Endoscopic Ultrasound Examination for Mediastinal Lymph Node Metastases of Lung Cancer

Endoscopic Ultrasound Examination for Mediastinal Lymph Node Metastases of Lung Cancer* Daizo Kondo, !t1.D.; Munehisa InUlizunli, M.D.; Toshio Abe, M.D.;

Tsuguo Naruke, M.D.,

F.C.C.~;

and Keiichi Suemasu, M.D.,

Among patients with primary lung cancer who were admitted to the National Cancer Center Hospital from July 1987 to April 1988 for surgical treatments, 132 underwent preoperative transesophageal endoscopic ultrasound examination (EUS) on mediastinal lymph nodes. Of the 132 patients, 101 were pathologically evaluated and studied in this article. A GF-UM2 radial scanner with 7.5-MHz (Olympus Co Ltd) was used for image examination. The lymph nodes were diagnosed as positive for metastasis when they had thickened images, clear contours, and low echoing images of fusion or lobulation. The results obtained from 509 sites were as follows: sensitivity, 53.6 percent; speci6city, 97.5 percent; positive predictive accuracy, 77.1

A t present, Inediastinallymph node Inetastases from 1"1. primary lung cancer are nonoperatively diag-

nosed mainly by computed tOlno~raphy (CT). However, as the imaging ability of CT is not sufficient to show lymph nodes clearly and identify lymph node metastases by their sizes, the accuracy of diagnoses on clinical N stage by CT has been as low as 59.8 percent. 1 On the other hand, transesophageal endoscopic ultrasound examination (EUS) has been significantly improved in the last ten years and has been mainly For editorial comment see page 526

used in the field of gastroenterolo~. Although there have only been a few reports on the diagnostic ability ofEUS for lymph node metastases from primary lung cancer, it is worth paying attention to the diagnostic capability ofEUS.2 Among patients with primary lung cancer \vho were admitted to the National Cancer Center Hospital from July 1987 to April 1988 for surgical treatment, 132 patients undelWent EUS. Pathologic examination was made on 101 of the 132 patients. In this article, we studied the diagnostic capability of EUS on these 101 ·FrO"l the Department of Thorac'ic Sur~er}~ Na~oya (Japan) University Schoo) of Medicine (Drs. Kondo, Imaizumi, and Abe), and the Department of Sur~ery, National Cancer Center Hospital (Drs. Nantke and Suemasu), lhkyo, Japan. Manuscript rec'eived Octoher 2; revision accepted February 20. Reprint requests: Dr. Kondo, DelHlrll1u~nt of Thoracic Surl{ery, Nagoya UniV(~rsity School of Aleclicine, 6.5 Tsuru'lUli, ShOWCI-ku, Na{!,oya, AicIJi 466, jalJCln 586

F.C.C.~

percent; negative predictive accuracy, 93.1 percent; and overall accuracy, 91.6 percent. The sensitivity rate was 80.6 percent excluding the result of the right superior mediastinal lymph nodes that were difficult to examine for anatomic reasons. Although EUS was considered to be an excellent method in diagnosing lymph node metastases, it had a blind angle in the 6eld. More accurate diagnoses of mediastinal lymph node metastases could be achieved by using EUS and computed tomography (CT) (Chest 1990; 98:586-93) together.

I EUS = endoscopic ultrasound examination I patients. The mediastinal lymph node dissection and the pathologic examination were not made on the other 31 patients for various reasons: no operation because of obvious N3 nodal involvement or distant metastasis, receiving only pulmonary resection as symptomatic therapy for their pneumonia and/or hemoptysis, and receiving only exploratory thoracotomy because of dissemination. PATIENTS

The patients were 79 men and 22 women. Their a~es ran~ed from 32 to HI years (avera~e, 63.3 years). Adenocarcinoma was ohserved in 55 patients; squarnous cell carcinoma, 33 patients; small cell carcinorna, five patients; )ar~e cell carcinoma, four patients; adenosquarnous cell carcinoma, two patients; and simultaneous adenocarl'inoma and squamous cell carl'inoma, t\\'O patients. The involved areas by tumors were as f()llo\\'s: ri~ht lun~ in 50 patients (upper lobe, 29; middle lohe, five; lower lobe, 16) and left lun~ in 51 patients (upper lobe, 30; lower lobe, 20; upper and lower lobes, one). METH()OS

