The Diagnostic Dilemma of Sub Centimeter Lung Nodules, Leveraging Tools in Shape-Sensing Robotic Bronchoscopy

The Diagnostic Dilemma of Sub Centimeter Lung Nodules, Leveraging Tools in Shape-Sensing Robotic Bronchoscopy



Objective: 
Shape-sensing robotic-assisted bronchoscopy (ssRAB) has expanded diagnostic evaluation of pulmonary nodules, but predictors of diagnostic yield, particularly in small nodules, remain poorly defined. The purpose of the study was to evaluate clinical and radiographic factors associated with a diagnostic yield.

Methods: 
We retrospectively reviewed 1,271 nodules that underwent ssRAB at a single institution. Nodules were categorized by size (0–1 cm, 1–2 cm, 2–3 cm, ≥3 cm) and CT morphology (solid, part-solid, ground-glass opacity [GGO], cavitary, consolidation). Multivariable logistic regression identified independent predictors of diagnostic yield, adjusting for demographics, lesion location/zone, use of radial EBUS, cryoprobe, cone-beam CT scan, and biopsy forceps.

Results: 
Overall diagnostic yield was 87.8% (1,116/1,271). Yield increased with lesion size (72.9% for 0–1 cm, 81.9% for 1–2 cm, 91.2% for 2–3 cm, and 93.2% for ≥3 cm). Yield did not differ significantly by morphology: 91.4% cavitary (96/105), 90.0% part-solid (108/120), 89.9% consolidation (169/188), 87.0% for solid (606/697), and 84.8% for GGO (134/158).

On multivariable analysis (n=1,116), nodule size ≥1 cm was an independent predictor of diagnostic yield (adjusted OR 2.60 [1.52–4.46], p<0.001, Figure) while nodule location in the left lower lobe was associated with decreased yield (aOR 0.44 [0.26–0.75], p=0.002). Morphology was not a significant factor in diagnosis. Use of radial EBUS, cryoprobe, cone-beam CT scan, biopsy forceps, or nodule zone (peripheral, middle, or central) did not independently predict diagnostic yield. However, in nodules <1 cm (n=85), cryoprobe use significantly improved diagnostic yield (aOR 13.5 [1.15-158.8], p=0.038). For nodules <1cm, diagnostic yield was higher when ssRAB was performed thoracic surgeons (27/32, 84.5%) compared to interventional pulmonologists (35/53, 66.0%).



Conclusions:
Lesions less than <1cm remain a diagnostic challenge irrespective of morphology. Contrary to prior studies, peripheral location and absent bronchus sign were not associated with decreased diagnostic yield. These findings can guide patient selection for robotic bronchoscopy while those with small nodules may require adjunctive sampling tools to improve diagnostic yield.

Vikram Krishna (1), Claire Perez (1), Drew Bolster (1), Kellie Knabe (1), Raffaele Rocco (2), Philicia Moonsamy (1), Harmik Soukiasian (1), Andrew Brownlee (1), (1) Cedars-Sinai Medical Center, Los Angeles, CA, (2) Cedars Sinai Medical Center, Los Angeles, CA