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Dentomaxillofacial Radiology (2000) 29, 133 ± 143 ã 2000 Macmillan Publishers Ltd. All rights reserved 0250 ± 832X/00 $15.00 www.nature.com/dmfr REVIEW Imaging of malignant cervical lymphadenopathy SEJ Connor*,1 and JFC Olli1 1 Department of Diagnostic Radiology, Queen Elizabeth Hospital, Birmingham, UK Diagnostic imaging is superior to clinical staging in the detection of malignant cervical lymphadenopathy, and thus helps in¯uence therapy and prognosis. The imaging modalities of CT, MRI, US and PET each have their own diagnostic criteria, accuracy and limitations. Newer innovations such as functional imaging, novel MRI contrast agents and FNAC are being appraised with the aim of identifying the micrometastases which are currently radiologically occult. Keywords: tomography, X-ray computed; magnetic resonance imaging; lymph nodes; head and neck neoplasms Introduction General principles Identi®cation of cervical lymphadenopathy is critical to the management and outcome of diseases that present with malignant nodal in®ltration. Conditions such as bacterial, viral and granulomatous infection may eect the cervical lymph nodes and it is important for the radiologist to be able to dierentiate malignant and benign cervical lymph nodes. Squamous cell carcinoma (SCC) of the head and neck is the commonest tumour of the upper aerodigestive tract and the presence of cervical lymph node metastases in these patients is of particular prognostic and therapeutic signi®cance, with a single lymph node metastasis reducing survival by one-half.1 The purpose of this article is to outline the abilities and limitations of the current diagnostic imaging techniques used to determine the presence of malignant nodal disease, with particular emphasis on those used to detect nodal metastases of head and neck squamous cell carcinomas. The individual modalities of CT, MRI, US and PET will be covered with the important issues of extracapsular spread and recurrent nodal disease being discussed separately. This will be followed by sections on the imaging features of cervical lymphoma and non head and neck metastatic disease and the impact of current imaging on management. The inaccuracies in physical examination of the cervical lymph nodes have been well documented2 and all diagnostic imaging modalities have been shown to have superior diagnostic accuracy.3 ± 7 This is in some part due to visualisation of non palpable deep lymph nodes and because some metastases in normal sized nodes may be detected using diagnostic imaging. Furthermore, imaging studies may contribute useful prognostic information such as extranodal spread in the case of anatomical imaging8 ± 10 and, possibly, tumour aggressiveness in the case of functional imaging.11 Reliable comparisons of sensitivities and speci®cities between dierent studies and imaging modalities are dicult, owing to diering study populations in terms of primary tumour characteristics, clinical neck staging and the use of diering radiological criteria. In addition, the accuracy of imaging techniques maybe presented in terms of predicting individual lymph node involvement or in making the more relevant distinction of a node positive from a node negative neck. When interpreting the results, it must also be remembered that the gold standard of histopathological examination will still miss some small metastases.12 The impact of imaging on treatment planning and outcome is of paramount importance and has generally not been addressed. The imaging criteria used to determine metastatic cervical lymphadenopathy have been extensively evaluated. Unfortunately, the most widely used features such as nodal enlargement or shape, are only `indirect' evidence and therefore less accurate. It is more desirable to use `direct' criteria, that include *Correspondence to: SEJ Connor, Department of Neuroradiology, King's Healthcare NHS Trust, King's College Hospital, Denmark Hill, London SE5 9RS Received 28 September 1999; accepted 14 January 2000 Malignant lymphadenopathy SEJ Connor and JFC Olliff 134 nodal necrosis or an heterogeneous appearance on CT or magnetic MRI and eccentric cortical widening on US. Recent imaging advances have concentrated on potential dierences in the `function' of malignant lymph nodes as demonstrated by dierential uptake of radiolabelled ¯uorodeoxyglucose (FDG) positron