A GF-UM2 radial scanner \\'ith 7.5-tvtHz (Olympus Co Ltd) was used in a balloon method with deaerated water. Usin~ endoS(.'opic ultrasound observation equiplnent of EU-M2 (Olympus Co Ltd), imawn~ pictures were ree-'orded on videotapes and pictures were taken \\rith a camera (Polaroid). The premedication was performed in the same way as upper ~astrointestinalendoscopy, and the patients assumed the left lateral decubitus position durin~ EUS. The dia~nostic standard for positive metastases was based on the thickness, clearness of contours, and existence of low echo ima~es of fusion or lobulation of lymph nodes. As an ima~ed lymph node and a resected one were occasionally very difficult to identify, the metastasis was determined in an individual site. Based on the classification of Naruke et aP (Fi~ 1), the sites of Endosoopic Ultrasound in Metastatic Lung Cancer (Kondo at 8/)

••

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4. Rif,(ht tracheobronchial lymph IUKle (rif,(ht No. 4): I~K'ated on the obtuse angle level between the trachea and rif,(ht maill hronchns. with and inside the azygos veill. 5. Left tracheohronchial lymph IUKle and Botallos lymph nCKle (left No. 4 and 5): Locat..d betw....n tIl(' aortic arch. th.. I..ft pulmonary artery, and th.. obtuse anf,(le ht'lween tilt' trachea and left main bronchus. 6. Parasubcarinal lymph node (No.7. II. and 10): sllhcarinal lymph node (No.7). paraesophaf,(eal lymph IICKle (No. II). ami hilar lymph 1I0de (No. 10) adjacelltto No.7 Wt'J'(' <'"mted as 011(' ref,(ioll. as they are difficult to distillf,(uish. espedally whell th.. lymph IUKle is swollen. 7. Pulmonary lif,(ament lymph node (No.9): Located 011 tilt' posterior wall and lower part of the inft'rior pulmonary vein 8. Retrotracheal lymph node (No. 3p): u><.'ated on the posterior portion of the trachea The imaf,(inf,( ability of EUS was examined by <11l1ntinf,( th.. number of sites in which lymph nodes were imaf,(..d and til<' number of imaged lymph nodes hy EUS in 509 sites in 101 patiellts on whom histopathologic examination had heen made. Study was carried out in line with reslllts obtained hy til<' imaf,(es recorded and the histopathologic results ill terms of til<' lilllowinf,(: (I) verification of sensitivity. spt'dfidty. positive predictive accuracy, nef,(ative predictive accuracy and overall accuracy of EUS imaf,(es; (2) analysis on total imaf,(es remrded by EUS. excludinf,( imaf,(es of the rif,(ht superior mediastinal lymph 1I0d... which was in tht' hlilld angle of EUS; and (3) histolof,(ically <"nfinn..d metastatic staf,(es. At the same time, CT imaf,(es takt'lI Ii". Ihe 101 patit'nts weI''' reviewed to confirm its imaginf,( <'apahility on metaslast's to lymph nodes in sizes larger than I cm in the shor\t>st dianlt'tt'r and til<' result of the review was mmpared with thaI attained by EUS. TIlt' CT scanners used in this study were TCT60A30 amVor TCT900S ('Iilshiba Co Ltd. lilkyo). The scannillf,( tinlt' Ii,r tIlt' former machine was 4.5 s. Twelve milliliters of 65 percenl dialrizoate mef,(lumiJlt' (Anf,(iof,(raphin) was injected at I to 2 mVs in one shot. and scanninf,( of one slice at one time was started 25 s after tilt' injectioll. For th.. latter machine, the scanninf,( time was I s. One hnndred millilitt'rs of65 percent diatrizoate mef,(lumine (Anf,(iof,(raphin) was injected at 0.8 to I mVs, and scanninf,( of six to sev..n slices at ont' time WllS started 40 s after the injection. To evaluate sensitivity. specificity. positive and nt'f,(ative predidive accnracy, as well as overall accuracy of EUS in percentaf,(e. al firsl each imaf,(e was diaf,(nosed and classifit·d into four such calef,(ories as "true positive:' "true nef,(ative:' "false positiw:' and "fal,,' nef,(ative, "Ii,lIowed hy ratinf,( in percentaf,(e caleulaled for resp..divt' catef,(C,ries in such manner as follows: St'nsitivity: numbt'r of "tnlt' positive" divided hy total numher of "true positivt," and "false nef,(ative." Specificity: lIumher of "true nef,(ative" divided by lotal number of "true nef,(ative" and "false positive." Positiv(' pr..didive accuracy: numher of "true positiVI'" dividt,d by tolal IIIlInlx'r of "true positiVI'" and "false positi"t·." N('f,(ativ(' prc'dictivt' accllra<'Y:

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FIGUIIE 1. Sites of lunf,( lymph nodes (classification of Naruke et al"). mediastinal lymph nodes were divided into the followinf,( eif,(ht f,(roups, includinf,( the supraclavicular lymph node and a part of the hilar lymph node. However. the examination on the site of the paraaortic lymph node (No.6) was not made as the identification of lymph nodes was difficult in that ref,(ion. 1. Supraclavicnlar lymph node: Located at the upper part of the horizontal line at the top of the upper rim of the subclavian artery or vein. 2. lIif,(hesl mediastinal lymph node (No.1): The site is defined by Ihe horizontal line at the top of the upper rim of the suhclavian artery or vein and the horizontal line at the left point of the trachea where the upper rim of the hrachiocephalic artery ascends to the rif,(ht. crossinf,( in front of the trachea. 3. Paratracheal and pretracheal lymph node (No. 2 and 3): hetween No. I and No.4

Table I-Results of Endoscopic Ultrasound Examination (EUS) (101 Cases with Primary Lung Cancer) in Imaging Abilities Lymph Nodes

No. of examined sitt'S No. of sites in which lymph IICKles imaf,(ed by EUS (No. of imaf,(ed lymph nodes) No. of sites in which lymph nodes imaf,(ed by CT (No. of imaJ,(ed lymph nodes)

«.tal

Supraclavicnlar

No. I

No.2 and 3

Rif,(ht No.4

Left No.4 and 5

No.7. II, and 10

HiJ,(hl No.9

l....,fl !'Ijo. H

No..1p

509 192 (482)

6 3 (8)

94 5 (10)

95 10 (15)

57 14 (20)

54 45 (120)

94 92 (274)

27 7 (I;)

29 15 (22)

5.1 I (5)

192 (326)

0 (0)

24 (42)

61 (112)

4 (6)

33 (63)

65 (96)

I (I)

2 (2)

2 (4)

CHEST I 98 I 3 I SEPTEMBER, 1990

587

node, right side of No.1, right No.2 and 3, and right No. 4 were generally impossible to be observed because of the air echoing through the trachea and bronchus, other regions were clearly and continuously observed by EUS. The number of sites in which lymph nodes were imaged and the number of lymph nodes imaged by EUS and CT were compared in Table 1. Both EUS and CT satisfactorily imaged lymph nodes in left No. 4 and 5 and No.7, 8, and 10, especially. EUS-imaged lymph nodes in almost all the cases. The lymph nodes in No.9 were rarely imaged by CT, but 22 of 56 cases were imaged by EUS. In the right superior mediastinum (the right side of No.1, right No.2 and 3, and

FI(;l'IlE 2. Ima!(..s of a m..tastatic lymph nod.. in the I.. ft tracheohronchial site (No.4). The lymph node ima!(..d hy endoscopic ultrasound ..xamination (EUS) was 16 x 18 mm in diameter with clear mntours and low ..cho ima!(e (upper). hut the same lymph node ima!(ed hy l'lmputed tomography (Cl) was 11 x 8 mm with a uniform appearance (lower). TR indicat..s trachea; AO. aorta; LPA. left pulmonary arl..ry; \( verlehra; E. esophagus; and N. lymph node.

