elecromagnetic navigation.pdf

7/27/2019 elecromagnetic navigation.pdf

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E l e c t r o m a g n e t i cN a v i g a t i o n

Yehuda Schwarz, MD, FCCPa,b,*

The first bronchoscopic procedure was performed

in 1897 by Gustav Killian using a laryngoscope and

a rigid esophageal tube to remove a foreign body

from the trachea.1 During the next century, bron-choscopy evolved from being a rigid technique

to one that uses a flexible bronchoscope devel-

oped by Ikeda and colleagues2 in 1968, opening

new horizons in the diagnosis and treatment of

pulmonary diseases. Flexible bronchoscopy is

a minimally invasive procedure, obviating general

anesthesia and eliminating potential associated

complications. New technological developments

emerged in the 80s to improve the yield in diag-

nosis; these innovations included videobroncho-

scopy, endobronchial ultrasonography (EBUS),autofluorescence bronchoscopy, and lately,

narrow-band imaging.3,4 Endoscopic therapeutic

procedures have also kept pace with these devel-

opments, with the introduction of laser photore-

section, cryotherapy, electrocautery, and stent

technology.5 The field of imaging also underwent

technological transformation at the same time.

The incidence of peripheral non-smallcell lung

cancer (NSCL, adenocarcinoma subgroup) has

also increased significantly during the last 30

years; probably because of the introduction and

use of filtered cigarettes and the subsequent distaldelivery of smaller cigarettes particles.

Patients with pulmonary nodules and masses

are routinely referred to pulmonologists, radiolo-

gists, and thoracic surgeons for evaluation and

tissue diagnosis. The rapidly increasing use of

chest computed tomography (CT) for screening

and ruling out pulmonary embolism and various

other indications has led to a significant increase

in the detection of lung nodules.6 More than 6.5

million CT scans of the chest were performed in

the United States alone in 2001, highlighting the

gravity of this clinical scenario.7Choosing the invasive diagnostic procedures to

perform a biopsy for tissue diagnosis in cases of

small peripheral nodules or opacities remains

a clinical challenge. The main options are bron-

choscopy, percutaneous needle aspiration, and

thoracoscopic lung biopsy. Percutaneous needle

aspiration biopsy still plays an important role in

the diagnosis of peripheral lung cancers, yet the

associated pneumothorax (20%34%) and

hemoptysis are unacceptable.811 The high inci-

dence of pneumothorax in percutaneous tech-niques can be partially explained by the fact that

most patients diagnosed with a peripheral lung

lesion also may have some degree of emphysema-

tous changes and poor pulmonary function from

smoking. Thoracoscopic and open surgical biopsy

have the obvious disadvantages of the procedures

being invasive, the patients having to undergo

general anesthesia, and the need to tolerate

single-lung ventilation during the procedure. The

rate of mortality for this procedure can be 0.5%

to 5.3%.12

In patients with a high probability of lung cancerand good lung function, it is often not necessary to

obtain tissue diagnosis. For all others, however,

there is a need for an approach with a low compli-

cation rate, especially in those with multiple

nodules and compromised lung function. Cohort

studies have demonstrated that most nodules so

detected are benign.13 As such, surgery, with its

associated morbidity and mortality, is not

a

Department of Pulmonology, Tel-Aviv Sourasky Medical Center, 6 Weisman Street, Tel-Aviv, 64239, Israelb Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel* Department of Pulmonology, Tel-Aviv Sourasky Medical Center, 6 Weisman Street, Tel-Aviv, 64239, Israel.E-mail address: [email protected]

KEYWORDS

Electromagnetic navigation bronchoscopy Peripheral lung lesion Transbronchial needle aspiration Fiducial markers Stereotactic radiosurgery

Clin Chest Med 31 (2010) 6573doi:10.1016/j.ccm.2009.08.0050272-5231/10/$ see front matter 2010 Published by Elsevier Inc. c

