Risk Factors for Invisible Intraoperative Markings After Virtual-Assisted Lung Mapping

Virtual-assisted lung mapping (VAL-MAP) is a preoperative bronchoscopic multispot dye-marking technique that can be combined with bronchoscopic placement of a microcoil (VAL-MAP 2.0). VAL-MAP can identify unpalpable pulmonary lesions; however, the markings are occasionally deemed invisible intraoperatively. We investigated preoperative risk factors for invisible markings after VAL-MAP.

We prospectively performed preoperative VAL-MAP in patients at the University of Tokyo between January 2014 and June 2020. Data of 219 patients (257 lesions) and 857 markings were retrospectively reviewed. Dye markings were categorized as grade 0 (invisible) or 1-5 (visible). The risk factors for grade 0 markings were assessed using multiple logistic regression analysis. Subsegments of the bronchus showing grade 0 markings were also evaluated for 133 lesions and 504 markings without missing data for the target segment.

Sixty-one of the 257 lesions (24%) displayed ≥1 grade 0 markings. Seventy-six (8.9%) of the 857 markings were grade 0 intraoperatively. VAL-MAP 1.0 was performed for 202 (79%) and 25 lesions (10%) without and with electromagnetic navigation bronchoscopy, and VAL-MAP 2.0 with a microcoil was performed for 30 lesions (11%). Upper lobe markings were associated with a significantly increased risk of invisible markings. There was no significant difference in the frequency of grade 0 markings among the VAL-MAP methods. Among all bronchi subsegments, left B1+2c exhibited the highest rate of grade 0 markings.

Markings placed using VAL-MAP are more likely to be invisible for upper lobe pulmonary lesions. Injecting markings for lesions in the left S1+2c thus require caution.