- Pictorial Review
- Open Access
FDG-PET/CT pitfalls in oncological head and neck imaging
© The Author(s) 2014
- Received: 4 March 2014
- Accepted: 21 July 2014
- Published: 26 August 2014
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.
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).
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.
- Positron emission tomography-computed tomography (PET/CT)
- Head and neck tumours
Positron emission tomography-computed tomography (PET/CT) with fluorine-18-fluorodeoxy-D-glucose (FDG) plays a major role today in the pre-therapeutic work-up and post-therapeutic monitoring of patients with head and neck tumours. FDG-PET/CT is now routinely used in the head and neck for the delineation of the primary tumour, detection of regional nodal metastases, distant metastases and second primary tumours. Further indications include assessment of post-treatment response, long-term surveillance to detect recurrence and, last but not least, detection of an unknown primary tumour [1–5]. Thus, FDG-PET/CT tremendously facilitates the management of head and neck cancer patients in whom treatment is often expensive and associated with a significant morbidity [1–4]. However, the interpretation of FDG-PET/CT studies in the head and neck may be quite challenging due to the inherently complex anatomy, physiological variants and unusual patterns of FDG uptake after radiation therapy and surgery [1–4, 6–9]. Because FDG is not a tumour-specific tracer, it can accumulate in a variety of benign processes including benign tumours, inflammatory, post-traumatic and iatrogenic conditions. Benign non-physiological FDG uptake may be seen in up to 25 % of whole-body PET/CT examinations, and FDG uptake may mimic malignant tumours in more than half of these lesions . Lesion characterisation on the CT portion of the PET/CT study is therefore of utmost importance as it increases the specificity of PET/CT reporting . Although FDG interpretation pitfalls are common in the head and neck, they have received only very limited attention in the literature. The purpose of this review is to discuss the most common interpretation pitfalls in the purview of head and neck PET/CT and how to avoid them. The added value of contrast-enhanced CT (CECT) and/or magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) sequences or ultrasound (US) to solve diagnostic dilemmas is equally discussed.
A detailed discussion of institutional PET/CT protocols used in head and neck cancer patients is beyond the scope of this article. Nevertheless, familiarity with the basic principles of PET/CT imaging in head and neck oncology is important as biological factors and the choice of imaging parameters, such as field of view (FOV), slice thickness or use of iodinated contrast material may influence the interpretation of PET/CT findings. In most institutions, head and neck tumour patients will often undergo a standard PET/CT examination without intravenous contrast material; the area investigated typically extends from the mid-forehead to the mid-thigh. Nevertheless, an increasing number of authors advocate the additional use of a dedicated high-resolution head and neck PET/CT (HR HN PET/CT) with small FOV, longer acquisition time per bed position and thinner slice thickness [11–13]. The additional use of intravenous contrast allows full diagnostic CT capability [11, 12] and improves diagnostic performance in the head and neck area . HR HN PET/CT is of particular help in the identification of subtle morphological findings essential for the diagnosis of local tumour spread and for the detection of small lymph node metastases and recurrent disease, thus reducing false-negative PET/CT readings (see below). Routinely, PET/CT examinations are performed after a 6-h fasting period and when the measured intravenous serum glucose concentration prior to study begin is within normal limits (<200 mg/dl). In general, 150–555 MBq (about 5–6 MBq of F18-FDG per kilogram of body weight)  are administered intravenously and during the following 60-min uptake period patients are encouraged to rest and to refrain from talking or chewing PET/CT imaging of diabetic patients may be problematic because elevated glucose levels can cause competitive inhibition of FDG uptake in different tissues. Although intravenous insulin before FDG injection is effective in reducing glycaemia, it can cause increased FDG uptake in muscle and fat. Therefore, in patients with very high glucose levels (>200–250 mg/dl), scanning should be rescheduled if reasonably convenient . A spiral CT scan for attenuation correction is obtained first, after which PET data are acquired. This unenhanced CT scan can be used not only for the attenuation correction of PET data but also for PET/CT image fusion thereby allowing precise lesion localisation. Typical whole-body CT parameters include: 120 kV, 240 mAs, 1.5 mm collimation, 40 cm FOV, soft tissue and bone window settings. PET data acquisition is usually started after CT with 3–6 min per bed position for a total of seven to nine beds covering the area from the mid-forehead to the proximal thigh. Typical whole-body PET parameters include: 168 PET matrix, 4 iterations, 8 subsets, 4-mm pixel size. After the total body PET acquisition, an HR CECT can be obtained for the head and neck with the following parameters: 120 kV, 210 mAs, 0.64–0.75 mm collimation, 20–25 cm FOV (small FOV compared with whole-body PET/CT) soft tissue and bone window settings, intravenous bolus of 100 ml iohexol (CT acquisition started 1 min after intravenous bolus). For the head and neck area, PET acquisition parameters can be changed as follows: 6–12 min bed time, 256 PET matrix, 6 iterations, 4 subsets, 1.82-mm pixel size . As suggested by several authors [11–13] and based on the experience in our institution, it is of utmost importance to obtain HR PET/CT images through the head and neck region with a separate acquisition from the body part to allow for detection of small lesions.
