Sonographic evaluation of cervical lymphadenopathy: is power Doppler sonography routinely indicated?

doi:10.1016/S0301-5629(02)00759-7

● Original Contribution

SONOGRAPHIC EVALUATION OF CERVICAL LYMPHADENOPATHY: ISPOWER DOPPLER SONOGRAPHY ROUTINELY INDICATED?

ANIL AHUJA and MICHAEL YINGDepartment of Diagnostic Radiology and Organ Imaging, Prince of Wales Hospital, The Chinese University of

Hong Kong, Shatin, NT, Hong Kong

(Received 11 June 2002; in final form 20 November 2002)

Abstract—Routine sonographic examination of neck nodes now includes both grey-scale and Doppler sonogra-phy. Although the addition of Doppler sonography to the well-established practice of grey-scale sonographyincreases the amount of information obtained by sonography, it also increases the examination time, particularlyif spectral Doppler and estimation of vascular resistance is performed. This study was, therefore, undertaken toevaluate whether Doppler sonography is routinely indicated in every case or its use should be limited to thosecases where grey-scale sonography is equivocal. We evaluated the grey-scale and power Doppler sonograms of101 fine-needle aspiration cytology (FNAC)-proven metastatic nodes and 72 FNAC-proven nonmetastatic nodes.All lymph nodes were evaluated with grey-scale and power Doppler sonography. The shape, echogenicity,internal architecture, vascular distribution and vascular resistance of the lymph nodes were evaluated. Grey-scale sonographic features evaluated in this study had a high sensitivity (95%) and specificity (83%) in classifyingmetastatic and nonmetastatic nodes. Metastatic and nonmetastatic lymph nodes that could not be classified bygrey-scale sonography demonstrated Doppler features that helped in their correct identification. Power Dopplersonography is not necessary for every case in routine clinical practice, but is essential and useful in patients wheregrey-scale sonography is equivocal. In this study, power Doppler sonography aided in the diagnosis in 5% and17% of patients with metastatic and nonmetastatic nodes, respectively. (E-mail: [email protected]) ©2003 World Federation for Ultrasound in Medicine & Biology.

Key Words: Grey-scale sonography, Power Doppler sonography, Metastases, Nonmetastatic, Cervical nodes.

INTRODUCTION

Assessment of cervical lymph nodes is essential forpatients with head and neck carcinomas because it helpsto determine the prognosis and select appropriate treat-ment (Baatenburg de Jong et al. 1989; Ishii et al. 1991;Vassallo et al. 1992). The presence of a metastatic nodein one side of the neck reduces the 5-year survival rate tohalf of that of a patient without a metastatic node, and thepresence of bilateral metastatic neck nodes reduces thesurvival rate to 25% (Som 1992).

The role of grey-scale sonography in evaluation ofcervical lymphadenopathy is well established. Grey-scale sonography evaluates the morphology, internalarchitecture, size and shape of the lymph nodes (van

den Brekel et al. 1990; Vassallo et al. 1992, 1993;Ahuja et al. 1997; Baatenburg de Jong et al. 1998).Power Doppler sonography allows evaluation of vas-cular distribution of cervical lymph nodes, and esti-mation of vascular resistance of intranodal vessels.There are a number of reports discussing the use ofDoppler ultrasound (US) in evaluation of neck nodes(Adibelli et al. 1998; Ariji et al. 1998; Wu et al. 1998a,2000; Dragoni et al. 1999). Our previous study docu-mented an overview of the sonographic appearances ofdifferent cervical lymphadenopathies (Ahuja and Ying2002). The addition of power Doppler sonography ofneck nodes does add to the examination time, whichincreases by 2 min if the use of Doppler is restricted toevaluating distribution only. However, if vascular in-dices are evaluated, the time taken is approximately 10min per node. This study was, therefore, undertaken toanswer a clinical problem; that is, is power Dopplersonography routinely indicated in all cases or shouldits use be limited to cases where grey-scale sonogra-phy was equivocal?

Address correspondence to: Dr. Anil Ahuja, Department of Di-agnostic Radiology and Organ Imaging, Prince of Wales Hospital, TheChinese University of Hong Kong, Shatin, NT, Hong Kong. E-mail:[email protected]

Dr. Ying’s present address is Department of Optometry andRadiography, The Hong Kong Polytechnic University, Hung Hom,Kowloon, Hong Kong.