numher of "tn... ne!(ati".... divided hy lolal numher of "Ime negalive" and "fals.. negative." Overall accuracy: total numher of "Irue positiv.... and "Iru.. negali"..·· divid..o hy tolal number of "Iru.. positive," "Iru.. Iw!(atiVt'," "false positiv..," and "false negative ... The metastases oflymph nod..s were hislopalho!o!(ically classified inlo the followin!( Ihree sla!(es: (I) milo mdaslasis: micromelastasis harely ohserved on the sinusoid; (ll) moderale metastasis: melaslasis helween I and Ill; and (III) s..vere melastasis: melaslasis invaded lIIore Ihan half of Ihe lymph node. The dia!(noslic capahilily of EUS in delerminin!( Ihe metaslatic Shl!(eS of Ihe lymph nooe was evalualed hy compariug Ihe results of EUS with Ihe ahov..-mentioned hislopalholo!(ic c1assificalion. RESULTS

The 111U1ging Ability of Lymph Nodes of EUS

Although the right side of the supraclavicular lymph 588

FIGURE 3. Images of a melaslatic lymph node in Ihe suhcarinal site (No.7). The lymph node imaged by endosmpic ultrasound examinalion (EUS) was 20x8 mm in diameter with dear l'Ontours and lohulated low echo image (upper). whereas the same lymph node ima!(ed hy computed lomo!(raphy (cr) was 13 x 8 mm with a uniform appearance (lower). LMB indicates left main bronchus; RMB, ri!(hl main hrouchus; LPA, left pulmonary artery; RPA, ri!(ht pulmonary artery; AO, aorta; V. vertehra; E, esophagus; and N, lymph node.

Endoscopic

U~rasound

in Melastatic lung Cancer (Kondo et a/)

o Lymph nodes diagnosed as negati,e of metastasis Shortest diameters •

LYRlph nldes diagnosed as positi,e of Rletastasis

(mm) 1

0.0- 5.0 5.0-10.0

:=================:~2~ 0

201

10.0-15.0 15.0- 20.0

o

50

100

150

Number of lymph nodes FIGURE

(EUS).

4. Sizes of mediastinal lymph nodes (482 pes) imaged by endoscopic ultrasound examination

right No.4), it was difficult to image lymph nodes by EUS except significantly enlarged ones. Except for the region of the right superior mediastinum, the numbers of imaged lymph nodes per one region were 1.6 by CT and 2.7 by EUS. There were some cases in which lymph nodes were imaged as one by CT but revealed as plural by EUS. Thus, the more detailed properties of each lymph node (configuration of marginal line, metastatic lobulation, etc, and internal echo) were observable by EUS compared with CT (Fig 2 and 3). Four hundred eight-two lymph nodes were imaged by EUS, of which 238 (49.4 percent) were less than 5 mm in the shortest diameter, 201 (41.7 percent) were between 5 and 10 mm. Among them, 45 (60.0 percent) of 75 metastatic lymph nodes diagnosed as positive by EUS were sized between 5 and 10 mm (shortest diameter) (Fig 4). The Diagnostic Ability of EUS to Detect Lymph Node Metastases

Among 509 sites studied, 69 were histopathologically positive for metastasis, but in the results of E US examination, 75 lymph nodes in 48 sites were positive (Table 2). The metastases in each site were accurately

diagnosed except the right superior mediastinum. The lymph nodes on the right superior mediastinum were difficult to be imaged, but once they were ima~ed, the accurate diagnoses were obtained. The comparison of the diagnostic results obtained by EUS and CT were summarized in Table 3. The results obtained by EUS in 509 sites were as follows: sensitivit~ 53.6 percent; specificity, 97.5 percent; positive predictive accuracy, 77.1 percent; negative predictive accuracy, 93.1 percent; and overall accuracy, 91.6 percent. The number of sites, excluding the right superior mediastinum, was 225, and their results were 80.6 percent, 95.0 percent, 72.5 percent, 96.7 percent, and 92.9 percent, respectively. There were many sites with false negative results by CT (47 sites), and the sensitivity of the whole site was 31.9 percent. Thus, the results obtained by EUS were more dominant than those of CT. The cases in which no lymph nodes or small-sized lymph nodes with negative signs of metastasis were imaged by CT, but were proved as positive by EUS, are shown in Fi~ures 5,6, and 7. Relation between the Histopathologic Findings and the Results of EUS on the Metastatic Lymph NOlles

In 509 sites, 69 sites were

patholo~ically proved

to

Table 2-Results of Endoscopic Ultrasound Examination (EUS) at Each Site (101 Cases with Primary Lung Cancer)