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indicated for most patients who present with inci-

dentally discovered pulmonary nodules. Tissue

diagnosis, on the other hand, is frequently

essential.12

The conventional flexible bronchoscopy proce-

dure is of limited diagnostic value in peripheral

lung nodules, that is, those located at the periph-eral third of the lung. Biopsy success is further

compromised if the lesion is smaller than 2 cm in

diameter.14 The main limitation of the broncho-

scopic approach is the difficulty in reaching

peripheral lesions with the biopsy tools. The tools

used to obtain biopsy tissue are difficult to steer

to the desired location. Once extended beyond

the tip of the bronchoscope, the physician per-

forming the bronchoscopy is faced with the diffi-

culty of precisely localizing the lesion under

fluoroscopy, whereas the alternatives of CT-

guided bronchoscopy and EBUS are more techni-

cally demanding and require special training.

EBUS enables the operator to see the lesion

but it cannot provide guidelines to the bronchos-

copist for choosing the correct airway to reach

a given peripheral lesion.

Moderate sedation is the current practice in

standard bronchoscopy and the procedure is

safe in the hands of trained personnel. Because

the mortality for bronchoscopy is low (1 in 4000)

and the complication rate for pneumothorax with

transbronchial biopsy is also much lower than allthe other available approaches (


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Fig. 1. (A) The sensor (1 mm diameter and 8 mm length) mounted at the tip of a flexible metal cablethe LG. TheLG has a built-in bending mechanism for active steering in 8 directions that allows bending of the tip. Courtesy of

superDimension, Inc., Minneapolis, MN; with permission. (B) The LG with the sensor is integrated into theextended working channel (EWC). The EWC is left at the desired location once it has been reached with theaid of the sensor, enabling easy access for bronchoscopic accessories. (C) The monitor and computer are placedon a trolley to receive input and visualization of the sensors position on the monitor in all orientations (X, Y,and Z planes and roll, pitch, and yaw movements) in real time. Courtesy of superDimension, Inc., Minneapolis,MN; with permission. (D) Magnetic board placed under the mattress of the bronchoscopy bed.

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direction in which to bend the LG to move toward

the lesion (see Fig. 2). The fully retractable probe is

incorporated into a flexible catheter (the EWC

sheath) that is 130 cm long and 1.9 mm in diam-

eter. Once the area of interest is reached, the LG

is removed leaving the sheath in place. Various

tools and endoscopic accessories can now be

introduced through the catheter: these include

forceps for biopsy, needle, brush or curette, radial

EBUS (used by some researchers for confirmation

of the proximity of the sensor to the nodule), or to

place fiducials surrounding the diagnosed tumors.

Schwarz and colleagues15 performed the first

trial to determine the practicality, accuracy, and

safety of real-time EMB in locating artificial periph-

eral lung lesions in a swine model. The study

showed a registration accuracy of 4.5 mm on

average. No adverse effects, such as pneumo-

thorax or internal bleeding, were encountered in

any animal. The authors concluded that real-timeelectromagnetic positioning with previously

acquired CT scans is an accurate technology

that can augment standard bronchoscopy to

assist in reaching peripheral lung lesions and in

performing biopsies. The first human study was

a prospective controlled clinical investigation that

was opened in June 2003; its result was published

in 2006.16 Of 15 subjects, 13 underwent EMB for

peripheral lung lesions, ranging in size from 1.5

to 5 cm, that were beyond the optical reach of

a bronchoscope. Four of the lesions were in the

left upper lobe, 3 in the right upper lobe; 5 in the

right lower lobe, and 1 in the right middle lobe. A

definitive diagnosis was established in 9 (69%) of

the 13 subjects. No device-related adverse events

were reported during or up to 48 hours after the

study. A parallel study17 was performed in

Germany from July to December, 2003, which

also attained diagnostic yield of 69%. There were

no serious complications. Both studies concluded

that real-time EMB with CT images is a feasible

and safe method for obtaining biopsies of periph-

eral lung lesions.

