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FDG-PET/CT pitfalls in oncological head and neck imaging.

Purohit BS, Ailianou A, Dulguerov N, Becker CD, Ratib O, Becker M - Insights Imaging (2014)

Bottom Line: The commonly encountered false-positive PET/CT interpretation pitfalls are due to high FDG uptake by physiological causes, benign thyroid nodules, unilateral cranial nerve palsy and increased FDG uptake due to inflammation, recent chemoradiotherapy and surgery.False-negative findings are caused by lesion vicinity to structures with high glucose metabolism, obscuration of FDG uptake by dental hardware, inadequate PET scanner resolution and inherent low FDG-avidity of some tumours.The interpreting physician must be aware of these unusual patterns of FDG uptake, as well as limitations of PET/CT as a modality, in order to avoid overdiagnosis of benign conditions as malignancy, as well as missing out on actual pathology. • Knowledge of key imaging features of physiological and non-physiological FDG uptake is essential for the interpretation of head and neck PET/CT studies. • Precise anatomical evaluation and correlation with contrast-enhanced CT, US or MRI avoid PET/CT misinterpretation. • Awareness of unusual FDG uptake patterns avoids overdiagnosis of benign conditions as malignancy.

View Article: PubMed Central - PubMed

Affiliation: Department of Imaging, Division of Radiology, Geneva University Hospital, Rue Gabrielle Perret Gentil 4, 1211, Geneva 14, Switzerland.

ABSTRACT

Objectives: Positron emission tomography-computed tomography (PET/CT) with fluorine-18-fluorodeoxy-D-glucose (FDG) has evolved from a research modality to an invaluable tool in head and neck cancer imaging. However, interpretation of FDG PET/CT studies may be difficult due to the inherently complex anatomical landmarks, certain physiological variants and unusual patterns of high FDG uptake in the head and neck. The purpose of this article is to provide a comprehensive approach to key imaging features and interpretation pitfalls of FDG-PET/CT of the head and neck and how to avoid them.

Methods: We review the pathophysiological mechanisms leading to potentially false-positive and false-negative assessments, and we discuss the complementary use of high-resolution contrast-enhanced head and neck PET/CT (HR HN PET/CT) and additional cross-sectional imaging techniques, including ultrasound (US) and magnetic resonance imaging (MRI).

Results: The commonly encountered false-positive PET/CT interpretation pitfalls are due to high FDG uptake by physiological causes, benign thyroid nodules, unilateral cranial nerve palsy and increased FDG uptake due to inflammation, recent chemoradiotherapy and surgery. False-negative findings are caused by lesion vicinity to structures with high glucose metabolism, obscuration of FDG uptake by dental hardware, inadequate PET scanner resolution and inherent low FDG-avidity of some tumours.

Conclusions: The interpreting physician must be aware of these unusual patterns of FDG uptake, as well as limitations of PET/CT as a modality, in order to avoid overdiagnosis of benign conditions as malignancy, as well as missing out on actual pathology.

Teaching points: • Knowledge of key imaging features of physiological and non-physiological FDG uptake is essential for the interpretation of head and neck PET/CT studies. • Precise anatomical evaluation and correlation with contrast-enhanced CT, US or MRI avoid PET/CT misinterpretation. • Awareness of unusual FDG uptake patterns avoids overdiagnosis of benign conditions as malignancy.

No MeSH data available.


Related in: MedlinePlus

a Axial PET/CT image depicts bilateral symmetrical areas of avid FDG uptake in the supraclavicular regions (arrows). These may be confused for metastatic supraclavicular adenopathy. b Corresponding axial CECT image detects no focal abnormality in the supraclavicular regions (arrows). Note that the areas of high uptake seen in a correspond to low attenuation fatty tissue (arrows) in b
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Fig6: a Axial PET/CT image depicts bilateral symmetrical areas of avid FDG uptake in the supraclavicular regions (arrows). These may be confused for metastatic supraclavicular adenopathy. b Corresponding axial CECT image detects no focal abnormality in the supraclavicular regions (arrows). Note that the areas of high uptake seen in a correspond to low attenuation fatty tissue (arrows) in b

Mentions: BAT can occur anywhere in the neck. It is, however, most often encountered in the lower neck and upper mediastinum. High physiological FDG uptake in BAT may sometimes mimic metastases (Fig. 6). Sympathetic stimulation stimulates brown adipocytes and increases their metabolic activity, leading to increased FDG uptake. A typical finding of BAT-related FDG uptake is symmetrical FDG uptake in the supraclavicular, mid-axillary, paraspinal and posterior mediastinal regions. These areas show fat attenuation (−50 to −150 Hounsfield units [HU]) on the corresponding CT images. Precise PET/CT image fusion, careful analysis of CT images and knowledge of human BAT distribution help to avoid misdiagnosis of brown fat deposits for pathology [2, 4, 6–9, 30]. Hypermetabolic BAT is more commonly seen in children than in adults and is more prevalent in females than in males. It occurs more frequently in patients with low body mass index and in cold weather [30]. Some authors describe variations in supraclavicular BAT FDG uptake in breast cancer patients after chemotherapy with drugs like docetaxel [31]. Hibernomas are benign fatty tumours arising from vestigeal fetal brown fat and are usually seen in the neck, back and mediastinum. These benign lesions often show intense FDG uptake, thereby mimicking soft tissue sarcomas [32]. FDG uptake in brown fat can be reduced pharmacologically with beta-blockers and benzodiazepines, if necessary [6–8].Fig. 5


FDG-PET/CT pitfalls in oncological head and neck imaging.