A variety of potential FDG-PET/CT interpretation pitfalls and artefacts can be observed on routine head and neck studies. The most common interpretation pitfalls are caused by variable physiological FDG uptake within Waldeyer’s ring, salivary glands, muscles or brown adipose fat (BAT) and by increased FDG uptake due to inflammatory and infectious conditions, recent surgery, previous chemoradiation, contralateral cranial nerve palsy and thyroid nodules with high glucose metabolism. Less often, lesions may be missed on PET/CT due to low FDG avidity, small lesion size or due to low scanner resolution. Common artefacts seen in the head and neck area are related to metallic implants and dental hardware or may occur due to patient motion between the CT and the PET acquisition. These interpretation pitfalls and artefacts, their pathophysiological mechanisms and key imaging features are discussed below. Special emphasis is put on how to avoid misinterpretation of findings and when additional imaging methods are of complementary value.
Physiological FDG uptake in the head and neck
Physiological FDG uptake is often seen in the muscles of the head and neck, which can constitute a diagnostic dilemma in the interpretation of PET scans [2–4, 6–9]. Prominent physiological uptake can be seen in the tongue and in the pterygoid muscles on vocalisation and chewing after FDG injection. Prominent FDG uptake is also often seen in the extraocular muscles due to eye motion. In the neck, physiological FDG uptake can be seen both in the visceral and non-visceral compartment musculature. In the visceral compartment, pronounced uptake in the cricopharyngeus and posterior cricoarytenoid muscles on phonation can interfere with the interpretation of PET scans in patients with hypopharyngeal, oesophageal and thyroid cancers, in whom this physiological uptake may mimic pathology [2, 4, 6, 27]. Uptake in the anterior portion of the genioglossus muscles can mimic or obscure small floor of the mouth cancers. Contraction-induced increased FDG uptake in the cervical muscles, strap muscles and paraspinal muscles in anxious patients (in particular sternocleidomastoid, scalenus anterior, longus colli, longus capitis and inferior obliquus capiti muscles) can mimic lymph node metastasis or, alternatively, may lead to false-negative findings obscuring disease truly present in underlying lymph nodes [2–4, 6–9, 28, 29]. Uptake in the anterior scalenus muscle mimicking supraclavicular lymph node metastasis in a case of lung cancer has been described . Muscle uptake is generally linear and can be traced from the origin to insertion on fused PET/CT images (Fig. 5) Therefore, careful analysis of two-dimensional (2D) multiplanar reconstructions in the coronal and sagittal planes is mandatory whenever findings are unclear on axial PET/CT images [2, 4, 7–9, 28]. The administration of benzodiazepines before FDG injection helps to decrease muscle uptake; however, it is rarely done in clinical routine. Also, patients may be advised to stay relaxed and avoid talking, eating and chewing after the injection of FDG [7–9, 28]. A further factor influencing FDG uptake in muscle is insulin. Insulin administration prior to FDG PET/CT leads to increased accumulation of FDG in muscle, degrading image quality and hampering correct image interpretation .
Brown adipose tissue (BAT)
Increased FDG uptake potentially causing false-positive findings
Inflammation and infection
Often the clinical history points to the cause of FDG uptake; however, inflammatory conditions (such as periodontal disease, dental infection, active atherosclerotic plaques or tuberculosis) and neoplastic disease can coexist. Reactive nodes are commonly encountered in the head and neck, and may result in a decreased specificity of FDG-PET/CT for the nodal staging of head and neck cancers. Precise image fusion, correlation of PET with morphological CT findings and 2D multiplanar reconstructions are essential in order to avoid overdiagnosis of benign conditions as malignancy, as well as missing out on actual pathology. Evaluation of SUVs may help to differentiate between benign and malignant disease, whereby SUVs greater than 3 are considered as a general guide to indicate neoplasm. Nevertheless, SUVs greater than 3 can also occur in acute infection, such as sinusitis, osteomyelitis, suppurative lymphadenopathy and abscess. If diagnostic dilemma still exists, sequential follow-up imaging, US examination of the neck and, at times, US FNAC may be needed [1, 3, 4, 7–9, 33, 34, 38, 39].
