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Comparing pulmonary nodule location during electromagnetic bronchoscopy with predicted location based on two virtual airway maps at different phases of respiration

STUDY
Brian S. Furukawa, MD, Nicholas J. Pastis, MD, Nichole T. Tanner, MD, Alexander Chen, MD, Gerard A. Silvestri, MD. Comparing Pulmonary Nodule Location During Electromagnetic Bronchoscopy with Predicted Location Based on Two Virtual Airway Maps at Different Phases of Respiration. Published online: June 16, 2017

OVERVIEW

  • + The study hypothesis was that a virtual airway map based upon a chest CT done at expiration (EXP) is more representative of a patient’s actual airway and pulmonary nodule location than one based on inspiration (INSP).
  • + 18 consecutive patients with 20 pulmonary nodules were enrolled. The difference between predicted ENB location and visualized PN location was calculated and then confirmed using R-EBUS ultrasound probe.
  • + The study was a prospective, single center, non randomized, observational study designed to compare predicted PN (pulmonary nodule) location on three airway maps at different phases of respiration: tidal breathing, maximal inspiratory breath hold (INSP) and expiratory breath hold (EXP).

OBJECTIVE
Determine if an electromagnetic navigation map based on expiration CT scans more accurately predicts actual nodule location vs. a map based on Inspiration only CT scans.

AUTHORS’ CONCLUSION
“Our study demonstrates that the predicted 3D nodule location using an EXP scan for ENB is significantly closer to actual nodule location when compared with an INSP scan. This may partly account for discrepancies between successful navigation and making a diagnosis in some cases as well as the drop off in yields for lower lobe nodules.”

“This study’s finding that predicted pulmonary nodule location during bronchoscopy is better estimated by reformatted images from an EXP scan performed at end-expiration rather than an INSP scan performed during a full inspiratory breath hold is not surprising.”

“The precision of any tracking system depends upon accurate information input and the results of this study suggest than an EXP map may better represent nodule location.”

KEY FINDINGS

  • + The mean distance between predicted PN location on a lumen registration generated airway vs. EXP airway map was 4.5mm±3.3m (range 0-12.7mm)
  • + The mean distance between predicted PN location on a lumen registration generated airway vs. INSP airway map was 14.8mm±9.7m (range 4.8-44.3mm)
  • + “During the bronchoscopy, the vPAD™ registration of the patient to the EXP virtual airway map as determined by “target-lock”, had a mean difference of only 3 mm ± 2.4mm which shows strong correlation for the initial registration method”
  • + “Our study found that a significant discordance in predicted nodule location during bronchoscopy compared to INSP in all locations, not just lower lobes.”
  • + The predicted PN location as compared with lumen registration location, was significantly closer on an EXP vs. INSP airway map (p<.0001).
Registration Error Distance
Lumen Registration – vPAD Mean (SD) 3.0mm (2.4mm)
Lumen Registration – EXP Scan Mean (SD) 4.5mm (3.3mm)
Lumen Registration – INSP Scan Mean (SD) 14.8mm (9.7mm)

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