At the end of the 2006, a larger prospectivestudy involving 60 patients was performed by

Gildea and colleagues18; the results showed an

improved yield of 74%, although 57% of lesions

were smaller than 20 mm in size. Their study

Fig. 2. The monitor depicting the reconstructed 3-dimensional CT scans (coronal, sagittal, and axial views), withthe position of the sensor probe at the tip-view showing a ring with an arrow giving an accurate direction tobend the LG for reaching the targeted lesion and 3-dimensional CT images of the focal sensors area.

Schwarz68


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was the first to demonstrate another application

of the navigation system, that is, the diagnosisof mediastinal lymph nodes. By adding lymph

node sampling, they improved the overall patient

diagnosis accuracy to 80.3%. Complications

were limited to pneumothorax, which occurred

in 3.5% of the patients. By giving the bronchos-

copist access to the peripheral lung area, itbecame apparent that there are cases in which

the steerable probe cannot be advanced to all

the lesions, as the bronchus leading to the lesion

may not exist.

Fig. 3. (A) CT data represented by the system software in axial, sagittal, and coronal cuts and VB images. ( B)Carina and major bronchial bifurcations on the VB images marked as reference points for the registration phase.

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Fig. 4. Targeting the mediastinal lymph nodes for TBNA. The software on-demand shows a transparent VBimage of the tracheal wall, thus allowing a view of the previously marked mediastinal lymph node for aspiration.(A) R4 lymph node and (B) lymph node at the aortopulmonary window.

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Makris and colleagues19 described their experi-

ence using the same EMB system in 40 patients

with lesions between 17 to 39 mm in size. They

emphasized that the average of CT-to-body diver-

gence, which represents the radius of the

expected difference in location between the tip

of the sensor probe in the actual patient and where

the tip is expected to be was 4.6015 mm, whereas

the distance between sensor probe and the center

of the lesion was 8.7608 mm. The yield they

reached was 62.5% in 25 out of the 40 cases,

improving if the CT-to-body divergence was less

than 4 mm. The sensitivity and negative predictive

value of EMB for malignancy were 57 and 25%,

respectively.

Eberhardt and colleagues20 reported their expe-

rience with EMB in 89 subjects in whom they

reached a diagnostic yield of 67%, (independent

of lesion size). They had a CT-to-body divergenceof 4.6 1.8 mm (range, 1 to 31). There was no

occurrence of pneumothorax. The mean naviga-

tion error was 9 6 mm. These investigators

also found that size of the lesion was not

a determinant in diagnostic yield, and noted that

the time needed for the electromagnetic naviga-

tion method is around 30 minutes or less. This is

similar to the time for performing bronchoscopy

on patients with interstitial lung diseases and for

obtaining a transbronchial biopsy.

The same group21

compared the added value ofusing the US probe to verify and correct the posi-

tion of the sensor once it had reached the lesion,

as indicated by the software. By doing so, they

were able to correct the position of the sensor

and thereby improved their yield. They concluded

that combined EBUS and EMB enhance the diag-

nostic yield of flexible bronchoscopy in peripheral

lung lesions without compromising patient safety.

Specifically, combined EBUS/EMB had a signifi-

cantly higher diagnostic yield (88%) compared

with EBUS (69%) or EMB alone (59%; P5 .02),

with an overall pneumothorax rate of 6%.Several explanations were given by the users of

the EMB for the failure to reach near 100%

success, one being the absence of an airway

leading to the targeted nodule, another being the

Fig. 5. Registration step: during the bronchoscopy the carina and the major bronchial bifurcations are marked onthe VB images at the planning step in the same position using the sensor applied lightly on the carina mucosa.



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lesion extrinsic to an airway making adequate

tissue sampling difficult.