Inflammation caused by radiotherapy and chemotherapy
Even if PET/CT is obtained after 12 weeks following completion of chemoradiation, false-positive findings may still occur. Post chemo-radiotherapy false-positive findings on PET/CT are caused by radiation-induced mucositis, reactive nodes, soft tissue necrosis and radionecrosis of bone [4, 8, 9, 33, 41]. CECT and MRI may also be equivocal in these situations. Radiation-induced mucositis is a common sequel of chemo-radiotherapy for oropharyngeal and laryngeal SCC and can persist for prolonged periods after treatment. Diffuse mild FDG uptake along the oropharyngeal and laryngeal walls are in keeping with inflammation; however, a more focal uptake should raise suspicion for ulceration or persistent disease. Osteoradionecrosis is a late complication of high-dose irradiation for squamous cell carcinoma of the oral cavity, pharynx and larynx, and constitutes a lifelong problem for cancer survivors. It can affect the jaws, larynx and hyoid bone, cervical spine, central skull base or temporal bone [43–45]. Although the risk of developing osteoradionecrosis has significantly diminished in recent years , osteoradionecrosis of the jaws and of the skull base still constitutes a common pitfall of FDG-PET/CT imaging [45, 46]. Often, osteoradionecrosis lesions show very high SUVs, equalling that of residual/recurrent tumour, and there is a significant overlap of SUVs in patients with osteoradionecrosis and tumour recurrence . Correlation with CT images may help in some instances, as the prevalence of bony sclerosis is significantly more common in osteoradionecrosis, whereas recurrent tumours rather display solid or cystic soft tissue masses . Nevertheless, in equivocal cases, a short-term follow-up PET/CT or MRI with diffusion-weighted sequences (DWI) may be additionally used for the differentiation between radiation-induced changes and residual/recurrent disease [4, 9, 33, 47]. Analysis of ADC values may help distinguish between residual cancer and benign post-treatment changes. Residual or recurrent SCCs show significantly lower ADC values than that of a benign post-treatment mass, with an ADC threshold value of around 1.3 × 10−3 mm2/s . Due to their capability to obtain anatomical, functional and metabolic information in a single examination, hybrid PET/MRI systems hold promise to facilitate differentiation between radiation-induced changes and recurrent disease [5, 48–51]. Nevertheless, very little data are currently available regarding the clinical implementation of hybrid PET/MRI scanners in the head and neck [5, 48–51], and future studies will show whether PET/MRI outperforms PET/CT, DWI MRI or the combination of these techniques.
Inflammation caused by recent surgery
Contralateral cranial nerve palsy
Asymmetrical FDG uptake in the vocal cords can be seen in patients with recurrent laryngeal nerve palsy from prior surgical intervention or tumour involvement or due to trauma. The compensatory activation of the non-paralysed vocal cord leads to increased metabolism and increased glucose consumption, especially in the thyroarytenoid muscle and in the posterior cricoarytenoid muscle; this increased metabolism is seen as a focal hypermetabolic spot on FDG PET images (Fig. 11). This imaging mimic may be confused with a tumour in the non-paralysed vocal cord unless CT images are carefully analysed [2, 4, 7, 8, 54–57]. On the contrary, if no FDG uptake is seen in both vocal cords and only in the posterior cricoarytenoid muscle, the interpreter may overlook vocal cord paralysis on FDG-PET/CT. Characteristic CT imaging findings of recurrent laryngeal nerve paralysis include paramedian position of the paralysed vocal cord, displacement of the ipsilateral arytenoid cartilage, compensatory medial rotation of ipsilateral aryepiglottic fold, dilated ipsilateral pyriform sinus and atrophy of posterior cricoarytenoid and thyroarytenoid muscles [4, 55, 57, 58]. PET/CT image fusion and clinical correlation can help to overcome this potential pitfall. History of hoarseness, prior surgery or radiation in the neck, larynx, thyroid or mediastinum may indicate injury to one of the recurrent laryngeal nerves [4, 55–57]. Laryngoscopic examination will help to confirm impaired movement of the contralateral vocal cord and also will rule out a primary pathology in the ipsilateral cord. However, any nodularity or apparent lesion in the vocal cord with focal FDG uptake is suspicious and warrants further evaluation [55–58].
