Page 13 - 18F-FDG PET as biomarker in aggressive lymphoma; technical and clinical validation

75 years old in the Netherlands in population based data [3]. Patients with a relapse or progression after first-line therapy with R-CHOP often have a poor response to second-line treatment [12-14]. Theoretically, it might be relevant to early identify the non-responders to maximize their chances of a successful second-line treatment and minimize side-effects of less effective first-line therapy.
Positron emission tomography
Positron emission tomography (PET) combined with computed tomography (CT) scan (together PET/CT) was announced as medical invention of the year 2000 by Time Magazine. PET/CT is a non-invasive imaging technique that provides visual and quantitative information on physiological and pathological processes in the body. A radioactive tracer is needed to visualize and quantify a specific process. 18F-fluoro-2-deoxy-D-glucose ([18F]FDG) is a radiolabelled glucose analogue and this tracer is nowadays widely used in the clinic for several malignancies known to show high glucose metabolism, resulting in high [18F]FDG uptake [15]. These areas with high [18F]FDG uptake can be either physiological tissues using glucose (e.g. brain), tissues involved in the elimination process of [18F]FDG (e.g. kidney and bladder) and tissues with pathologically increased use of glucose (e.g. malignant tissues such as lymphoma) [16]. The combination with a CT scan is needed for attenuation and scatter correction and adds information about the anatomical location of the increased [18F]FDG uptake. Nowadays [18F]FDG PET/CT is used for both staging (i.e. to assess the extent of a certain malignancy) before treatment and response assessment after treatment.
The role of PET in lymphoma
Staging
Staging of lymphoma was originally based on symptoms, physical examination, radiological studies, laboratory tests of urine and blood and initial biopsy results. Acknowledging the importance of reproducible results from one center to another, the Ann Arbor classification system, consisting of 4 clinical stages, was developed in 1971 for HL [17], but later also adopted for NHL. During the Cotswolds meeting in 1988 the staging system was modified with the addition
General introduction
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