No. of examined sites No. of sites diagnosed as positive metastasis by EUS No. of tnle positive sites by EUS No. of pathologically positive sites

lbtal

Supraclavicular

509 48

6 3

37

3

69

5

No.2 and 3

Ri~ht

No.4

Left No.4 and 5

No.7, 8, and 10

Rj~ht

No.1

No.9

Left No.9

No.3p

94

95 1

57 3

54 14

94 23

27 1

29 2

53 0

3

9

18

5

11

22

1

8

15

CHEST / 98 / 3 / SEPTEMBER, 1990

0

589

Table 3-Results of Endoscopic Ultrasound Eramination (EUS) 101 Cases with Primary IJlmg Cancer EUS All Siles (509)

Wilholll Righi SlIperior Mediaslillllm (255)

CT, All silt's (509)

29 201l 11 7 29/36 (HO.6) 208/219 (95.0) 29/40 (72.5) 20&'215 (00.7) 237/2.55 (92.H)

22 42. 13 4. 22/6H (.31.9) 427/4-10 (97.0) 22/35 (62.9) 427/474 (90.1) 449/509 (8S.2)

Tnit' posilin' Tnit' lIegalin' FaiSt· posilin' FaiSt· lIegalin' S"lIsili\·ity

No. No. No. No. No. (%)

37 -129 11 .'32 37/6H (5.'3.6)

Sp"l'ifil'ily

!lio.

-I2~J/-l-lO

(Ok)

(97.5) 37/4R (j'j .1) -129/461 (93.1) 466/509 (H1.6)

Posili\'<' predidin' at·(·tlra<:~·

Negalive predidin' al'(·tlral'~·

Ow' rail aeellraey

No. (%)

No. (%)

!lio. (Ok)

have lymph node metastases. Among them, 30 of 42 sites with severe metastases, 5 of 17 with moderate metastases, and 2 of 10 with mild metastases were proved true positive by EUS. And in the sites excluding the right superior mediastinal lymph node, the metastases were pathologically identified in 37 sites, and of these, E US revealed the metastases in 22 of 23 sites with severe metastases, 5 of 8 with moderate metastases, and 2 of 6 with mild metastases (Table 4). The diagnoses determined for severe lymph node metastases by EUS were comparatively accurate, while the diagnoses by EUS were inaccurate for the cases with mild metastases. DISCUSSION

FI<;l'IlE 5. Images of n1l'laslalie I"mph IIlKII'S in tl1l' prelraeheal and paralradlt'al sill' (No.2 and 3). Endoseopic IIltrasound examinalion (EUS) showed Ih.. filSion of two lymph lIod..s sized 12 X 9111111 and 10 X 6 11Im, and lolmlated lymph node sized 10 X 6 mill, in which metaslaSt·s wen' highly sllg,gl·sl..d (III'/JI"·). hilI only Iwo lighl and slllall lymph n'KI"s l'mld he seen hy '''lIIpllted IOlllography (Cl) (lower). TR indicales lraehea; B. hraehiol'ephalie arlery; C. left eoml1lon carolid arIel'''; S. left sllhdavian art,-r,,; I. left inllominale vein; V. verlehra; and ·N. lymph IIlKle. .

590

The five-year survival rates of patients with N2 lung cancer undergoing surgical treatment have recently been reported to be approximately 23 percent! and 30 percent. s These survival rates showed improvement to some extent, but the improvement was not sufficient enough. Therefore, multidisciplinary treatments, such as neoadjuvant therapy, etc, should he used more in the future. Taking this into consideration, accurate pretreatment staging for patients with lung cancer is extremely important as a fundamental procedure although it is very difficult to accomplish. At present, preoperative diagnoses filr mediastinal lymph node metastases of primary lung cancer are mainly made by CT scanning. Since CT has no blind angle, all of the mediastinum could be examined. However, its ability to image lymph nodes is not sufficient. Due to the movement and the partial volume effect of the pulmonary artery and vein, the aortic arch and the left atrium, aortopulmonary window (left No.4 and 5), suhcarinal and paraesophageal lymph nodes are not sufficiently imaged by CT.6-~ According to a report on lung cancer, the sites of No. 3p, 4, 5, 7, 8, and 10 had been observable by Endoscopic UMrasound in Metastalic Lung Cancer (Kondo et al)