Palsy of the hypoglossal nerve (XII), spinal accessory nerve (XI) or the mandibular division of the trigeminal nerve (V3) may also result in contralateral intense FDG muscle uptake. CT findings in long standing V3, XI and XII palsy are pathognomonic and usually do not require further imaging as long as the cause of nerve injury is known [59, 60]. In long standing XII palsy, CT reveals atrophy of the affected hemitongue with fatty infiltration, a clear-cut linear demarcation between the affected and non-affected muscles as well as tongue deviation. Prolapse of the paralysed hemitongue into the oropharynx when the patient is in the supine position is a further characteristic finding.
In early muscle denervation due to recent palsy, muscle atrophy is not obvious on CT and contralateral compensatory FDG uptake may be mistaken for non-specific tracer accumulation or contralateral tumour in particular in the tongue . Partial glossectomy can cause tongue fasciculations, which can lead to false-positive FDG uptake, thereby mimicking recurrent tumour [4, 33]. As MRI is more sensitive than CT for the detection of early signs of muscle denervation, correlation with MRI findings and with clinical data including electromyography helps to overcome this pitfall [4, 33].
Increased FDG thyroid gland uptake
Factors potentially causing false negative PET/CT readings
Low FDG uptake, low image resolution and small lesion size
Small-sized malignant tumours (diameter below 6–8 mm) and especially small-sized metastatic lymph nodes may not be detected by PET/CT unless intense FDG uptake is present because these lesions are below the resolution of current PET scanners (Fig. 15). Partial volume effect may cause significant decrease in perceived SUV in such small lesions and thereby yield a false-negative result. This pitfall can be partly overcome today by using dedicated HR PET/CT acquisitions (see above), whereas future developments in PET detector technology hold promise to further improve scanner resolution [1, 4, 9, 33, 42, 67].
Lesion proximity to areas with high metabolism
Common FDG-PET/CT artefacts
Artefacts related to dental hardware and metallic implants
Involuntary patient motion between the CT and the PET data acquisition of a PET/CT study can lead to poor data fusion, making correct localisation of focal uptake impossible especially in smaller lesions and in the supraclavicular area (see “Increased FDG thyroid gland uptake”). In addition, respiratory mismatch or vigorous swallowing can also influence the quality of PET/CT images as head and neck cancer patients often present with major dyspnoea, coughing or swallowing problems. In order to optimise PET/CT image fusion, the respiratory levels during the PET and CT data acquisition should be similar. Therefore, in most institutions, patients are asked to breathe in a shallow fashion during the neck acquisition and refrain from vigorous inspiratory or expiratory manoeuvres. In addition to adequate patient instruction, immobilisation during scanning often prevents motion artefacts. Nevertheless, it is important to point out that mis-coregistration artefacts from patient motion are a lesser problem in head and neck PET/CT studies compared with PET/CT scans of the chest or abdomen.
FDG-PET/CT imaging has dramatically changed head and neck cancer imaging and management. FDG, however, is not tumour-specific and various image interpretation pitfalls may occur due to false-positive and false-negative causes of FDG uptake. This article reviews the causes of physiological FDG uptake in the head and neck, and of uncommon patterns of uptake due to benign lesions, artefacts, recent surgery, inflammation and scarring. Awareness of these tumour mimics along with accurate clinical information, detailed anatomical evaluation and—if necessary—correlation with other imaging modalities, such as CECT, US or MRI help to avoid misinterpretation of head and neck PET/CT studies.
Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.
