Background: Small pulmonary lesions with ground-glass
opacity (GGO) are increasingly detected by CT; however, intraoperative
localization of such lesions is difficult because these lesions are
often invisible and nonpalpable.
Study objectives: To
localize and resect nonpalpable and invisible small pulmonary lesions,
a new marking technique that we call “agar marking” was
Methods and patients: Powdered agar was
dissolved in distilled water at a concentration of 5% and kept at>
50°C to maintain its liquid form. Agar was injected through an
18-gauge needle and placed near the target lesion with CT. After animal
experiments, agar marking was applied to the nine patients who had
lesions < 20 mm in diameter and lesions with GGO. The mean diameter
of these lesions was 11 mm, with a mean depth of 19 mm from the pleural
surface on CT.
Results: Agar could be detected as a
hard nodule by manual palpation, and the lesion was resected during
thoracotomy in all cases. There were no complications associated with
the agar injection, aside from one case of slight pneumothorax.
Conclusions: Agar marking may represent a feasible
alternative technique for localizing nonpalpable occult lesions located
away from the pleural surface.