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.
IMAGE OF THE YEAR: PSMA PET before and after lutetium-177 PSMA617 theranostics in 8 patients with metastatic prostate cancer who exhausted standard therapeutic options.
68Ga-PSMA11 PET maximum intensity projection (MIP) images at baseline and 3 months after 177Lu-PSMA617 in 8 patients with PSA decline ≥ 98 percent in a prospective phase II study. Any disease with SUV over 3 is in red. Credit: Michael Hofman, John Violet, Shahneen Sandhu, Justin Ferdinandus, Amir Iravani, Grace Kong, Aravind Ravi Kumar, Tim Akhurst, Sue Ping Thang, Price Jackson, Mark Scalzo, Scott Williams and Rodney Hicks, Peter MacCallum Cancer Centre, Melbourne, Australia.
Nuclear imaging scan showing very good tissue delineation. It offers crisp overall image quality and sharply delineates the muscle and fat planes, vertebral margins and end plates, billiary radicals, renal calyces, aortic wall and papillary muscles of the heart. Scan performed on a Biograph Vision positron emission tomography/computed tomography (PET-CT) system from Siemens Healthineers.
Coronal 18F-FEDAC PET/CT section of a mouse with collagen-induced arthritis. (A) On day 23 and day 37, increased uptake is noted in the front and hind paws of this mouse with collagen-induced arthritis. (B) Predictive performance of day 23 18F-FEDAC uptake for the development of clinical arthritis. ROC = receiver operating characteristic; Sn = sensitivity; Sp = specificity. Credit: Seoul National University and Ewha Womans University, Seoul, South Korea
In scans of a 62-yr-old man with Gleason 4+3 PCa treated with radical prostatectomy, with rising PSA level (1.32) and PSA doubling time of 3.7 months, 64CuCl2-PET/CT images revealed 2 positive small left iliac lymph nodes (A,C), whereas 18F-Choline PET/CT (B,D) was negative (arrows). Image courtesy of A Piccardo et al., Galliera Hospital, Genoa, Italy.
68Ga-PSMA PET/CT images showing multifocal PCA in peripheral zone with GS of 5 1 5 5 10. (A and C) Axial PET images. (B and D) Fused PET/CT images. SUVmax of lesion in B was 84.3 and that of lesion in D was 5.7. IRS was 3, and 80% of cells were stained. Credit: Senior author V Prasad, Charité Universitätsmedizin Berlin, Berlin, Germany.
Representative PET/CT images of 18F-FDS and 18F-FDG in inflamed mice. Mice were inoculated with dead K. pneumoniae (10^8 CFU/mL). Imaging was performed for days 1, 2, 3 and 4 using 18F-FDG and 18F-FDS. CT images showed clear inflammation on day 2 and day 3 with corresponding high 18F-FDG uptake on PET. No significant uptake of 18F-FDS was detected for any of those 4 days. Credit: J Li et al., University of Louisville School of Medicine, Louisville, Ky.