- Subramaniam RM, Truong M, Peller P, Sakai O, Mercier G (2010) Fluorodeoxyglucose-positron-emission tomography imaging of head and neck squamous cell cancer. AJNR Am J Neuroradiol 31:598–604PubMedView ArticleGoogle Scholar
- Blodgett TM, Fukui MB, Snyderman CH et al (2005) Combined PET-CT in the head and neck: part 1. Physiologic, altered physiologic, and artifactual FDG uptake. Radiographics 25:897–912PubMedView ArticleGoogle Scholar
- Fukui MB, Blodgett TM, Snyderman CH et al (2005) Combined PET-CT in the head and neck: part 2. Diagn Pitfalls Oncol Imaging Radiogr 25:913–930Google Scholar
- Schöder H (2013) Head and neck cancer. In: Strauss HW, Mariani G, Volterrani D, Larson SM (eds) Nuclear oncology: pathophysiology and clinical applications. Springer, New York, pp 269–295View ArticleGoogle Scholar
- Becker M, Zaidi H (2014) Imaging in head and neck squamous cell carcinoma: the potential role of PET/MRI. Br J Radiol 87:20130677PubMedPubMed CentralView ArticleGoogle Scholar
- Kostakoglu L, Hardoff R, Mirtcheva R, Goldsmith SJ (2004) PET-CT fusion imaging in differentiating physiologic from pathologic FDG uptake. Radiographics 24:1411–1431PubMedView ArticleGoogle Scholar
- El-Haddad G, Alavi A, Mavi A, Bural G, Zhuang H (2004) Normal variants in [18 F]-fluorodeoxyglucose PET imaging. Radiol Clin North Am 42:1063–1081PubMedView ArticleGoogle Scholar
- Bhargava P, Rahman S, Wendt J (2011) Atlas of confounding factors in head and neck PET/CT imaging. Clin Nucl Med 36:e20–e29PubMedView ArticleGoogle Scholar
- Castaigne C, Muylle K, Flamen P (2006) Positron emission tomography in head and neck cancer. In: Hermans R (ed) Head and neck cancer imaging. Springer, Berlin Heidelberg, pp 329–343Google Scholar
- Metser U, Miller E, Lerman H, Even-Sapir E (2007) Benign nonphysiologic lesions with increased 18 F-FDG uptake on PET/CT: characterization and incidence. AJR Am J Roentgenol 189:1203–1210PubMedView ArticleGoogle Scholar
- Rodrigues RS, Bozza FA, Christian PE et al (2009) Comparison of whole-body PET/CT, dedicated high-resolution head and neck PET/CT, and contrast-enhanced CT in preoperative staging of clinically M0 squamous cell carcinoma of the head and neck. J Nucl Med 50:1205–1213PubMedView ArticleGoogle Scholar
- Rangaswamy B, Fardanesh MR, Genden EM et al (2013) Improvement in the detection of locoregional recurrence in head and neck malignancies: F-18 fluorodeoxyglucose-positron emission tomography/computed tomography compared to high-resolution contrast-enhanced computed tomography and endoscopic examination. Laryngoscope 123:2664–2669PubMedView ArticleGoogle Scholar
- Chatziioannou SN, Georgakopoulos AT, Pianou NK, Kafiri GT, Pavlou SN, Kallergi M (2014) Recurrent thyroid cancer diagnosis: ROC study of the effect of a high-resolution head and neck 18 F-FDG PET/CT scan. Acad Radiol 21:58–63PubMedView ArticleGoogle Scholar
- Haerle SK, Strobel K, Ahmad N, Soltermann A, Schmid DT, Stoeckli SJ (2011) Contrast-enhanced (18)F-FDG-PET/CT for the assessment of necrotic lymph node metastases. Head Neck 33:324–329PubMedGoogle Scholar
- Boellaard R, O’Doherty MJ, Weber WA et al (2010) FDG PET and PET/CT: EANM procedure guidelines for tumour PET imaging: version 1.0. Eur J Nucl Med Mol Imaging 37:181–200PubMedPubMed CentralView ArticleGoogle Scholar
- Chen YK, Su CT, Chi KH, Cheng RH, Wang SC, Hsu CH (2007) Utility of 18 F-FDG PET/CT uptake patterns in Waldeyer’s ring for differentiating benign from malignant lesions in lateral pharyngeal recess of nasopharynx. J Nucl Med 48:8–14PubMedGoogle Scholar
- Davison JM, Ozonoff A, Imsande HM, Grillone GA, Subramaniam RM (2010) Squamous cell carcinoma of the palatine tonsils: FDG standardized uptake value ratio as a biomarker to differentiate tonsillar carcinoma from physiologic uptake. Radiology 255:578–585PubMedView ArticleGoogle Scholar