Ultrasound in Med. & Biol., Vol. 29, No. 3, pp. 353–359, 2003Copyright © 2003 World Federation for Ultrasound in Medicine & Biology

Printed in the USA. All rights reserved0301-5629/03/$–see front matter

353

MATERIALS AND METHODS

We retrospectively evaluated neck node sonogramsof 101 patients with known carcinoma of the head andneck or other regions, and fine-needle aspiration cytol-ogy (FNAC)-proven malignant lymph nodes in the neck.Another group consisted of 72 patients with no knowncarcinoma (in the head and neck or any other regions),and FNAC-proven reactive lymph nodes. These patientssubsequently had follow-up in the outpatient departmentand remained well otherwise. The lymph nodes of thesetwo groups of patients were examined using the samescanning protocol.

In the 101 patients with metastatic nodes, all had aknown primary; 41 patients had head and neck squamouscell carcinomas (SCC) (tongue 12 patients, pyriformfossa 7 patients, larynx 6 patients, tonsil 4 patients,pharynx 3 patients, 2 patients each for nasal cavity,alveolar, floor of mouth, and 1 patient each for softpalate, hypopharynx, maxilla), 26 had nasopharyngealcarcinoma (NPC) and 34 patients had infraclavicularprimaries (lung 13 patients, breast 5 patients, cervix 4patients, oesophagus 3 patients, 2 patients each for colonand stomach, 1 patient each for adrenal, liver, ovary,pancreas and testis). None of these patients had under-gone previous radiotherapy of the tumor or the nodes atthe time of the examination.

The lymph nodes were evaluated to classify anddocument how many of these nodes had grey-scale fea-tures that would suggest malignancy. Because, in ourinstitution, power Doppler sonography is routinely per-formed on all neck nodes, the same nodes were alsoevaluated for the presence of Doppler features that wouldhelp to classify them as malignant. In each patient, grey-scale sonography was performed on multiple nodes bythe same radiologist (A. Ahuja), and the largest node wasincluded in the study, which was then assessed withpower Doppler sonography by the same sonographer (M.Ying). To prevent operator bias, the sonologist who didthe grey-scale US was unaware of Doppler features andthe sonographer who did Doppler restricted himself toevaluating only Doppler parameters. FNA was then per-formed on the largest node. US examinations were per-formed with a 12- to 5-MHz linear transducer (Philips,HDI 5000, Bothell, WA). On grey-scale sonography,lymph nodes were assessed for their distribution, shape,internal architecture and echogenicity. The shape of thelymph node was determined by the short axis to long axisratio (S:L). An S:L ratio less than 0.5 indicates a long oroval node, whereas greater than or equal to 0.5 indicatesa round node (Fig. 1) (Vassallo et al. 1992, 1993).

The internal architecture of lymph nodes was as-sessed for the presence or absence of cystic necrosis (Fig.2) and echogenic hilus (Sakai et al. 1988; Evans et al.

1993).Echogenicity of the lymph nodes was compared

with the adjacent muscles and classified as being hypo-echoic, isoechoic or hyperechoic.

For grey-scale sonography, lymph nodes were con-sidered to be metastatic if they demonstrated intranodalnecrosis or if they met at least three of the followingcriteria:

1. Short axis to long axis (S:L) ratio � 0.5 (this criterionis not applicable to submandibular nodes becausenormal submandibular nodes are also round) (Ying etal. 1996).

2. Hypoechoic3. Absence of echogenic hilus

Fig. 1. Transverse sonogram shows a round malignant node(arrows).

Fig. 2. Sonogram shows a malignant node (arrows) with in-tranodal cystic necrosis (arrowheads).

354 Ultrasound in Medicine and Biology Volume 29, Number 3, 2003

4. In the drainage site of the primary (Ahuja et al. 1997).

Lymph nodes were considered to be nonmetastatic ifthey demonstrated at least two of the followingfeatures:

1. Short axis to long axis (S:L) ratio � 0.5 (this criterionis not applicable to submandibular nodes)

2. Presence of echogenic hilus3. In the submandibular, parotid, upper cervical regions

and posterior triangle, where normal lymph nodes arecommonly seen in Oriental populations (Ying et al.1996, 2000).