FIGURE 6. Ima~es of metastatic lymph nodes in the left tracheohronchial and hilar site (No. 4 and 10). End<)S(.'lpic ultrasound examination (EUS) showed lohulated lymph nodes with clear l.11Otours, in which metastases were hi~hly su~ested (upper), wherea.~ mmputed tomo~mphy(CD showed no lymph node (lower). LMB indicates; left main bronchus; RMB, ri~ht main hronchus; LPA, left pulmonary artery; RPA, ri~t pulmonary artery; AO, aorta; V, vertehm; and N, lymph node.

FIGURE 7. Ima~es of metastatic lymph node in the suhcarinal site (No.7). Endosl.'lpic ultrasound examination (EUS) showed the fusion and lobulation with low echo interior ima~es of lymph nodes (upper). wherea~ mmputed tomography (CD showed li!1:ht and Hat l.11Otours of lymph nodes, which su~ests no si!1:n of metastasis (lower). LMB indicates left main hronchus; RMB. ri!1:ht main hronchus; LPA, left pulmonary artery; RPA, ri!1:ht pulmonary artery; AO, aorta; V, vertehm; and N, lymph node.

Table 4-Results of Endoscopic Ultrasound Emmination (EUS); Relation between Pathologic Findings of Metastatic Lymph Nodes and True Positive Without Ri!1:ht Superior Mediastinum (37)

All Sites (69)

Metastatic Sta!1:es

No. of Sites

No. of Positive Metastatic Sites hyEUS

Severe Mooemte Mild

42

30

23 8

2

6

17 10

5

No. of Sites

No. of Positive Metastatic Sites hy EUS 22

5

2

CHEST I 98 I 3 I SEPTEMBER. 1990

591

Table 5-Findings o/Ultrasound Examination on Cervical Lymph Nodes (Nine Sites, 17 Lymph Nodes in Seven PathologicaUy Examined Patients) Positive Metastasis (15)

Contours Clear Partly clear Unclear Internal echoes Homo~enous, str()n~ly hypoechoic Fine ~ranular, diffuse, stron~ly hypoechoic Fine ~ranular, irreJ?;ular, stron~ly hypoechoic

9 6

o 3 7

2

2

o 2

o

strongly hypoechoic

3

str()n~ly hypoechoic

Shapes Flat Thickened, lobulated, fi.lsed Round, weak

o

o

Rou~hly ~ranular, irre~ular,

Rotl~hly ~rantllar, irre~tllar,

Ne~ative

Metastasis (2)

o

15

o

o o

()

2

EUS.2 The site of para-aortic lymph nodes could not be diagnosed, as it had been barely possible to identify the node with the 7.5-MHz radial scanning system of EUS. However, we identified sites from the left supraclavicular to the left superior mediastinum (No. 1 and 2), from left No. 4 to 9 \\'ere observed in succession by EUS in all the cases, while the right superior mediastinum was not observed since it was in a blind angle to the EUS due to the positions of the esophagus and trachea. Mitani et al9 reported that CT scanning at the interval of 1 cm made it possible to image lymph nodes in only 25 percent of targeted sites. With the detailed study on normal subjects, Genereux and Howie lO reported that about 40 percent of lymph nodes had not been imaged in No.7 and left No.4. In this study, lymph nodes in the left No.4 and 5 and No.7, 8, and 10 were imaged by EUS in almost all the cases, and lymph nodes in No.9 were imaged in 40 percent of the subjected cases. When imaging abilities of EUS and CT were compared for sites excluding the right superior mediastinum, which could not be observed by EUS, it \vas verified that EUS showed significantly more superior ability than CT, with results in imaging of 62.3 percent against 40.1 percent attained by CT, and the numbers of lymph nodes imaged in one site were 2.7 (EUS) and 1.6 (CT). The diagnoses of lymph node metastases by CT are made in accordance with the sizes of lymph nodes. However, various diagnostic standards for positive metastases have been reported as follows: all the imaged lymph nodes, II 1 cm or more in diameter, 12,13 1.5 cm or more,7,~,14.15and 2 cm or more. 6 This suggests 592