- Basu S, Houseni M, Alavi A (2008) Significance of incidental fluorodeoxyglucose uptake in the parotid glands and its impact on patient management. Nucl Med Commun 29:367–373PubMedView ArticleGoogle Scholar
- Hadiprodjo D, Ryan T, Truong MT, Mercier G, Subramaniam RM (2012) Parotid gland tumors: preliminary data for the value of FDG PET/CT diagnostic parameters. AJR Am J Roentgenol 198:W185–W190PubMedView ArticleGoogle Scholar
- Roh JL, Ryu CH, Choi SH et al (2007) Clinical utility of 18 F-FDG PET for patients with salivary gland malignancies. J Nucl Med 48:240–246PubMedGoogle Scholar
- Terraz S, Poletti PA, Dulguerov P et al (2013) How reliable is sonography in the assessment of sialolithiasis? AJR Am J Roentgenol 201:W104–W109PubMedView ArticleGoogle Scholar
- Becker M, Dulguerov P, Terraz S (2014) Reply. AJR Am J Roentgenol 202:W120PubMedView ArticleGoogle Scholar
- Abdullah A, Rivas FF, Srinivasan A (2013) Imaging of the salivary glands. Semin Roentgenol 48:65–74PubMedView ArticleGoogle Scholar
- Bajaj Y, Singh S, Cozens N, Sharp J (2005) Critical clinical appraisal of the role of ultrasound guided fine needle aspiration cytology in the management of parotid tumours. J Laryngol Otol 119:289–292PubMedView ArticleGoogle Scholar
- Friedman ER, Saindane AM (2013) Pitfalls in the staging of cancer of the major salivary gland neoplasms. Neuroimaging Clin N Am 23:107–122PubMedView ArticleGoogle Scholar
- Celebi I, Mahmutoglu AS, Ucgul A, Ulusay SM, Basak T, Basak M (2013) Quantitative diffusion-weighted magnetic resonance imaging in the evaluation of parotid gland masses: a study with histopathological correlation. Clin Imaging 37:232–238PubMedView ArticleGoogle Scholar
- Zhu Z, Chou C, Yen TC, Cui R (2001) Elevated F-18 FDG uptake in laryngeal muscles mimicking thyroid cancer metastases. Clin Nucl Med 26:689–691PubMedView ArticleGoogle Scholar
- Jacene HA, Goudarzi B, Wahl RL (2008) Scalene muscle uptake: a potential pitfall in head and neck PET/CT. Eur J Nucl Med Mol Imaging 35:89–94PubMedView ArticleGoogle Scholar
- Su HC, Huang CK, Bai YL, Lin CY, Hung GU (2009) Physiologically variant FDG uptake in scalene muscle mimicking neck lymph node metastasis in a patient with lung cancer. Ann Nucl Med Sci 22:239–243Google Scholar
- Perkins AC, Mshelia DS, Symonds ME, Sathekge M (2013) Prevalence and pattern of brown adipose tissue distribution of 18 F-FDG in patients undergoing PET-CT in a subtropical climatic zone. Nucl Med Commun 34:168–174PubMedView ArticleGoogle Scholar
- Rousseau C, Bourbouloux E, Campion L et al (2006) Brown fat in breast cancer patients: analysis of serial (18)F-FDG PET/CT scans. Eur J Nucl Med Mol Imaging 33:785–791PubMedView ArticleGoogle Scholar
- Tsuchiya T, Osanai T, Ishikawa A, Kato N, Watanabe Y, Ogino T (2006) Hibernomas show intense accumulation of FDG positron emission tomography. J Comput Assist Tomogr 30:333–336PubMedView ArticleGoogle Scholar
- Schmalfuss I (2012) Positron emission tomography in head and neck cancer. In: Hermans R (ed) Head and neck cancer imaging, 2nd edn. Springer, Berlin Heidelberg, pp 363–385Google Scholar
- Zhuang H, Yu JQ, Alavi A (2005) Applications of fluorodeoxyglucose-PET imaging in the detection of infection and inflammation and other benign disorders. Radiol Clin North Am 43:121–134PubMedView ArticleGoogle Scholar
- Walter MA, Melzer RA, Schindler C, Muller-Brand J, Tyndall A, Nitzsche EU (2005) The value of [18 F]FDG-PET in the diagnosis of large-vessel vasculitis and the assessment of activity and extent of disease. Eur J Nucl Med Mol Imaging 32:674–681PubMedView ArticleGoogle Scholar
- Jezovnik MK, Zidar N, Lezaic L, Gersak B, Poredos P (2014) Identification of inflamed atherosclerotic lesions in vivo using PET-CT. Inflammation 37:426–434PubMedView ArticleGoogle Scholar
- Harrigal C, Branstetter BF, Snyderman CH, Maroon J (2005) Teflon granuloma in the nasopharynx: a potentially false-positive PET/CT finding. AJNR Am J Neuroradiol 26:417–420PubMedGoogle Scholar
