To the Editor, It is important to have a thorough knowledge about the conditions or situations which may lead to insufficient fluorine-18 fluorodeoxyglucose (FDG) uptake and false-negative results, particularly in oncological FDG-positron emission tomography/computed tomography (PET/CT) practice. Small tumor or metastatic lymph node dimensions (1, 2), necrotic areas within the tumor, high levels of blood glucose and insulin (3) may be the causes of false-negative FDG-PET/CT findings. In suspicious cases with unexpectedly low FDG affinity, history of corticosteroid treatment with increased doses, radiation therapy and chemotherapy should be questioned (3, 4). Well-differentiated forms of various malignancies such as hepatocellular carcinoma, some cases of genitourinary tract carcinomas including prostate cancer (3), some cases of ovarian cancer (5), various neuroendocrine tumours and malignancies of the thyroid gland (3), some head and neck squamous cell carcinomas without a known primary (6), some cases of esophageal carcinoma (7), some subtypes/cases of bronchioloalveolar carcinomas (8, 9), some cases of multiple myeloma (10), various metastatic bone tumours (particularly the sclerotic ones) (11), some cases of lobular breast carcinomas, as well as some low-grade malignancies (e.g. some central nervous system tumours and some sarcomas), lymphoma, and malignancies including high amounts of mucin may present with low FDG uptake (3). In order to overcome this diagnostically challenging situation, it is mandatory to evaluate the plain CT components of FDG-PET/CT images meticulously. But since this may not give sufficient data in some patients, the images which have readily or previously been obtained by other tools such as plain radiography, fluoroscopy, ultrasonography, mammography, contrast enhanced CT and magnetic resonance imaging should be evaluated at the same setting. Also, all the clinical and laboratory findings should be correlated with FDG-PET/CT findings. In indeterminate cases, the diagnosis should be verified by biopsy in appropriate patients.
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It is important to have a thorough knowledge about the conditions or situations which may lead to insufficient fluorine-18 fluorodeoxyglucose (FDG) uptake and false negative results, particularly in oncological FDG-positron emission tomography / computed tomography (PET/CT) practice. Small tumour or metastatic lymph node dimensions ( 1
, 2
), necrotic areas within the tumour, high levels of blood glocose and insulin ( 3
) may be the causes of false-negative FDG-PET/CT findings. In suspicious cases with unexpectedly low FDG affinity, history of corticosteroid treatment with increased doses, radiation therapy and chemotherapy should be questioned ( 3
, 4
). Well-differentiated forms of various malignancies such as hepatocellular carcinoma, some cases of genitourinary tract carcinomas including prostate cancer ( 3
), some cases of ovarian cancer ( 5
),variousneuroendocrine tumours and malignancies of the thyroid gland ( 3
), some head and neck squamous cell carcinomas without a known primary ( 6
), some cases of esophageal carcinoma ( 7
), some subtypes/cases of bronchioloalveolar carcinomas ( 8
, 9
), some cases of multiple myeloma ( 10
), various metastatic bone tumours (particularly the sclerotic ones) ( 11
), some cases of lobular breast carcinomas, as well as some low-grade malignancies (e.g.some central nervous system tumours and some sarcomas), lymphoma, and malignancies including high amounts of mucin may present with low FDG uptake ( 3
).
In order to overcome this diagnostically challenging situation, it is mandatory to evaluate the plain CT components of FDG-PET/CT images meticulously. But since this may not give sufficient data in some patients, the images which have readily or previously been obtained by other tools such as plain radiography, fluoroscopy, ultrasonography, mammography, contrast enhanced CT and magnetic resonance imaging should be evaluated at the same setting. Also, all the clinical and laboratory findings should be correlated with FDG-PET/CT findings. In indeterminate cases, the diagnosis should be verified by biopsy in appropriate patients.
ReferencesAyaz S. Letter to editor: FDG-PET/CT evaluation of breastBoellaard R, Delgado-Bolton R, Oyen WJ, Giammarile F, Tatsch K, Eschner W, et al. FDG PET/CT: EANM procedure guidelines for tumour imaging: version 2.0. Eur J Nucl Med Mol Imaging 2015; 42: 328– 54.Delbeke D, Coleman RE, Guiberteau MJ, Brown ML, Royal HD,Siegel BA, et al. Procedure guideline for tumor imaging with 18F-FDG PET/CT 1.0. J Nucl Med 2006; 47: 885−95.Glazer ES, Beaty K, Abdalla EK, Vauthey JN, Curley SA. Effectiveness of positron emission tomography for predicting chemotherapy response in colorectal cancer liver metastases. Arch Surg 2010; 145: 340−5.De Iaco P, Musto A, Orazi L, Zamagni C, Rosati M, Allegri V, et al. FDG-PET/CT in advanced ovarian cancer staging: value and pitfalls in detecting lesions in different abdominal and pelvic quadrants compared with laparoscopy. Eur J Radiol 2011; 80: e98−103.Mani N, George MM, Nash L, Anwar B, Homer JJ. Role of 18-Fludeoxyglucose positron emission tomography-computed tomography and subsequent panendoscopy in head and neck squamous cell carcinoma of unknown primary. Laryngoscope 2016; 126: 1354−8.Noble F, Bailey D; SWCIS Upper Gastrointestinal Tumour Panel, Tung K, Byrne JP. Impact of integrated PET/CT in the staging of oesophageal cancer: a UK population-based cohort study. Clin Radiol 2009; 64: 699−705.Wu HB, Wang L, Wang QS, Han YJ, Li HS, Zhou WL, et al. Adenocarcinoma with BAC features presented as the nonsolid nodule is prone to be false-negative on 18F-FDG PET/CT. Biomed Res Int 2015; 2015: 243681.Aquino SL, Halpern EF, Kuester LB, Fischman AJ. FDG-PET and CT features of non-small cell lung cancer based on tumor type. Int J Mol Med 2007; 19: 495−9.Dammacco F, Rubini G, Ferrari C, Vacca A, Racanelli V. ¹⁸F-FDG PET/CT: a review of diagnostic and prognostic features in multiple myeloma and related disorders. Clin Exp Med 2015; 15: 1−18.Huyge V, Garcia C, Vanderstappen A, Alexiou J, Gil T, Flamen P. Progressive osteoblastic bone metastases in breast cancer negative on FDG-PET. Clin Nucl Med 2009; 34: 417−20.