Imaging of Extranodal Lymphoma With PET/CT

Abstract

Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL) represent a spectrum of malignant neoplasms arising from the lymphoid system with an incidence of around 8% of all malignancies. Although they are generally known as tumors of lymph nodes, 25% to 40% of HD/NHL tumors, especially NHL, arise at extranodal sites along the gastrointestinal tract, head and neck, orbit, central and peripheral nervous system, thorax, bone, skin, breast, testis, thyroid, and genitourinary tract. Extranodal involvement is an important pretreatment prognostic factor for patients with lymphoma and its incidence has increased in the past 2 decades. Imaging plays an important role in the noninvasive pretreatment assessment of patients with extranodal lymphoma. This involvement can be subtle and may be overlooked during computed tomography (CT). Positron emission tomography/CT (PET/CT) has evolved into an important imaging tool for evaluation of lymphomas, facilitating the detection of affected extranodal sites even when CT shows subtle or no obvious lesions. Familiarity with extranodal manifestations and suggestive PET/CT features in different sites is important for accurate evaluation of lymphoma. This article reviews the extranodal PET/CT imaging findings regarding HD and NHL.

Fluorine-18 fluorodeoxyglucose PET-CT for extranodal staging of non-Hodgkin and Hodgkin lymphoma

“…F-FDG distribution must be confirmed by anatomical imaging modalities, endoscopic studies and biopsies for a definitive diagnosis. Some studies have also reported that structural CT abnormalities and uptake intensities can improve the reliability of 18 F-FDG PET-CT for the differentiation of lymphomatous infiltration from physiological tracer activity, but the uptake pattern has not been found to be a reliable marker (3,4,8,(19)(20)(21)(22). The Waldeyer's ring and lungs are also sites that have relatively high false positive results due to infectious or inflammatory reasons (23).…”

Molecular Imaging of Urogenital Diseases

“…PET/CT can detect multifocal renal involvement or involvement of adjacent abdominal lymph nodes. Detection of metabolically active lymph nodes increases diagnostic certainty since interpretation of renal lymphoma can be hampered by physiologic renal uptake of FDG ( 94 ). Diffuse renal lymphoma results in diffusely increased FDG uptake ( 95 ).…”

18F-Fluorodeoxyglucose positron emission tomography/computed tomography comparison of gastric lymphoma and gastric carcinoma

“…Hybrid positron emission tomography (PET)/computed tomography (CT) integrates 18 F-fluorodeoxyglucose (FDG) PET and CT scanning, thus simultaneously providing functional, metabolic information based on PET and structural, anatomical information based on CT[8-10]. A growing number of studies have supported the application of 18 F-FDG PET/CT in initial staging, treatment response assessment, and follow-up of patients with gastric lymphoma of various histological subtypes[11-14].…”