emission tomography (PET)5,11,13 or tissue speci®c MRI contrast media.14 Finally, the importance of accurate pre-operative diagnosis, has led to the evaluation of more `invasive' techniques such as US guided ®ne needle aspirate cytology (FNAC).15 As well as predicting metastatic nodal involvement it is important for the radiologist to communicate accurately the location of abnormal lymph nodes to the surgeon, since this may eect the planning of a selective neck dissection. Head and neck surgeons have adopted a simpli®ed numerical classi®cation with major nodal groups classi®ed as levels one to six. Details of this and other anatomical classi®cations are well described.9,16,17 Diagnostic imaging techniques Computed tomography CT remains the most widely used modality for neck imaging. The CT examination is performed in the axial plane with contiguous sections of 3 ± 5 mm whilst a bolus of intravenous contrast media is administered. CT criteria for assessing lymph node metastases are based on size, shape, the presence of central necrosis and the appearance of a cluster of nodes in the expected lymph drainage pathway for the tumour.10 Use of lymph node size operates on the assumption that the larger the lymph node, the more likely it is to be diseased. Traditional `abnormal' values of greater than 10 ± 15 mm16 have been challenged as the resolution of CT scanners has improved. The most eective size criteria for indicating metastatic involvement are now de®ned as minimum axial diameters in excess of 11 mm in the jugulodigastric region and in excess of 10 mm elsewhere.18 Using these sizes a sensitivity of 42% and speci®city of 99% per node were produced; however, the sensitivity increased to 89% if assessed per neck side dissected, that is 11% of necks would have been mislabelled as N0 by CT.18 It has recently been proposed that the cross-sectional area of the lymph node is a more valid criterion than any measurement of the diameter.19 However, this will still not overcome the inadequacy of using size, since reactive nodes may be large and 39% of clinically occult metastases measure less than 3 mm.12 Using the additional feature of nodal shape, there is a slight improvement in the sensitivity of CT. If a lymph node is of `borderline' size, then a `spherical' shape increases the likelihood of tumour involvement.10 With the use of spiral CT, it is possible to reconstruct the image in any plane with good quality, allowing more accurate calculation of the maximal Dentomaxillofacial Radiology axial and longitudinal dimensions and thus assessment of nodal shape. One study concluded that a ratio of maximal longitudinal to maximal axial dimension of less than two was a more accurate criterion than size.20 Nodal grouping in the drainage chain of a tumour is a further indicator of metastatic disease (Figure 1). This is de®ned as three or more contiguous or con¯uent lymph nodes, each of which has a minimal axial diameter of 8 ± 10 mm.18 Combined with a minimal axial dimension of 10 mm, the criterion of nodal grouping slightly improves both sensitivity and speci®city for malignancy.18 The most accurate CT predictor of metastasis is the presence of central necrosis, which has been said to have a 100% speci®city.18,20 This is seen as a central area of low attenuation surrounded by a thick, irregular rim of enhancement9,10 and is due to nodal replacement of the medulla by less enhancing tumour (Figure 2). Unfortunately, nodal necrosis is more commonly seen in large nodes which may be diagnosed on size criteria alone. Nodal necrosis may be mimicked by lipid metaplasia which represents fatty degeneration secondary to in¯ammation or irradiation. However, this fatty change generally occurs at the periphery of the node (Figure 3). Abscess formation may also have a similar appearance but such suppurative transformation is usually evident clinically. Figure 1 Axial CT scan with intravenous contrast demonstrating bilateral deep cervical (level two) lymph nodes. The group of left sided lymph nodes (three of which (arrowheads) measured 8 mm in minimum axial diameter) is indicative of malignant involvement in this patient with an oral SCC Malignant lymphadenopathy SEJ Connor and JFC Olliff Using all these combined CT criteria, a sensitivity of 87% and speci®city of 94% per neck dissection specimen has been achieved.18 The most recent studies in which CT has been used to