Electromagnetic Navigation Diagnostic Bronchoscopy Am J Respir Crit Care Med Vol 174. pp 982–989, 2006 R4 Byunghyuk Yang

INTRODUCTION I Limitations of diagnostic flexible bronchoscopy –Inability to guide biopsy instruments directly to the lesion –20~84 % diagnostic yield –Diagnostic success rate : for lesions<2cm  14% v.s. 31% Size Location –TBNA for mediastinal lymph node : 15~83% EBUS and computed tomography fluoroscopy –Real-time guidance –Ability to precisely direct a biopsy instrument

INTRODUCTION II Electromagnetic navigation bronchoscopy The superDimension/bronchus system (superDimension Ltd, Hertzliya, Israel) : image-guided localization system –Planning software –Steerable probe –Electromagnetic board Aims –to determine the ability of ENB to reach peripheral lung lesionsand mediastinal lymph nodes

METHODS 60 patientsbetween December 2004 and September 2005 –Presumed difficult bronchoscopy, prior nondiagnostic bronchoscopy, or lesions traditionally notreachable by routine bronchoscopy Primary endpoint –To determine the feasibility of ENB in reaching lung targets as demonstrated by location of steerableprobe tip displayed on SDBS screen Secondary endpoint –To determine the ability of ENB to assist in obtaining tissue with TBBX,brush, and/or TBNA –Diagnostic(ENB success) or nondiagnostic(ENB failure) value Safety of ENB during the bronchoscopic procedure

PROCEDURE ENB –Electromagnetic location board –Steerable probe served as a retractable sensor probe –Extendable working channel –Computer software CT scans with slices of 3 mm thickness at 1.5 mm intervals Conscious sedation with intravenous 2-mg boluses of both midazolam and morphine with topical lidocaine Washing to collect 25 ml of aspirated saline before navigation Bronchoalveolar lavage to collect 50 ml of aspirated saline before navigation Olympus 1T160, 2.8-mm working channel, adult therapeutic bronchoscope (Olympus, Tokyo, Japan)

REGISTRATION, NAVGATION, BIOPSY Registration is the process by which the computer links the five to six virtual fiducial markers to the actual position in the patient. Average fiducial target registration error (AFTRE) score Radius of expected difference of the location of the tip of the steerable probe in the actual patient compared with where it is expected to be in the virtual patient Navigation with simultaneous advancement of the steerable probe toward the target and directing steerable probe to the lesion Brushings and TBBXs or TBNA through the extendable working channel

RESULTS

ENB procedure completion on 58 subjects among 60 pts. –23 women, 35 men; ages 43–86 yr; mean –mechanical failure and lack of cooperation 36 subjects in peripheral lesions, 9 subjects in lymph nodes sampled, and 13 subjects in both peripheral lesions and lymph nodes Total numbers of peripheral lesions and lymph nodes sampled were 56 and 31, respectively, with mean sizes of mm and mm, respectively. Nondiagnostic two patients(one subject died before any additional procedures could be performed, another was lost to follow up)

Ability to reach target area : 100% Procedure time : mean min(range, 33~86min) Mean registration time : 3 2 min(range, 10~13min) Mean navigation time –7 6 min for peripheral lesion –2 2 min for lymph node

Neither procedure time nor navigation time differed by lesion size.

Thoracotomy CT-fine needle aspiration Mediastinoscopy PET

SAFETY Pneumothorax in two patients ( 3.5% ) –Extremely pph. lesions in upper lobes Chest pain in five patients Fever in three patients Sore throat in seven patients Clinically insignificant hemoptysis in three patients Emesis in four patients

DISCUSSION Excellent yield of ENB –Multiplanar CT planning : appropriate identification of the airway –Electromagnetic navigation : no additional radiation –Steerable probe The use of ENB requires training and development of a learning curve. One limitation of this study is that the number of biopsy attempts and techniques are variable. The use of the peripheral needle was limited by its ability to make the turn through the EWC to navigate to upper lobe lesions. Better flexible instruments may need to be developed to further increase yield.

CONCLUSION This is the first study in a large scale of patients with peripheral lesions and/or mediastinal lymph node enlargement to assess the utility of ENB. It is a safe procedure that, with some training, is associated with high diagnostic success— higher then those reported for routine diagnostic bronchoscopy and perhaps similar or superior to some other advanced techniques such as EBUS independent of size and location. Prospective comparison with other complementary methods such as EBUSmay be studied in the future. Yield may be further increased with more flexible dedicated peripheral instruments. In future applications, ENB may be used with fusion CT/PET for procedure planning; in addition, guided instruments may further extend the utility of this new technology.