On power Doppler sonography, the vascular distri-bution and intranodal vascular resistance were evaluatedduring real-time scanning. In all patients, power Dopplersonography was performed using standardized parame-ters (Cosgrove et al. 1993; McNicholas et al. 1993;Ahuja et al. 2001b). Settings of the power Doppler USwere set for high sensitivity, with a low wall filter toallow detection of vessels with low blood flow. Pulse-repetition frequency (PRF) was 700 Hz and mediumpersistence was used. The color gain was adjusted untilthe color was just apparent. When consistent Dopplersignals were obtained, the color map was used to guidethe placement of the pulsed Doppler gate and tracings ofthe arterial signal recorded using a sample volume of 1

Fig. 3. Power Doppler sonogram of a reactive node with hilarvascularity (arrows).

Fig. 4. Power Doppler sonogram of a malignant node withcapsular vascularity (arrow).

Fig. 5. Power Doppler sonogram of a malignant node with hilar(arrows) and capsular (arrowheads) vascularity.

Fig. 6. Power Doppler sonogram of a reactive node withoutvascular signal (apparently avascular).

Sonography of cervical nodes ● A. AHUJA and M. YING 355

millimeter (mm). The vascular resistance was evaluatedat random sites within three vessels that consistentlydemonstrated three consecutive Doppler spectral wave-forms. The mean resistive index (RI) and pulsatilityindex (PI) were estimated.

The vascular patterns of lymph nodes were classifiedinto four main categories according to the location of thevascularity:

1. Hilar � flow signals branching radially from the hilusand the signals are not along the periphery of thenodes (Fig. 3)

2. Capsular (or peripheral) � flow signals along theperiphery of the lymph nodes, with branches perfo-rating the periphery of the node and not arising fromthe hilar vessels (Fig. 4)

3. Mixed � presence of hilar and capsular flow (Fig. 5)4. Apparently avascular � absence of vascular signals

within the lymph nodes (Fig. 6).

For power Doppler sonography, lymph nodes wereconsidered to be metastatic if they demonstrated at leastone of the following criteria: 1. Presence of peripheral ormixed vascularity, 2. RI � 0.8, and 3. PI � 1.6.

Lymph nodes were considered to be nonmetastatic ifthey demonstrated at least one of the following criteria:1. Presence of central vascularity, absence of peripheralvascularity or apparent avascularity, 2. RI � 0.8, and 3.PI � 1.6.

The number of lymph nodes that were correctlyclassified solely by grey-scale sonography, solely bypower Doppler sonography and by a combination ofgrey-scale and power Doppler sonography were re-corded. When power Doppler sonography is routinelyperformed, the grey-scale information cannot be sup-pressed because the color signals are overlayed on thegrey-scale image. However, we focused on the Dopplerfeatures of the lymph nodes, such as vascular pattern andresistance.

RESULTS

A total of 173 lymph nodes were included in thestudy. They ranged in size from 4 mm to 36 mm inmaximum short axis diameter. There were 36 (87.8%)metastatic nodes from SCC, 25 (96.2%) metastatic nodesfrom NPC, 28 (82.3%) metastatic nodes from infracla-vicular carcinomas and 30 (41.7%) reactive nodes with amaximum short axis diameter greater than or equal to 8mm.

Table 1 shows the number of metastatic and non-metastatic nodes that were correctly classified solely bygrey-scale sonography, solely by power Doppler sonog-raphy, or by the combination of grey-scale and powerDoppler sonography. Of metastatic nodes, 95% (true-

positive, 96 of 101) and of nonmetastatic nodes, 83.3%(true-negative, 60 of 72) were correctly classified withgrey-scale sonography. Those lymph nodes that couldnot be correctly diagnosed by grey-scale sonographydemonstrated Doppler features that would help in theircorrect identification. Results show that there is a signif-icant improvement in the classification of metastatic andnonmetastatic lymph nodes when power Doppler sonog-raphy was combined with grey-scale sonography in thediagnosis (p � 0.05 for metastatic and nonmetastaticnodes).