assess the status of the cervical lymph nodes have not improved on these results.19,21,22 Magnetic resonance imaging Advances in MRI technology has led to its increased use in evaluating cervical lymph nodes. Dedicated neck surface coils, 3 ± 5 mm sections, increased matrix size (512 line images) and a smaller ®eld of view have all led to improvement in spatial resolution. MRI oers the advantages over CT of multiplanar imaging Figure 2 Axial CT scan with intravenous contrast demonstrating a left-sided tongue SCC extending across the midline. There are bilateral enlarged submandibular (level one) lymph nodes demonstrating marked necrosis Figure 3 Axial CT scan with intravenous contrast demonstrating lipid metaplasia (arrow) eccentrically placed in a left submandibular (level one) lymph node which has a 6 mm minimum axial diameter without the need for computer reconstruction, the absence of ionizing radiation, the lack of streak artifact as a result of ®llings and dense cortical bone and superior contrast resolution of the tissue without the need for intravenous contrast medium. MRI is precluded in certain individuals with ferromagnetic prostheses, such as older intracranial aneurysm clips and cardiac pacemakers. Standard protocols for MRI of the cervical lymph nodes include a selection of T1- and fast spin echo T2weighted axial, coronal and sagittal images. The use of fat suppressed techniques also help to increase the contrast between lymph nodes and adjacent high signal fat on both sequences. STIR sequences allow a combination of T1- and T2-weighting with fat suppression, and malignant nodes are clearly demonstrated as high signal. T1-weighted images depict lymph nodes as being of intermediate signal intensity, similar to muscle, whilst T2-weighted images show them as hyperintense signal (Figure 4). Unfortunately these signal characteristics do not dier consistently between normal and abnormal lymph nodes23 so these conventional MR techniques will only allow discrimination on the basis of morphology. Hence MRI will have the same inaccuracy as other modalities using `indirect' morphological criteria. The presence of internal nodal abnormality, seen on CT as central low attenuation, can also be noted as central hypointensity on T1-weighted and hyperintensity on T2-weighted MRI. Gadolinium enhanced T1weighted scans24 with or without fat suppression25 have been reputed to allow more accurate detection of central necrosis. However CT sensitivity for nodal necrosis is 20% greater than MRI.26 Using these criteria, there were early claims of 100% sensitivity at the cost of poor speci®city using a nodal size of greater than 5 mm to identify nodal involvement.27 However when a more conventional upper limit of 10 mm has been used, sensitivities of 57 ± 84% and speci®cities of 50 ± 92% for a positive neck dissection have been recorded.7,25,27 ± 29 Direct comparisons have shown CT to perform better than MRI even when using current technology.26,29 The sensitivities for level four nodes have been shown to be particularly poor which is probably due to breathing artifact.25 However, newer MR techniques have aimed to overcome the inherent disadvantages of indirect criteria, by using tissue-speci®c imaging which may detect metastases in normal sized nodes. Both intravenous ultrasmall superparamagnetic iron oxide particles14 and magnetization transfer imaging30 have been evaluated for this purpose and deserve further investigation. 135 Ultrasound Ultrasound assessment of cervical lymph nodes has the bene®ts of rapidly and cheaply demonstrating all three nodal dimensions without the need for ionizing radiation or intravenous contrast medium. Deeper Dentomaxillofacial Radiology Malignant lymphadenopathy SEJ Connor and JFC Olliff 136 lymph nodes, as in the retropharyngeal region cannot be assessed by ultrasound. The optimal size to de®ne pathological lymph nodes ultrasound are minimum diameters of 9 mm for level two nodes and 8 mm for the remaining levels31,32 which oer a sensitivity of 74% and speci®city of 78%.31 It is easy to evaluate nodal shape by rotating the probe, and the ratio of minimal to maximal axial diameter has been reported to be a valuable predictor of malignancy.6,32,33 A ratio of greater than 0.55 indicates malignancy with a speci®city of 63% and sensitivity of 92%.6 The improved spatial and contrast resolution of high a frequency ultrasound