that the diagnoses of metastases by the sizes of lymph nodes are apt to be inaccurate. As the rates of false positive diagnoses of swelling lymph nodes due to inflammation are from 15 to 33 percent, the necessity of histopathologic examination for confirmation has been reported quite often.&H,Il-14 Martini et aP and Patterson et aJl6 have also pointed out that as far as the sizes of lymph nodes are used as standards for diagnosing metastases, the accuracy of diagnosis is limited. Some articles have discussed the findings of ultrasound examination of lymph nodes,17,18 and we also have reported our experiences with ultrasound examination in the cervical region for prescalene nodes. 1 Table 5 shows the findings of ultrasound examination of lymph nodes discussed in that stud~ It shows the findings of internal echoes of the lymph nodes were not specific to the metastasis. However, the metastasized lymph nodes could be differentiated from nonmetastasized nodes by their clear contours and thickened images with fusion or lobulation. Thus, we decided to exclude the sizes of lymph nodes from the standard factors for diagnosing metastases. Excellent results were obtained in sensitivity, specificity, positive predictive accuracy, negative predictive accuracy, and overall accuracy. Among the lymph nodes examined by EUS, 91 percent were less than 10 mm in diameter, and 60.5 percent of lymph nodes diagnosed as positive for metastasis were also less than 10 mm in diameter. Thus, diagnosis of metastasis by size of lymph nodes is difficult, and the sensitivity rates obtained by CThave shown inaccuracy of31.9 percent. Therefore, EUS imaging is an appropriate diagnostic procedure for lymph node metastases not in line with the sizes of lymph nodes, but established standards, because serious metastases to lymph nodes small in size could be detected and diagnosed by EUS imaging, although EUS imaging has difficulty in identifying micrometastases accurately to the extent of other imaging means. According to the results of this study, E us is useful for diagnosing mediastinal lymph node metastases originating from primary lung cancer. The features EUS confers are: (1) all sites except the right superior mediastinum can be observed; (2) compared with CT, the imaging ability of lymph nodes within the observable extent centering around the middle and inferior mediastinum is significant; (3) furthermore, metastases could be diagnosed from some factors except size, as each lymph node is clearly seen in an imaged area. There have been many reports7,15,19-21 in which mediastinoscopy and CT were used together in considering the limited diagnoses obtained by CT only. However, EUS is not only useful in covering sites invisible to mediastinoscopy, but it is also able to make accurate prognoses nonsurgically and noninvasively. Therefore, more accurate diagnoses of mediastinal Endoscopic Ultrasound in Metastatic Lung Cancer (Kondo et 8/)

lymph node metastases can be obtained by using EUS and CT together, which covers the EUS's blind angle of the right superior mediastinum.

9

CONCLUSION

Endoscopic ultrasound examination showed significant images of lymph nodes except in the right superior mediastinum. Using EUS, metastases to mediastinal lymph nodes were diagnosed with some standards except the size. The results were as follows: sensitivity, 80.6 percent; specificity, 95.0 percent; positive predictive accuracy, 72.5 percent; negative predictive accuracy, 96.7 percent; and overall accuracy, 92.9 percent. Endoscopic ultrasound examination was able to accurately diagnose highly metastasized lymph nodes even if they were small, but it was inaccurate in diagnosing micrometastases.