Wilson and Bartlett22 performed a larger EMB

retrospective consecutive study in a community

bronchoscopic unit using rapid on-site cytologic

evaluation (ROSE) on 248 patients referred for

diagnosis of peripheral lesions or mediastinallymph nodes (71). Pneumothorax was reported

in 1.2%, mainly because of the efforts to reach

a diagnosis, which occurred in 70%. Mean size of

targeted peripheral lung lesion (PLL) and lymph no-

des was 2.1 1.4 (SD) cm and 1.8 0.9 (SD) cm,

respectively. The mean follow-up period was 6

5 (SD) months. Fifty-one percent of PLLs were in

the upper lobes; EMB 1 ROSE success was

96% for PLL (34 samples per patient with

forceps and needle). Lymph nodes success

was 94.3% (56 samples with needle biopsy).

Overall diagnosis was made in 173 patients of

the 248 (70%). The investigators used fluoros-

copy to verify the location of the LG and biopsy

forceps.

Therapeutic uses of the EMB have also been

described in the literature. In year 2006, Harms

and colleagues23 applied EMB technology to ther-

apeutic objectives and described the successful

placement of a brachytherapy catheter after navi-

gation to a peripheral, unresectable lung cancer. A

second article showing the applicability of EMB in

therapeutics was published by Kupelian andcolleagues.24 They placed metallic markers for

radiation therapy for a small early-stage lung

cancer using the EMB system transbronchially.

They concluded that the markers placed using

this less invasive method remained stable within

the tumors throughout the treatment duration

without any incidence of pneumothorax as

compared with the 8 out of 15 in whom the trans-

thoracic route was used and who developed the

complication.

Anantham and colleagues

25

reported theirexperience with placement of 39 fiducial markers

in 9 patients. The success rate was 89% (8 of 9

patients). The mean number of fiducial markers

placed in each patient was 4.9 1 1.0 (range, 4

to 6). No migration was encountered in 90% of

the patients.

Weiser and colleagues26 published their experi-

ence in diagnosis and in placing fiducial markers in

and around the lesions to enable stereotactic

radiosurgery. They used ROSE and in case of

a negative result, they continued surgically for

additional biopsies. Krimsky and colleagues27

used the EMB system to tattoo the subpleural

area of the lung nodules after malignant diagnosis

and to perform a therapeutic video-assisted

thoracoscopic surgery.

Electromagnetic navigation bronchoscopy

using overlaid CT images is a safe procedure. It

improves the diagnostic yield of the flexible bron-

choscopy for peripheral lesions and also allows

sampling of the mediastinal lymph nodes. Also,

the system affords several other advantages: there

is no additional radiation, and it has a shortlearning curve. It can also be used for fiducial

marker placement for brachytherapy or stereo-

tactic radiosurgery. It plays a complementary

role to other modalities such as an ultrathin

bronchoscopy or an EBUS.

REFERENCES

1. Killian G. Meeting of the Society of Physicians of

Freiburg. December 17, 1897. Munchen Med Wschr

1989;45:378.

2. Ikeda S, Yanai N, Ishikawa S. Flexible bronchofiber-

scope. Keio J Med 1968;17:116.

3. Lam S, Kennedy T, Unger M, et al. Localization of

bronchial intraepithelial neoplastic lesions by fluo-

rescence bronchoscopy. Chest 1998;113:696702.

4. Herth FJF, Becker HD. Endobronchial ultrasound of

the airways and the mediastinum. Monaldi Arch

Chest Dis 2000;55:3645.

5. Baram D. Palliation of endobronchial disease: flex-

ible and rigid bronchoscopic options. Respir Care

Clin N Am 2003;9:23758.

6. Healthcare Cost and Utilization Project. Rockville(MD): Agency for Healthcare Research and Quality;

2001.

7. Sharma SK, Pande JN, Dey AB, et al. The use of

diagnostic bronchoscopy in lung cancer. Natl Med

J India 1992;5:1626.

8. Laurent F, Michel P, Latrabe V, et al. Pneumothora-

ces and chest tube placement after CT-guided

transthoracic lung biopsy using a coaxial technique.

Am J Roentgenol 1999;172(4):104953.