- Wong RJ, Lin DT, Schoder H et al (2002) Diagnostic and prognostic value of [(18)F]fluorodeoxyglucose positron emission tomography for recurrent head and neck squamous cell carcinoma. J Clin Oncol 20:4199–4208PubMedView ArticleGoogle Scholar
- Metser U, Even-Sapir E (2007) Increased (18)F-fluorodeoxyglucose uptake in benign, nonphysiologic lesions found on whole-body positron emission tomography/computed tomography (PET/CT): accumulated data from four years of experience with PET/CT. Semin Nucl Med 37:206–222PubMedView ArticleGoogle Scholar
- Porceddu SV, Jarmolowski E, Hicks RJ et al (2005) Utility of positron emission tomography for the detection of disease in residual neck nodes after (chemo)radiotherapy in head and neck cancer. Head Neck 27:175–181PubMedView ArticleGoogle Scholar
- Schoder H, Fury M, Lee N, Kraus D (2009) PET monitoring of therapy response in head and neck squamous cell carcinoma. J Nucl Med 50(Suppl 1):74S–88SPubMedView ArticleGoogle Scholar
- Kapoor V, Fukui MB, McCook BM (2005) Role of 18FFDG PET/CT in the treatment of head and neck cancers: posttherapy evaluation and pitfalls. AJR Am J Roentgenol 184:589–597PubMedView ArticleGoogle Scholar
- Becker M, Schroth G, Zbaren P et al (1997) Long-term changes induced by high-dose irradiation of the head and neck region: imaging findings. Radiographics 17:5–26PubMedView ArticleGoogle Scholar
- Nabil S, Samman N (2012) Risk factors for osteoradionecrosis after head and neck radiation: a systematic review. Oral Surg Oral Med Oral Pathol Oral Radiol 113:54–69PubMedView ArticleGoogle Scholar
- Avril L, Lombardi T, Ailianou A et al (2014) Radiolucent lesions of the mandible: a pattern-based approach to diagnosis. Insights Imaging 5:85–101PubMedPubMed CentralView ArticleGoogle Scholar
- Alhilali L, Reynods AR, Fakhran S (2014) Osteoradionecrosis after radiation therapy for head and neck cancer: differentiation from recurrent disease with CT and PET/CT imaging. AJNR Am J Neuroradiol 35:1405-1411PubMedView ArticleGoogle Scholar
- Thoeny HC, De Keyzer F, King AD (2012) Diffusion-weighted MR imaging in the head and neck. Radiology 263:19–32PubMedView ArticleGoogle Scholar
- Platzek I, Beuthien-Baumann B, Schneider M et al (2013) PET/MRI in head and neck cancer: initial experience. Eur J Nucl Med Mol Imaging 40:6–11PubMedPubMed CentralView ArticleGoogle Scholar
- Boss A, Stegger L, Bisdas S et al (2011) Feasibility of simultaneous PET/MR imaging in the head and upper neck area. Eur Radiol 21:1439–1446PubMedView ArticleGoogle Scholar
- Vargas MI, Becker M, Garibotto V et al (2013) Approaches for the optimization of MR protocols in clinical hybrid PET/MRI studies. MAGMA 26:57–69PubMedView ArticleGoogle Scholar
- Varoquaux A, Rager O, Poncet A et al (2014) Detection and quantification of focal uptake in head and neck tumours: (18)F-FDG PET/MR versus PET/CT. Eur J Nucl Med Mol Imaging 41:462–475PubMedPubMed CentralView ArticleGoogle Scholar
- Desmouliere A, Redard M, Darby I, Gabbiani G (1995) Apoptosis mediates the decrease in cellularity during the transition between granulation tissue and scar. Am J Pathol 146:56–66PubMedPubMed CentralGoogle Scholar
- Kumar V, Abbas AK, Aster JC (2012) Inflammation and repair. In: Kumar V, Abbas AK, Aster JC (eds) Robbins basic pathology, 9th edn. Elsevier Saunders, Philadelphia, pp 29–74Google Scholar
- Romo LV, Curtin HD (1999) Atrophy of the posterior cricoarytenoid muscle as an indicator of recurrent laryngeal nerve palsy. AJNR Am J Neuroradiol 20:467–471PubMedGoogle Scholar
- Heller MT, Meltzer CC, Fukui MB et al (2000) Superphysiologic FDG uptake in the non-paralyzed vocal cord. Resolution of a false-positive PET result with combined PET-CT imaging. Clin Positron Imaging 3:207–211PubMedView ArticleGoogle Scholar
