SESSION TITLE: Ultrasound and Other Imaging Posters
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 29, 2014 at 01:30 PM - 02:30 PM
PURPOSE: Peripheral pulmonary nodules (PPN) are commonly found on computed tomography (CT).The gold standard for obtaining tissue in those with an intermediate risk of malignancy is transthoracic needle aspiration (TTNA). The diagnostic yield is ~ 90%, but is associated with a significant complication rate. Advanced diagnostic bronchoscopy is safe, but despite significant advances, its yield is ~70%. Electromagnetic navigation bronchoscopy (ENB) is a technique that utilizes a thin slice full inspiratory pre-procedure chest CT to perform virtual airway reconstruction. An electromagnetic sensor is then superimposed on this reconstructed airway model and aligned using registration points. It is unclear if the lower diagnostic yield of this procedure is due to limitations in the technology or technical challenges during the procedure. We hypothesize that respiratory movement may be significant, and nodule location will vary with the phase of respiration.
METHODS: Each patient underwent two CT scans of the chest, one at total lung capacity (full inspiration) with arms up and another at functional residual capacity (tidal expiration) with arms down. Pulmonary nodules were then located independently by two physicians on each of the two CT scans performed on each patient. Image registration of the CT scan pairs was performed via alignment of the main carina as a common point of translation between the datasets and the physical 3D motion was calculated.
RESULTS: Forty-six patients with a total of 85 nodules were evaluated. Average nodule size was 16.6mm (6 - 42mm). There were 23 (27%) nodules in the right upper lobe (RUL), 21 (25%) in the right lower lobe (RLL), 21 (25%) in the left upper lobe (LUL), and 20 (23%) in the left lower lobe (LLL). The average movement between full inspiration and tidal expiration was 17.5mm. When separated by anatomic location, the average movement of PPN in the RUL was 12.2mm, 10.6mm in the LUL, 25.3mm in RLL, and 23.8mm in the LLL. Movement in the Y (anterior-posterior) and Z (superior-inferior) axis accounted for the majority of the vector movement.
CONCLUSIONS: The respiratory variation of PPN is significant, with lower lobe movement greater than upper lobe.
CLINICAL IMPLICATIONS: The position of a nodule on a full inspiratory planning CT does not correlate with the location of the nodule at bronchoscopy. Nodule movement during bronchoscopy may explain some of the differences in accuracy between TTNA and ENB. Confirming the differences during bronchoscopy is warranted.
DISCLOSURE: The following authors have nothing to disclose: Brian Furukawa, Essam Mekhaiel, Nicholas Pastis, Gerard Silvestri, Alexander Chen
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