Novel development of Spectra-A using indocyanine green for segmental boundary visibility in thoracoscopic segmentectomy

Our previous report suggested that fluorescence thoracoscopic anatomical segmentectomy (TAS) using intravenous (IV) indocyanine green (ICG) injection is safe, feasible, and efficacious for identifying segmental boundaries. However, contrast visualization in the conventional indocyanine green mode (CIM) remains relatively obscure in smoking-related comorbidities. Our aim was to evaluate the safety and efficacy of recently released Spectra-A with CIM by simultaneous observation.We postoperatively analyzed captive imaging using histogram counts in 29 patients who underwent TAS and previously reported that Δ indicates the index of visualization obtained by subtraction from its representative illuminated signal quantities of maximum pixels so that light-shade, intensity-removed image signals are obtained.Sixteen (55.2%) patients were male, and 13 (44.8%) were female. Segmental boundaries were successfully visualized in all patients (100%). The histogram count widths in dim and bright segments with CIM were 13.3 ± 3.8 and 52.5 ± 12.2, and those with Spectra-A were 19.4 ± 6.1 and 118.1 ± 37.4, respectively. The mean value was 4.3-fold higher for ΔSpa-A (61.4 ± 33.2) than for ΔCIM (14.2 ± 8.5) (P 0.01). In 14 (48.3%) patients, the segmental boundary could not be clearly visualized using CIM but was explicitly identified using Spectra-A.Spectra-A is a safe and promising noninvasive alternative like CIM, and more effective because of overcoming the limitation of CIM, but its use should be studied further to determine its usefulness in identifying segmental boundaries.