- Pai M, Kim HK, Kim HS (2006) Hypermetabolism of compensatory laryngeal muscles in unilateral vocal cord palsy: comparison study between speech and silence with normal subjects by co-registered PET-CT fusion images. Nucl Med Mol Imaging 40:23–27Google Scholar
- Paquette CM, Manos DC, Psooy BJ (2012) Unilateral vocal cord paralysis: a review of CT findings, mediastinal causes, and the course of the recurrent laryngeal nerves. Radiographics 32:721–740PubMedView ArticleGoogle Scholar
- Becker M, Leuchter I, Platon A, Becker CD, Dulguerov P, Varoquaux A (2014) Imaging of laryngeal trauma. Eur J Radiol 83:142–154PubMedView ArticleGoogle Scholar
- Policeni BA, Smoker WR (2008) Pathologic conditions of the lower cranial nerves IX, X, XI, and XII. Neuroimaging Clin N Am 18:347–368PubMedView ArticleGoogle Scholar
- Becker M, Kohler R, Vargas MI, Viallon M, Delavelle J (2008) Pathology of the trigeminal nerve. Neuroimaging Clin N Am 18:283–307PubMedView ArticleGoogle Scholar
- Werner MK, Pfannenberg C, Oksuz MO (2011) Nonspecific FDG uptake in the tongue mimicking the primary tumor in a patient with cancer of unknown primary. Clin Imaging 35:405–407PubMedView ArticleGoogle Scholar
- Chen W, Parsons M, Torigian DA, Zhuang H, Alavi A (2009) Evaluation of thyroid FDG uptake incidentally identified on FDG-PET/CT imaging. Nucl Med Commun 30:240–244PubMedView ArticleGoogle Scholar
- Choi JY, Lee KS, Kim HJ et al (2006) Focal thyroid lesions incidentally identified by integrated 18 F-FDG PET/CT: clinical significance and improved characterization. J Nucl Med 47:609–615PubMedGoogle Scholar
- Lin EC (2002) Thyroid nodule mimicking cervical adenopathy on FDG positron emission tomographic imaging. Clin Nucl Med 27:656–657PubMedView ArticleGoogle Scholar
- Weiler-Sagie M, Bushelev O, Epelbaum R et al (2010) (18)F-FDG avidity in lymphoma readdressed: a study of 766 patients. J Nucl Med 51:25–30PubMedView ArticleGoogle Scholar
- Purohit BS, Dulguerov P, Burkhardt K, Becker M (2014) Dedifferentiated laryngeal chondrosarcoma: combined morphologic and functional imaging with positron-emission tomography/magnetic resonance imaging. Laryngoscope 124:E274–E277PubMedView ArticleGoogle Scholar
- Avril NE, Weber WA (2005) Monitoring response to treatment in patients utilizing PET. Radiol Clin North Am 43:189–204PubMedView ArticleGoogle Scholar
- Harvey RJ, Pitzer G, Nissman DB et al (2010) PET/CT in the assessment of previously treated skull base malignancies. Head Neck 32:76–84PubMedGoogle Scholar
- Muzaffar R, Shousha MA, Sarajlic L, Osman MM (2013) Ophthalmologic abnormalities on FDG-PET/CT: a pictorial essay. Cancer Imaging 13:100–112PubMedPubMed CentralView ArticleGoogle Scholar
- King AD, Ma BB, Yau YY et al (2008) The impact of 18 F-FDG PET/CT on assessment of nasopharyngeal carcinoma at diagnosis. Br J Radiol 81:291–298PubMedView ArticleGoogle Scholar
- Goerres GW, Hany TF, Kamel E, von Schulthess GK, Buck A (2002) Head and neck imaging with PET and PET/CT: artefacts from dental metallic implants. Eur J Nucl Med Mol Imaging 29:367–370PubMedView ArticleGoogle Scholar
- Abdoli M, Ay MR, Ahmadian A, Dierckx RA, Zaidi H (2010) Reduction of dental filling metallic artifacts in CT-based attenuation correction of PET data using weighted virtual sinograms optimized by a genetic algorithm. Med Phys 37:6166–6177PubMedView ArticleGoogle Scholar
- Park HH, Shin JY, Lee J et al (2013) A study on the artifacts generated by dental materials in PET/CT image. Conf Proc IEEE Eng Med Biol Soc 2013:2465–2468PubMedGoogle Scholar
- Nahmias C, Lemmens C, Faul D et al (2008) Does reducing CT artifacts from dental implants influence the PET interpretation in PET/CT studies of oral cancer and head and neck cancer? J Nucl Med 49:1047–1052PubMedView ArticleGoogle Scholar
- Delso G, Wollenweber S, Lonn A, Wiesinger F, Veit-Haibach P (2013) MR-driven metal artifact reduction in PET/CT. Phys Med Biol 58:2267–2280PubMedView ArticleGoogle Scholar