10 11

12

13

14

REFERENCES

2

3

4

5 6

7

8

Kondo D, Naruke T, Kondo H, Coya T, Tsuchiya R, Suemasu K. Evaluation on significance of neck ultrasound examination in primary lun~ cancer: detection of non-palpable metastatic scalene nodes. J Jpn Assoc Chest Sur~ 1988; 2:117-24 S()~a H, Takeuchi R, Kurita H, Komatsubara S, Shimizu N, Teramoto S. Ultrasonic evaluation of mediastinal lymph node metastasis, especially to subcarinal node, in lun~ cancer by trans-esopha~eal radial scan. Rinsho Ceka 1987; 42:1405-10 Nanlke T, Suemasu K, Ishikawa S. Lymph node mapping and curability at various levels of metastasis in resected lung cancer. J Thorac Cardiovasc Sur~ 1978; 76:832-39 Sawamura K, Lee Y, Suemasu K, Miyazawa N, Yamaguchi Y, Nakada T, et aI. Analysis of N2 lung cancer undergoing surgical resection with complete mediastinal lymph node dissection. Haigan 1988; 28:1-9 Martini N, Flehinger BJ. Surgical treatment of lung carcinoma. Surg Clin North Am 1987; 67:1037-49 Ferguson MK, MacMahon H, Little AC, Golomb HM, Hoffman PC, Skinner DB. Regional accuracy of computed tomography ofthe mediastinum in staging oflun~ cancer. J Thorac Cardiovasc Surg 1986; 91:498-504 Martini N, Heelan R, Westcott J, Bains MS, M(.Cormack ~ Caravelli J, et al. Comparative merits of conventional, computed tomographic, and ma~netic resonance ima~ing in assessin~ mediastinal involvement in surgically confirmed lun~ carcinoma. J Thorac Cardiovasc Sur~ 1985; 90:639-48 Falin~ LJ, Pugatch RD, Jung-Le~ Y, Daly BDT Jr, H()n~ WK,

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Robbins AH, et a1. Computed tomo~raphic scannin~ of the mediastinum in the stawn~ ofbr()ncho~eniccarcinoma. Am Rev Respir Dis 1981; 124:690-95 ~fitani N, Shimotakahara T, Sannou K, Nishijima II, Arimura T, Baba K, et al. CT dia~n()sis of rnediastinal lymph node metastasis of lung cancer: comparison hetween renloved lymph nodes and cr in finn areas. Haigan 1986; 26:643-49 Geneureux G~ Ho\\ie JL. Normal mediastinal lymph node size and number: CT and anatomic study. AJR 1984; 142:1095-1100 Rea HH, Shevland JE, House AJS. Accuracy of computed tomowaphic scanning in assessment of the mediastinum in bronchial carcinoma. J Thorac Cardiovasc Sur~ 1981; 81:825-29 Backer CL, Shields ~ Lockhart CG, V<)~elzan~ R, LoCicero J III. Selective preoperative evaluation for possible N2 disease in carcinoma of the lung. J Thorac Cardiovasc Surg 1987; 93:33743 Richey HM, Matthews JI, llelsel RA, Cable H. Thoracic (.1 scanning in the stawng ofhronchogenic carcinoma. Chest 1984; 85:218-21 Daly BDT, Faling Lj, Bite G, Gale ME, BankoffMS, Jung-Le~ Y, et al. Mediastinal lymph node evaluation by (.·omputed tomography in lung cancer. J Thorac Cardiovasc Surg 1987; 94:664-72 Schnyder PA, Gamsu G. L"T of the pretracheal retrocaval space. AJR 1981; 136:303-08 Patterson GA, Ginsberg RJ, Poon PY, Cooper JD, (;oldber~ M, Jones D, et aI. A prospective evaluation of magnetic resonance imawng, computed tomography, and mediastinos(.'opy in the preoperative assessment of mediastinal node status in bronchogenic carcinoma. J Thorac Cardiovasc Sur~ 1987; 94:679-84 Kume~awa H. Study of the endoscopic ultrasonography for esophageal carcinoma. Jpn J Gastroenterol Sur~ 1985; 18: 177483

18 Murata Y, Muroi M, l()shida M, Okushima N, Sugiyama A, Ide 1-1, et al. Endoscopic ultrasonography in the dia~nosis of esophageal carcinoma. J Jpn Bronchoesopha~ol Soc 1986; 37:378-85 19 Osborne DR, Korohkin M, Ravin CE, Putman CE, \Volfe \VG, Sealy WC, et al. COlnparison of plain radio~raphy, ("onventional tomography and computed tomowaphy in detecting intrathoracic lymph node metastasis from lun~ carcinoma. Radiolo~ 1982; 142:157-61 20 Coughlin M, Deslauriers J, Beaulieu M, Fournier B, Piraux M, Rouleau J, et al. Role of mediastinos(.'Opy in pretreatment stagin~ of patients with primary lung cancer. Ann Thorac Sur~ 1985; 40:556-60 21 Baron RL, Levitt RG, Sage) SS, White MJ, Roper CL, Marbarger JE Computed tomography in the preoperative evaluation of bronchogenic carcinoma. Radiology 1982; 145:727-32

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