probes have allowed the internal architecture of lymph nodes to be studied. Varying appearances of the echogenic lymph node hilum and the surrounding hypoechoic cortex have been shown to be helpful in distinguishing malignant from benign normal sized nodes33,34 (Figure 5). However, this degree of spatial resolution is only possible with relatively super®cial lymph nodes. The distribution of blood ¯ow in lymph nodes has recently been evaluated using Doppler ultrasound35,36 with areas of vascular sparing and isolated peripheral ¯ow being suggestive of malignancy. Newly available intravenous ultrasound contrast media may contribute to such Doppler assessments in the future. The most promising contribution of US is in the guidance of FNAC. Aspirates are obtained from any readily visible lymph nodes, with enlarged and rounded nodes being primarily chosen for sampling. An 18 gauge needle is rotated within the lymph node whilst suction is applied via connecting plastic tubing. FNAC increases the speci®city of ultrasound in detecting lymph node metastases to 100%.15,37,38 However, reported sensitivities remain between 50 ± 98%15,37 ± 39 and depend on whether the study population includes patients with N0 necks, since these lymph nodes will be smaller and more dicult to aspirate. Direct comparisons of US-guided FNAC with CT and MRI have shown it to be the most accurate technique in staging both the clinically metastatic and normal neck.3,39 Ultrasound is better suited than the other modalities for guiding the nodal sampling since it can be performed in `real time'. However, its acceptance as an isolated investigation has been hindered by the lack of easily interpretable hard copy images as well as its time consuming and invasive nature. Its opponents have also suggested that results are predominantly a b Figure 4 (a) T1 weighted and (b) T2 weighted sagittal MRI scans demonstrate a large pathological deep cervical lymph node (level two/ three) which is of intermediate signal on T1 and high signal on T2 Dentomaxillofacial Radiology Figure 5 US image of a deep cervical (level four) lymph node in a patient with a nasopharyngeal SCC. The nodal hilum is hyperechoic relative to the hypoechoic peripheral cortex. The increased size (14 mm) and the eccentric cortical widening are indicators of malignant involvement Malignant lymphadenopathy SEJ Connor and JFC Olliff re¯ection of the operator's expertise, even though interoperator variability has been demonstrated to be low.15 However, its imperfect sensitivity remains problematic, particularly for the N0 neck. Positron emission tomography Most head and neck PET imaging is performed with the radiolabelled glucose analogue 18FDG which has increased uptake in viable malignant tumour due to enhanced glycolysis. The uptake can be mapped by two opposing detectors which are able to construct a three dimensional representation of the tracer distribution. The result can be expressed as a standardised uptake value (SUV), with those values greater than two being considered abnormal. PET scanning provides functional rather than anatomical imaging. This overcomes some of the disadvantages of US, CT and MRI since it does not rely on structural change but rather on the ability to map metabolism or function. Sensitivities of up to 90% and speci®cities of up to 94% have been recorded for individual lymph nodes in FDG-PET studies11,40 and direct comparisons with CT, US and MRI have shown it to be at least as accurate.11,13,40,41 Some of the false positive results are due to uptake in reactive or granulomatous lymph nodes.11 This distinction between tumour and in¯ammation may not be achievable with FDG-PET and may require the use of other substances labelled with positron emitters such as 11CH3 methionone.40,42 Sensitivity will be limited by the low spatial resolution of PET. However, current scanners can detect malignant lymph nodes less than 5 mm11,40 which would be negative on anatomical size criteria. Sensitivity and speci®city will vary with visual interpretation of the PET scans,43 and whilst this is partially overcome by measuring the SUV, borderline values still represent a problem. Since FDG-PET is able to measure tumour metabolism, it also oers the potential to evaluate tumour proliferation rate and tumour hypoxia which may help guide therapy.41 Tracer uptake has already been shown to be associated with aggressive