9. Mullan CP, Kelly BE, Ellis PK, et al. CT-guided fine-

needle aspiration of lung nodules: effect on outcome

of using coaxial technique and immediate cytolog-

ical evaluation. Ulster Med J 2004;73(1):326.

10. Baaklini WA, Reinoso MA, Gorin AB, et al. Diag-

nostic yield of fiberoptic bronchoscopy in evaluating

solitary pulmonary nodules. Chest 2000;117:

104954.

11. Santambrogio L, Nosotti M, Bellaviti N, et al. CT-

Guided fine-needle aspiration cytology of solitary

pulmonary nodules. Chest 1997;112(2):4235.

12. Gould MK, Sanders GD, Barnett PG, et al. Cost-

effectiveness of alternative management strategies

for patients with solitary pulmonary nodules. AnnIntern Med 2003;138:72435.

13. Swensen SJ, Jett JR, Hartman TE, et al. Lung cancer

screening with CT: Mayo Clinic experience. Radi-

ology 2003;226:75661.

Schwarz72


9/9

14. Schreiber G, McCrory DC. Performance characteris-

tics of different modalities for diagnosis of sus-

pected lung cancer. Summary of published

evidence. Chest 2003;123:115S28S.

15. Schwarz Y, Mehta AC, Ernst A, et al. Electromag-

netic navigation during flexible bronchoscopy.

Respiration 2003;70(5):51622.16. Schwarz Y, Greif Y, Becker H, et al. Real-time elec-

tromagnetic navigation bronchoscopy to peripheral

lung lesions using overlaid ct images: the first

human study. Chest 2006;129(4):98894.

17. Heinrich D, Becker HD, Herth F, et al. Bronchoscopic

biopsy of peripheral lung lesions under electromag-

netic guidance. A pilot study. J Bronchol 2005;12:913.

18. Gildea TR, Mazzone PJ, Karnak D, et al. Electro-

magnetic navigation diagnostic bronchoscopy:

a prospective study. Am J Respir Crit Care Med

2006;174(9):9829.

19. Makris D, Scherpereel A, Leroy S, et al. Electromag-

netic navigation diagnostic bronchoscopy for small

peripheral lung lesions. Eur Respir J 2007;29(6):

118792.

20. Eberhardt R, Anantham D, Herth F, et al. Electro-

magnetic navigation diagnostic bronchoscopy in

peripheral lung lesions. Chest 2007;131(6):18005.

21. Eberhardt R, Anantham D, Ernst A, et al. Multimodal-

ity bronchoscopic diagnosis of peripheral lung

lesions: a randomized controlled trial. Am J Respir

Crit Care Med 2007;176(1):3641.

22. Wilson DS, Bartlett RJ. Improved diagnostic yield

of bronchoscopy in a community practice: combi-

nation of electromagnetic navigation system and

rapid on-site evaluation. J Bronchol 2007;14:

22732.23. Harms W, Krempien R, Grehn C, et al. Electromag-

netically navigated brachytherapy as a new treat-

ment option for peripheral pulmonary tumors.

Strahlenther Onkol 2006;182:10811.

24. Kupelian PA, Forbes A, Willoughby TR, et al. Implan-

tation and stability of metallic fiducials within pulmo-

nary lesions. Int J Radiat Oncol Biol Phys 2007;69:

77785.

25. Anantham D, Feller-Kopman D, Shanmugham LN,

et al. Electromagnetic navigation bronchoscopy

guided fiducial placement for robotic stereotactic ra-

diosurgery of lung tumorsa feasibility study. Chest

2007;132:9305.

26. Weiser TS, Hyman K, Yun J, et al. Electromagnetic

navigational bronchoscopy: a surgeons perspec-

tive. Ann Thorac Surg 2008;85:S797801.

27. Krimsky W, Sethi S, Cicenia JC. Tattooing of pulmo-

nary nodules for localization prior to vats. Chicago,

IL: ACCP meeting, October 22, 2007, Volume 132,

Issue 4.


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