What is Molecular Imaging ?
Molecular imaging is measuring, characterization and imaging of biological funtions of organisms at cellular level. Conventional methods like computarized tomography and magnetic rezonance imaging can supply information on anatomical and morphological situations besides positron emission tomography and single photon emission computarized tomography can supply information about functional and phenotypical gradients of pathological situations due to radioisotope using.
What is Positron Emiting Tomography ?
Radiological imaging methods like computarized tomography, magnetic resonance or ultrasonography are used in detecting structural changes in normal anatomy. On the other hand detecting structural changes with proper details is not sufficient to solve clinical situations. Usually, biochemical changes appear before anatomical changes in diseased tissues. For example, considering each nodule detected by computarized tomography as methastatic improve in lung cancer disease brings failure and hardens monitoring disease. Since, not also malign diseases but also benign diseases can cause nodule generations. Cases that anatomical imaging is insufficient to enlight the situation requires funtional imaging to show biochemical changes and characterize in diseased tissues. Positron emission tomography is the most sophisticated imaging method to show biochemical and metabolic changes for supplying functional information among imaging methods in nuclear medicine. PET and CT combined PET are most complicated methods since they created structural and functional information together and most useful methods to evaluate and monitoring cardiology, neurology and oncology at patient management of diagnosis and therapy in disease based and patient based cases.
What is (18F)FDG-PET Scanning ?
Radionuclids that used in PET are low atom numbered and short half lived elements. Primary positron emitters are; carbon (11C), nitrogen (13N), oxygen (15O) ve florine (18F). All these elements are ingradients of the cellular membrane and short lived. E.g. 15O 2min 13N and 11C are 20 min. 18F is relatively long half life element among others since it is most preferable in routine studies. 2-deoxy-D-glucose is created as a chemotherapeutical agent to inhibit glucose uptake by tumor cells in 1960 and it illuminates metabolic steps of glucose use in cellular level. After that, first FDG sythesized to evaluate cerebral glucose mechanism in 1976. First PET brain scanning has conducted following years. PET scan with positron emitting agent allows measuring invivo glucose metabolism. (18F)-FDG is a glucose analogue. It is uptaken like glucose, kept in cell like glucose as well but it is relatively low metabolising capability than glucose. Thats why disturbed changes in keeping FDG reflects pathological situations like cancer and it supplies chance to evaluate process of abnormal glucose metabolism. First FDG-PET scan conducted in 1976 after fisrt sythesis in 1970. It has started to use in early 80’s and widely accepted primarily in Europe. Recently there is huge experience on FDG using.
Which Cases (18F)FDG-PET Scan Used in ?
(18F)FDG-PET Scan is used following cases due to show abnormal glucose metabolism;
Oncology: cancer cases, cancer suspicious cases, benign/malign dinstictive diagnosis of lesions monitoring of disease and monitoring of therapeutical progress of disease.
Cardiology: Determination of myocardial viability and metabolism before revascularization surgery in patients with impaired left ventricular function,
Neurology: Differential diagnosis of epileptogenic foci by demonstrating interstitial glucose hypometabolism before surgery and differential diagnosis of dementia of Alzheimer type from other dementias
Infection: Detection of unknown fever and infection foci.