tumours and a poor outcome.44 PET scanning is a relatively expensive modality due to the high cost of both the scanner and the radiopharmaceutical. However, cost eectiveness has been demonstrated by contraindicating surgery in nonresectable tumours.45 More recently, conventional gamma cameras have been adapted to image the higher energy gamma rays of positron emitters but these scanners have reduced sensitivity. Although spatial resolution continues to improve on newer PET scanners, there is not the anatomical detail, such as bony erosion, soft tissue in®ltration and vascular invasion, that is vital for surgical planning. The anatomical localization of MRI may be combined with the functional imaging of PET (Figure 6) by combining the two images in `fusion images' or `co-registration'.46 A particularly useful role of PET is in localising occult primary tumours in the presence of metastatic cervical lymphadenopathy. These head and neck tumours are frequently small and submucosal and are therefore elusive in 3 ± 6% of patients despite anatomical imaging, panendoscopy and biopsy of likely primary sites.47 FDG-PET has been shown to establish the location of primary malignancy in 47% of patients as compared with 33% using CT and MRI. No patients with negative PET studies subsequently demonstrated an overt primary focus.48 137 Speci®c imaging features and tumour types Extranodal spread and invasion of surrounding structures The presence of tumour outside the nodal cortex is associated with a 50% decrease in 5-year survival, increases the risk of local recurrence by tenfold8 and may indicate the need for postoperative radiotherapy.49 Recognition of extracapsular spread in a normal sized node will help distinguish tumour involvement. Therefore it is a useful feature to identify on imaging. CT ®ndings that indicate extranodal spread include irregular nodal boundaries and in®ltration of adjacent fat planes. These criteria are only accurate if the patient has not had recent surgery, radiation therapy or infection in the area.9,10 Although similar ®ndings may be evident using MRI, CT has been shown to be more speci®c in determining extranodal spread.24 US may detect hypoechogenicity and loss of fat planes in surrounding tissues but its ability to detect extranodal spread has not been fully evaluated. Once extracapsular spread has occurred, vital structures such as blood vessels, nerves and skull base in the near vicinity are under threat. No current imaging study can accurately predict carotid invasion. If greater than 2708 circumference of the artery is in contact with the tumour on CT (Figure 7) then there is a strong possibility that adherent tumour will necessitate surgical sacri®ce of the vessel.50 Greater accuracy may be achieved with US in which the arterial wall is normally depicted by an echogenic band, which is lost when in®ltrated with tumour.51 Carcinomatous extension of lymph nodes into the skull base is best seen on coronal scans. Early cortical bone erosion is best demonstrated by CT whilst marrow in®ltration, intracranial and dural extension is well documented by MRI.10 Residual and recurrent nodal disease Residual and recurrent disease may occur in the cervical lymph nodes following treatment. Random biopsies are often non-diagnostic and biopsy-initiated necrosis following radiotherapy may lead to devastating complications. Thus timely non-invasive evaluation of residual or recurrent lymph node disease would be a great asset. Following surgery and radiotherapy, normal anatomical structures become extensively distorted and Dentomaxillofacial Radiology Malignant lymphadenopathy SEJ Connor and JFC Olliff 138 a (i) (ii) (iii) (iv) Dentomaxillofacial Radiology Malignant lymphadenopathy SEJ Connor and JFC Olliff lymph nodes may be mimicked by haematoma, focal scar tissue, abscesses or pseudo-aneurysm.52 As well as limiting clinical examination, this makes anatomical assessment with US, MR and CT dicult. In the months following radiotherapy, there may be a general shrinkage of metastatic nodes, but there are no morphological features to distinguish nodes that contain residual or recurrent tumour from these which have been successfully treated.53 Once recurrent lymph node involvement has been diagnosed, MR or CT is indicated to establish the anatomical extent of disease. There is an even greater role for functional imaging in the