Using grey-scale sonography alone, 95% (96 of 101nodes) of metastatic nodes demonstrated features thatwould have helped to classify them as malignant nodes.Five metastatic nodes were not classified by grey-scalesonography; 1 of these 5 had an S:L � 0.5 and wasisoechoic when compared to adjacent muscles. Fournodes were not in the drainage site of the primary and 2of them were isoechoic, 1 node had an echogenic hilusand 1 node had echogenic hilus and an S:L � 0.5.Therefore, incorrect diagnoses in grey-scale sonographywere mainly due to the presence of metastatic nodes notin the expected drainage site of the primary (4 of 5 nodes,80%), isoechogenicity (3 of 5 nodes, 60%), presence ofan echogenic hilus (2 of 5 nodes, 40%) and S:L � 0.5 (2of 5 nodes, 40%). When power Doppler sonography wasused on these 5 nodes, 2 nodes showed peripheral vas-cularity and 3 nodes demonstrated both hilar and periph-eral vascularity. In these 5 metastatic nodes, 3 of themhad a RI � 0.8 and PI � 1.6, one node had a RI and PIless than 0.8 and 1.6, respectively, and in one nodeintranodal vascular resistance could not be accuratelyestimated.

When the metastatic nodes were evaluated by powerDoppler features alone, 91 (90%) of 101 metastaticnodes could be correctly classified. The 10 nodes, whichcould not be classified by power Doppler sonography,included 8 apparently avascular nodes and 2 nodes withhilar vascularity and RI � 0.8 and PI � 1.6.

For the nonmetastatic nodes, 60 of 72 nodes dem-onstrated features of benignity on grey-scale featuresalone (83%). In the 12 nonmetastatic nodes that could

Table 1. Number of metastatic and nonmetastatic nodesclassified by grey-scale and power Doppler sonography

Number of lymph nodes (%)

Metastases(n � 101)

Nonmetastases(n � 72)

Grey-scale sonography 96 (95.0) 60 (83.3)Power Doppler sonography 91 (90.1) 72 (100)Grey-scale sonography �

power Doppler sonography 101 (100) 72 (100)


not be classified, 10 of them were present at sites wherenormal nodes are not routinely visualized, had an S:L �0.5 and did not demonstrate echogenic hilus. Anothertwo nodes had an S:L � 0.5 and did not show echogenichilus. Therefore, incorrect identification of nonmetastaticnodes by grey-scale features alone were mainly due totheir presence at unexpected sites and absence of anechogenic hilus. When these 12 nonmetastatic nodeswere further evaluated with power Doppler sonography,all of them showed normal hilar vascularity, even innodes that did not show a echogenic hilus on grey-scalesonography (Ahuja et al. 2001a). In this study, 11 of 72nonmetastatic nodes did not show echogenic hilus ongrey-scale sonography, but all the 11 nodes showed hilarvascularity on power Doppler sonography. In these 11nonmetastatic nodes, 10 nodes had a RI � 0.8 and PI �1.6, and 1 node had a RI � 0.8 and PI � 1.6.

When the 72 nonmetastatic nodes were evaluatedwith power Doppler sonography, 71 nodes showed hilarvascularity and 1 node appeared apparently avascular,consistent with the known vascular patterns of nonmeta-static nodes.

Tables 2 to 4 show the performance of grey-scalesonography, power Doppler sonography and a combina-tion of the two methods, respectively, in classifyingmetastatic and nonmetastatic lymph nodes. There is ahigh sensitivity, specificity, positive predictive value andnegative predictive value of grey-scale (95%, 83%, 89%,92%, respectively) and power Doppler sonography(90%, 100%, 100%, 88%, respectively) in classificationof metastatic and nonmetastatic nodes. The performanceis improved when combining the two methods (100% for

sensitivity, specificity, positive predictive value and neg-ative predictive value).

DISCUSSION

Sonography of neck nodes in routine clinical prac-tice consists of two parts, grey-scale sonography andDoppler sonography. The role of grey-scale sonographyin evaluation of cervical nodes is well established(Bruneton et al. 1984; Baatenburg de Jong et al. 1989;Chang et al. 1990; van den Brekel et al. 1990; Ahuja etal. 1997; Ying et al. 1998), and power Doppler sonog-raphy has also been reported to be an imaging tool thatprovides further information about the vasculature ofcervical nodes and helps in the differential diagnosis(Giovagnorio et al. 1997; Ariji et al. 1998; Wu et al.1998a, 1998b). This study evaluated the accuracy ofgrey-scale features in differentiating metastatic fromnonmetastatic nodes and investigated the extent of im-provement when combined with power Doppler sonog-raphy.

