Positron Emission Tomography- Computer Tomography (PETCT) with [18F]

Positron Emission Tomography- Computer Tomography (PETCT) with 18F fluoro-2-deoxy-d-glucose (FDG) imaging is a fusion imaging technique that has emerged as a new diagnostic, screening and management tool for anatomical and functional evaluation in breast cancer. This new imaging tool provides valuable insight pertaining accurate lesion detection and localization, lesion characterization, proper staging, and appropriate treatment. 18 F FDG PETCT generally involves two steps. First, a positron emission tomography (PET) is performed. This generates images that are attributed to the three-dimensional radioactivity distribution from annihilation emitted by positron emitter. This mode of imaging allows non-invasive quantitative assessment of biochemical and functional processes. The second part of 18 F FDG PETCT generates computer tomography (CT) images. The produces images by using x-ray beams. As a result, high resolution anatomic and morphological structures are displayed6. Thus, PETCT allows acquisition of functional and morphological imaging in the same setting 7. Besides this advantage, other benefits of PET/CT are lesion detection and characterization. Studies have shown that comparison of between PET and CT alone with hybrid imaging PETCT reveals the later to be more precise or sensitive in terms of accuracy. FDG (Flurodeoxyglucose- a glucose analogue) is the routine tracer used in breast cancer patients . 18 Fluorine is a positron-emitting radionuclide radioactive trace tagged onto FDG9. FDG is transported into cells after intravenous administration. Subsequently, FDG undergoes phosphorylation by hexokinase it remains trapped in cells as FDG-6-phosphate. Hence, cellular glycolytic rate is proportional to accumulation of FDG in cells by reflecting cellular glucose transport and hexokinase activity which is potentially semi-quantitative with standardized uptake value (SUV) 11. The detection of phosphorylated 18F-labeled metabolite by PETCT is the basis of accurate lesion detection and localization, lesion characterization. An important note also should be made to factors that influence FDG uptake for example tumor size and grade. In addition to that certain histological types of breast cancer namely lobular carcinoma have reduced or no FDG uptake12. These are pertinent information that affect the tumour uptake on 18F FDG PETCT and determines the maximum standardize uptake value (SUVmax). It is imperative to distinguish normal and abnormal radiotracer uptake in 18 F FDG PETCT13, 14. Some of the normal or better coined as physiologically increased FDG uptake occurs in brain, heart, brown fat, urinary tract, the intestinal tract and muscles. Abnormal or pathological FDG uptake is demonstrated in malignant cells as there is an increased membrane glucose transporter proteins (notably GLUT1 and GLUT3) and enzymes (intracellular hexokinase and phosphofructokinase) along the glycolytic pathway. In addition to patient preparation, fasting is crucial to promote FDG accumulation in abnormal tissues and reduce competition of blood glucose with FDG