surgery and neurosurgery. d) Includes allergology, cardiology, geriatrics, general internal medicine, pulmonology, gastroenterology, and rheumatology. Image courtesy of American Roentgen Ray Society (ARRS), American Journal of Roentgenology (AJR)
Tau (blue) and amyloid (orange) distribution patterns for super-agers, normal-agers and MCI patients, when compared to a group of younger, healthy, cognitively normal, amyloid-negative individuals. Brain projections are depicted at an uncorrected significance level of p < .0001. Color bars represent the respective t-statistic. Image courtesy of Merle C. Hoenig, Institute for Neuroscience and Medicine II - Molecular Organization of the Brain, Research Center Juelich, Juelich, Germany, and Department of Nuclear Medicine, University Hospital Cologne, Cologne, Germany.
PSMA PET/CT accurately detects recurrent prostate cancer in 67-year-old man. 18F-DCFPyL-PSMA PET/CT shows extensive, intensely PSMA-avid local recurrence in prostate (bottom row; solid arrow) in keeping with the known tumor recurrence in the prostate. Right: PET shows extensive, intensely PSMA-avid local recurrence in prostate (top row; solid arrow) and a solitary bone metastasis in left rib 2 (bottom row; dotted arrow). Image courtesy of Ur Metser, et al.
Total-body dynamic 18F-FDG PET imaging with the uEXPLORER scanner allows us to monitor the spatiotemporal distribution of glucose concentration in metastatic tumors in the entire body (a). As compared to a typical clinical standardized uptake value image (b), the parametric image of FDG influx rate (Ki) can achieve higher lesion-to-background (e.g., the liver) contrast. In addition to glucose metabolism imaging by Ki, total-body dynamic PET also enables multiparametric characterization of tumors and organs using additional physiologically important parameters, for example, glucose transport rate K1 (d), across the entire body. Image courtesy of G.B. Wang, M. Parikh, L. Nardo, et al., University of California Davis, Calif.
Representative maximum-intensity projection PET images of a healthy human volunteer injected with 64Cu-NOTA-EB-RGD at 1, 8, and 24 hours after injection. Axial MRI and PET slices of glioblastoma patient injected with 64Cu-NOTA-EB-RGD at different time points after injection. Image courtesy of Jingjing Zhang et al., Peking Union Medical College Hospital, Beijing, China/ Xiaoyuan Chen et al., Laboratory of Molecular Imaging and Nanomedicine, NIBIB/NIH, Bethesda, USA
PET/CT imaging showing uptake and retention of 86Y-NM600 (imaging agent) in immunocompetent mice bearing prostate tumors. PET imaging data was employed to estimate tumor dosimetry and prescribe an immunomodulatory 90Y-NM600 (therapy agent) injected activity. Image courtesy of R Hernandez et al., University of Wisconsin-Madison, WI.
Adult male with decades of right neck pain, discomfort and tightening following birth injury. The patient had failed multiple standard therapeutic maneuvers before presenting for 18F-FDG PET/MR imaging. Images shows abnormally elevated FDG uptake (white arrows; SUVmax = 1.2) observed in a linear pattern in the space in the posterolateral right neck, between the oblique capitis inferior and the semispinalis capitis muscles, where the greater occipital nerve resides. By comparison, the same region on the contralateral, asymptomatic side of the neck has an SUVmax = 0.7. This result encouraged a surgeon to explore the area. The surgeon ultimately found a collection of small arteries wrapped around the nerve in this location. The small arteries underwent lysis by the surgeon and the patient reported tremendous relief of symptoms. (A) Coronal thick slab MIP of 18F-FDG PET. (B) Axial LAVA FLEX MRI through the cervical spine. (C) Axial PET at the same slice as the axial MRI. (D) Fused axial PET/MRI. Image courtesy of Cipriano, et al., Stanford University, CA.
Left: Total-body PET/CT in psoriatic arthritis: multiple joints affected, shoulders, elbows, wrists, knees, ankles and small joints of the hands/feet. Arrow: left wrist; arrowhead: right wrist. Middle: Total-body PET/CT in rheumatoid arthritis: multiple joints affected, right shoulder, small joints of the left hand. Arrowhead at the 4th proximal interphalangeal joint shows classic ring-like uptake pattern. Arrow on the foot images demonstrates the hammer toe deformity besides big toe arthritis. Right: Total-body PET/CT in osteoarthritis: affected joints include the left elbow, right knee (arrow) and right big toe (arrowhead). Image courtesy of YG Abdelhafez et al., University of California Davis, Sacramento, CA.