In patients with a known primary, when lymphnodes show intranodal cystic necrosis or, at least, threeabnormal features (S:L � 0.5, hypoechoic, absence ofechogenic hilus, located in the known drainage site of theprimary) on grey-scale sonography, power Dopplersonography may not be indicated. In this study, 95% ofmetastatic nodes were classified with grey-scale sonog-raphy based on these criteria, showing a sensitivity of95% of grey-scale sonography in classifying metastaticnodes in patients with a known primary. However, inlymph nodes without intranodal cystic necrosis and withonly two or less abnormal features on grey-scale sonog-raphy alone, power Doppler sonography may be neces-sary to confirm the diagnosis. The identification of pe-ripheral vascularity is a useful feature for the diagnosisof a malignant node. In this study, those metastatic nodesthat could not be classified by grey-scale sonographyshowed peripheral vascularity with power Dopplersonography. Therefore, with the combination of grey-scale and power Doppler sonography, the sensitivity inclassifying metastatic nodes is 100%.

Table 2. Performance of grey-scale sonography in classifyingmetastatic and nonmetastatic lymph nodes

US (GS) Pathology � � Total

� 96 TP 12 FP 108� 5 FN 60 TN 65Total 101 72 –

Sensitivity 95%; specificity 83%; positive predictive value 89%;negative predictive value 92%.

Table 3. Performance of power Doppler sonography inclassifying metastatic and nonmetastatic lymph nodes

US (PDS) Pathology � � Total

� 91 TP 0 FP 91� 10 FN 72 TN 82Total 101 72 –


Table 4. Performance of combining grey-scale and powerDoppler sonography in classifying metastatic and

nonmetastatic lymph nodes

US (GS � PDS) Pathology � � Total

� 101 TP 0 FP 101� 0 FN 72 TN 72Total 101 72 –



For the patients without a known primary, whenlymph nodes show at least two normal features (S:L �0.5, except submandibular nodes, presence of echogenichilus, in the location where normal nodes are usuallyfound) on grey-scale sonography, power Doppler sonog-raphy may not be indicated. In this study, 83% of non-metastatic nodes were correctly classified by grey-scalesonography based on these criteria above, showing aspecificity of 83% of grey-scale sonography in classify-ing nonmetastatic nodes in patients without a knownprimary. However, when lymph nodes show one or noneof these normal features, power Doppler sonographyshould be used. The presence of solely central vascular-ity is a useful feature to suggest a nonmetastatic node. Inthe present study, all the nonmetastatic nodes that werenot classified by grey-scale sonography, showed solitarycentral vascularity with power Doppler sonography.

The high level of discrimination of lymph nodesfound in this study is because of the strict criteria forclassification of metastatic and nonmetastatic nodes ongrey-scale sonography, and also because of the highsensitivity of power Doppler sonography in detection ofintranodal vessels, which helps identification of the vas-cular pattern of the lymph nodes. Optimal setting ofpower Doppler sonography was used to optimize thedetection of intranodal vessels. Low wall filter was usedto allow detection of vessels with low blood flow, and thecolor gain was adjusted until the color was just apparent,so that it has a high sensitivity in blood vessel detectionwith minimal noise.

When power Doppler sonography was used, therewas a high specificity (100%) and it is because of the factthat all nonmetastatic nodes showed solitary central vas-cularity or appeared apparently avascular. Because noneof the nonmetastatic nodes showed peripheral vascular-ity, the presence of peripheral vascularity was stronglysuggestive of metastatic and, thus, the positive predictivevalue of power Doppler sonography is 100%.

Because the sensitivity (95%), positive predictivevalue (89%) and negative predictive value (92%) ofgrey-scale sonography are high, metastatic and nonmeta-static nodes can be accurately classified with this tech-nique. The relatively lower specificity (83%) of grey-scale sonography is due to the high false-positive rate(17%); however, these false-positive nodes can be clas-sified with power Doppler sonography, where they showcentral vascularity or appear apparently avascular, orthey can be confirmed with FNAC.

This study found that identification of vascular pat-tern is adequate for diagnosis. Therefore, measurementof RI and PI is not necessary in routine clinical practice,thus reducing the examination time.

CONCLUSION

Grey-scale sonography has a high accuracy in clas-sifying metastatic and nonmetastatic nodes. Therefore,power Doppler sonography may not be indicated in ev-ery case in routine practice, but should be used for thosecases where grey-scale sonography is equivocal.

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Sonographic evaluation of cervical lymphadenopathy: is power Doppler sonography routinely indicated?

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