post-therapy patient. Most series have looked at primary site recurrence41,42 However, recurrence of nodal disease has been detected with a sensitivity of greater than 90%54 which makes it a useful ®rst step in assessing the patient with equivocal clinical ®ndings. None the less the shortcomings of FDG-PET in distinguishing tumour from in¯ammation are a particular problem following radiation or surgery when uptake may be seen in the post-surgical bed for at least 3 months and in areas of radionecrosis. Pretreatment with steroids or antibiotics may reduce the number of false positive diagnosis, but patients with positive FDG-PET scans and negative biopsies will remain a serious problem. Cervical lymph node lymphoma After squamous cell carcinoma, lymphoma is the second most common malignancy to aect the extracranial head and neck.55 Nodal non-Hodgkin's lymphoma (NHL) is he most common manifestation and most frequently of a large cell subtype.55 Although there is considerable variation in the imaging appearances, a distribution of multiple bilateral lymph nodes is suspicious for lymphoma (Figure 8). Deep cervical chains are frequently involved55,56 but nodes in the submental, submandibular, retropharyngeal or posterior triangle regions are more suggestive because these are less typical drainage routes for squamous cell carcinomas.56,58 Contrast-enhanced CT scanning reveals homogenous, clearly delineated lymph nodes which occasionally enhance.10 Irradiation may lead to nodal necrosis or calci®cation.10,55 US features which are useful in dierentiating NHL from other metastases include distal enhancement and lack of nodal necrosis.57 Hodgkin's disease is more likely than NHL to cause contiguous lymph node enlargement and extranodal sites are less common. A high index of suspicion for lymphoma is required in order to avoid unnecessary surgical procedures and to prevent a vain search for an occult primary squamous cell carcinoma. 139 Other metastatic disease Cervical lymph nodes may also be involved by metastatic disease other than head and neck squamous cell carcinoma. Thyroid carcinoma, salivary gland tumours, hypernephroma, breast carcinoma, cervical carcinoma and lung carcinoma have all been reported to metastasise to cervical lymph node sites.53,58 Thyroid papillary carcinoma has already spread to the cervical nodes in 50% of cases at presentation.59 This may b Figure 6 (a) 18FDG PET images demonstrating uptake in the nasopharyngeal region (axial (i) and coronal (ii)) at the site of a nasopharyngeal primary SCC and on the left side of the neck (axial (iii) and coronal (iv)) at the site of level three malignant nodal involvement. (b) Axial post gadolinium T1-weighted MRI image demonstrates a left sided nasopharyngeal SCC (arrow) with superior anatomical detail. (Images courtesy of Dr P. Guest, Queen Elizabeth Hospital, Birmingham) Dentomaxillofacial Radiology Malignant lymphadenopathy SEJ Connor and JFC Olliff 140 a b Figure 7 Axial CT scan with intravenous contrast demonstrates a large left deep cervical (level three) lymph node mass surrounding the left common carotid artery (arrow) indicating that the artery may need to be sacri®ced at surgery Figure 9 Axial CT scans (a) and (b) with intravenous contrast demonstrate recurrent cervical lymphadenopathy at multiple levels in a patient who had previously undergone a total thyroidectomy for a papillary carcinoma of the thyroid. The intense enhancement of the right level three and four lymph nodes (arrowheads) with intravenous contrast is characteristic of these metastases Figure 8 STIR MRI coronal image demonstrating bulky bilateral cervical lymph node enlargement (arrowheads) in a patient with nonHodgkin's lymphoma produce homogenous nodes, extensive nodal necrosis leading to the appearance of a benign cyst, intensely contrast enhancing nodes or, rarely, high attenuation nodes due to local haemorrhage10 (Figure 9). The presence of thyroid protein or haematoma may manifest as increased signal on T1-weighted MRI.10 The most common infraclavicular tumours to metasDentomaxillofacial Radiology tasise to cervical lymph nodes are breast, lung and renal carcinomas. The presence of supraclavicular and inferior posterior triangle lymph node enlargement should alert the radiologist to the possibility of an infraclavicular tumour.53 Renal carcinoma also causes hypervascular lymph nodes which may haemorrhage