Purohit BS, Ailianou A, Dulguerov N, Becker CD, Ratib O, Becker M - Insights Imaging (2014)

a Axial PET/CT image depicts bilateral symmetrical areas of avid FDG uptake in the supraclavicular regions (arrows). These may be confused for metastatic supraclavicular adenopathy. b Corresponding axial CECT image detects no focal abnormality in the supraclavicular regions (arrows). Note that the areas of high uptake seen in a correspond to low attenuation fatty tissue (arrows) in b
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig6: a Axial PET/CT image depicts bilateral symmetrical areas of avid FDG uptake in the supraclavicular regions (arrows). These may be confused for metastatic supraclavicular adenopathy. b Corresponding axial CECT image detects no focal abnormality in the supraclavicular regions (arrows). Note that the areas of high uptake seen in a correspond to low attenuation fatty tissue (arrows) in b
Mentions: BAT can occur anywhere in the neck. It is, however, most often encountered in the lower neck and upper mediastinum. High physiological FDG uptake in BAT may sometimes mimic metastases (Fig. 6). Sympathetic stimulation stimulates brown adipocytes and increases their metabolic activity, leading to increased FDG uptake. A typical finding of BAT-related FDG uptake is symmetrical FDG uptake in the supraclavicular, mid-axillary, paraspinal and posterior mediastinal regions. These areas show fat attenuation (−50 to −150 Hounsfield units [HU]) on the corresponding CT images. Precise PET/CT image fusion, careful analysis of CT images and knowledge of human BAT distribution help to avoid misdiagnosis of brown fat deposits for pathology [2, 4, 6–9, 30]. Hypermetabolic BAT is more commonly seen in children than in adults and is more prevalent in females than in males. It occurs more frequently in patients with low body mass index and in cold weather [30]. Some authors describe variations in supraclavicular BAT FDG uptake in breast cancer patients after chemotherapy with drugs like docetaxel [31]. Hibernomas are benign fatty tumours arising from vestigeal fetal brown fat and are usually seen in the neck, back and mediastinum. These benign lesions often show intense FDG uptake, thereby mimicking soft tissue sarcomas [32]. FDG uptake in brown fat can be reduced pharmacologically with beta-blockers and benzodiazepines, if necessary [6–8].Fig. 5

Bottom Line: The commonly encountered false-positive PET/CT interpretation pitfalls are due to high FDG uptake by physiological causes, benign thyroid nodules, unilateral cranial nerve palsy and increased FDG uptake due to inflammation, recent chemoradiotherapy and surgery.False-negative findings are caused by lesion vicinity to structures with high glucose metabolism, obscuration of FDG uptake by dental hardware, inadequate PET scanner resolution and inherent low FDG-avidity of some tumours.The interpreting physician must be aware of these unusual patterns of FDG uptake, as well as limitations of PET/CT as a modality, in order to avoid overdiagnosis of benign conditions as malignancy, as well as missing out on actual pathology. • Knowledge of key imaging features of physiological and non-physiological FDG uptake is essential for the interpretation of head and neck PET/CT studies. • Precise anatomical evaluation and correlation with contrast-enhanced CT, US or MRI avoid PET/CT misinterpretation. • Awareness of unusual FDG uptake patterns avoids overdiagnosis of benign conditions as malignancy.

View Article: PubMed Central - PubMed

Affiliation: Department of Imaging, Division of Radiology, Geneva University Hospital, Rue Gabrielle Perret Gentil 4, 1211, Geneva 14, Switzerland.

ABSTRACT

Objectives: Positron emission tomography-computed tomography (PET/CT) with fluorine-18-fluorodeoxy-D-glucose (FDG) has evolved from a research modality to an invaluable tool in head and neck cancer imaging. However, interpretation of FDG PET/CT studies may be difficult due to the inherently complex anatomical landmarks, certain physiological variants and unusual patterns of high FDG uptake in the head and neck. The purpose of this article is to provide a comprehensive approach to key imaging features and interpretation pitfalls of FDG-PET/CT of the head and neck and how to avoid them.

Methods: We review the pathophysiological mechanisms leading to potentially false-positive and false-negative assessments, and we discuss the complementary use of high-resolution contrast-enhanced head and neck PET/CT (HR HN PET/CT) and additional cross-sectional imaging techniques, including ultrasound (US) and magnetic resonance imaging (MRI).

Results: The commonly encountered false-positive PET/CT interpretation pitfalls are due to high FDG uptake by physiological causes, benign thyroid nodules, unilateral cranial nerve palsy and increased FDG uptake due to inflammation, recent chemoradiotherapy and surgery. False-negative findings are caused by lesion vicinity to structures with high glucose metabolism, obscuration of FDG uptake by dental hardware, inadequate PET scanner resolution and inherent low FDG-avidity of some tumours.

Conclusions: The interpreting physician must be aware of these unusual patterns of FDG uptake, as well as limitations of PET/CT as a modality, in order to avoid overdiagnosis of benign conditions as malignancy, as well as missing out on actual pathology.

Teaching points: • Knowledge of key imaging features of physiological and non-physiological FDG uptake is essential for the interpretation of head and neck PET/CT studies. • Precise anatomical evaluation and correlation with contrast-enhanced CT, US or MRI avoid PET/CT misinterpretation. • Awareness of unusual FDG uptake patterns avoids overdiagnosis of benign conditions as malignancy.

No MeSH data available.


Related in: MedlinePlus