and undergo central necrosis.10 Current impact of imaging It is clear that the various imaging modalities oer unique abilities but that none are able to challenge the gold standard of histopathological examination of the neck dissection. The choice of imaging or whether to perform imaging at all, depends largely on local availability, whether and how the primary tumour is Malignant lymphadenopathy SEJ Connor and JFC Olliff imaged, and the surgeon's preference in each clinical scenario. In turn, the relevance of false positive and false negative imaging results depend on how the nodal disease is managed. The management of the clinically N0 neck has been particularly controversial. More than 25% of patients who present with head and neck tumours and no palpable lymph nodes have cervical lymph node metastases. Although a discussion of the therapeutic options60 is beyond the scope of this article, in general prophylactic radiotherapy or surgery is widely practised if the risk of occult metastases is felt to be greater than 20 ± 30%.8 This assessment is based on the site, thickness, T staging, histological dierentiation and identi®able molecular markers of the primary tumour.60,61 However such management will lead to overtreatment in the majority of cases and it is argued that elective surgery may not oer a therapeutic advantage over a `wait and see' policy.62,63 In addition, radiotherapy makes subsequent clinical and imaging assessment dicult. If the risk of occult metastases can be suciently diminished by the presence of normal lymph node imaging, then it may be possible to avoid elective surgery and monitor the lymph nodes. In order to select patients who do not need elective surgery, a highly sensitive imaging modality with highly sensitive criteria is more important than speci®city since undertreatment is not as acceptable as overtreatment. This has led to further re®nements of the optimal size criteria31 and the use of sensitive, but not speci®c, modalities such as PET.42 Unfortunately in the N0 neck, sensitivities are likely to be lower due to a greater incidence of micrometastases and therefore radiologically occult disease.12 Another way in which imaging techniques may in¯uence disease management is in the selection of conservative surgery for the node-positive neck. Modi®ed radical neck dissections which preserve one or more non-lymphatic structures or selective neck dissections which preserve one or more lymph node groups64 may be used in the N1- neck and preserve function more eectively than the traditional radical neck dissection. The decision as to which neck dissection to perform depends on the risk of nodal metastases at each level and accurate imaging should help facilitate this decision. Finally, imaging studies may help guide management of the contralateral neck (the opposite side to the primary tumour). In stage T2c or more tumours, or in tumours at sites such as the tongue base, nasopharynx or supraglottis, there is an increased likelihood of bilateral nodal metastases even if there are no palpable nodes on the contralateral side. Imaging can be used in a similar capacity to an ipsilateral N0 neck and there remain the same shortcomings. 141 Conclusion We have outlined the current imaging techniques used to evaluate malignant cervical lymphadenopathy, and their potential in¯uence on therapy. Current imaging improves on clinical staging but does not detect the micrometastases, which are found in 25% of N0 neck dissections, reliably.13 Hence, our current modalities cannot alone dictate whether and how to operate, but should play a signi®cant role in the multifactorial decisions concerning treatment. Innovations such as PET imaging, novel MRI contrast agents and FNAC show promise and need to be reappraised continually in the light of advancing technology. Advances in imaging should be used alongside other non imaging strategies in order to achieve the goal of minimal morbidity without overtreatment. References 1. Batsakis JG. Squamous cell carcinoma of the oral cavity and the oropharynx. In: Tumors of the head and neck. Clinical and pathological considerations, 2nd (ed). Baltimore: Williams and Wilkins 1979 pp 240 ± 250. 2. Friedman M, Roberts N, Kirshenbaum G, Colombo J. Nodal size of metastatic squamous cell carcinoma of the neck. Laryngoscope 1993; 103: 854 ± 856. 3. 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